TXB0104: BW of TXB0104

"Bandwidth" is an analog concept. The TXB is a digital device.

The data rate of a digital signal can be described with Mbps, or with MHz (as the frequency of a square wave). One full cycle of a square wave consists of two pulses, low and high, so it can be described at two bits. However, when using SPI, only one edge of the clock is used, so in that case, there is one bit per full cycle.

The TXB supports 60 Mbps, or 30 MHz, or 30 Mbps with SPI.

What is the actual problem you're trying to solve? Are the individual signals really bidirectional? (Unidirectional translators can be faster.)

got it ,

BTW, they use SPI in bi-directional 

Is that plain old SPI with CS, CLK, MOSI, and MISO? Or quad SPI (which uses more than four lines)?

Hi Ladisch,

Quad SPI,

any concern?

Hi Ladisch,

60MHz in TXB0106 seems work just fine to my customer's 40MHz need.

so which scenario do you recommend us use TXB0304?

larger load? or longer trace?

With the TXB010x, more than 30 MHz is not guaranteed to work.

Hi Ladisch,

I'm confused,

TXB0106 datasheet claim that it can support 60Mbps.

why would you say over 30MHz is not guaranteed?

do you mean some factor like output load or long trace may affect?

60 Mbps = 30 MHz.

Hi Ladisch,

I get it now,

so TXB0106 can't support 40MHz clock freq in 1.8Vcca to 3.3Vccb scenario,

I'll have to use  one TXB0304 and one TXB0302 to guarantee 40MHz spec, right?

what's the risk if they insist use TXB0106 

The Mbps specification does not apply to SPI, because the SPI data has half the speed of the clock (MISO or MOSI transmit one bit per clock cycle, but a clock cycle has two bits, low and high.)

The TXB010x supports 30 MHz SPI. The TXB0304 supports 70 MHz SPI.

Hi Ladisch,

thanks you reply

I'll have to use  one TXB0304 and one TXB0302 to replace TXB0106 and  guarantee 40MHz spec, right?

what's the risk if they insist use TXB0106

The risk is that the TXB0106 might not handle 40 MHz.

Hi  Ladisch,

if the bottleneck is the clk,

can I use one TXB0104  for data  and one TXB0302 for clock?

Regards,

Fred

got it