BQ21040: Start-up charge current

tateo yamashiro

Part Number: BQ21040

Hi,

We got a question from customer about bq21040.
When the device is start-up, charge current is fall to zero temporary. They would like to know cause of it.
We can provide waveform. But we want to share it by private E2E or e-mail. Could you help us?

Best Regards,
tateo

over 8 years ago

0 Kerry Song over 8 years ago

TI__Intellectual 1980 points

Hello

what's your VIN and VBAT voltage? You could share waveform to me.

Regards

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Thank you for your reply. I send a request of E2E friendship. Please approve my request.

And their condition is below.

Vin=5V

Vbatt=4V

Ichg=450mA

Best Regards,

tateo

0 Kerry Song over 8 years ago in reply to tateo yamashiro

TI__Intellectual 1980 points

Hello

I cannot see your request of E2E friendship, you can attach relative waveform and data at here.

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Hi, I attach the waveform here. Could you check it and give us your feedback?
When Vbatt is 3.2V, current falling is not occurred. Does the battery voltage relate with this behavior?

bq21040 Start-up_03Apr17.pptx

Best Regards,
tateo

0 Kerry Song over 8 years ago in reply to tateo yamashiro

TI__Intellectual 1980 points

Hello,

From your waveform, What I could see is that the VBAT is not 3.2V, it may near to regulation voltage. so do you think about the voltage drop between VBAT pin and battery.

Besides, could you add the TS pin voltage waveform in your picture, stop charge may because of thermal performance.

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Hi, Please see attached file. There are 3 waveforms.

Page 1: Vbatt=4V, ch1: Ichg, ch2: Vout, ch3: Vin
Page 2: Vbatt=4V, ch1: Ichg, ch2: Vout, ch3: /CHG, ch4: TS
Page 3: Vbatt=3.2V, ch1: Ichg, ch2: Vout, ch3: /CHG, ch4: TS

0550.bq21040 Start-up_03Apr17.pptx

Best Regards,
tateo

0 Kerry Song over 8 years ago in reply to tateo yamashiro

TI__Intellectual 1980 points

Hello,

I confirm it on our EVM, it's a normal phenomenon for this part when start up with VBAT 4V, current down to 0 exists exactly.

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Thank you for your reply. Our customer would like to make sure what function of the IC relate to this phenomenon. They need this information for their internal review. Now it is almost DIN phase. Could you give us your feedback?

Best Regards,
tateo

0 tateo yamashiro over 8 years ago in reply to tateo yamashiro

Guru 10890 points

Hi, Do you have any update on this?

Best Regards,
tateo

0 Kerry Song over 8 years ago in reply to tateo yamashiro

TI__Intellectual 1980 points

Hello,

This is about the charger's design and internal logic, will need longer time to ask design team confirm it.

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Hi, Sorry for rush, but could you give us your feedback by next Wednesday?

Best Regards,
tateo

0 Kerry Song over 8 years ago in reply to tateo yamashiro

TI__Intellectual 1980 points

Hello

I cannot confirm the time now. Can you give the business opportunity? what's the volume? This can help us prioritize the request.

0 tateo yamashiro over 8 years ago in reply to Kerry Song

Guru 10890 points

Hi, I can give the business opportunity. Could you tell me your e-mail address? It is confidential information. But I can send it by e-mail.

Best Regards,
tateo

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BQ21040: Start-up charge current