TCA9517-Q1: TCA9517-Q1 partical power down question

junsong gu

Part Number: TCA9517-Q1

Hi TI,

For TCA9517DGKRQ1,if partical power down of VCCB, what is the state of pin SDAB/SCLB ? and if VCCB power on again will the device work normally?

Junsong

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 317680 points

Section 11 of the datasheet says:

The TCA9517-Q1 includes a power-up circuit that keeps the output drivers turned off until V_CCB is above 2.5 V and the V_CCA is above 0.8 V.

0 junsong gu over 2 years ago in reply to Clemens Ladisch

Prodigy 170 points

hi Clemens，

If VCCA keep power on and VCCB power off , the pin"SDAB/SCLB" goes to hign impedance state?

Junsong

0 Clemens Ladisch over 2 years ago in reply to junsong gu

Guru 317680 points

Yes; inputs have a high impedance.

0 Jack Guan over 2 years ago in reply to Clemens Ladisch

TI__Mastermind 41996 points

Hey Junsong,

Clemens' is correct here. For the output drivers to be turned on, it must meet the requirement such that VCCA is above 0.8V and VCCB is above 2.5V. Since only one of these conditions are met (VCCA >0.8V), this means the output drivers will be turned off and signals will not be able to propagate through the I/Os.

Also note that the I/Os will also be over-voltage tolerant (up to 5.25V) when VCCA and/ or VCCB is powered off.

Regards,

Jack

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TCA9517-Q1: TCA9517-Q1 partical power down question