SN7400: Looking for a Bidirectional Level Shifter from 3.3V to -3.3V

Rafael Gerges

Part Number: SN7400
Other Parts Discussed in Thread: TMUX6201, TLV1871, P82B96

Tool/software:

Hello everyone,

I’m searching for a bidirectional level shifter that can convert signals from 3.3V to -3.3V and vice versa. Ideally, it should support a symmetric power supply (e.g., ±3.3V).

Most level shifters I’ve found work with unipolar supplies (e.g., 3.3V 5V), but I need one that can handle negative voltages. If anyone knows of an integrated solution or has suggestions for a discrete circuit, I’d appreciate any recommendations!

Thanks in advance!

7 months ago

0 Clemens Ladisch 7 months ago

Guru 317480 points

Is this for analog or digital signals? If digital, what are the four voltages?

0 Rafael Gerges 7 months ago in reply to Clemens Ladisch

Prodigy 30 points

Hi Clemens

It is for digital signal, it is for a EEPROM 1-Wire memory.

3.3V to -3.3V
0V to 0V

Bidirectional.

Best regards.

0 Clemens Ladisch 7 months ago in reply to Rafael Gerges

Guru 317480 points

Where does this requirement come from? Why does the EEPROM use a negative voltage? Are you sure that the voltages are inverted, and that you do not simply need to shift both voltages by 3.3 V?

0 Rafael Gerges 7 months ago in reply to Clemens Ladisch

Prodigy 30 points

This requirement comes from the need to implement a Transducer Electronic Datasheet (TEDS) in a sensor where the signal line is shared with the EEPROM. The EEPROM require a negative voltage for specific read/write operations, according to a class 1 MMI (IEEE 1451.4).

0 Clemens Ladisch 7 months ago in reply to Rafael Gerges

Guru 317480 points

This looks as if you have a pull-up to 3.3 V or a pull-down to −3.3 V, and you need to drive towards 0 V.

There is no integrated device that can do this.

For your TX, you can use the TMUX6201 to connect the line to 0 V or not.
For your RX, you can use the TLV1871 to compare the line against a reference voltage of about −1.6 V.
If you cannot have separate pins for the TX and RX signals, then use one channel of the P82B96 to split the signal into TX and RX.

Logic

Logic forum

SN7400: Looking for a Bidirectional Level Shifter from 3.3V to -3.3V