BQ24297EVM-021

Hi Kunal,
the reason why the registers configuration changes after few seconds is because the WatchDog timer is not disabled. As you can see in your setting, it is set to 40 s, so after that timer expires, the registers go back to their factory default values.

As regards the fact that you are measuring a different current from the one that you are setting, it is because the device is in DPM regulation. Check section 9.3.2.2 of the datasheet for more information. The reason for the negative current is because the adapter is not able to provide enough power to the load, so the battery is entering is supplement mode (section 9.3.2.3 of the datasheet), sourcing discharge current rather than being charged. The first thing that you might try is to keep the input current limit at 3.0A as in the default settings.

Sergio

Hi Sergio 

Thanks for your kind attention.

After disabling I2C watchdog timer limit the register configuration does not changes automatically.

As per your suggestion i kept input current limit at 3.0A :

But it is still it is in DPM regulation & charging with 0.01454A.

input voltage limit = 5.00V

Charger adapter : 5.0V  2.1A 

Observation are :

Input current limit vs Ammeter reading.

In DPM mode

5.00V    0.01454 A
4.92V    0.03554A
4.84V    0.0536 A
4.76V    0.7348 A
4.68V   0.09341A
4.52V   0.130 A
4.44V   0.147A
4.36V   0.164 A
4.28V   0.180 A

Still in DPM mode.

 

Then i changed the adapter and used iPhone charger adapter ( 5.0V 1A) & reduces ICHR to 512mA ( input current limit was 3A).

Observation are :

Input current limit vs Ammeter reading

In DPM Mode

5.08V   0.01354 A
5.00V   0.03503 A
4.92V   0.05508 A
4.84V   0.7320 A
4.76V   0.9291 A
4.68V   0.1111 A
4.52V   0.146 A
4.44V   0.162A
4.36V   0.1783 A
4.28V   0.19342 A
4.20V   0.207 A
4.12V   0.2214A
till 4.12 it was In DPM mode

on 4.04  ammeter reading drops to negative ampere.

After that i used Regulated DC power supply ( 5.1V ) , ICHR to 1024mA ( input current limit = 3A).

Observation are :

in DPM
5.08V 0.155 A
5.00V 0.318A
4.92V 0.460A

till 4.92 V it was in DPM mode.

On 4.84 V i came out from DPM mode 

4.84V 0.538A
4.76V 0.534A
4.36V 0.542A

Why on 4.84V itcame out from DPM mode as DC power supply voltage is 5.1V?

After 4.84V  it is not in DPM mode then why it is not getting charged by 1024mA ?

TIA

Kunal

 

Hi Kunal,

I saw that the adapter that you were using had 2.1A and 1A current limit. The DC supply instead might be able to supply any current up to the current limit set by the GUI. So of course, having up to 3A with the DC supply it would be easier to exit DPM earlier than with the chargers.

For the second question, are you connecting any load to the device? Because this might be the reason why all the current is not going in to the battery.

Also make sure that the resistor at the ILIM pin is pulled to its minimum, so that nothing is limiting the current to the device.

Last point is the input voltage limit, you might want to set it lower in order not to enter DPM region.

Sergio

Hi

We will use a adapter to charge our product. May be of 1 Amps.

No i have not connected any load.

ILIM is 130 Ohm.

As you can see in above observations with chargers that after exiting DPM mode current drops to negative.

Hi Kunal,
I will replicate your issue in the lab and I will let you know.
What you might want to do in the meantime is
- checking what current is at the input when using the adapters
- checking any faults: temperature faults may reduce charging current
- trying to simulate the battery with a DC power supply and check if the issue still occurs

Sergio