BQ25792: Ship FET is not properly working from VBAT only

George Deborin

Part Number: BQ25792

Hello!

We are facing the strange waveform on the SDRV pin connected to ship FET when it is supplied from VBAT only:

If BQ25792 is supplied from VBUS, we can see the constant voltage level on the SDRV pin.

This waveform causes the ship FET to switch on and off periodically. How can we fix that?

Thank you!

over 4 years ago

0 Jeff F over 4 years ago

TI__Guru**** 167236 points

Hi George,

First, you can't place a regular voltage scope probe on SDRV. If you want to measure SDRVE, you will need a low impedance JFET probe to prevent loading the SDRV pin.

Second, on the EVM, the shunt on JP9 must be connected to pin 1 labelled BATTERY. I recently discovered that some EVMs were shipped the shunt installed on pin 2.

Regards,

Jeff

0 George Deborin over 4 years ago in reply to Jeff F

Prodigy 20 points

Hi Jeff,

Thank you! Your advice cleared up the situation.

Regards,

George

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BQ25792: Ship FET is not properly working from VBAT only