LVTH244 cold sparing

Sean Rosekrans

I was curious why in the datasheet for the LVTH244 buffer Ioff data is included for the 74LVTH244 but left blank for the 54LVTH244. Can you tell me the reason for this? Do you have data for Ioff on the 54LVTH244?

over 11 years ago

0 Wade Vonbergen over 11 years ago

TI__Guru 62930 points

Sean,
I apologize for the delay on replying to this.
You actually sent it prior to me leaving on vacation, but somehow I did not receive the notification.
I will look into this, and reply soon.
Regards,
Wade

0 Wade Vonbergen over 11 years ago in reply to Wade Vonbergen

TI__Guru 62930 points

Sean,
I was able to dig up a little more data.
Ioff is not specified due to higher leakage currents at elevated temperatures.
In order to operate as cold spare with < 100uA of current, the temperature would need to be less than 85c.
This impacts Ioff for the entire LVTH family.
Regards,
Wade

0 John Stephens10 over 10 years ago in reply to Wade Vonbergen

Prodigy 50 points

Hi Wade-

Is this also true for the ACT family?

Thanks,

John

0 Wade Vonbergen over 10 years ago in reply to John Stephens10

TI__Guru 62930 points

John,

The ACT family does not have Ioff feature.

Regards,

Wade

0 John Stephens10 over 10 years ago in reply to Wade Vonbergen

Prodigy 50 points

Wade-
Sorry if I'm not understanding your answer. The 54ACTxxx devices are or are not cold sparing?

Thx,
John

0 Wade Vonbergen over 10 years ago in reply to John Stephens10

TI__Guru 62930 points

Sorry for late reply. Sometimes difficult to track "answered" threads with new questions.
The ACT family does not have Ioff.
Cold sparing requires high impedance on control/data lines when no power applied. Ioff feature accomplishes this.
The ACT family has ESD protection diodes present on inputs/outputs to VCC. Since VCC is 0, this will cause large current, and essentially pull the shared inputs and outputs to near ground through the ESD diode.
Regards,
Wade

Space & High Reliability (Read Only)

Space & High Reliability Forum (Read Only)

LVTH244 cold sparing