TPS55289: Shutdown effect on I2C bus

Jan Van Bogaert

Part Number: TPS55289

Tool/software:

Hello. The specification of the TPS55289 states:

"When the EN/UVLO pin voltage is pulled below 0.4 V, the TPS55289 is in shutdown mode, and all functions are disabled. All internal registers are reset to default values"

I have the impression that the I2C bus is not only inactive but also forced to ground. This is undesired as it blocks communication with other chips on the same bus. Can you confirm this behavior?

Thanks

Jan

5 months ago

0 Bryce Xun 5 months ago

TI__Mastermind 27800 points

Hi Jan,

The SCL and SDA pins are open-drain connection, when TPS55289 is in shutdown mode, the SCL and SDA will be floating, not forced to GND, thus I don't think it will affect the communication of MCU with other chips.

BRs,

Bryce

0 Jan Van Bogaert 5 months ago in reply to Bryce Xun

Prodigy 80 points

Hi Bryce.

The specification also states:

"When the input voltage is below 2.6 V, the TPS55289 is disabled" . Is that the same as shutdown mode?

I am experiencing that when VIN is 0, the chip pulls SCL and SDA to ground, even in case the device an external VCC is applied. Possibly the input protection diodes are creating a path to VIN?

0 Bryce Xun 5 months ago in reply to Jan Van Bogaert

TI__Mastermind 27800 points

Hi Jan Van,

Yes, when Vin is below 2.6V, the device is also shutdown. And both SCL and SDA pins are high-impedance.

It could be pulled to GND by other devices for example MCU, but for TPS55289, as I mentioned, both SCL and SDA pins are high-impedance when in shutdown mode.

BRs,

Bryce

+1 Jan Van Bogaert 5 months ago in reply to Jan Van Bogaert

Prodigy 80 points

OK, seems not the TPS55289 that causes the problem

Power management

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TPS55289: Shutdown effect on I2C bus