TXS0102: LEVEL TRANSLATION

SATHYA SHREE S

Part Number: TXS0102
Other Parts Discussed in Thread: TXU0204

Hi,

We are using FT230XS-R part for USB to UART interface in our design, which has true 1.8V CMOS drive output and TTL input which needs to be interfaced with Arria 10 FPGA 10AX115S2F45I1SG, FPGA has 1.8V LVCMOS logic. Can we interface 1.8V LVCMOS with 1.8V TTL logic. Do we need any voltage translation. If yes kindly suggest voltage translator.

Thanks

S Sathya shree

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 316940 points

TTL uses a 5 V supply, with a high-level voltage near 3.3 V. There is no such thing as "1.8 V TTL".

The FT230X datasheet shows that with a 1.8 V I/O supply, the switching levels are compatible with 1.8 V signals. You do not need a translator. (The FT230X datasheet mentions level shifters, but only when interfacing with RS-232 or RS-422 voltages.)

0 Michael Ikwuyum over 2 years ago

TI__Guru 51106 points

Hi Sathya,

Please see Voltage Translation Application Quick Reference for UART recommendations (TXU and AXC family, TXU0204 for example).

Note that the device's VIH/VIL input levels can accept TTL, thanks.

Best Regards,

Michael.

0 James Mrowca over 2 years ago in reply to Clemens Ladisch

Intellectual 265 points

Last time I ever heard "3.3V TTL" was back in BiCMOS ASIC in the 90's. TTL is generally associated with bipolar transistor technologies implementation. 1.8V logic and below should be CMOS (bipolar transistors are too large for that io nowadays).

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TXS0102: LEVEL TRANSLATION