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TPS92690: power led driver

Fabrizio Borra
Prodigy 30 points
Part Number: TPS92690
Other Parts Discussed in Thread: TPS92691, TPS92692

I'm designing a power led driver. The white led array is composed by 20 parallel rows each row with 10 led in series. Total current 6A and array voltage 34 V. I need to dimmer the light with external digital PWM signal.

I found 3 IC:

TPS92690
TPS92691
TPS92692

My question is

TPS92690 is a controller, so the current depends on external components, so why in the datasheet the description says that is suitable for currents up to 5A, where is the limitation?
This controller uses only 1 MOS for current control, there is no PWM mos on the load. Why?

TPS92691 uses 2 MOS instead of only one of the TPS92690: Is it a better solution?

TPS92692 uses an High side PWM P channel MOS instead of a Low side N channel PWM MOS: what is the advantage of this solution?

Thank You

  • 0
    TI__Expert 3885 points

    Hi Fabrizio,

    Depending on the main switching MOSFET's characteristic and the gate driver capability, all 3 devices can support output current above 5 A in theory.

    The key differences of the 3 devices are listed as follow:

    1. TPS92690 -- basic low-side NFET controller with current sensing resistor connecting at LED cathode to ground.

    2. TPS92691 -- low-side NFET controller with current sensing resistor connecting either at LED cathode to ground or LED driver output to LED anode. The other NFET is being used in PWM dimming, but this NFET must be connected between LED cathode and ground.

    3. TPS92692 -- low-side NFET controller with current sensing resistor connecting at LED driver output to LED anode (highly recommend). The other PFET is being used in PWM dimming and it must be connected through CSN to LED anode.

    TPS92692 provides a better solution for customers who must have LED cathodes connected to ground. And, the PFET can be a protection in case output short to ground in a boost configuration.

    Thank you very much!

  • 0 in reply to Issac Hsu
    Prodigy 30 points

    Thank You for Your answer.

    My project is in progress and is not an automotive project, so the LED cathode connected to ground is not  must.

    So I think that the proper IC for me could be TPS92691.

    Do You agree?

    Can I project the driver with this component with the help of webwnch?

    Best Rregards

    Fabrizio Borra - Lupo srl

  • 0 in reply to Fabrizio Borra
    TI__Expert 3885 points

    HI Fabrizio,

    TPS92691 is a good choice for your application.

    I believe we have PSPICE model available on web for this device, however, I'm not sure if Webench support this device.

    Thanks!

  • 0 in reply to Issac Hsu
    Prodigy 30 points

    Thank You

    Best Regards

    Fabrizio Borra - Lupo srl