3.3V regulator in HP 14-dw1700nd

[dr.thodt]

Could somebody please identify u60100? It goes up and down between 3.3V and 0V.

[mon2]

If the power rail is cycling then the regulator is in chirp mode. This is probably due to an excessive current draw on the output power rail or the current sense circuit is reporting it as such. Remove all power. Measure the resistance (not diode mode) to ground of this same 3v3 rail that is pulsing. What is the resistance in ohms?

A typical pinout and use of this regulator:




10pieces SY8286BRAC SY8286B (AWV5QB AWV5BB AWV5JA AWV...) QFN-20 chipset - AliExpress 502

SY8286BRAC Silergy Corp | C358653 - LCSC Electronics

[dr.thodt]

Thanks for the good info.
The resistance to GND from the 3.3V coil is 2K, just like the 5V coil which is stable.
The pulsating coil takes about 4 seconds to cycle.

[mon2]

Check the resistance to ground on LDO pin #17.

Are the ENx (enable signal) pins also pulsing?

[dr.thodt]

Thank you.
LDO = 16K
EN2 = 1.6V steady
EN1 = pulsating up to 3.1V

[dr.thodt]

Check the resistance to ground on LDO pin #17.

Are the ENx (enable signal) pins also pulsing?

Hi mon2. Is there something you can think of with the values I gave in the previous post?