Looking for synchronous average current mode buck regulator IC
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Posted by on January 14, 2006, 11:45 am
Please log in for more thread options Hello, I am designing a synchronous buck regulator with average current-mode control (not ramp-compensated peak mode control) that must be able to source and sink 10 amps at varying output voltages (capacitive load). I'm looking for an IC that would work for this purpose. Unfortunately, most PWM IC's seem to operate on peak current-mode control and expect a unipolar current signal. I can sense current on the low side of the load, giving me a continuous current signal suitable for average current-mode control with a small common mode range, but nonetheless a bipolar signal. I have a design with two LM3478 PWM IC's and a gate driver, but the challenge is getting suitable ramp compensation when the output voltage is swinging. I'd like something more elegant. I'd prefer an IC because I'll be switching at 500kHz and would like as much noise immunity as possible. Am I stuck rolling my own? Would a "beyond the rails" op amp be a good choice for level shifting the current signal into the single-supply realm? Thanks Justin | |||||||||||||
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Posted by Joerg on January 15, 2006, 1:37 am
Please log in for more thread options Hello Justin, Did you look at the UC3849? An expensive but nifty chip. > Would a "beyond the rails" op amp be a good choice for level shifting
> the current signal into the single-supply realm? > Just be careful. I only did peak current mode so far but there the bandwidth had to be really high. It's just a matter of microseconds between something going wrong and the trigger of a major kaboom, leaving a crater where the switching device was. Regards, Joerg http://www.analogconsultants.com | |||||||||||||
> I'd prefer an IC because I'll be switching at 500kHz and would like as
> much noise
> immunity as possible. Am I stuck rolling my own? ...