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BQ76940: About BQ7694003 question

Timsen
Expert 1660 points
Part Number: BQ76940

Hi all:

    I used about 1A discharge, CC_HI=0XFF, CC_LO=0XE3, according to the datasheet formula on page 23

    CC Reading (in µV) = [16-bit 2’s Complement Value] × (8.44 µV/LSB)

It was calculated as 29*8.44=244.76 V, and the sampling resistance was 0.0005 ohm

The calculated current is 0.4895A

This result is half different from the actual current. Is there any problem with my algorithm?

  • 0
    TI__Guru 54715 points
    Hi Timsen,
    I think your math looks correct. The CC is an integrating converter. Good questions might be if the current was continuous, and with continuous current is the voltage to the sense pins 0.5 mV or 0.24 mV? You might measure across both the sense resistor and after the filter components.
    Also confirm that the CC_CFG REGISTER (0x0B) is set to 0x19. It may be informative to try 1 A charge current, it should give similar calculated current magnitude.