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TPS99001-Q1: LS_SENSE(N/P)

Samson Lee
Prodigy 205 points
Part Number: TPS99001-Q1
Other Parts Discussed in Thread: TIDA-080007

Hello.
Currently evaluating the LED Driver control signal (white LED) for DMD headlights.
The "LS_SENSE(N/P)" signal is included in "Figure 8-1. Headlight System Block Diagram" of the TPS99001-Q1 spec.

But the HL_Driver of the DLP5531Q1 EVM is not used. What is the purpose and function of the "LS_SENSE(N/P)" signal in the headlight application? Is it a necessary signal?

In addition, the three groups of LED Drivers in the HL_Driver circuit diagram use the same components, but why is the maximum output voltage of LED_Driver_0 (12V) different from the other groups (4V)?
Thanks

  • +1
    TI__Mastermind 27780 points

    Hello Samson,

    The LS_SENSE feature is specific to a HUD application, which is why the DLP5531Q1 HL Driver EVM does not utilize these signals, but it can still be optionally monitored in a headlight application. Our default simplified recommendation per the TIDA-080007 DLP® auto headlight reference design is to ground and not use the LS_SENSE_P/N pins.

    In the event you do decide to use the LS_SENSE feature, take note of the datasheet comments: "The TPS99001-Q1 uses a sense resistor to measure the current delivered to the LEDs. These differential sense lines are the inputs to the part LS_SENSE_P and LS_SENSE_N. It is important to notice that although LS_SENSE_N may be electrically connected to ground by the netlist, this signal must be routed as a separate trace to prevent it from being affected by changes in the ground plane."

    All three LED_Driver_0/1/2 channels can support the same 12V at 8A output .The three LED drivers can support a variety of LED configurations given that the total power (LED forward voltage drop, LED maximum current, efficiency, etc.) does not exceed 96W (16V, 6A max) delivered from the buck/boost pre-regulator. The values in the HL_Driver schematic show examples of various configurations that can be supported, not the limits.