BQ40Z60: Problem using emergency Shutdown and Pre-charge features at the same time.

Steven Shenker

Part Number: BQ40Z60

We have a design where we are controlling the battery Precharge FETs via PIN 14 (GPIO 0) and are using Pin15 (GPIO1) for Emergency Shutdown. It seems that these features are mutually exclusive since precharge will not work if ESHUT_EN == 1, according to the datasheet: "Pin 14 can be used to control an external circuit for precharge when NR is 1, ESHUT_EN is 0".

How can it be possible that these two features are mutually exclusive of each other? Is there no workaround for this? We have already designed our hardware.

Thanks in advance for your help.

over 7 years ago

0 Miguel Angel Rios over 7 years ago

TI__Expert 4640 points

Hi Steven,

We are working to find out why the design is the way it is.

Thanks

Miguel

0 Steven Shenker over 7 years ago in reply to Miguel Angel Rios

Intellectual 930 points

Hi Miguel, any update on this? Please let me know when you have an update. Thanks!

0 James Peverill73 over 7 years ago in reply to Steven Shenker

Prodigy 70 points

We also have the same question after reviewing the datasheet. Very curious about this.

0 Swaminathan Ramanathan75031 over 7 years ago

TI__Expert 6575 points

Unfortunately only PIN14 can be configured for Emergency shutdown or external pre-charge, so these features can not be used simultaneously on bq40z60.
Regards,
Swami

0 James Peverill73 over 7 years ago in reply to Swaminathan Ramanathan75031

Prodigy 70 points

In the TRM it says this:

The input is read on pin 15 when ESHUTBUT is 1 and on pin 14 when ESHUTBUT is 0

We are using Pin 15 for ESHUTBUT. We assumed, maybe incorrectly, that precharge could be used if they weren't sharing a pin.

0 Steven Shenker over 7 years ago in reply to Swaminathan Ramanathan75031

Intellectual 930 points

Would it be correct to assume then that we can still use the standard charge FET to do pre-charge? In other words, the bq40z60 will still pre-charge the battery by using the standard charge circuitry with a lower current setting / PWM duty cycle?

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BQ40Z60: Problem using emergency Shutdown and Pre-charge features at the same time.