TCA5405: About a interval.

Kengo.Y

Guru 11345 points

Part Number: TCA5405

Hi team.

Thank you for your always support.

I have a question about TCA5405.

We want to output data continuously.

Is it need to interval next signal(S0) after sending(D0) ?

If it so, let me know how long interval it need.

Sincerely.

Kengo.

over 7 years ago

0 BOBBY over 7 years ago

TI__Guru* 78361 points

Hello Kengo,

"Is it need to interval next signal(S0) after sending(D0) ?"

From my testing I found that if I did not add about ~20 microseconds of delay the output would sometimes not be set correctly. I suggest you leave a ~40 microsecond delay though just to be sure.

Thanks,

-Bobby

0 Kengo.Y over 7 years ago in reply to BOBBY

Guru 11345 points

Hi Bobby-san

Thank you so much for your reply.

Could you tell me one more question.

What status is each Q*pin before 'power on reset'.
(Low or HighZ or unstable)

Sincerely.
Kengo.

0 BOBBY over 7 years ago in reply to Kengo.Y

TI__Guru* 78361 points

Hey Kengo,

"What status is each Q*pin before 'power on reset'.
(Low or HighZ or unstable)"

When you say before power on reset, you mean if Vcc is GND correct?
If so then they should be high impedance (floating).

Thanks,
-Bobby

0 Kengo.Y over 7 years ago in reply to BOBBY

Guru 11345 points

Hi Bobby-san.

Thank you for your reply.

Do you have any idea how about below area's status?

(Between the Vcc rise up from 0V and the Vpor until 1V.)

Sincerely.

Kengo.

0 BOBBY over 7 years ago in reply to Kengo.Y

TI__Guru* 78361 points

Hey Kengo-san,

I will check on Monday and get back to you. I am working from home today and won't be back in the office until next week. Sorry for the delay.

Thanks,

-Bobby

0 BOBBY over 7 years ago in reply to BOBBY

TI__Guru* 78361 points

Hey Kengo-san,

I powered on the device and watched Q1 to see what it would do. I ended up seeing Q1 holding GND the entire time.

What I actually think is happening is while the device is under Vpor, Q1 is Hi-Z until Vcc is above Vpor afterwards the device holds Q1 to GND.

Thanks,
-Bobby

0 Kengo.Y over 7 years ago in reply to BOBBY

Guru 11345 points

Hi Bobby-san

Thank you for your support and answer.

Sincerely.

Kengo.

Interface

Interface forum

TCA5405: About a interval.