BQ25570: bq25570 reverse battery insertion protection

Nicolas Goy

Prodigy 90 points

Part Number: BQ25570

I am using a bq25570 in a design where the battery can be user replaced.

How does the bq25570 react if the battery (VBAT) polarity is reversed?

If the bq25570 need protection, do you have a recommendation of the most efficient design for protection?

over 6 years ago

0 Jing Zou over 6 years ago

TI__Mastermind 20570 points

Hello Nicolas,

The BQ25570 does not have protection against battery polarity reversed plug in. You can refer to the app note in the post below.

0 Nicolas Goy over 6 years ago in reply to Jing Zou

Prodigy 90 points

As I understand it, the problem with the MOSFET or diode approach is that it prevents the reverse current flow, thus preventing the BQ25570 from charging the battery.

0 Jing Zou over 6 years ago in reply to Nicolas Goy

TI__Mastermind 20570 points

The FET’s body diode is oriented in the direction of normal current flow. When the battery is installed incorrectly, the NMOS (PMOS) FET’s gate voltage is low (high), preventing it from turning on.

0 Nicolas Goy over 6 years ago in reply to Jing Zou

Prodigy 90 points

Ho yeah I got confused by the symbol used in the application note, when ON the MOSFET will allow current to flow in both direction, thus allowing recharging the battery.

I used an SI3477 which should allow good efficiency.

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BQ25570: bq25570 reverse battery insertion protection