TMUX1104: please recommend device to multiplex the output of an LDO to 4 separate loads.

Adam Torma

Part Number: TMUX1204
Other Parts Discussed in Thread: TMUX1104, TS3A4751, SN74CB3T3125, SN74CBTLV3126

e2e,

Do we have a 1-4 switch/mux for voltage supplies?

Below picture is what I was trying to solve.

I am looking for a single small IC with either 4 ENs (or 2 ENs) that control switching/muxing of 1 input from an LDO to 4 outputs, where only one output is turned On at a time.

The propagation delay has to be very small.

The output for the LDO needs to go to four separate inputs. Not all inputs need the LDO output at the same time, which is why exploring the 1:4 switch/mux option.

My other option is to use 4 separate LDOs, but again, not all 4 LDOs would be On at the same time; only 1 will be On at a time.

Thank you,

Adam

over 5 years ago

0 Kate Dickson over 5 years ago

TI__Expert 5660 points

Hello,

Thanks for the detailed information and diagram.

What is the LDO voltage and supply voltage? What is the expected continuous current through the switch?

TMUX1104 is a 4:1 mux that may be a good fit for this application due to its low on-resistance and low leakage current. Take a look and let me know what you think.

Thanks!
Kate

0 Ravikiran Deshpande over 5 years ago in reply to Kate Dickson

TI__Prodigy 680 points

For loading on the LDO, assume 25mA, 50mA and 200mA, for now.

TMUX1104 given bidirectional how can we ensure that there is no reverse voltage feedback happening ?

What is the expected voltage drop across these mux parts if output current from the LDO is 25mA or 100mA?

What do R_ON and delta_R_ON represent?

i. Would the voltage drop be: 100mA*1.5ohm = 0.15V ??

Thanks

Ravi

0 Ravikiran Deshpande over 5 years ago in reply to Ravikiran Deshpande

TI__Prodigy 680 points

Aah output of the LDO is 1.8V coming from 3.3V Vin.

0 Kate Dickson over 5 years ago in reply to Ravikiran Deshpande

TI__Expert 5660 points

Hi Ravi,

I do not think that TMUX1104 is suitable due to the absolute maximum source/drain continuous current rating of TMUX1104 is +/-30mA. I will look for a device with up to 200 mA I/O continuous current rating, as most signal muxes support lower continuous current ratings.

You are correct in your use of Ohm's Law, Ron is the resistance inserted into the on-state switch signal path. Delta Ron is the matching of Ron between channels.

TMUX1104 is bidirectional, and the "direction" of the signal is determined by the driving signal (in this case, the LDO).

Take a look at this TI Precision Labs training video to learn more about Ron (on-state resistance of the switch).

You can also use this Multiplexers and Signal Switches Glossary as a reference for all switch parameters and features (such as Ron).

Thanks,
Kate

0 Kate Dickson over 5 years ago in reply to Ravikiran Deshpande

TI__Expert 5660 points

Hi Ravi,

Another configuration to consider is a 4-channel 1:1 (SPST) switch. Searching for this configuration, sorted by low Ron, I found a few options, however none are able to support up to 200mA continuous channel current.

TS3A4751 has lowest typical Ron of this configuration and has a maximum continuous current rating of 100mA.

SN74CB3T3125 and SN74CBTLV3126 both have low Ron and have a maximum continuous current rating of 128mA.

Let me know what you think about these options.

Best regards,
Kate

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TMUX1104: please recommend device to multiplex the output of an LDO to 4 separate loads.