BQ34Z100: First use BQ34Z100, Please help to review the schematic.

Yuan_1980

Part Number: BQ34Z100

Hi,

This is my first design of BQ34Z100, 7S cells and HDQ communication need. My first question is can this device support I2C and HDQ interface at the same time?

In my case, I need to use both of these interface.

Also Please kindly help to review this design.

Some differences compared with ref design are as below:

Shunt resistor : used 5mΩ instead of 10mΩ，due to bigger current .
Used R40 at BAT+ to limit the current .
Used two 300K resistor, R74,R60, according to datasheet, but not sure if it is suitable.

Thanks.

over 5 years ago

0 Damian Lewis over 5 years ago

TI__Mastermind 34775 points

5mΩ shunt is fine. shunt < 0.1/Max current?
I don't think R40 is necessary. You already have R74, R60 and R51 that serves as better current limits.
You have a 7S pack, so you divider need to be 35x, so you need ~562k resistor, which can be a single resistor to replace R74 and R60.

0 user6303433 over 5 years ago in reply to Damian Lewis

Prodigy 110 points

1. what's the meaning of shunt<0.1/Max current ?

2. connect R55 to VEN , no button is OK ?

0 Damian Lewis over 5 years ago in reply to user6303433

TI__Mastermind 34775 points

Ohms law shunt resistor value < 0.125V (SRN and SRP input voltage range) divided by Max current expected for your application. In your case 5mΩ shunt allows a max current of 25A for your application. Better yet 20A to give some headroom margin.
That's fine it's used for LED MODE, which you're not using in your application.

0 user6303433 over 5 years ago in reply to Damian Lewis

Prodigy 110 points

What will happen for BQ34Z100 if the short current is ＞ 40A ？

0 Damian Lewis over 5 years ago in reply to user6303433

TI__Mastermind 34775 points

That's fine since it does exceed the -0.3V ABS Max for SRN and SRP. 0.3V/0.005 = 60A.

0 user6303433 over 5 years ago in reply to Damian Lewis

Prodigy 110 points

Thanks very much.

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BQ34Z100: First use BQ34Z100, Please help to review the schematic.