BQ76940 boot problem

user3927583

I can get single voltage.But I put a 9K thermistors between C21 and C23 and set ADN_EN=1 TEMP_SEL=1,but the value in TS_HI and TS_LO is very small,

and no voltage between thermistors was found.

When I set TEMP_SEL=0,I can read the Die temperature, it is nearly the indoor temperature.

Why no voltage in thermistors ?

over 8 years ago

0 Vish Nadarajah over 8 years ago

TI__Expert 6085 points

The current comes from the upper power pin of the group VC5X for TS2; VC10X for TS3; The current of the TSx should ~ 3.3K/(10K) =0.33mA if thermistor is shorted.

So for 9K, the V= 0.33mA)*9K=2.7mV.

hope this helps out....

0 user3927583 over 8 years ago in reply to Vish Nadarajah

Prodigy 40 points

I get the reason, TSx pins are accidentlly shorted to the BAT-.
for 9K resistor , I think the voltage is 9000* (3.3/(9000+10000)) = 1.5 V
thanks

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BQ76940 boot problem