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ADP5587 Key Matrix

Question asked by Mochi on Sep 14, 2017
Latest reply on Sep 18, 2017 by Mochi

I have a question about ADP5587.
My customers are considering ADP5587 as Keypad Controller.
My customers want to install and arrange damping resistors and filters in the key matrix.
Please give me some advice for my customers to design the key matrix.


1) Do you have any advice on installing damping resistance or RC filter?
    My customers are concerned that overshoot and undershoot will hurt the circuit.

2) How accurate is a 100 kΩ pull-up resistor?
     How much do we have to prepare for variations?

3) How accurate is debounce time 275 μS?
    My customers are trying to improve accuracy and method by adding elements.

    I recognize that the debounce function is for the key matrix not to be pressed by noise.
    Is there any other significance to the debounce function?

4) How accurate is the key scan period?
    Does the key scan cycle vary with temperature and operating voltage?
    My customer is trying to estimate the impact of key scan.

5) How long does it take for the device to generate an interrupt after the key matrix recognizes the press?


6) Are there any documents on internal state machines that operate the key matrix?


Best regards