TXB0304: output capability

Mark Chen52

Part Number: TXB0304
Other Parts Discussed in Thread: SN74LVC125A, SN74AUC125

Hi Expert,

Due to AMD SPI interface only support 4inch of driver length, so customer would to use TXB0304 to extend the output drive length for SPI interface.

if the SPI signal speed is 66MHz/bps to 100MHz, odes TXB0304 could to use here? if yes how long the distance of output driver length could support?

the device spec as attached. please help to check it.

or any more suitable solution to recommendation if TXB0304 can not support.

FLASH datasheet.pdf

Regards,

Mark

over 3 years ago

0 Clemens Ladisch over 3 years ago

Guru 316220 points

The TXB is not a buffer. (As a bidirectional translator, its outputs are deliberately very weak to allow other devices to override the voltage.)

To buffer standard SPI, use a plain buffer like the SN74AUC125 or SN74LVC125A (depending on the voltage).
Buffering dual/quad SPI is not possible without knowing the current direction of the data signals.

0 Mark Chen52 over 3 years ago in reply to Clemens Ladisch

TI__Expert 7825 points

Thanks Clemens,

what's signal frequency for both devices(SN74AUC125 or SN74LVC125A)? do them could be work on 66MHz to 100MHz?

due to i didn't see this information on datasheet, could you help to check it ?

Regards,

Mark

0 Clemens Ladisch over 3 years ago in reply to Mark Chen52

Guru 316220 points

LVC does 175 MHz at 3.3 V. AUC does 200 MHz at all voltages above 1.2 V.

0 Mark Chen52 over 3 years ago in reply to Clemens Ladisch

TI__Expert 7825 points

thanks Clemens,

one more question, you say " Buffering dual/quad SPI is not possible without knowing the current direction of the data signals" , could you explain more detail for this ?

Regards,

Mark

0 Clemens Ladisch over 3 years ago in reply to Mark Chen52

Guru 316220 points

A bidirectional buffer must know which side is input and which side is output. Many translators (SN74xxxT245) use separate direction control pins. With the TXB, the outputs on both sides are always active, but they are extremely weak to allow other devices to override the voltage; this implies that the TXB cannot increase the drive strength.

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TXB0304: output capability