SN3257-Q1: Avoiding a level shifter

Antonio Faggio

Part Number: SN3257-Q1
Other Parts Discussed in Thread: SN74CB3T3257

Hi,

I would ask you for information about the operation of SN3257-Q1.

If powered at 3.3V, if on S1A, S1B there is a CMOS signal that switches between 0 and 1.8V, on D1, the logical value 1 is 1.8V or 3.3V?

I need to know, to avoid a level shifter. Being a mosfet with 5Ohm of resistance I expect 1.8V also on D1, is it correct? Or is the MOSFET off when there is a '1' so I will have 3.3V at the output?

If you can get the information it would be useful, otherwise I have to insert a level shifter.

Many Thanks,

Antonio

over 5 years ago

0 Clemens Ladisch over 5 years ago

Guru 318050 points

A closed switch behaves like a small resistor; the voltage between the S/D pins is noticeably different only if a large current flows.

If you cannot use the SN74CB3T3257, you need an actual level shifter.

0 Saminah C over 5 years ago in reply to Clemens Ladisch

TI__Genius 9132 points

Hi Antonio,

The SN3257-Q1. doesn't have any level shifting capability but will pass any signal from 0V to VDDx2 when VDD > 1.5V; with a maximum input and output voltage of 5.5 V.

To achieve level shifting function you will need to use a signal path level translator like Clemens mentioned..

Regards

Saminah

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SN3257-Q1: Avoiding a level shifter