SN74LV4T125: VOH min when VCC=3.3V

Takuma Ito

Part Number: SN74AVC16T245
Other Parts Discussed in Thread: SN74LVC2T45

The VIH of connected device has few margin when I use VCC=3.0V condition, so i would like to check if VOH could be increased when VCC=3.3V is used.

Could you tell me what the VOH min is when VCC=3.3V?

Also I consider VCC=5V. Could you tell me if the device will work properly with 1.8V input when VCC=5V is used?

over 6 years ago

0 Clemens Ladisch over 6 years ago

Guru 297310 points

The actual V_O value depends on the actual current. The output transistors behave pretty much like resistors, so you can interpolate from the specified V_OH. If you have a CMOS input with V_I < 20 µA, you will get V_O > V_CC − 0.1 V.

The voltage drop decreases with increasing V_CC, so for 3.3 V, it is safe to add0.3 V to the specified V_OH. (However, do you know how accurate your power supply is?)

At V_CC = 5 V, V_IH is 2 V. For such a large difference, better use a level shifter with two power supplies, e.g., SN74LVC2T45.

0 ShreyasRao over 6 years ago in reply to Clemens Ladisch

TI__Guru 59720 points

Please refer to the FAQ on the Voh and Vol calculation here:

[FAQ] How do I determine the output voltage (VOH, VOL) or output current (IOH, IOL) of a CMOS logic device...

e2e.ti.com

FAQ: Logic and Voltage Translation > Output Parameters >> Current FAQ The high logic level output voltage of a logic device with no load will be the supply voltage

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SN74LV4T125: VOH min when VCC=3.3V

[FAQ] How do I determine the output voltage (VOH, VOL) or output current (IOH, IOL) of a CMOS logic device...