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Original question:

DLP5530S-Q1: RGB LED connection

DLP5530S-Q1: 'LED_ANODE_DIVIDED' voltage level according to LED q'ty.

Jin Cho
Prodigy 180 points
Part Number: DLP5530S-Q1
Other Parts Discussed in Thread: TPS99000-Q1

Tool/software:

If we used  LED  Osram Q7WP that has 2 LED chip in a LED package to improve brightness,

you said there was no change in reference design.

In your reference design, the 'LED_ANODE_DIVIDED' is connected with TPS99000-Q1 ADC_IN1.

If 1LED chip is applied,  'LED_ANODE_DIVIDED' voltage level is about 0.46V.

Our design, 2 series LED are applied, do we need to change resistor value in below schematic?

  • 0
    TI__Expert 6155 points

    Hello Jin Cho,

    Let me reach out to a more experienced member of my team to get back to you.

    Expect an answer in the next couple business days.

    Thank you!

    Aaron

  • 0
    TI__Expert 3940 points

    Hi again Jin,

    As Fizix and Jason have previously said, using the newer Q7 LED in place of the Q8 LED that TI uses is essentially 2x the LED as using a Q8.

    You must ensure, as Fizix has mentioned, that you do not lower the voltage to the LED Driver.

    The minimum voltage on the LED Driver's high side should be...

    •  VDriver,H = VMargin + 2*VForward,Typical

    •  VDriver,H =  (1 V) + 2*(2.95 V)

    •  VDriver,H ~= 7V

    The voltage divider you have circled above may or may not have to be changed depending on your input voltage there. The purpose of it is to limit the voltage divider (LED_ANODE_DIVIDED voltage) to a level under 1.6 V.

    If you have 7 V driving the high side, the voltage divider equation would give (10 / 72) * (7) V ~= 972 mV. This gives 972 mV < 1.6 V.

    In short, you should not need to change this unless you are applying more than 11.5 V on the high side.

    Regards,
    Michael Ly