BQ25890: BQ25890 design and Register question

Jay Liao

Prodigy 10 points

Part Number: BQ25890
Other Parts Discussed in Thread: BQ25895

Please help to Schedule review as attached.

My setting as blow

Battery is 1900mA

Input 7.6V/3.25A

Battery_Volt want to charging 2A

BV_vol need 4A~5A (include Battery Dynamic Power Management)

We want to used it without USB interface and only power input at 7.6V/3.25A, is it ok ?

If no, which chip can we use ?

If yes, which Register should I set ?

My set Register as blow, please help to check enough or not

REG00[7:0] = 01111111

REG02[7:0] = 00110100

REG04[7:0] = 00100000

REG0E meet I can get real battery voltage right ?

REG12 meet I can get real battery charging current right ?

REG13 I want to have Dynamic Power Management, how should I set ?

others used default.

over 4 years ago

0 Ning T over 4 years ago

TI__Guru 59141 points

Hi,

Please visit https://e2e.ti.com/support/power-management/f/196/t/874557 for BQ2589X: Schematic Review and PCB Layout Design Tips and https://e2e.ti.com/support/power-management/f/power-management-forum/875386/faq-bq25890-bq2589x-bq25898x-faqs for BQ2589x FAQs.

If D+/D- detection is not needed, it is ok to short D+/D- pins together.

The Charging Parameter Settings in Table 5 on the d/s can be programed by the host as needed.

It is highly recommended to get familiar with the charger operations by testing the device EVM before making customized designs.

Thanks,

Ning.

0 Holly Hong over 4 years ago in reply to Ning T

TI__Intellectual 1850 points

Hi,

here is a key question about BQ25895.

Register setting as blow. current and voltage is not zero according to the test, but REG0E and REG0F always read 0x00. So, Is any register we set the wrong value ?

REG00 -7F

REG01 -06

REG02 -3C

REG03 -1A

REG04 -1E

REG05 -13

REG06 -5E

REG07 -9D

REG08 -03

REG09 -44

REG0A -93

REG0B -(Read Only)

REG0C -(Read Only)

REG0D -12

REG0E -(Read Only)

REG0F -(Read Only)

REG10 -(Read Only)

REG11 -(Read Only)

REG12 -(Read Only)

REG13 -(Read Only)

REG14 -Bit 7 is R/W

Thank you very much!

0 Ning T over 4 years ago in reply to Holly Hong

TI__Guru 59141 points

Hi,

We will get and get back to you.

Thanks,

Ning.

+1 Wyatt Keller over 4 years ago in reply to Ning T

TI__Guru** 106010 points

Hello Holly,

It looks like the register setting for REG02 is not set to take continuous ADC measurements. I would suggest to try enabling conversion every second by setting REG02 to 0x7C, or set REG02 to 0xBC and it will take one ADC measurement to populate REG0E and REG0F.

I attached a screen shot of the datasheet for REG02:

Sincerely,

Wyatt Keller

0 Jay Liao over 4 years ago

Prodigy 10 points

May I know which the registers I can set

ACOV, SYSOVP, BATOVP, BAT_OVP, BAT_Over discharge

and System Over Current Protection ?

0 Wyatt Keller over 4 years ago in reply to Jay Liao

TI__Guru** 106010 points

Hello Jay,

Can you clarify your question? Many of these protections are described in the datasheet and are always present, you can see which one of the faults is set by checking the registers.

Sincerely,

Wyatt Keller

0 Jay Liao over 4 years ago

Prodigy 10 points

Sorry for my English is poor, let me clarify my question.

I want to test all protection which BQ25895 in buck mode.
My setup is VBUS=7.6V, D+ and D- short together.

If I want to test Input Overvoltage (ACOV)
Datasheet show "The input voltage for buck mode operation is VVBUS_OP.
If VBUS voltage exceeds VACOV, the device stops switching immediately. During input over voltage (ACOV),
the fault register CHRG_FAULT bits sets to 01. An INT is asserted to the host."
So where should I set VACOV, if can set it that I can see the CHRG_FAULT bits or INT to be change based on my want.

If I want to test System Overvoltage Protection (SYSOVP)
I can't find which the register can be set.

0 Ning T over 4 years ago in reply to Jay Liao

TI__Guru 59141 points

Hi,

For ACOV test, please set VBUS to ~15V.

For SYOVP, there's no register bit indication.

Thanks,

Ning.

0 Jay Liao over 4 years ago

Prodigy 10 points

Hi
Thanks for reply

let me double check

1. For ACOV test
-> "ACOV" means Maximum Operating Input Overvoltage, not my set Voltage, right ?

2. For SYOVP, there's no register bit indication
-> Could you please let me know how can I test "SYSOVP"

+1 Wyatt Keller over 4 years ago in reply to Jay Liao

TI__Guru** 106010 points

Hello Jay,

To test the safety functionality you would need VBUS to be around 15V.

This thread may help you with the SYSOVP functionality: https://e2e.ti.com/support/power-management-group/power-management/f/power-management-forum/483446/bq24297---how-does-sysovp-work-exactly

Sincerely,

Wyatt Keller

0 Jay Liao over 4 years ago

Prodigy 10 points

Thanks, last question

Could you please let me how can I test BATOVP.
My step is when Battery charging, use 7.6V to touch Battery Voltage Pin.
And wish can find INT is asserted to the host.

0 ezhao over 4 years ago in reply to Jay Liao

TI__Genius 10240 points

Hi Jay,

You should use a battery simulator. The way you plan to do is dangerous.

Best regards,

Eric

0 Jay Liao over 4 years ago

Prodigy 10 points

May I know how can I test BATOVP ?

I used 2 battery series which Voltage is 7.5V, and connect to BAT pin.

BQ25895 still work, and INT pin still no function.

0 Jay Liao over 4 years ago

Prodigy 10 points

May I know how can I test BATOVP ?

I used 2 battery series which Voltage is 7.5V, and connect to BAT pin.

BQ25895 still work, and INT pin still no function.

0 Wyatt Keller over 4 years ago in reply to Jay Liao

TI__Guru** 106010 points

Hello Jay,

As Eric mentioned is it not safe to test with real batteries for this protection, you should use a battery simulator for protection testing.

Sincerely,

Wyatt Keller

0 Jay Liao over 4 years ago

Prodigy 10 points

Understood,

Can I can set REG06=3.8V, and use 4.2V Battery to test it ?

0 Wyatt Keller over 4 years ago in reply to Jay Liao

TI__Guru** 106010 points

Hello Jay,

This is still not recommended and can be dangerous to attempt protection feature testing with real batteries.

Sincerely,

Wyatt Keller

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BQ25890: BQ25890 design and Register question