TPS61165: Led driver don't turn off.

Luan H Alves

Part Number: TPS61165

Hello,

I'm using the TPS61165 to drive six parallel LED, and I would like to be able to control the LED via PWM ( ON, OFF and brightness light). However, the led driver is always on.

Any suggestions appreciated.

over 6 years ago

0 Sean Zhou over 6 years ago

TI__Mastermind 22745 points

Hi,
From your schematic, your inductor is 10mH? that should be too large, it shoulbe be 10uH.
Regards
Sean

0 Luan H Alves over 6 years ago in reply to Sean Zhou

Prodigy 70 points

Hi,

Sorry for my mistake, the value of the inductor is wrong on the schematic, I am using a 10uH inductor as specified in the datasheet.

Component list:

D1: MBR0540T1G

C1: 4.7µF, 10V, X5R CL10A475KP8NNNC

C2: 220nF ±20% 6.3V GRM033R60J224ME15D

C3: 1µF, 10V, X7R CL10B105KP8NNNC‎

R3: R1 0.3Ω, 0.5W, 1% RL1632R-R300-F

L1: 10µH, 1.49A #A915AY-100M=P3 murata

LED: LXML-PB01-0030

0 Sean Zhou over 6 years ago in reply to Luan H Alves

TI__Mastermind 22745 points

Hi ,
what's your meaning about the "Led drive ris always on"?

0 Luan H Alves over 6 years ago in reply to Sean Zhou

Prodigy 70 points

I meant that the LED Driver does not switch off the LEDs. Even if the CTRL low or high or PWM signal, the Led driver is switched on.

0 Sean Zhou over 6 years ago in reply to Luan H Alves

TI__Mastermind 22745 points

Hi Luan,
That's should be impossible, can you provide the wavefrom when it can't control the led driver with "CTRL""SW""Vin""Vout"?
Regards
Sean

0 Luan H Alves over 6 years ago in reply to Sean Zhou

Prodigy 70 points

Hi,

Below are the waveforms.

Yellow - SW

Green - CTRL (low)

Yellow - Vin

Green - CTRL (low)

Yellow - Vout

Green - CTRL (low)

Even when "CTRL" is HIGH or using a PWM signal the waveforms are the same as shown above.

0 Sean Zhou over 6 years ago in reply to Luan H Alves

TI__Mastermind 22745 points

Hi Luan,
I know the issue now, you can't parallel connect the LEDs, you need to connect serially. Since TPS61165 is a boost led driver.
Regards
Sean

0 Luan H Alves over 6 years ago in reply to Sean Zhou

Prodigy 70 points

Hi,
that was the issue.

Could you recommend a led driver that can parallel connect the LEDs?

Thanks for your help!

0 Sean Zhou over 6 years ago in reply to Luan H Alves

TI__Mastermind 22745 points

Hi Luan,

For your application and spec, I suggest you using the sepic topology of TPS61165, you can find the reference circuit in datasheet.

Regards

Sean

0 Luan H Alves over 6 years ago in reply to Sean Zhou

Prodigy 70 points

Hi,

I have tested the TPS61165 using the SEPIC topology but does not work with LEDs in parallel. The LEDs keep on with CTRL low.

In my application, I'm using 2 LED Driver with 2 blue LED (LXML-PB01-0030) in parallel per Led Driver and 1 LED Driver with 2 red LED (LXM2-PD01-0050) in parallel for the high intensity of light, and with LEDs connect serially isn't possible to reach the needed high intensity.

LEDs :LXML-PB01-0030 (blue)

:LXM2-PD01-0050 (red)

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TPS61165: Led driver don't turn off.