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TPS7A84: Control ANY-OUT by MCU/FPGA

Eli Hait54
Prodigy 240 points
Part Number: TPS7A84

Hello,

Is it possible  to control Vout of TPS7A84/TPS7A84A by MCU by tying the ANY-OUT pins to GND using Analog Switch? Or directly connecting Open Drain Digital Output?

What are requirements for such control signals?

Thanx,

Eli.

  • 0
    TI__Genius 14245 points
    Hi Eli,

    Yes, the ANY-OUT feature of the TPS7A84 family allows the output to be set using an MCU. The only requirements are that the ANY-OUT pins should be pulled as close to 0V as possible when pulling them low (the output accuracy will be affected if they are not pulled to 0V), when they are being pulled high they should not be pulled up above the voltage on OUT, this could be tricky if pulling them up to a voltage instead of simply floating them due to Vout=0V at start up. Also note that when the device is enabled there is no way for the device to pull the output down, so if you change the output to a lower voltage the output will only decrease due to the load on the output, if this load is very low then this could take a significant amount of time depending on the difference between the initial output voltage and the newly set output voltage.

    -Kyle
  • 0 in reply to Kyle Van Renterghem
    Prodigy 240 points

    Thanx, Kyle.

    I consider to connect SPST Analog Switches (or MOSFET) to GND to each ANY-OUT signal. Can you tell what maximum Ron value will do the output voltage programming to precision of 1.5%-2%? 

  • 0 in reply to Eli Hait54
    TI__Genius 14245 points

    Hi Eli,

    I think using a switch to ground should have a minimal impact on the accuracy regardless of the switch used. The smallest resistor value used in the ANY-OUT configuration is 6.05 kOhm so to get a 1.5% error would require an switch with an Ron=90.75 Ohm.

    -Kyle