LP5009: Independent control mode (LP5009RUKR): turning on LEDs

Karol Schulewitz

Prodigy 10 points

Part Number: LP5009

Tool/software:

Our four LED board (photo, below) is configured as follows:

LED 1 (UV): OUT_0
LED 2 (UV): OUT_1
LED 3 (UV): OUT_2
LED 4 (White): OUT_3

Each LED shall display independently in sequence.

These initialization commands are sent via I2C (register / value):

0x00 / 0x40
0x02 / 0x00
0x07 / 0xFF
0x08 / 0xFF
0x0B / 0x00
0x0C / 0x00
0x0D / 0x00
0x0E / 0x00

The OUT_3 command (below) successfully turns ON the WHITE LED 4 individually (photo of WHITE LED 4 ON with UV shield, below).

0x0E / 0xFF

After successfully commanding OUT_3 OFF (WHITE LED 4 OFF, below), all lights display OFF. Next, the OUT_2 command (below) successfully turns ON the UV LED 3 (photos with UV shield, below; first photo, UV LED ON; second photo, UV LED ON masked with tape).

HOWEVER, in error, the WHITE LED 4 also turns ON simultaneously (marked in photos, below; displays RED / PINK? tint).

0x0E / 0x00
0x0D / 0xFF

Thank you for insight into why the independent control commands do not produce the expected results (i.e., turn ON UV LED 3 independently).

Karol S. Schulewitz

over 1 year ago

0 Jared Zhou over 1 year ago

TI__Mastermind 20515 points

Hi Karol,

Can you please show me your layout file?

I totally understood the problem you met, but I can't rebuild the same behavior on the EVM board, so I don't think it's the IC problem. I think the reason might be related to PCB layout, the OUT4 might be coupled by OUT3, then you can obverse the OUT4 ON while you turn on the OUT3. If possible, please capture the waveform on OUT3 and OUT4.

BR, Jared

0 Karol Schulewitz over 1 year ago in reply to Jared Zhou

Prodigy 10 points

Thank you, Jared --

Here is the schematic of the LP5009 interfacing with the LEDs.

Karol

0 Zhiqian Wu over 1 year ago in reply to Karol Schulewitz

TI__Mastermind 31405 points

Our expert will reply you on next Monday

0 Jared Zhou over 1 year ago in reply to Karol Schulewitz

TI__Mastermind 20515 points

Hi Karol,

I think there is no problem for the schematic, please help to capture the waveform for the output.

BR, Jared

0 Karol Schulewitz over 1 year ago in reply to Jared Zhou

Prodigy 10 points

Thank you for the schematic affirmation. Please send sample code for turning ON/OFF each LED individually. Thank you. Also, my waveform snippet is forthcoming.

Karol

0 Karol Schulewitz over 1 year ago in reply to Karol Schulewitz

Prodigy 10 points

Snippet 1 (below) displays all LEDs OFF (3V; line 1, WHITE LED/OUT 3; line 2, UV1/OUT 0 ; line 3, UV3/OUT 2):

Snippet 2 (below) displays WHITE LED ON (line 1, 2.5V; OUT 3); UV1/UV3 LEDs OFF (lines 2/3, 2.8V; OUT0/OUT2):

Snippet 3 (below) displays WHITE LED OFF (line 1, 2.8V; OUT 3); UV1/UV3 LEDs ON (lines 2/3, 2.2V; OUT0/OUT2)::

0 Jared Zhou over 1 year ago in reply to Karol Schulewitz

TI__Mastermind 20515 points

Hi Karol,

Please refer the LP50xx family sample code below : LP5024_MSP430F5529.zip

For the waveform, actually, I want to see the OUT4 turn on in error when OUT2 is ON. But I can't find any waveform about the OUT4. I think your capture waveform is no problem for the OUT1,2,3. But as you can see, when you open the OUT1, the output voltage of OUT2,3 will be coupled down to about 0.2V. And the output voltage of OUT1 will be also coupled down to about 0.2V by OUT2,3.

Please capture the waveform for the error turn on output OUT4 and normal control output OUT2, thanks!

BR, Jared

0 Karol Schulewitz over 1 year ago in reply to Jared Zhou

Prodigy 10 points

Thank you, Jared, for the sample code.

Per our schematic (below), OUT4 is UNUSED/floating.

I suspect we are each referring to the same waveform while using different verbiage. Please note our naming convention: OUT0/pin2 connects to LED1, OUT1/pin3 to LED2, OUT2/pin4 to LED3, OUT3/pin5 to LED4.

The waveform snippet (below; same as in above response) shows LED4/OUT3 (WHITE LED; waveform yellow line 1; 2.8v) in OFF state when LED1/OUT0 (UV1; waveform blue line 2; 2.2v) and LED3/OUT2 (UV3; waveform pink line 3; 2.2v) are ON. We use 100% duty cycle, so line is steady instead of periodic square waves.

Please confirm whether this waveform data is what is needed (i.e., LED4/OUT3 waveform, not OUT4, since OUT 4 is floating/unused).

Thank you, again --

Karol