LP8863-Q1: Relation about EN pin and register

Satoshi

Guru 19645 points

Part Number: LP8863-Q1

Please let me know about EN pin setting below;

・When EN control is unused, is EN pin pullup to VDD no problem?

・If EN to VDD no problem, is below condition on default register setting not to lighting?

　IFSEL pin: Low (SPI)

　SDO_PWM pin: High

　EN pin: High

　⇒When no problem (not to lighting), please let me know about which default register is affecting.

I guess that above condition occur to SDO_PWM pin valid PWM input because default BL_MODE Register is "0h = Brightness controlled by PWM Input", but power up timing is SDO_PWM pin left high level.

Is these understand correct?

Best regards,

Satoshi

over 4 years ago

0 Charles-Chen over 4 years ago

TI__Genius 11836 points

Hi Satoshi,

Can you provide the power up sequence through waveform? Actually, we have requirements for power up sequence.

0 Satoshi over 4 years ago in reply to Charles-Chen

Guru 19645 points

Hi Chen

Thank you for reply,

I will confirm to sequence waveform, please wait a few days.

Sequence image is attached below, and current LED is not lighting on start up timing.

If there possibility to problem, please let me know.

Best regards,

Satoshi

0 Charles-Chen over 4 years ago in reply to Satoshi

TI__Genius 11836 points

Hi Satoshi,

OK. By the way, you can read back all the fault register for analysis.

0 Satoshi over 4 years ago in reply to Charles-Chen

Guru 19645 points

Hi chen

I confirmed waveform and register, but I didn't get because the reason of customer's confidential.

First of all, please let me confirm about below and default register condition problem or no problem.

　IFSEL pin: Low (SPI)

　SDO_PWM pin: High

　EN pin: High (Pull-up to VDD)

Or, is there same (EN to VDD pull-up) example case?

Best regards,

Satoshi

0 Charles-Chen over 4 years ago in reply to Satoshi

TI__Genius 11836 points

Hi Satoshi,

If you pull EN and PWM always high, the device are supposed to still work normally. But we recommend to do as required in the datasheet since that power on and power off timing sequence have been verified.

0 Satoshi over 4 years ago in reply to Charles-Chen

Guru 19645 points

Hi Chen

I apologize my reply delay.

I understood that SDO_PWM pin: High on SPI condition is normal startup operation.

And EVM can choice EN pullup to VDDIO, customer will refined EN pullup to VDDIO.

By the way, when set EN: High and PWM: Low on startup timing, is these condition possibility to light up during startup?

Best regards,

Satoshi

0 Charles-Chen over 4 years ago in reply to Satoshi

TI__Genius 11836 points

Hi Satoshi,

The output channel will not open and the LED string can't be lighted up during startup.

0 Satoshi over 4 years ago in reply to Charles-Chen

Guru 19645 points

Hi chen

Thank you for reply,

I understood that no problem (no light up) for power up timing.

Sorry for additional question, is power up and complete register setting also no problem?

(Between power up ⇒ default register ⇒ setting register)

I didn't find the flow condition for SDO_PWM: High with SPI below.

If no problem, please let me know where these notice on datasheet or application note.

(I guess that Red line is default flow and I2C setting will light up, SPI setting is unknown)

Best regards,

Satoshi

0 Charles-Chen over 4 years ago in reply to Satoshi

TI__Genius 11836 points

Hi Satoshi,

For SPI interface, the output channel still can't be on even if the default brightness_mode is PMW input. I have already checked the internal circuit for you.

0 Charles-Chen over 4 years ago in reply to Charles-Chen

TI__Genius 11836 points

Hi Satoshi,

Do you have any other questions?

0 Satoshi over 4 years ago in reply to Charles-Chen

Guru 19645 points

Hi Chen

Above questions for LP8863 was cleared.

Thank you for support and checked the internal circuit.

Best regards,

Satoshi

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LP8863-Q1: Relation about EN pin and register