[SOLVED] Battery charging circuit problem

[gowtham velusamy]

Hi,
I am working in MCP73837 microchip charger circuit,it does not works properly.I have attached the charger circuit. When input is given to the circuit, power good(PG-RED) LED is glowing then the charging(YELLOW) LED blink one time only. Now the problem is the battery(3.7V Li-Po 850mAH) does not charge even battery connecting more than four hours. Any one help me......

 

[KlausST]

Hi,

I see some issues:
* At V_USB you use 1uF, but datasheet say 4.7uF
* R_Therm needs to be a 10k NTC and needs to be placed to sense the battery´s temperature
* R4 at PROG1. I´d choose 10k for 100mA/500mA current limit.

I assume R4 most likely generates the problem, but maybe it is caused by a PCB layout / wiring.

Klaus

 

[treez]

otherwise it may be the battery that has gone bad.....the lithiums usually have a protection cct in them and it may have blown.....so you could just put say a 22r 0.5w resistor from the 5v supply to the battery and see if any current flows through it.

 

[gowtham velusamy]

* R4 at PROG1. I´d choose 10k for 100mA/500mA current limit.

I assume R4 most likely generates the problem.

Klaus

As per your suggestion,I have changed R4 resistor value for about 10k but there is no improvement in charging and I measured output voltage and current value,it shows zero.

you could just put say a 22r 0.5w resistor from the 5v supply to the battery and see if any current flows through it.

I did this test,The battery is charging good.so the problem is in my circuit

 

[gowtham velusamy]

hi,
I have done a blended mistake, i connected PROG2(Pin 7) directly to Vusb(Pin 2). Now i have pull downed the PROG2 pin, my circuit is working well. Thanks for your support.

 

[M.Rehan]

You should hit mark as solved button in your thread when you find your answer

 

[KlausST]

Hi,

hi,
I have done a blended mistake, i connected PROG2(Pin 7) directly to Vusb(Pin 2). Now i have pull downed the PROG2 pin, my circuit is working well. Thanks for your support.

Interesting.
According datasheet Prog2 is connected to Vusb. It switches charge current from 500mA (non USB) to 100mA (USB).

To me it seems you did something that is not according the datasheet.

We don't know what your inpug voltage and current capability is, nor do we know what charging current(s) you want.

Klaus

 

[gowtham velusamy]

Hi,

We don't know what your inpug voltage and current capability is, nor do we know what charging current(s) you want.

Klaus

I did not use Vusb instead of that i have used Vac. Input voltage is 5V/1A, I got 4.3V/666mA(Prog1 resister 1.5k) output.

According datasheet Prog2 is connected to Vusb.
Klaus

i had connected according to the datasheet,i did not get output and charging LED(yellow) did not glow. The line between prog2 and Vsub is pull downed with 10k, now i get output.