BQ2004E battery charger

Manjunatha S2

7612.BQ2004 ckt.pdf

Please find the attached circuit and suggest me...

DCIN = 21V, 10 cell NimH,

problem is as soon as the power is ON both LEDs are ON(charge pending) and immediately after 2 to 3 seconds it will enter into fast charge mode.

fast charge mode remains only for a minute or so and then it enters into trickle charge. and the mosfet Q2 is getting heat during the fast charge.

Observation: MOD signal is very noisy, could not see the pulses.

thanks and regards manju

BQ2004 ckt.pdf

over 11 years ago

0 Charles Mauney over 11 years ago

TI__Mastermind 31120 points

It could be noise like you say or the 5V reference that is varying and causing a termination. The 5V input is used as a ADC reference and if it changes may look like a -dV transition. U2 has to be very stable. If this varies much at all, the part will get a termination signal. Use a similar part to what is on the DV2004,

http://www.ti.com/general/docs/lit/getliterature.tsp?baseLiteratureNumber=sluu016&fileType=pdf

0 Manjunatha S2 over 11 years ago in reply to Charles Mauney

Prodigy 50 points

Hi charles Mauney thank you for your reply.

I am using same part(78L05ACZ) which is used in DV2004. Here in this circuit, i have just observed the MOD signal by removing the connection between BAT+ and C3 junction, the pulses are ok at gate of Q2 also, i feel the switching part is working fine.

0 Charles Mauney over 11 years ago in reply to Manjunatha S2

TI__Mastermind 31120 points

ok, let me know if you need more support.

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BQ2004E battery charger