Hello,
I have a question for ILIM of TPS61376.
The average input current can be limited by ILIM function.
But the peak switch current can be changed by only ILIM stting, 4.5A or 2.5A.
I can't understand what happens if average input current hits the ILIM programmed average current.
Could you tell me how it works?
Regards,
Oba
Hi Oba,
When the inductor current hits the peak current, the switch goes to off (your guess is correct). After the turn-off duration which is generated by the internal toff block, the switch turns on, and off again when hits the peak current limit.
The average input current limit control is a little complicated. The current which flows through the ISO FET will be sensed and averaged to get the input current, then compare with the limit set by the ILIM pin. The compared result control the switch on/off to make the input current equals to the set limit.
The overall behaviors when the average input current hits the limitation or inductor current hits the peak current are very similar: The Vout drops if the Iout further increases.
The set average input current is calculated as below.
In normal work conditions and the load jumps from light to heavy, the input current limit function usually works fast enough to limit the input current without spike. I attached a waveform for your reference, in which the Iout jumps from 0 to 400mA. The ch4 is input current.
Regards
Lei
