TPS61194: Varying Output current observed

Rushi Gajjar

Intellectual 765 points

Part Number: TPS61194

Hello E2E,

During the characterisation test of TPS61194

Test Conditions:

Input Voltage=12V

RIset = 49K , Rfset = 160K , PWM=100%, Feedback: R1= 470K, R2=130K

Vout = 15V, Iout = 50mA per channel.

Observation: Current Measured through Anode is going low every 9.8 seconds. Despite this drop duration being longer (About 1.5Seconds), we are not observing any perceivable brightness change in the LED brightness. Attached waveform for your reference.

Is this the expected behaviour? I couldn't find any mention in the datasheet about this.

over 6 years ago

0 Sean Zhou over 6 years ago

TI__Mastermind 22745 points

Hi Rushi,

Please add the waveform of "PWM" and "Fault", I want to make sure is there any faults occurs.

Regards

Sean

0 Rushi Gajjar over 6 years ago in reply to Sean Zhou

Intellectual 765 points

Hi Sean,

Thanks for the reply.

My primary check shows that the Fault is not reported and PWM is stable, I do not see any variation in the backlight brightness as well. I will aid you with the waveforms as soon as possible.

0 Sean Zhou over 6 years ago in reply to Rushi Gajjar

TI__Mastermind 22745 points

Hi Rushi,

Ok, let's look at the waveforms when you get it.

Regards

Sean

0 Rushi Gajjar over 6 years ago in reply to Sean Zhou

Intellectual 765 points

Hi Sean,

I figured out that the Oscilloscope sampling is causing this beyond 100ms timescale. This seems not to be a part/design issue. We can close this thread.

Power management

Power management forum

TPS61194: Varying Output current observed