BQ4802Y: BQ4802Y: Pin function & power sequence understanding

Kaushik Thumar

Part Number: BQ4802Y

Tool/software:

Hi team,

I am using BQ4802Y in my design. i had connected CEIN with VCC.
Datasheet describe this pin as a chip enable input.

I have a doute that if it is a chip enable than it should be logic high in both mode (Powered by VCC & Battery backup), but as per power sequence when VCC is absent, CEIN pin voltage does not effect.

Also, in the power sequence as per my understanding CSIN goes high after VCC reach its max level. but what will happen if both pins are connected togater.

1 day ago

0 Maxwell Verboncoeur 1 day ago

TI__Mastermind 22090 points

Hi Kaushik,

I think it should be fine, the diagram indicates that the CEIN state is not considered when in battery backup mode.

Regards,

Max Verboncoeur

0 Kaushik Thumar 1 day ago in reply to Maxwell Verboncoeur

Prodigy 40 points

Apologies for more information.

The can you explain the RST pin function to me. I read it in datasheet that its out put but in which case RTC provide reset. Also does this pin can be configured as input?. If yes what resister bits we need to change.

0 Maxwell Verboncoeur 6 hours ago in reply to Kaushik Thumar

TI__Mastermind 22090 points

Hi Kaushik,

RST is used to indicate the power mode of the device as well as offering a way to reset the part if it is pulled low.

Looking at your other E2E, you might try adding the recommended 5k pullup to VCC onto the pin.

Regards,

Max Verboncoeur

0 Kaushik Thumar 2 hours ago in reply to Maxwell Verboncoeur

Prodigy 40 points

Pull up on RST line is preset, it just not visible in the shared schematic image.
I also tried removing pull up resister, but results are same in both case (With pull up and without pull up).

The same RST is connected with MCU and it has a RST control with it. When i read datasheet about RST i guess that RTC has reset output and MCU is also configured as RST output. than it is possible that it could create the issue.

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BQ4802Y: BQ4802Y: Pin function & power sequence understanding