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TPS92512: LED flickering problem
Part Number: TPS92512
i am using TPS92512 ,for dimming purpose
i am using 24v supply and 4 X20 led matrics (4 series)
i get the flickering during the period when current in between 600mA and 800mA
i am using the same circuit given in the data sheet please give me a solution
total voltage 24
volatge across led 11V
no of led series 4
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In reply to Irwin Nederbragt:
we are varying duty cycle from 0 to 100% at frequency 500 Hz
Vin is 24 V
indiactor current 0-3mA
we are getting smooth dimming if risense is high value lke 1ohm but the current is low like 350mA
our application needs atleast 1A maximum
flickering occures when current is between 750mA anf 800mA, we dont have problem when current in between
0-500mA and 800mA-1A which is between duty cycle 60-80%
In reply to Jishnu Prakash Nambiar:
It sounds like possibly a noise issue. I cannot help without oscilloscope pictures showing waveforms asked for above. I also don't know what indiactor current is? If this is inductor current, 0-3 mA with a 800 mA current set point will not work.
hi this is image of Vin at 50% PWM
Vled at 50% PWM
these noises appear when the flickering occurs else it is perfect DC
Doesn't matter, the input should not do that. Or let me rephrase, the flickering occurs when the noise appears. If the input moves that much it will flicker. BTW can you get oscilloscope pictures of Vin with the correct voltage range. I don't think your input is near 125 volts so I don't know if you have an offset or the V/div is wrong. If it is there is too much impedance which can cause instability. I can see instability in the waveforms. Get a low impedance power source and see what happens, or bypass your EMI filter if that's what is causing this.
vin when pwm signal is not applied sorry for image quality
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