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DLP5530PROJQ1EVM: DLPC230

Bruce Yang
Prodigy 120 points
Part Number: DLP5530PROJQ1EVM
Other Parts Discussed in Thread: LM25141, LM3409

Hello, now we are going to design the driver board of DLP5530, which is used in automotive electronic products. The working voltage is DC 9V-16V. I see that there is a pre-regulator circuit of LM25141 in the LED driver part, which reduces the input power to 6.5V or 8V, and then inputs to the LM3409 chip. Is this LM25141 pre-regulator circuit necessary? We design whether the input power supply can be directly connected to the LM3409 without using the pre-regulator circuit.thanks

  • 0
    TI__Intellectual 2315 points

    Hi Bruce,

    The provided circuit is provided as a reference that meets necessary automotive use cases.  Additionally, the image quality would be impacted without pre-regulating the voltage.  This is due to the fact that the LED drive circuit delivering exact amounts of energy for the DMD is required to be controlled.  In order to achieve good image quality, then this circuit or one that is very similar is required.  There could be other issues for example, if you had surge voltage (up to 42V in cars) or low voltage during current cranking that would cause other problems.

    If you are not working directly with the battery from a car and have a stable input, then you may be able to select a simpler Buck converter, but we would recommend to keep a buck converter to have a stable LED drive voltage.

    Jason

  • 0 in reply to Jason Thompson
    Prodigy 120 points
    Hi jason Thank you for your answer, I will keep this circuit. There is another question, the power supply of TP9900 chip on DEMO, the input power supply 12V needs to be buck to 3.3V, and then boosted to 6.5V. Is this for timing consideration? Can directly reduce the 12V to 6.5V
  • 0 in reply to Bruce Yang
    TI__Intellectual 2315 points

    Bruce,

    The 12V buck to 6.5V is needed by the TPS99000.  The TPS99000 uses this input to create VRESET, VBIAS, and VOFFSET DMD voltage supplies.  Since we must have 6.5V input, then we decided to use 6.5V to buck down to 3.3V.    This would prevent the need to have additional protection circuitry on the 3.3V buck as well.

    Jason