CV Mode Not Working

Suresh Samynathan

Hi,

In our application, both AC and USB charger circuits are present and both are supplied with 5.0V through USB. The BCIAUTO is pulled down with 499K. The ADCIN1 pin is left floating. Seperate 4.3V LDO is used with Power selection MUX, one input connected to LDO output and other input conencted to VBAT. The power pins will be supplied the LDO power if USB is present; otherwise it will be supplied with VBAT.

If the battery is not connected USB power is applied, the VBAT pin starts from 0 to 1.2V and stabilizes at 2.0V. As per the CV mode, the voltage should be 4.0V in CV mode. The TPS also not stating UP in this condition.

Can you please clarify what could be the issue.

over 16 years ago

0 Gandhar Dighe over 16 years ago

TI__Genius 15100 points

Hi,

I did not understand your MUX logic. However, based on the following statement:

If the battery is not connected USB power is applied

I can tell that CV mode will not work. CV mode functions only with AC power.

0 Suresh Samynathan over 16 years ago in reply to Gandhar Dighe

Intellectual 360 points

Hi,

To isolate the system current from battery charging current MUX logic is used. The MUX logic one input is 4.3V derived from the AC input and other input is VBAT. The output of the MUX is connected to all the power supply pins of TPS.

The AC charger input is shorted with USB VBUS. Our system is powered through USB, for the charging AC charger is used.

0 Gandhar Dighe over 16 years ago in reply to Suresh Samynathan

TI__Genius 15100 points

Can you please share your schematics and send it via Selva?

0 Gandhar Dighe over 16 years ago in reply to Gandhar Dighe

TI__Genius 15100 points

Can you tell me the symptom when you use the CV mode. I see that you have shorted AC and VBUS (as you have said earlier). So, now when you connect a charger (I assume it is AC charger, if you connect USB supply then let me know the current limitation on that one) and ADCIN1 is floating you expect that CV mode should trigger and power the system - is this use case correct?

CV mode has a limitation of 1A. What is your load?

Power management

Power management forum

CV Mode Not Working