SN74HCS245: How to understand VT+

Rocky Chen

Part Number: SN74HCS245

Dear,

For example, for 4.5V supply, input logic level is 3.3V, as datasheet said, VT+ range is 1.7V min to 3.15V max, so could it consider 3.3V input as a logic high?

Thanks!

over 1 year ago

0 Clemens Ladisch over 1 year ago

Guru 243220 points

All voltages above V_T+ are considered high. However, with a 5 V supply, the maximum V_T+ is 3.5 V, and the tolerances of your power supply might shift it even higher.

To convert from 3.3 V to 5 V, use a device with TTL-compatible inputs (AHCT, HCT), or a level shifter.

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SN74HCS245: How to understand VT+