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Original question:

TPS7A85: configuring Output voltage by ANY-OUT Programmable pins.

TPS7A85: ANY-OUT configuration

nikhil sankar
Prodigy 50 points
Part Number: TPS7A85

The above design as per webench tool doesn't connect from SNS to ANY-OUT pins for 0.925V output.

Is it issue with the tool , please comment on this.

  • 0
    Prodigy 50 points

    please review my resign and comment, FB resistors are BOM-NO (not mounted) .

  • 0 in reply to nikhil sankar
    TI__Expert 4120 points

    Hello Nikhil,

    Thanks for bringing this to our attention. Not sure if it is an issue with the tool, but I will let our team know. 

    For your designs below here are my comments:

    -First design:

    1. The way the ANY-OUT voltage pins are connected the output is programmed to 0.925V.

    2. When using Vbias a 10uF capacitor must be connected between Bias pin and GND.

    3. When a Vbias is used, there are sequencing requirements that need to be met. The sequencing requirement is that Ven must always be high after Vin is established.

    4. There are no input nor output capacitors shown. Please refer to Section 8.1.2 Input and Output Capacitor Requirements (CIN and COUT) of datasheet for more details.

    -Second Design:

    1. Resolution of image is not good, so I was not able to check the capacitors nor feedback resistors values.

    2. For the feedback resistors can see there are two resistors in parallel for R1. It is recommended to just use one resistor of 12.1kOhms to optimize noise and PSRR.

    3. Same as before when a Vbias is used, there are sequencing requirements that need to be met. Please make sure Ven is always high after Vin is established.

    4. Since using the adjustable operation, my assumption is that the ANY-OUT voltage pins and SNS pin are left floating. Is this correct?

    5. If power-good functionality is used it is recommended to have a pullup resistor (10kOhms-100kOhms) to OUT (like connection on webench circuit) to ensure proper operation.

    Best,

    Eunize Tobias

  • 0 in reply to Eunize Tobias
    Prodigy 50 points

    Hi Eunize,

    thanks for the reply.

    Both the snaps i shared is of same design, first one was the top level module (for reusable block) for the IC and second one is the IC symbol and schematic.

    - Design is using ANY-OUT pins 

    - The feedback resistors are there in design as a backup ( its not mounted or present in original design) , so please ignore the feedback resistors.

    thanks,

    Nikhil

  • 0 in reply to nikhil sankar
    TI__Expert 4120 points

    Hello Nikhil,

    Thanks for the clarification, I was a bit confused since from schematic cannot really see where the connections are. If the ANY-OUT pins are connected like the top module then Vout,nom is 0.925V.

    Best,

    Eunize Tobias

  • 0 in reply to Eunize Tobias
    Prodigy 50 points

    Hi Eunize,

    can you comment on the SNS connection? what if it's not connected to the Vout as per the above design?

    thanks,

    Nikhil

  • 0 in reply to nikhil sankar
    TI__Expert 4120 points

    Hello Nikhil,

    If the ANY-OUT connections are used, then connect the SNS pin to the output. By connecting the SNS pin to the 800mV pin it reduces the resolution by 50%. SNS pin can be left floating if ANY-OUT feature is not used.

    Best,

    Eunize Tobias