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TIC12400-Q1: tic12400-q1 comparator (input pin with component and floating)

Jeff Wang100039
Intellectual 1860 points
Part Number: TIC12400-Q1

Hi,

Tic12400-q1 inx external circuit: 10nf cap +1k resistor+10nf cap ,

wetting current set to 0.

comparator  threshold level set to 4V.

measurement inx pin voltage close to 1V.

but comparator output is high.!!!!, what reason for that?

if input voltage form 0 to 5V (inx pin), then <4V, comparator output is low, >4V comparator output is high.

best regards,

jeff wang

  • 0
    TI__Mastermind 23830 points

    Hi Jeff,

    Can you provide all of the values of the configuration registers you are using (addresses 0x1A to 0x32)?  I can assume that any registers you don't provide are still in their default state.  Can  you also provide the relevant status registers such as the INT_STAT and INT_STAT_COMP to see the same status you are seeing?  This will help determine whether this is a configuration or hardware issue.

    Why are you using 0mA (or no wetting current)?  Are you providing an external voltage on the pin that you are trying to sample?  Or are you using some sort of switch and if so, is it a switch to the supply voltage, or a switch to ground?

    If you are not providing an external voltage and current source to the input, then you will likely need to use some amount of wetting current in order to create a voltage difference between an open and closed switch state. 

    Regards,

    Jonathan

  • 0
    TI__Intellectual 1860 points

    Hi  Jonathan,

    following is the register setting:

    address

    value

    1Dh-1Eh

    0h = no wetting current

    21h

    3h = comparator threshold set to 4V

    22h-23h

    0h = no interrupt generation for IN11

    24h

    1h = INT pin assertion due to SSC event enabled

    32h

    0h = comparator mode for INX

    addresses 0x1A to 0x32，other use default

    we are not providing external voltage on the pin, the pin are floating.

    this pin have two state: short to battery(related function enable), floating(related function disable).

    customer expect floating state, comparator output is low.

    In floating state, wetting current is 0, comparator threshold set to 4V, comparator output is high.

    best regards,

    jeff wang

  • 0 in reply to Jeff Wang100039
    TI__Mastermind 23830 points

    Hi Jeff,

    I noticed that the Input Enable (IN_EN) register 1Bh was not set and by default all Input Pins are Disabled.  Can you have them set the IN_EN_x bits for the input pins they are using?

    Can you also explain the reasoning for 0mA wetting current?  This could potentially be problematic if a voltage is supplied on the pin, but there is no current sink enabled.  When the voltage is supplied, the capacitors will charge, but there is not a current sink to discharge that voltage when the input is floating.  The voltage from the caps could hold a positive voltage on the input pin after the input is no longer connected to the voltage source and give false readings.

    Regards,

    Jonathan