Hello
I am trying to design a 48Vin-30Vout-10Aout current-limited
(programmable from microprocessor) step-down DC-DC converter.
To do this I am looking for a current mode synchronous buck
controller. The only one I found is a Linear LT1339: it can
easily handle voltages up to 60V and directly drive the two
mosfets. Nevertheless it has some drawbacks: mainly it is
not born to be current-programmable, therefore I am not sure
I will be able to set the current limit from the micro; then
it needs 12V to be supplied; and finally it seems to be quite
old and very expensive (about 7$ + vat !!).
Can anyone confirm this is a good choice anyway? ...or maybe
suggest me an effective alternative? Perhaps a lower voltage
IC connected to an high voltage mos-driver (like a IRF2110
from International Rectifier)?

Thanks everybody for supporting.
Davide


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Or, since you've jumped into the microprocessor camp anyway, how about
sampling voltage and current with the microprocessor and generating the PWM
directly from the microprocessor? Or if that makes you uncomfortable how
about setting the voltage command to the converter from the microprocessor
and servoing current in software?

"Davide Fabri" wrote in message
news:cdf3134b17417d63cdf6642a66b32060.68471@mygate .mailgate.org...
Hello
I am trying to design a 48Vin-30Vout-10Aout current-limited
(programmable from microprocessor) step-down DC-DC converter.
To do this I am looking for a current mode synchronous buck
controller. The only one I found is a Linear LT1339: it can
easily handle voltages up to 60V and directly drive the two
mosfets. Nevertheless it has some drawbacks: mainly it is
not born to be current-programmable, therefore I am not sure
I will be able to set the current limit from the micro; then
it needs 12V to be supplied; and finally it seems to be quite
old and very expensive (about 7$ + vat !!).
Can anyone confirm this is a good choice anyway? ...or maybe
suggest me an effective alternative? Perhaps a lower voltage
IC connected to an high voltage mos-driver (like a IRF2110
from International Rectifier)?

Thanks everybody for supporting.
Davide


--
Posted via Mailgate.ORG Server - http://www.Mailgate.ORG

Hello Tim
the microprocessor has a 14kHz maximum PWM frequency, taht is not high
enough to avoid bulky inductors for 10A output current: that's why
I need an integrated switcher, that moreover has the advantage of
integrating the mos drivers.
Setting the voltage command for to the switcher from the microprocessor
and servoing current in software is exactly what I would do: the problem
is that I cannot use the voltage reference command to servo the current
because the voltage loop is closed inside the switcher: playing with
the Vref to set the current I guess it is not much sane.
Hence I must act on another input of the LT1339 with another command
(Iref) to clamp the maximum current when I want to limit it.







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