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LMH32401: Input impedance of LMH32401 with enable pin high

Part Number: LMH32401

Can I de-activate the transimpdance amplifier by driving the enable pin high? What will the input impedance be for fast pulse currents (in the 10ns to 50ns range)? In other words, will the input load the detector for fast pulse currents? Will the 100mA clamp still be active? I want to divert the current to another amplifier with low gain to extend the dynamic range.

Is it possibe in the above case to still  activate the DC cancellation, while I de-activate the amplifier?

Does the SPICE model support this functionality, so that I can test by simulation?

Your help will be appreciated.

  • Hello AJ,

    Please refer to the following:

    "When the amplifier is in its low-power mode, the clamp circuitry is still active thereby protecting the TIA input. The ambient light cancellation loop is disabled when the amplifier is placed in power-down mode. When the LMH32401 device is brought out of power-down operation the ambient light cancellation loop requires several time constants to settle. Figure 9 shows the low-frequency loop response which in turn determines the time constant needed for the loop to settle."

    The SPICE model likely won't match this functionality.


    Hasan Babiker