BQ21061: Single-Cell Charger IN BQ21061

Raymond Koosha4

Part Number: BQ21061

Hi TI Team,

When I connect a charged 3.7V Li-Ion single cell between pins BAT1&BAT2 and GND of BQ21061, I see the voltage dropping to 0.385V !!!
This loading effect cannot come from the chip itself.
I have also checked my board for shorts and have seen none.

1. What is going wrong here?

At this time, there is no USB power to power up the IC.

2. Can the charger be operative when only a cell is connected to it?
Or, USB power source should also be connected?

In the DS, a capacitor is connected between BAT1/2 and GND part
3. What is the reason for using that cap?

The voltage from the cell is ripple free hence no need to connect a cap there.

4. Is there an application note for this part?

I am not using an NTC. 4. Is that okay?

I do look forward to your feedback!

Thanks,

Raymond K.

over 5 years ago

0 Raheem over 5 years ago

TI__Mastermind 21590 points

Hello,

When you plug in battery only, the device will enter shipmode. You'll need to hold down /MR for 125ms to exit shipmode and power up the rails.

The capacitor on the battery is a decoupling cap to prevent ripple.

Its okay to not use NTC. You can either disable this function through I2C or place a 5k resistor on TS pin.

0 Raymond Koosha4 over 5 years ago in reply to Raheem

Intellectual 300 points

Hello,

Thank you for your reply!

1. I did hold down the /MR for 125ms but no voltage was seen at PMID1/PMID2 rails.

2. I connected a power supply with 3.7V at pins BAT1/BAT2 and GND and noticed that BQ21061 continuously drains 21mA !!!

Please could you tell me what is going on.

Thank you,

Raymond K.

0 Raheem over 5 years ago in reply to Raymond Koosha4

TI__Mastermind 21590 points

What voltage do you measure on VDD?

IS there any difference when you have 5V on VIN?

0 Raymond Koosha4 over 5 years ago in reply to Raheem

Intellectual 300 points

Hello,

We see 0V on VDD.

The voltages on VINLS and LSLDO are also 0V.

FYI, I am using 10k Ohms pull-up resistors on /PG, /INT, SCL, and SDA.

As before, there is 20mA drainage when 3.7V is connected between BAT1/2 and GND.

A snapshot of PS,

Thanks,

Raymond

0 Raheem over 5 years ago in reply to Raymond Koosha4

TI__Mastermind 21590 points

When you connect 5V on VIN, do you see PMID and VDD power up?

0 Raymond Koosha4 over 5 years ago in reply to Raheem

Intellectual 300 points

Hello,

When 4.5 V is connected to VIN, PMID = 4.5V

I followed the Charge Mode test as recommended in Section 2.2 of BQ21061 EVM User Manual.

2.2 Charge Mode
Connected:
PS#1: VIN 5V
PS#2: VBAT 3.7V

Scoped:
VPMID: 4.5V
VBAT 3.7V BUT PS#2 was supplying 30mA to BQ21061 ??

/CE was connected to ground, but no charging started.

Is there anything else that I need to do?

Thanks,

Raymond K.

0 Raheem over 5 years ago in reply to Raymond Koosha4

TI__Mastermind 21590 points

Hello,

Have you tried replacing the unit?

0 Raheem over 5 years ago in reply to Raheem

TI__Mastermind 21590 points

Hello Any updates here?

0 Raymond Koosha4 over 5 years ago in reply to Raheem

Intellectual 300 points

Hi Raheem,

Thank you for reaching out!!

The issues are still there and I am trying to find the cause of the problem.

I have never had problems with TI parts except for this one. So please tell me what else I need to do in order to find what is wrong.

Is there an EVM for this charger IC?
If yes, I like to get and try it.

Kind Regards,

Raymond

0 Raheem over 4 years ago in reply to Raymond Koosha4

TI__Mastermind 21590 points

Hello,

Yes you can get the EVM below.

www.ti.com/.../

0 Raheem over 4 years ago in reply to Raheem

TI__Mastermind 21590 points

Hello,

Were you able to try this on an EVM?

0 Raheem over 4 years ago in reply to Raheem

TI__Mastermind 21590 points

Hello,

Any updates here?

0 Raheem over 4 years ago in reply to Raheem

TI__Mastermind 21590 points

I haven't heard back so i'll close this thread.

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BQ21061: Single-Cell Charger IN BQ21061