TXS4558: About VCC and VBATT

Tao_2199

Genius 5680 points

Part Number: TXS4558

Hello,

Regarding to TXS4558, my customer is asking some question.

(Question)

(1)For power up, is power sequence is needed?

Or don’t we need to care power procedure ? (VCC and VBATT)

(2)VBATT is always input to power source but VCC is repeated power on/off

or VCC is unstable as 2.95V⇔1.8V. (It’s changed voltage between 1.8V and 2.95V.)

In this case, is there any impact to TXS4558?

Regards,

Tao 2199

over 5 years ago

0 ShreyasRao over 5 years ago

TI__Guru 56790 points

Hi Tao,

I will take a look at this and reply at the earliest.

0 ShreyasRao over 5 years ago

TI__Guru 56790 points

Tao,

There is no required power sequencing mentioned in the datasheet.
The device is designed for operation for Vcc between 1.65 to 3.3V, hence there is no reliability concerns with the device operation in between the range.

0 Tao_2199 over 5 years ago in reply to ShreyasRao

Genius 5680 points

Hello Shreyas,

Thank you for reply.

One more question.

When VBATT is input to power source and Vcc=0V, how status do output became?

VSEL1/2 -> 0V ?

SIMI/O,SIMRST,SIMCLK -> 0V or Hi-Z?

Regards,

Tao 2199

0 ShreyasRao over 5 years ago in reply to Tao_2199

TI__Guru 56790 points

Hi Tao,

I didnt see a clear answer to that in the datasheet, but since this is the internal reference for the device operation, I would think that the device IOs will be disconnected from each other/Hi-Z.

0 Tao_2199 over 5 years ago in reply to ShreyasRao

Genius 5680 points

Hello Shreyas,

Thank you for reply.

I informed your answer to my customer and I have a question.

AS you say, when Vcc=0, control logic to translator might be low level.

In same way, when Vcc=0, control logic to LDO might be low level.

So LDO output might be 0V.

If it doesn’t have discharge, output might be remained.

Do you think that there is the above possible about LDO output?

Could you please give some comment?

Regards,

Tao 2199

0 ShreyasRao over 5 years ago in reply to Tao_2199

TI__Guru 56790 points

Tao,

Assuming both the EN pins are held low, the LDO output is internally discharged and the IO ports are disconnected from each other and low.

Logic

Logic forum

TXS4558: About VCC and VBATT