AD5413 - capacitive load

What capacitive load can the AD5413 drive in current output mode?

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  • +1
    •  Analog Employees 
    on May 6, 2020 11:20 AM

    The relationship of capacitance and current with a current source is I = C * dU/dt -> dU/dt = I/C.

    In current output mode, there will be no issue driving large caps (they look like a short to ground when initially connected and then charge as above)

    If there is no load resistance then eventually the output driver will charge the capacitor all the way to the headroom of the current output driver and the open circuit alarm will assert.

    If there is resistive load (as is usual/necessary for current output), then the output will go to Iout x Rload but only after the cap has charged to that level.

    If the current is removed the capacitor discharges through the resistor.

Reply
  • +1
    •  Analog Employees 
    on May 6, 2020 11:20 AM

    The relationship of capacitance and current with a current source is I = C * dU/dt -> dU/dt = I/C.

    In current output mode, there will be no issue driving large caps (they look like a short to ground when initially connected and then charge as above)

    If there is no load resistance then eventually the output driver will charge the capacitor all the way to the headroom of the current output driver and the open circuit alarm will assert.

    If there is resistive load (as is usual/necessary for current output), then the output will go to Iout x Rload but only after the cap has charged to that level.

    If the current is removed the capacitor discharges through the resistor.

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