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BQ34Z100: Pull up resistor for ALERT

Riccardo Tornese
Prodigy 10 points
Part Number: BQ34Z100


I would like to use P2 (Pin 1) BQ34Z100 as ALERT pin in order to know when the ,batteri SOC goes below a threshold.

In order to test this feature I'm using the BQ34z100-EVM. I have programmed the BQ34Z100-G1 firmware on the BQ34z100-EVM chip.
I have set the following registers of the BQ34Z100(please see the following picture):
  • LED_Comm configuration: 0x00
  • Aler Configuration: 0x00
  • SOC 1 Set Threshold: 23100 mAh
  • SOC 1 Clear Threshold: 23150 mAh
On the BQ34z100-EVM I've made the following jumper configuration
  1. J3 position B closed, posiotion A, C, D opened
  2. J6 all position opened
On the ALERT pin (pin 1 of TB1) the voltage is always 0V, also when the  SOC1 flag in FLAGS register is cleared.
In triyed to put a pull-up resistor (10K) betwween REG25 pin and P2 and I see the righ beavior: ALERT pin is high when the SOC1 flag is cleared and low (0V) when the SOC1 flag is asserted. 
A pull-up resistor is necessary on the P2 pin? Is ALERT open drain?
Thanks for the support