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DDC232: SOME PROBLEMS

Mojtaba pourdara
Prodigy 230 points

Part Number: DDC232

Hi

I have some problem with ddc232.

1- does the inputs need any additional protection circuit?

2- to connect photodiode to the ddc232's input ,does it need any highpass or lowpass filter?

3- what does changing master clock (CLK) do? if we change the frequency which properties will be changed?

  • 0
    TI__Guru 50036 points

    Hello Mojtaba,

    Regarding your questions on DDC232:

    1. The device has internal ESD protection at the inputs. But if you need more at the system level, you could add them but these will take up space and there is also the risk for leakage. Typically our CT customers connect the PD arrays directly to the inputs all internal within the system, hence there had been no need for additional protection.
    2. We have never seen anyone using a filter in front between the detector and device. There is a need to keep the input capacitance low as it affects the transfer function for the amplifier noise sources increasing their effects. Additionally, the series resistors add noise plus there is also the need to keep the input impedance low as you want the sensor current to flow into the device, etc... So, folks simply focus on keeping the signal from the detector as clean as possible, to begin with.
    3. The device ADC conversion process and the internal state machine controlling the 2 modes of operation, continuous and non-continuous mode, is primarily the function of the system clock (CLK) speed.