BQ24630EVM: Charging not occurring

Lucas Uecker

Part Number: BQ24630EVM
Other Parts Discussed in Thread: BQ24630

Hello.

I'm using the BQ24630EVM to evaluate the BQ24630 for a battery pack of 6s LiPO4 batteries.

I've changed R7 to 22k to limit adapter current to 3A, R12 to 14k to set charge current to ~2.1A, and R25 to 976k to set charge voltage to ~19.3V.

I'm supplying 24V to ACin. ISET1 testpoint is 0.429v, ISET2 testpoint is 0.299V, and ACSET testpoint is 0.594V as expected

Power switching from Vbatt to ACin works fine, Bat/ACdrv LEDs indicate correctly, PG and CE LEDs indicate correctly, but charging does not occur with batteries depleted to 14.8V.

I've probed test points and TP13 (VFB) is always the same as VCC. Is this a problem with the chip? I assumed VFB is always to be 1.8V on the BQ24630.

over 4 years ago

0 Kedar Manishankar over 4 years ago

TI__Mastermind 24075 points

Hi Lucas,

VFB should not measure VCC. BQ24630 regulates charge regulation voltage based off of the VFB pin, so a voltage of 1.8V on VFB should correspond to a fully charged battery. VFB only has an abs max rating of 14V so a voltage of 24V VCC would mean the part would have exceeded its abs max and is damaged. Can you measure the voltage on VFB pin of the IC, instead of the test point to verify if you are indeed seeing VCC voltage on VFB?

0 Lucas Uecker over 4 years ago in reply to Kedar Manishankar

Prodigy 110 points

Hi Kendar,

Embarrassing. It looks like I was probing TP3 instead of TP13. VFB measures 1.498V

0 Kedar Manishankar over 4 years ago in reply to Lucas Uecker

TI__Mastermind 24075 points

Hi Lucas,

Happens to all of us. Are you still seeing the issue of charge not occurring?

0 Lucas Uecker over 4 years ago in reply to Kedar Manishankar

Prodigy 110 points

Hi Kedar,

Charge is still not occurring. Moving through the list in 8.3.7 of the datasheet:

-CE is high with jumper placed on JP5

-I don't think it's in UVLO or VCCLOWV mode with ACPWR supplied at 24V

-SLEEP mode would be off if !ACDRV signal is going out to the LED

-ACPWR is lower than ACov

-30ms delay

-RGEN is at 6v and VREF is at 3.3v

-TSHUT shouldn't have tripped, no unusual heating is occuring

-TS voltage is at the divider voltage from the factory, 2.49V

Should the TS divider be altered?

0 Kedar Manishankar over 4 years ago in reply to Lucas Uecker

TI__Mastermind 24075 points

Hi Lucas,

Not necessarily TS divider but TS voltage should be altered. The divider out of the box is to be used with an external NTC thermistor. Please source between 50% to 70% of VREF (3.3V) on TS. If you follow the steps on the user guide it mentions to connect Power supply #2 to TS and GND, and then in section 3.4 Procedure step 3 of section 3.4.1: mentions to source 1.8V. This would be normal operating range for TS, but right now you are operating in COLD range, during which charge will not start.

0 Kedar Manishankar over 4 years ago in reply to Kedar Manishankar

TI__Mastermind 24075 points

If not using external NTC, you can just fix the resistor divider to give you a ratio that keep TS voltage in the NORMAL temperature operating range,

0 Lucas Uecker over 4 years ago in reply to Kedar Manishankar

Prodigy 110 points

I added a 10k NTC and charging started. Thanks!

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BQ24630EVM: Charging not occurring