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#1
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Behavior of Regulators Near and Below Drop-out
This rainy afternoon (East-coasters beware, that usually spells more
snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! Thanks! ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#2
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
Jim Thompson wrote:
This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. |
#3
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
Jim Thompson wrote:
This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. |
#4
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom"
wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John |
#5
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin
wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#6
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
"Jim Thompson" wrote in
message ... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LM337? In an earlier thread you noted it also uses an NPN output device. Tim -- Deep Friar: a very philosophical monk. Website: http://webpages.charter.net/dawill/tmoranwms |
#7
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson
wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF |
#8
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson
wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF |
#9
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 16:57:41 -0600, John Fields
wrote: On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF I checked the Tequila availability... enchiladas tonight ;-) I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#10
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 16:13:14 -0700, Jim Thompson
wrote: On Sat, 20 Feb 2010 16:57:41 -0600, John Fields wrote: On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF I checked the Tequila availability... enchiladas tonight ;-) --- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, and it seems that JL is passive-aggressively challenging him, but with no direct reference. What a chicken****. JF |
#11
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 16:13:14 -0700, Jim Thompson
wrote: On Sat, 20 Feb 2010 16:57:41 -0600, John Fields wrote: On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF I checked the Tequila availability... enchiladas tonight ;-) --- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, and it seems that JL is passive-aggressively challenging him, but with no direct reference. What a chicken****. JF |
#12
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 18:20:47 -0600, John Fields
wrote: On Sat, 20 Feb 2010 16:13:14 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 16:57:41 -0600, John Fields wrote: On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF I checked the Tequila availability... enchiladas tonight ;-) --- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, He's certainly a thinking young man! and it seems that JL is passive-aggressively challenging him, but with no direct reference. What a chicken****. JF What a Chicken**** "Ol' Git" :-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
#13
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
pimpom wrote:
Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. .... and LDOs are real bitches; talk about how to build an oscillator - just design an amplifier. |
#14
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
John Fields wrote:
--- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. I see you like ingredients of Indian origin in your recipes. I'm in India, but I live far from where stuff are produced - both culturally and geographically. Is Basmati rice grown in the west or is it all imported from India? I have an extremely limited knowledge of Hindi, but I do know that "garam' means 'hot' and masala is the word for spices. So "garam masala" literally means "hot spices". --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, and it seems that JL is passive-aggressively challenging him, but with no direct reference. What a chicken****. I have no time for "my dick is bigger than your dick" stuff. Being entirely self-taught in a primitive environment without anyone to guide me, I'm aware that I have huge gaps in my knowledge. I try to contribute when I think can, answering questions in parts when I don't have a complete answer. I try to fill those gaps by discussing, asking questions or simply reading in these groups. I've been lurking on and off in the sci.electronics groups for a little over a decade now, which is the length of time that Internet access has been available here. I made occasional posts but didn't always use the nym "pimpom". Flexing my muscles? I didn't think what I did could be interpreted as such. I was just trying to be helpful by sharing my experience. |
#15
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
John Fields wrote:
--- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. I see you like ingredients of Indian origin in your recipes. I'm in India, but I live far from where stuff are produced - both culturally and geographically. Is Basmati rice grown in the west or is it all imported from India? I have an extremely limited knowledge of Hindi, but I do know that "garam' means 'hot' and masala is the word for spices. So "garam masala" literally means "hot spices". --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, and it seems that JL is passive-aggressively challenging him, but with no direct reference. What a chicken****. I have no time for "my dick is bigger than your dick" stuff. Being entirely self-taught in a primitive environment without anyone to guide me, I'm aware that I have huge gaps in my knowledge. I try to contribute when I think can, answering questions in parts when I don't have a complete answer. I try to fill those gaps by discussing, asking questions or simply reading in these groups. I've been lurking on and off in the sci.electronics groups for a little over a decade now, which is the length of time that Internet access has been available here. I made occasional posts but didn't always use the nym "pimpom". Flexing my muscles? I didn't think what I did could be interpreted as such. I was just trying to be helpful by sharing my experience. |
#16
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
Jim Thompson wrote:
On Sat, 20 Feb 2010 18:20:47 -0600, John Fields wrote: PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, He's certainly a thinking young man! Thanks. But "young man"? You may be inching towards your 70th birthday but I'll have you know that, if I hadn't married late, I would be surrounded by grandchildren now :-) |
#17
Posted to sci.electronics.design,alt.binaries.schematics.electronic,sci.electronics.cad
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Behavior of Regulators Near and Below Drop-out
Jim Thompson wrote:
On Sat, 20 Feb 2010 18:20:47 -0600, John Fields wrote: PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, He's certainly a thinking young man! Thanks. But "young man"? You may be inching towards your 70th birthday but I'll have you know that, if I hadn't married late, I would be surrounded by grandchildren now :-) |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 17:07:07 +0530, "pimpom"
wrote: I see you like ingredients of Indian origin in your recipes. I'm in India, but I live far from where stuff are produced - both culturally and geographically. Is Basmati rice grown in the west or is it all imported from India? --- All the basmati rice here is imported, but there's a cross between basmati and American long-grain rice grown by a company called RiceTek in Alvin, Texas: http://www.ricetec.com/page.asp?id=144 and sold as "Texmati", "Delta Rose", and "Cajun Country Popcorn Rice", among others I'm sure. .. .. .. JF |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 17:20:07 +0530, "pimpom"
wrote: Jim Thompson wrote: On Sat, 20 Feb 2010 18:20:47 -0600, John Fields wrote: PimPom just joined the fray recently and has kind of tried to flex his muscles with his "rule of thumb" stuff, He's certainly a thinking young man! Thanks. But "young man"? You may be inching towards your 70th birthday but I'll have you know that, if I hadn't married late, I would be surrounded by grandchildren now :-) Everyone is young compared to me ;-) BTW, I have 8 grandchildren! ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 00:32:50 -0800, Robert Baer
wrote: pimpom wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. ... and LDOs are real bitches; talk about how to build an oscillator - just design an amplifier. I'm intent on modeling these suckers accurately enough that oscillation can be predicted. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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Behavior of Regulators Near and Below Drop-out
"Jim Thompson" kirjoitti om... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 19:11:51 +0200, "E"
wrote: "Jim Thompson" kirjoitti viestissä:iro0o5hmfbejuo9lt3udkodidv4nitjd1m@4ax. com... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek Thanks! I'll check that out. Although my past experiences in the "jelly bean" business is those schematics are usually "simplified" to hide IP. This is getting to be a really amusing mental endeavor! For instance, how might an LM7805 behave with a zener inserted in its ground lead to boost the voltage ?:-) ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 19:11:51 +0200, "E"
wrote: "Jim Thompson" kirjoitti viestissä:iro0o5hmfbejuo9lt3udkodidv4nitjd1m@4ax. com... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek Thanks! Looks good! ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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Behavior of Regulators Near and Below Drop-out
Jim Thompson wrote:
This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! Thanks! ...Jim Thompson What are your assumptions about the source? A battery going flat might induce limit-cycle oscillations that wouldn't show up with a stiff source?? or not... |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 10:15:31 -0800, mike wrote:
Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! Thanks! ...Jim Thompson What are your assumptions about the source? A battery going flat might induce limit-cycle oscillations that wouldn't show up with a stiff source?? or not... From my modeling point of view, the "source" is just "something" connected to the "IN" terminal. BUT, The way I am envisioning the model, a flaky source, if you have a model for it, would induce the very behavior you want to see. Maybe model "source" as a voltage source with a parameterized impedance rise? Or get out a battery manual and model "Charge", a parameter that reflects both voltage and impedance effects? ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 11:41:49 -0700, Jim Thompson
wrote: On Sun, 21 Feb 2010 10:15:31 -0800, mike wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! Thanks! ...Jim Thompson What are your assumptions about the source? A battery going flat might induce limit-cycle oscillations that wouldn't show up with a stiff source?? or not... From my modeling point of view, the "source" is just "something" connected to the "IN" terminal. BUT, The way I am envisioning the model, a flaky source, if you have a model for it, would induce the very behavior you want to see. Maybe model "source" as a voltage source with a parameterized impedance rise? Or get out a battery manual and model "Charge", a parameter that reflects both voltage and impedance effects? ...Jim Thompson Overlay multiple un-synched signals to create a psuedo-random average modulation 'noise' in the drive signal that can be amplitude modulated to mimic anomalous source events. |
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Behavior of Regulators Near and Below Drop-out
On Sat, 20 Feb 2010 18:20:47 -0600, John Fields
wrote: On Sat, 20 Feb 2010 16:13:14 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 16:57:41 -0600, John Fields wrote: On Sat, 20 Feb 2010 15:36:23 -0700, Jim Thompson wrote: On Sat, 20 Feb 2010 13:56:56 -0800, John Larkin wrote: On Sun, 21 Feb 2010 03:13:45 +0530, "pimpom" wrote: Jim Thompson wrote: This rainy afternoon (East-coasters beware, that usually spells more snow for you), I was amusing myself trying to behavioral model a voltage regulator when you hit drop-out. Then I realized, I've never designed an integrated voltage regulator for general use, only those inside ASIC's where I can control all the conditions. Thus I'm clueless of behavior of commercial offerings at or below VDO. I'm guessing that output voltage drops linearly with VIN once the drop-out point is hit?? But what about current capability? Does it drop sharply, linearly, or linearly to some critical point then drop like a rock. Pointers/data appreciated! I haven't done an in-depth study either, but I know that the output voltage drops in an approximately linear manner down to a certain level of Vin. I've observed input ripple reproduced linearly at the output. I expect that behaviour below a critical Vin level will be design-specific and will be hard to predict without careful analysis. The critical level would be reached when active devices can no longer be biased in the active region. I know even less about their actual behaviour regarding current capability, but I do know that they do not drop sharply right after dipping below Vdo. All this is assuming that we're talking about common linear regulators like the 78xx series. The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. --- In all fairness, you didn't indicate you were talking about LDO's and since "dropout voltage" applies to both beasts, who knew? Glad it got clarified though since, on a rainy Saturday afternoon in Austin, with nothing better to do than appreciate the difference between the bottle in front of me and a frontal lobotomy, I was heading for the soldering iron and the scope... JF I checked the Tequila availability... enchiladas tonight ;-) --- Yum! We're having leftover "Chicken Tagine" over newly boiled Basmati rice tonight. The recipe called for dried apricots and Garam Masala, but since we didn't have any dried apricots we substituted Smucker's Apricot Preserves. Sweetart don't hurt chicken; what a nice surprise! I'll post the recipe if you like, since it seems recipes aren't off-topic here. --- I know there are various drop-out behaviors. JL was just trying to be rude and dismissive with his "Some people (?)". --- I noticed that. Some people could also try running the LT Spice models of their LDOs. Or even fire up some chips and see how they actually work... if they don't mind using a soldering iron. John |
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Behavior of Regulators Near and Below Drop-out
On 2/21/2010 12:29 PM, Jim Thompson wrote:
On Sun, 21 Feb 2010 19:11:51 +0200, wrote: "Jim kirjoitti om... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek Thanks! I'll check that out. Although my past experiences in the "jelly bean" business is those schematics are usually "simplified" to hide IP. This is getting to be a really amusing mental endeavor! For instance, how might an LM7805 behave with a zener inserted in its ground lead to boost the voltage ?:-) ...Jim Thompson Works great as long as the zener isn' too big. 7800s push about 5 mA through their ground pins at zero load, iirc. LM317s put most of the quiescent current out their outputs, and only 50 uA or so out the adjust pin. Cheers Phil Hobbs -- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 13:59:58 -0500, Phil Hobbs
wrote: On 2/21/2010 12:29 PM, Jim Thompson wrote: On Sun, 21 Feb 2010 19:11:51 +0200, wrote: "Jim kirjoitti om... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek Thanks! I'll check that out. Although my past experiences in the "jelly bean" business is those schematics are usually "simplified" to hide IP. This is getting to be a really amusing mental endeavor! For instance, how might an LM7805 behave with a zener inserted in its ground lead to boost the voltage ?:-) ...Jim Thompson Works great as long as the zener isn' too big. 7800s push about 5 mA through their ground pins at zero load, iirc. LM317s put most of the quiescent current out their outputs, and only 50 uA or so out the adjust pin. Cheers Phil Hobbs One can stack regulators too, putting the adj pin of one reg on the output of another. I've done that three deep on occasion. Works great with LM1117s for 1.25 and 2.5 for FPGA core and Vaux voltages... no resistors! You can also drive the adj pin from an opamp. John |
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Behavior of Regulators Near and Below Drop-out
On Sun, 21 Feb 2010 11:06:45 -0800, John Larkin
wrote: On Sun, 21 Feb 2010 13:59:58 -0500, Phil Hobbs wrote: On 2/21/2010 12:29 PM, Jim Thompson wrote: On Sun, 21 Feb 2010 19:11:51 +0200, wrote: "Jim kirjoitti om... The internal schematics of classics like LM317 and LM1117 and such are on the data sheets. Some people (?) could deduce their behavior from that. John Those aren't LDO's, they're NPN "followers"; not PNP or PMOS, whose behavior would be radically different, and quite process dependent. LP2950 has schematics on datasheet (National version). -ek Thanks! I'll check that out. Although my past experiences in the "jelly bean" business is those schematics are usually "simplified" to hide IP. This is getting to be a really amusing mental endeavor! For instance, how might an LM7805 behave with a zener inserted in its ground lead to boost the voltage ?:-) ...Jim Thompson Works great as long as the zener isn' too big. 7800s push about 5 mA through their ground pins at zero load, iirc. LM317s put most of the quiescent current out their outputs, and only 50 uA or so out the adjust pin. Cheers Phil Hobbs One can stack regulators too, putting the adj pin of one reg on the output of another. I've done that three deep on occasion. Works great with LM1117s for 1.25 and 2.5 for FPGA core and Vaux voltages... no resistors! You can also drive the adj pin from an opamp. John Yep. But what do they do when pulled into current limit when stacked, say the simple zener case? I know that bipolar types will forward bias the substrate, at least momentarily. LTspice models are already behavioral, not device level, so they model behavior under "normal" circumstances. Analog Devices' models are like that, as many have discovered ;-) I guess that the lab is the only way to get data for a reasonable model. ...Jim Thompson -- | James E.Thompson, CTO | mens | | Analog Innovations, Inc. | et | | Analog/Mixed-Signal ASIC's and Discrete Systems | manus | | Phoenix, Arizona 85048 Skype: Contacts Only | | | Voice480)460-2350 Fax: Available upon request | Brass Rat | | E-mail Icon at http://www.analog-innovations.com | 1962 | I love to cook with wine. Sometimes I even put it in the food. |
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