TCA9406: power isolation feature

ajayt

Part Number: TCA9406

I am I right in assuming that it either of the Vcc rails fails then the outputs will go in high impedance states and the no damage will be effected on the chip?

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 276380 points

The datasheet says:

V_CC Isolation Feature: If Either V_CC Input Is at GND, Both Ports Are in the High-Impedance State

0 ajayt over 2 years ago in reply to Clemens Ladisch

TI__Genius 9555 points

Thats what I summize as well from the data sheet, but what if one the power rails is effectively disconnected ie floating? - I a more concerned about potential chip damage

0 Clemens Ladisch over 2 years ago in reply to ajayt

Guru 276380 points

"Floating" is not a voltage. Assuming that you have proper decoupling cacapaitors, those capacitors can still contain a charge, i.e., the device is still powered. But this depends on how much supply current your entire circuit is using.

0 BOBBY over 2 years ago in reply to ajayt

TI__Guru 57930 points

Hi ajayt,

No damage is expected if one of the Vcc rails is unpowered assuming it still is within the absolute max ratings we set for the device. We do have a clause in the datasheet which states that the VCCA is not to exceed the VCCB so if you do remove VCCB and leave VCCA powered, you may see leakage current from VCCA pin into VCCB pin.

-Bobby

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TCA9406: power isolation feature