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msp430g2553 driving tps22966

Andres Rodriguez
Intellectual 520 points
Other Parts Discussed in Thread: TPS22966

Good day,

I want to use the tps22966, but I can not see in the datasheet the proper way to connect it to a msp430g microcontroller, I mean, can not find the info about the current input, if I need a transistor to do not force the output current in the microcontroller GPIO. The source will work at 3.3 volts

I have this in the page 5 of the datasheet.

Thanks

  • 0
    Guru 227245 points

    If you don’t need to drive any current (high-impedance inputs), you can simply add a series resistor in the signal line. Using 4k7 will give a current of 0.2mA per V signal difference. The MSP input pins can bear up to 2mA. However, the voltage must not be too different, so the one with the higher I/O voltage will consider the lower one still as high.
    Alternatively, you can us a combination or diode and pull-up to signal from a high-voltage output to a low-voltage input. On the input side, pull the line to the (lower) input side’s VCC, and put the diode so that the output side can only pull it low. This virtually makes the high-voltage output an open collector output.
    However, this won’t work for a very-low-voltage output to a high-voltage input. Here you’ll need a Darlington transistor or something similar.

    But in your case, the 2.5V output of the TPS will be considered as high on the 3.3V MSP (high-going threshold <= 0.7*3.3=2.31V). No interfacing needed at all. While for the opposite direction (MSP to TPS), you can use the pull-up/diode version.

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