SN3257-Q1: Does this device support a daisy-chain topology?

Leo Wang

Prodigy 20 points

Part Number: SN3257-Q1
Other Parts Discussed in Thread: TMUX1309, , SN74HCS138, SN74HCS151

As shown in the figure below, whether SN3257 can implement this topology, please help to confirm

over 2 years ago

0 Clemens Ladisch over 2 years ago

Guru 280090 points

Yes, this is possible.

2× TMUX1309 would be cheaper. What frequency do you need?

0 Parker Dodson over 2 years ago

TI__Mastermind 46687 points

Hi Leo,

The short answer is yes - this is a possible configuration of the device.

The long answer is that it depends on the SPI frequency that you are running at. Putting multiplexers in parallel like this is going to increase the effective capacitance of the switch block which could degrade bandwidth; however it may not be an issue depending on what frequency you are trying to achieve with this SPI implementation.

Please let me know the frequency you are working at and I will verify if this is okay or not.

Best,

Parker Dodson

0 Leo Wang over 2 years ago in reply to Parker Dodson

Prodigy 20 points

thanks Parker Dodson，the frequency of spi is 10Mhz

0 Leo Wang over 2 years ago in reply to Clemens Ladisch

Prodigy 20 points

thanks，10MHz

0 Clemens Ladisch over 2 years ago in reply to Leo Wang

Guru 280090 points

10 MHz is much below the limit of either the SN3257-Q1 or the TMUX1309, and will work fine.

Alternatively, it would also be possible to handle the /CS signal with a demultiplexer like the SN74HCS138, and the MISO signal with a multiplexer like the SN74HCS151.

0 Parker Dodson over 2 years ago in reply to Leo Wang

TI__Mastermind 46687 points

Hi Leo,

The SN3257-Q1 should work fine in this configuration with 10MHz.

If you have any other questions please let me know!

Best,

Parker Dodson

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SN3257-Q1: Does this device support a daisy-chain topology?