TPS61378-Q1: Hicup timer behavior when OC event is removed during short protection

Hi Kazuki,

Nice to see you again.

let me explain with a short-open picture.

CH1 Yellow Vout  CH2 blue Vin  CH4 green Iout

t1,t5,t9,t11 are the output short points

t2,t4,t6,t8 are the points Vin=Vo

t3,t7,t10 are points that short disappear

It can be seen:

at t2,Vin=Vo, the time count start to accumulate, at t3 the short disappear, but the count will still accumulate.

during t3 to t4,the output start to ramp up ,and the current is limited, and count is still accumulating.

at t4,Vin=Vo, the time count is about 1.6ms, not enough to trig shut down. then the count is cleared at t4.

the count accumulates from t6 to t8 ,and still not enough to trig shut down. the count is cleared at t8

from t9 to t11 the time is enough and no time point Vin=Vo(actually Vin<Vo) ,so the shut down is trigged.

To sum up, just as the datasheet says:

If the output current causes the low-side FET to reach current limit and pull the output voltage below the input voltage, the device enters into short circuit protection mode, triggering the hiccup timer.

Hope it solves your problem.

Best Regards

Fergus

Hi Fergus,

Thank you for your kindly explanation.

I understand that short circuit protection hicup-timer require to exceed Vout to Vin clearing timer.

Please let me know, if there is miss understanding.

Thank you and best regards,
Kazuki Kuramochi