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I have a problem with interaction between the DC/DC converter and its protecting IC TPS25944 which is before the DC/DC.
The protector TPS25944 has current limit set to 0,7A and if dc dc converter is overloaded and shorted it starts to limit current cycle by cycle. This makes a problem for the TPS25944 to be proper trigerred and switched off when system starts with the overload already at the output what can happens. The current spikes are smaller than single shot Itrip value and they are to short, for the internal 4ms timer, which is switching off the TPS if overload is higher than 0.7A and longer than 4ms.
So the solution could be find a simple switcher which has no cycle by cycle current limitation. the general idea to protect the dc/dc on its input is to safe battery which supplies the circuit. I know the nominal output current on the 3.3 output, I can recalculate its for the input current, and if something happens DC/Dc is switched off. What is also behind this solution is also this, that the battery is protected also in case of internal failure or short in the dc/dc, internal diode or internal low high side short.
So I am looking for a simple switcher:
9-12V input, 3.3 V output 2-3A. With thermal pad and no cycle by cycle current limit. Just simple PWM modulator with voltage control loop ( internal current loop can be for better stability), can be with internal diode and with internal FET and also internal low side FET, instead of the diode.
The post with my problem was also described here:
BSR-CCP LV/MV DC/DC Applications
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In reply to JohnTucker:
Hi, Thanks for the suggestions. I am considering these without PMBus. TL494 looks quite good as well but external the FET is needed in this case. What is also important is a low Iq, so What i see only TPS53353 would fit or 355.
In reply to christopher2:
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