0
\$\begingroup\$

I want to control an LED using LED driver (LED2000 in STEVAL-ILL051v2 is used for my project).
When the LED driver is powered on the output is 0. Then I tried changing the DIM input (PWM here) linearly using a Raspi PICO microcontroller.
I tried measuring the voltage using multimeter. When the input to the PWM is around 2.3 V, the current suddenly shoots up to the maximum possible value.
How can I control such that the current may not shootup at the start, because if I have LEDs connected the driver might then fry the LEDs.

So there are 5 pins in the STEVAL-ILL051V2. The IN, GND Vled+, Vled- and DIM.
I have IN and GND connected to +5V and ground respectively. The +5V source can provide upto 10A (50W).I connected the Vled+ and Vled- across a power resistor. I measured the current through the power resistor. I didnt want to burn the LED because they were expensive.

enter image description here

\$\endgroup\$
2
  • 2
    \$\begingroup\$ Which current shoots up? How are you measuring it? Please edit your question with additional details, and a schematic of what you have connected where. \$\endgroup\$
    – brhans
    Commented Jul 18, 2023 at 8:42
  • \$\begingroup\$ Can you have a look now? have updated detials \$\endgroup\$
    – Paul Jose
    Commented Jul 18, 2023 at 8:50

1 Answer 1

1
\$\begingroup\$

When the input to the PWM is around 2.3 V, the current suddenly shoots up to the maximum possible value.

The input pin is digital: it sounds like that it the point at which it's crossed a "1" threshold.

Now, that's because you're discussing the input PWM as if it was an analogue signal. It will in fact be a waveform - a series of pulses with a frequency and duty cycle. You haven't told us what that detail is.

I suspect the PWM frequency is simply too high. There is some discussion of this in the datasheet for the LED2000. Try 200Hz or 1kHz at, say, 10% duty cycle to start with.

\$\endgroup\$
4
  • \$\begingroup\$ Hi! thank you for the reply I am using frequency of 30 KHz and is varying duty cycle from 1 to 100%. This high frequency is so as to not interfere with the other signals. But I will try lower frequency and see if it changes something! \$\endgroup\$
    – Paul Jose
    Commented Jul 18, 2023 at 9:06
  • \$\begingroup\$ Hi I tried your solution and it works! but how can I run it at higher frequeuncy? \$\endgroup\$
    – Paul Jose
    Commented Jul 18, 2023 at 11:10
  • \$\begingroup\$ If the LED2000 chip does not work at higher frequency then .. you can't? Unless you swap that for something that does support that. \$\endgroup\$
    – pjc50
    Commented Jul 18, 2023 at 12:03
  • \$\begingroup\$ It works at higher frequency of 30KHz. The ony problem is that at startup there is an in rush current, which amounts to the maximum current possible by the LED driver. It is possible to control the current thereafter but this inrush current might damage the LED. \$\endgroup\$
    – Paul Jose
    Commented Jul 18, 2023 at 13:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.