BQ24725A: ACOK line not going low

Sam Evans

Part Number: BQ24725A

I have a battery charger whose AC OK line seems to be stuck high despite input power being cut (ACDET = 0V). There is no short circuit between AC DET and a 3.3V rail, so I'm not seeing an obvious reason this should be held high. If the AC OK output circuit is working properly, this should be pulled low... Any easy way to debug if this is an IC failure or something else outside of just probing for a short on the line?

Thanks
Sam

over 4 years ago

0 Kedar Manishankar over 4 years ago

TI__Mastermind 24075 points

Hi Sam,

Can you measure the VCC input voltage close to the IC, ACDET voltage and SRN voltage?

0 Sam Evans over 4 years ago in reply to Kedar Manishankar

Prodigy 150 points

Hi Kedar

There is no external supply connected, the system is running off of the battery

Just probing now:

Vcc = 0V
ACDET = 0V
SRN = 7.8V
ACOK = 3.3V

0 Kedar Manishankar over 4 years ago in reply to Sam Evans

TI__Mastermind 24075 points

Hi Sam,

If ACDET is not valid then ACOK should indeed be pulled low, so this isn't normal IC operation. Can you recreate the waveform shown in figure 1 of the datasheet. Let us observe the start up waveform when valid VCC voltage is plugged in.

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BQ24725A: ACOK line not going low