SN74LV1T126: Logic forum

Tuomo Nikkila

Part Number: SN74LV1T126
Other Parts Discussed in Thread: TXU0101,

In new buffer data sheet there is strange power consumption figure:

I don't understand what consumption this is. 0.3V is clearly "0" and 3.4V clearly "1". How come there is 1.35 mA consumption?

over 2 years ago

0 Michael Ikwuyum over 2 years ago

TI__Guru 54636 points

Hi Tuomo,

That is for TTL applications where you have a 5.5V supply with inputs far from 5.5V. Hence, consuming more current.

Per the second condition, you can have a 1.8V supply with inputs closer to 1.8V for less current.

I.e red will consume more current than blue, below.

You may also use TXU0101 and have VCCA and VCCB = same supply of 5.5V for less current, thanks.

Best Regards,

Michael.

0 Clemens Ladisch over 2 years ago in reply to Michael Ikwuyum

Guru 318050 points

When the input voltage is not near the supply rails, you get shoot-through currents; see [FAQ] How does a slow or floating input affect a CMOS device?

When the voltage is even farther away from the rails, the currents get even larger. There is no better documentation for LV1T inputs, but they should behave similar to AHCT:

0 Michael Ikwuyum over 2 years ago in reply to Clemens Ladisch

TI__Guru 54636 points

In addition, you may also see below from the Q1 version i.e SN74LV1T126-Q1, thanks.

Best Regards,

Michael.

0 Tuomo Nikkila over 2 years ago in reply to Clemens Ladisch

Prodigy 10 points

Yes, This is basic behavior of logic gate, but this part is sold as level shifter

0 Tuomo Nikkila over 2 years ago in reply to Michael Ikwuyum

Prodigy 10 points

Actually I was planning to use with variating VCC 3-4.5V and constant control voltage 2.8V. Any remcommendation?

0 Clemens Ladisch over 2 years ago in reply to Tuomo Nikkila

Guru 318050 points

Level shifters have similar CMOS inputs. The only difference between LV1T inputs and normal inputs is that LV1T switching thresholds are lower to allow translating from somewhat lower voltages.

If you want to avoid the shoot-through currents for input voltages much lower than the supply, then you need to use a level shifter with two supplies, e.g., TXU0101.