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Original question:

TLV3604EVM: How to set the comparator threshold on this board

TLV3604EVM: Using the TLV3604EVM as comparator for analogue output from APD

Shaun viola
Prodigy 90 points
Part Number: TLV3604EVM
Other Parts Discussed in Thread: TLV3604

Hi,

I want to connect an APD module to in+ on TLV3604EVM and lowpass filter the APD module and supply that to in- as a threshold which will vary with the DC output of the APD module. I then want the EVM to act as a comparator and output LVDS determined by whether or not the input to in+ is above the threshold in-. I know that to look at the LVDS signal on out+ on an oscilloscope I need to connect a 100 ohm resistor to R4 but I'm not sure what to do with the other resistors, does the board come with 0 ohm resistors as standard and should I just leave these as is?

Cheers,

Shaun

  • 0
    TI__Mastermind 40245 points

    Hi Shaun,

    R1 and R2 are used for force and sense of IN+. The intention would be to connect your square wave source to J2, and through R1 it would be connected to IN+ of the comparator. R2 is used to connect J3 to the node for a scope to take a look at the input signal with minimal loading and distortion. In addition, this configuration allows for the scope to provide 50 ohm termination if applicable to the source of the signal.

    R5 and R6 are used in the same fashion for IN- of the comparator.

    These are all populated initially and are 0 ohms. The only components on the EVM that are not populated are R3 (LVDS termination for the input signal, if applicable) and R4 (LVDS termination for TLV3604, which you are populating). If you are not planning on viewing the inputs on a scope, then R2 and R6 can be uninstalled and left open.

    Also as a note, if you are populating R4 with a 100 ohm resistor, ensure that when you connect the scope to J6 (OUT+) that the channel is set to High-Z.

    Hope this helps.

    Sincerely,

    Gerome