LP5569: LP5569

Navy Gupta

Prodigy 30 points

Part Number: LP5569

Tool/software:

Hi TI Team,

We are using LP5569RTWR in one of our design and having a query related to LED Intensity.

3 RGB LEDs are connected with the LED Driver and we are controlling the brightness of LED using PWM from SW.

We are facing an issue that the PWM signal is not lowing till 0V it is lowing till ~900mV.

I/P supply of LED driver is 3.3V and MISC Register is write as 48h.

Could you please confirm if the PWM low level is its expected behavior or we need to do any modifications.

Attaching images of the signal we are getting while setting 15% duty cycle. Let me know if any further details would be required.

4 months ago

+1 Felix Wang 3 months ago

TI__Expert 5600 points

Hi Navy,

The waveform should be the expected behavior.

The voltage on the output (LEDx) = VLED (supply of LED) - LED forward voltage, normally the LED forward voltage is between 2V to 3V when turned on, which can be found in the LED datasheet. And the LED forward voltage when turned off is about 1V.

So, in this case,

the low level output voltage = 3.3V - LED forward voltage (ON) = ~0.9V.
the high level output voltage = 3.3V - LED forward voltage (OFF) = ~2V

Best regards,

Felix

0 Navy Gupta 3 months ago in reply to Felix Wang

Prodigy 30 points

Hi Felix,

Thanks for the update, got the answer.

0 Felix Wang 3 months ago in reply to Navy Gupta

TI__Expert 5600 points

Hi Navy,

You are welcome.

By the may, may I know who is the customer? And what's the end equipment?

Besides that I'd like to recommend the latest LP5813: 12-channels RGB LED driver with integrated boost and autonomous animation control, but has simple control than LP5569.

Best regards,

Felix

0 Navy Gupta 3 months ago in reply to Felix Wang

Prodigy 30 points

Hi Felix

I can't disclose the customer name here. But we have an end product with multiple application and we have 3RGB LEDs in device to indicate the different operating conditions of device.

We can check the suggested part to. But in current design our requirements are fulfilled by LP5569 LED Driver.

Thanks and Regards,
Navy Gupta

+1 Felix Wang 3 months ago in reply to Navy Gupta

TI__Expert 5600 points

Hi Navy,

Thanks for your information. Let's keep in touch.

Best regards,

Felix

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LP5569: LP5569