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DLPA2005: How are the SENS1 & SENS2 inputs to be used?

Part Number: DLPA2005
Other Parts Discussed in Thread: DLP2010,

Hi All,

I am designing a projector application using the DPLC3470, DLP2010 and the DLPA2005 for high-speed 3D imaging.  Most of the circuitry from the reference DLP2010 design makes sense but there are a couple of things I haven't yet figured out -- the use of DLPA2005's SENS1 and SENS2 inputs.

The reference schematic shows a thermistor and passive resistor network interfacing to the SENS2 input.  So that makes sense.   But I am confused by the connector J3, which presumably allows an external thermistor to monitor temperature at some other physical location.  Wouldn't an external thermistor bias the resulting readings substantially lower (that without it) and distort the readings?  This is quite confusing since the reference design mention any use of this connector (J3).

More confusing is the use of the SENS1 input.  The literature refers to it as a light sensor input, which is for white-point correction, but again it  is not used in the reference design.  Further, there are two external connectors (J4, J5), I guess for photodiodes/phototransistors to monitor the projector LEDs.  Since there is no mention in the documentation of how they are used, does this mean there is no monitoring of the LED drive light output?  Are these optional features that typically don't need to be used?

Thanks for your help.

Best regards,

Scott

  • Hi Scott,

    SENS1 is used for light sensor but there is no inbuilt sensor to measure the light output for WPC and LABB, So j4 and j5 external connectors has been provided to install the external photodiodes (as you already mentioned). Yes these are optional features.

    SENS2 is used for thermistor, In reference design thermistor is inbuilt installed, and providing th SENS2 signal to DLPA2005 (In this case you can measure the thermistor output by probing the pins on J3), but if someone wants to use the External thermistor they can use it on external connector J3 (but in this case you need to remove the R21 ).

    I hope this helps your query.

    Thanks,
    Navneet
  • Thanks Navneet, just what I was looking for.

    Scott