BQ24780S: ACOK not high

Edward Dhuyvetter

Part Number: BQ24780S

Hello,

I tried to repair a laptop motherboard (internal battery failure, burned 10 Ohm Vcc resistor of the bq24780S, and a killed bq24780S device (the Vcc pin was 0 Ohm to ground instead of open line), I replaced the bq24780S with a new one and I replaced the burned 10 Ohm resistor with a new one). But when plugging the laptop adaptor, I can not get the bq24780S to have ACOK high. What am I doing wrong? Did I kill the new bq24780S by soldering it on the motherboard (360 degrees celcius hot air soldered)?

over 5 years ago

0 Jeff F over 5 years ago

TI__Guru**** 166126 points

Hi Edward,

I wouldn't expect replacing the IC to damaged it. Is the voltage on REGN pin 24V ~=6V? What is the voltage on ACDET?

Regards,

Jeff

0 Edward Dhuyvetter over 5 years ago in reply to Jeff F

Prodigy 40 points

The ACDET is 2,61 Volt. I measure on Vcc 19 Volt, but REGN is about 0 Volt

0 Jeff F over 5 years ago in reply to Edward Dhuyvetter

TI__Guru**** 166126 points

Hi Edward,

Is it possible that the REGN capacitor is shorted to ground? Can you replace that capacitor?

Regard,

Jeff

0 Edward Dhuyvetter over 5 years ago in reply to Jeff F

Prodigy 40 points

I took that capacitor out to follow your lead, measured it's resistance, but it is not a short, then I plugged the connector in, but the REGN was still zero, then I replaced the capacitor back, plugged the adapter in but regn is still zero. I still want to mention that BATPRES pin is close to zero volt, but there is no battery plugged in, I ordered a new battery, but it didn't arrive yet, and I wanted to start up the motherboard without battery first.

0 Edward Dhuyvetter over 5 years ago in reply to Edward Dhuyvetter

Prodigy 40 points

I soldered the part again and it boots and the motherboard has power. Thanx for the heads up.

problem solved

Power management

Power management forum

BQ24780S: ACOK not high