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BQ24650: BQ24650

Part Number: BQ24650

I did some preliminary work with the BQ24650 solar panel battery charger controller eval board, it seemed to work ok with a 12V Lead Acid battery.  I’ve got the circuit on a custom PCB now and I have some questions because it indicates charging but there is no current going to the battery:

  1. I’m only getting 2mA of current from the bench supply set to 9.0V (going into the solar cell input), the STATUS signals says we are charging after the start up delay.
  2. The buck regulator is switching.  It detects the battery. 
  3. I’ve tried both states of TERM_EN with no difference in charging.  I don’t understand that feature.
  4. I discharged the battery to 4.8V last night (VFB set to 5.6V at the voltage divider).
  5. I can force it to stop indicating charging by setting:

MPPSET < 1.2V

Thermocouple input out of range

VFB >2.1

 The voltage across the current sense resistor (0.04 ohms for 1.0A current limit) is virtually 0.0V.

I did a point-to-point verification between our schematic and the eval board, no issues found.

 We are using a NiMH battery pack (4S, 4.8V nominal, charge to 5.6V), but at 1Amp charge there should not be a problem.