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TS5A3359: Safe Power-Up Conditions for COM

AP
Intellectual 370 points
Part Number: TS5A3359

Hello,

regarding the TS5A3359 analog mux,
is there a "safest way" to have no-glitch on COM during power-up?
E.g. assume the COM options should be passing either 5V, 3.3V or 0V (GND) to COM (depending on IN1 and IN2).
So VCC has to be 5V and the 3.3V should be generated from the 5V supply (3.3V ramp later than the 5V ramp).
Now when the power-up default setting should be to pass 0V to COM and we don't want to see any voltage level >0V on COM during power-up,
would the best option be having the 0V at the NO2 input and to have pull-ups to VCC (5V) on IN1 and IN2?
There doesn't seem to be any kind of UVLO, so may the switch briefly turn on NO0 or NO1 to COM during the VCC ramp-up (even with having 5V pull-ups on IN1 and IN2)?

Thanks

  • 0
    TI__Mastermind 23373 points

    Hey AP,

    Are you currently seeing a glitch or just looking for advice on best practices? 
    I wouldn't expect to see a glitch but as you power the device up the whichever channel is selected via the control inputs will determine where it starts. Given your scenario with this device, best practice would be to pulldown the IN1 and IN2 so that the COM to NOx connection is off during ramp up. So you'll be in this state:

    There isn't a UVLO in the datasheet but there will still be one. Given the supply recommended operating conditions is 1.65V to 5.5V, I would assume that the UVLO is closer to 1V. VIH and VIL are dependent on the supply voltage though, so I wouldn't try to ramp up on one of the NOx channels. Ramp up in the off state. 

    Thanks,
    Rami