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TPS61500: minimum duty for analog dimming

JeffYC Yang
Expert 1290 points
Part Number: TPS61500

Hi,

My customer have TPS61500 current accuracy issue as below.

They using analog dimming as attached file schematic.

But found when duty cycle~ 1%, output current is 0.5%~3% of maximum current(PWM frequency is 30kHz),

is there any method to improve it? Change DIMC pin capacitor? Or it have minimum duty limited for TPS61500 analog dimming?

Ether unplugged Ver_B3.pdf

Thanks!

Jeff

  • 0
    TI__Expert 4550 points
    Hi Jeff,
    For TPS61500, it could support dimmingt to 1%, but the accuracy is not guaranteed. You could find in EC table, only for full output current, the accuracy is guaranteed.
    To improve the current accuracy, you may improve from other factors: improve the accuracy of PWM signal, such as using lower PWM frequency; or use high accuracy feedback resistor. They could be some help.
  • 0 in reply to Caryss Li
    Expert 1290 points

    Hi Caryss,

    What is the EC table? You mean the "Figure 9. Analog Dimming Linearity"?

    So if my customer PWM frequency is fixed, have other way to improve it?(Except feedback resistor accuracy)

    Thanks!

    Jeff

  • 0 in reply to JeffYC Yang
    TI__Expert 4550 points
    Hi Jeff,
    EC table is the Electrical Characteristic table, which lists all the parameters of the device and could be gruanteed.
    I'm afraid there is not much to do to improve it, since the device itself is the main reason.