SN74AUC16245: Fast bus switching or selection in a 1v8 to 3v6 system

Bill Kury

Prodigy 220 points

Part Number: SN74AUC16245
Other Parts Discussed in Thread: TXV0106, LSF0002, TMUX1574, TS5A23157

Tool/software:

I am designing a new system to validate a new device. My design has 2 interfaces that use i2c and SPI.

I need to be able to drive those interfaces from one of two sources. I would select the source via software.

I would like the SPI interface to run at 50 MHz so I would like the prop time of the device to be as low as possible.

On the i2c side, the prop time can be less since that interface runs at 400 KHz.

I have been looking at the AUC family but that appears only work with 1v8 to 2v7.

Is there a better solution?

Bill

7 months ago

0 Clemens Ladisch 7 months ago

Guru 299840 points

Does "1v8 to 3v6" mean that you want a level shifter? The fastest level shifter would be the TXV0106/8.

For I²C, use the LSF0002.

0 Bill Kury 7 months ago

Prodigy 220 points

Hey Clemens, please to meet you.

I need logic, bus switches, etc that has a 1v8 to 3v6 voltage tolerance. My system has to operate across those voltage ranges. As I mentioned previously, I am switching SPI so I need to keep the delays as small as possible, so I don't incure major timing hits. Is there a logic family around that works across the 1v8 to 3v6 range and has low prop times like the AUC family?

Bill

0 Clemens Ladisch 7 months ago in reply to Bill Kury

Guru 299840 points

So what you want is not level shifting, and not buffering, but a 2:1 switch? Then you can use any analog switch that supports the desired voltages and frequencies, e.g., TMUX1574 or TS5A23157.

0 Bill Kury 7 months ago in reply to Clemens Ladisch

Prodigy 220 points

The TMUX1574 looks really good. The prop time appears to be less than 1 nS which is really short.

thanks this helps

Bill

0 Clemens Ladisch 7 months ago in reply to Bill Kury

Guru 299840 points

Please note that the specified propagation delay is measured with an infinitely strong signal source. The actual delay depends on the source's drive strength and on the load; see [FAQ] How do I Approximate Propagation Delay and Channel to Channel Skew in an Analog Switch/Multiplexer?

0 Bill Kury 7 months ago in reply to Clemens Ladisch

Prodigy 220 points

ok, I take a look at the above app note and get back to you.

Bill

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SN74AUC16245: Fast bus switching or selection in a 1v8 to 3v6 system