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TSC2046E: If the power supply of TSC2046E should be isolated from the digital part?

user4999129
Intellectual 550 points
Part Number: TSC2046E
Other Parts Discussed in Thread: TSC2046

Hi, everyone:

I am planning to use TSC2046E and I am confused about the power supply. Here is a connection diagram from datasheet.

It seems that this design does not distinguish analog power from digital power. The chip contains AD and also includes the SPI bus interface. In my opinion, the former belongs to analog circuits, and the latter belongs to digital circuits.

The power supply pin of the AD sampling section is VCC and GND, and the power supply port of the SPI bus section only sees IOVDD, then its ground should also be GND. In this case, the chip itself does not isolate the two inside, does this really matter?

  • 0
    TI__Mastermind 22950 points
    Hello user4999129,

    The TSC2046 enables the user to have different supplies, the +Vcc supply which feeds the core circuits (MUX, SAR, Temp Sensor, int reference) and the IOVDD supply which feeds the I/O digital interface buffers.

    Having different supplies allows the user to set the TSC2046 threshold I/O levels to match that of the microcontroller, independently from the analog supply circuitry.

    It is possible to use the same voltage supply for both IOVDD and +Vcc, provided that the supply voltage is above 2.7V to meet the specified performance in the electrical characteristics table. It should be noted that care must be taken to use a low noise, well bypassed voltage supply. The +Vcc supply feeds the analog circuitry and therefore should be low noise.

    In general, 1uF- to 10uF bypass capacitors are recommended to be placed in close proximity to the +Vcc pin, and another 1-10uF bypass capacitor will be installed in close proximity to the IOVDD pin. The GND pins should also remain at the same potential.

    Please let me know if you have any additional questions.

    Best regards,
    Aaron
  • 0 in reply to Aaron Estrada
    Intellectual 550 points

    Hi, Aaron:

    In order to provide a relatively clean power supply, I intend to use the LDO to power the TSC2046 separately. The current solution is as follows：

    Is it OK?

  • 0 in reply to user4999129
    TI__Mastermind 22950 points
    Hello user499129,

    An LDO is a good choice. I would make sure that you use one that has an excellent transient response to help keep the noise as low as possible.

    You should make sure you are using the recommended capacitor types at the input and output. Also, the resistor between GNDA and DGND should be placed in close proximity to the TSC2046.

    Best regards,
    Aaron