SN74LXC8T245: Maximum Data rate

Danilo A.

Mastermind 31940 points

Part Number: SN74LXC8T245
Other Parts Discussed in Thread: SN74AXC8T245, SN74AUC125, SN74AXC4T774, TXU0304, TXG8041

Hi Team,

Posting on behalf of our customer.

I will share this E2E post to our customer so he can reply when needed.

I want use a voltage translator A to B, VCCA = 3.3V and VCCB =1.2V.

I select the reference SN74LXC8T245 in his DS we can see page 15 a MAX data rate to 20 MBPS

https://www.ti.com/lit/ds/symlink/sn74lxc8t245.pdf?ts=1768412786473&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FSN74LXC8T245

in SN74AXC8T245 I don't see the same tab with Max data rate in MBPS comparaison we have only this information "Up to 380Mbps support when translating from 1.8V to 3.3V "

https://www.ti.com/lit/ds/symlink/sn74axc8t245.pdf?ts=1768448674929

but with propagation tab we can deduce AXC in more speed than LXC, with my configuration, could you confim ? What is Max data rate in MBPS for AXC (A to B, VCCA = 3.3V and VCCB =1.2V) ?

Have you voltage translator with Max data rate 120 MBPS (A to B, VCCA = 3.3V and VCCB =1.2V) ?

Regards,

Danilo

1 month ago

0 Clemens Ladisch 1 month ago

Guru 320660 points

The AXC datasheet specifies a maximum propagation delay of 7 ns, which corresponds to 142 Mbps. (This is a safe estimate; you could do your own tests to find out if higher rates work.)

The SN74AUC125 has overvoltage-tolerant inputs and supports 270 Mbps at 1.2 V.

0 Joshua Salinas 1 month ago

TI__Mastermind 31790 points

Hello Danilo,

I agree with the comment made by Clemens. We can estimate the max data rate by using 1/tpd.

Using tpd = 7ns, we get ~142Mbps.

Regards,

Josh

0 Jeremy BALLESTER 1 month ago

Prodigy 20 points

Ok thanks the SN74AXC8T245 is pin to pin compatible in TSSOP, it's a great news.

For others SPI Signals I used, TXU0304QPWR in same voltage range, but it's the same problem I can up to 25 MBPS max, do you know a similar component (A to B - 3bits and B to A 1bit for MISO , VCCA = 3.3V and VCCB =1.2V) with this performance of 100MBPS ? pin to pin compatible with TXU TSSOP14 ?

I found TXG0804 but voltage min is 1.8V and not exactly same package...

Have a good day!

Best regards.

0 Clemens Ladisch 1 month ago in reply to Jeremy BALLESTER

Guru 320660 points

SN74AXC4T774 is not pin compatible.

0 Joshua Salinas 1 month ago in reply to Jeremy BALLESTER

TI__Mastermind 31790 points

Hello Jeremy,

TXU0304 won't be able to work at 100Mbps with those voltages, see max data rate below.

I would stick with AXC products like SN74AXC4T774

Regards,

Josh

0 Jeremy BALLESTER 1 month ago in reply to Joshua Salinas

Prodigy 20 points

Thanks for reference i SN74AXC4T774 seem up to 83 MBPS (Tpd= 12ns) in B to A way. but TXG8041 has a min of 1.8V but transfer up to 126MBPS.

do you think I can test to decrease VCCB until 1.2V and have a correct outputs ?

0 Joshua Salinas 1 month ago in reply to Jeremy BALLESTER

TI__Mastermind 31790 points

Hello Jeremy,

TXG8041 is recommend to operate from 1.71V to 5.5V. At 1.2V the part may not turn on.

Regards,

Josh

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SN74LXC8T245: Maximum Data rate