LSF0204D: Bus switching between number of devices

Billy Parthipan

Part Number: LSF0204D
Other Parts Discussed in Thread: TS3USB221, , SN74CBTLV3257, TMUX1574

Tool/software:

Hi, I have a requirement of switching SWD lines (programming signals from STLINK) and SPI Lines (from Host MCU) between a number of devices. This is a bi-directional data transfer in the 3V3 logic domain on both sides. I have previously used LSF0204DPWR for level translation. But I am not sure if this is suitable for Bus switching and fast signal (12 MBits/s roughly). The image illustrate what I am trying to do.

Ideally I do not want to use any pull ups. But I know this device requires them. I could not find any other suitable device that can automatically do the bi-directional transfer. When disabled I will require the ports to be high impedance/tri-state.

Do you think this will work? Thanks

10 months ago

0 Billy Parthipan 10 months ago

Prodigy 90 points

Hi,

while waiting for a reply on this, I have came across a USB switch of P/N TS3USB221. If the solution based on LSF0204DPWR is not appropriate, do you think I can use a switch something like TS3USB221? Thanks

+1 Clemens Ladisch 10 months ago

Guru 321340 points

The LSF0204D could be used for this, but it does not pass high-level signals ner Vref_A, so it requires pull-up resistors at the outputs.

You can use any general-purpose switch that supports the required voltages and frequencies. The SN74CVTLV3126 is a four-channel 1:1 switch, but you probably want an integrated 2:1 switch like the SN74CBTLV3257 or TMUX1574.

+1 Billy Parthipan 10 months ago in reply to Clemens Ladisch

Prodigy 90 points

Hi, Thanks for your guidance here. I'll use TMUX1574. Regards Billy

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LSF0204D: Bus switching between number of devices