On Jul 2, 6:20*pm, Steve wrote:
wrote in news:16ea6110-be19-4a21-aecc-
:





On Jul 2, 3:35 pm, alphamnemonic wrote:
Hi Everybody

This chip normally puts out square pulses. In the power supply I am
working on (http://www.laserfaq.org/sam/150rcsch.pdf) it is putting
out a sawtooth wave. I am testing it in 'standby mode', in which Q4 is
off and R33 is in control of the duty cycle. Replacing the IC1 has no
effect. Does anyone have any ideas?

Where are you seeing sawtooths? *Pin 13?

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That is my question. Why do you have output A and output B (pin 11 and 14)
grounded?

Also, pin 13 is VC in for the transistor collectors. Why do you have this
connected as an output?- Hide quoted text -

- Show quoted text -

Yes the sawtooth is on pin 13. Pin 13 is being used as an output and
pins 11 and 14 are grounded because the chip is being used in single-
ended supply mode (see http://www.datasheetcatalog.org/data...a/SG3525AN.pdf
p.6 for an example of this configuration). I can see why you find that
strange--I did too!