SN74LVC8T245: IOFF, Power-Off Leakage Current Parameter

Abe Hortillano

Part Number: SN74LVC8T245

Hello,

In measuring the IOFF parameter of this device, say at Ports A (A1...A8), what should be the pin state of the other pins while not under test, especially output enable (OE) and DIR pins?

Thank you for your help.

Regards,

Abe

over 6 years ago

0 Emrys Maier over 6 years ago

TI__Guru* 97046 points

Hi Abe,
I would recommend grounding all pins except the one under test. This will provide the maximum leakage path for the Ioff test.

The only absolute requirement is that Vcc is connected to ground for the Ioff test (by definition of Ioff).

0 Abe Hortillano over 6 years ago in reply to Emrys Maier

Prodigy 215 points

Hello Sir Emrys,

If all pins and power pins are grounded, except for the pin under test, this methodology will forward biased the protection diode. With this, I won't be able to measure the leakage current effectively. So, I still have my doubts.

Thank you.

Regards,
Abe

0 Clemens Ladisch over 6 years ago in reply to Abe Hortillano

Guru 317280 points

LVC family devices do not have protection or parasitic diodes from any input or output pin to V_CC:

0 Emrys Maier over 6 years ago in reply to Abe Hortillano

TI__Guru* 97046 points

Hey Abe,
In addition to what Clemens said (which is correct), the whole point of Ioff circuitry is to prevent current from going through parasitic and protection diodes -- even devices that do have positive clamp diodes will not have the diodes active if they have the Ioff feature and the circuitry is active (ie Vcc = 0V).

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SN74LVC8T245: IOFF, Power-Off Leakage Current Parameter