TCA9555: Address Pin Floating

Allan Fan

Part Number: TCA9555

Hi expert,

Customer has a production product used TCA9555 and TCA9548 and forgot to mount pull high/low resistor on the board of address pins.

So far didn't see any issues but wondering what would be the status of address pin if floating? We want to know the impact of the risk.

Would it be high/low/unknown?

Thanks,

Allan

over 2 years ago

+1 Clemens Ladisch over 2 years ago

Guru 317370 points

If the pins are floating, the address can be random. There is no guarantee that it powers up with the same state.

Futhermore, floating inputs result in high shoot-through currents and might damage the device; see [FAQ] How does a slow or floating input affect a CMOS device?

0 BOBBY over 2 years ago

TI__Guru 73971 points

Hi Allan,

As Clemen's pointed out the I2C device address could change on the fly since we do not latch the I2C address at power up. Worst case scenario is if you have two devices with the same I2C address and get data collision during reads and also write to both devices unintentionally.

-Bobby

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TCA9555: Address Pin Floating