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LP8552: LP8552

Rajesh Kumar72
Intellectual 500 points
Part Number: LP8552
Other Parts Discussed in Thread: LP8556, LP8556TM-EVM

Hello E2E Team,

We are planning to use LP8552 High-Efficiency LED Backlight Driver .

We have got following requirement specs for the backlight LEDs module:

In day mode, operating voltage and current are typically 28.5V and 50mA. In night mode, these are 26.5V and 5mA respectively.

1. We understand that using LP8552 driver, we shall be able to set these two different voltage and current requirements using EEPROM register bits <VBOOST[4:0]> and <CURRENT[7:0]>. Using 15K ohm current limit set resistor and changing the EEPROM register bits <CURRENT[7:0]>, we shall be able to configure 50mA and 5mA driver currents on each output. Is there any limitations on setting the minimum current of 5mA?

2. Out of six channels, we want to use only one for our application and other 5 channels will be left unconnected, is there any issue with this scheme? In this single driver configuration, can driver be operated in automatic adaptive voltage control mode? To meet the night mode brightness requirement, we are thinking of setting the driver current as 5mA and boost voltage expected to adapt the  LED characteristics. Do we have to use DRIVER_HEADER[2:0] EEPROM register bits to change the boost output voltage? 

3. To set 5mA of average current, can we go with PWM method. By setting the peak current of 50mA and varying the PWM duty factor to 10%, we shall able to achieve 5mA of average current without changing the EEPROM register bits <CURRENT[7:0]>. Do you foresee any challenge in this method?

4. Do you have any evaluation board with LP8552 driver for testing the backlight LED module?

Thanks & Regards,

Rajesh Kumar

  • 0
    TI__Genius 13001 points

    HI Rajesh,

    Considering that you need only one channel, how about single channel LED drivers?

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Intellectual 500 points

    Hi Robin,

    I am ok with single channel driver provided it meets our requirements:

    Input voltage : 12V

    Brightness control: PWm/I2C

    we ned boost converter to meet following LED bias voltage requirement:

    In day mode, operating voltage and current are typically 28.5V and 50mA. In night mode, these are 26.5V and 5mA respectively.

    Please let me know if you require additional details.

    Regards,

    Rajesh 

  • 0 in reply to Rajesh Kumar72
    TI__Genius 13001 points

    Hi Rajesh,

    There is no I2C control for single channel LED drivers, but they have EasyScale one-wire interface except PWM control.

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Intellectual 500 points

    Hi Robin,

    In that case we are planning to use LP8552 High-Efficiency LED Backlight Driver .

    We have got following requirement specs for the backlight LEDs module:

    In day mode, operating voltage and current are typically 28.5V and 50mA. In night mode, these are 26.5V and 5mA respectively.

    1. We understand that using LP8552 driver, we shall be able to set these two different voltage and current requirements using EEPROM register bits <VBOOST[4:0]> and <CURRENT[7:0]>. Using 15K ohm current limit set resistor and changing the EEPROM register bits <CURRENT[7:0]>, we shall be able to configure 50mA and 5mA driver currents on each output. Is there any limitations on setting the minimum current of 5mA?

    2. Out of six channels, we want to use only one for our application and other 5 channels will be left unconnected, is there any issue with this scheme? In this single driver configuration, can driver be operated in automatic adaptive voltage control mode? To meet the night mode brightness requirement, we are thinking of setting the driver current as 5mA and boost voltage expected to adapt the  LED characteristics. Do we have to use DRIVER_HEADER[2:0] EEPROM register bits to change the boost output voltage? 

    3. To set 5mA of average current, can we go with PWM method. By setting the peak current of 50mA and varying the PWM duty factor to 10%, we shall able to achieve 5mA of average current without changing the EEPROM register bits <CURRENT[7:0]>. Do you foresee any challenge in this method?

    4. Do you have any evaluation board with LP8552 driver for testing the backlight LED module?

    Thanks & Regards,

    Rajesh Kumar

  • 0 in reply to Rajesh Kumar72
    TI__Genius 13001 points

    Hi Rjaesh,

    1. No limitation.

    2.You can use only one channel and device still works with adaptive control.

    3.This is a normal PWM dimming method and no challenge.

    4.LP8552 has no corresponding EVM, but LP8556 can also meet your requirements and has EVM with two package.

    BR,

    Robin

  • 0 in reply to Yuting Shao
    Intellectual 500 points

    Thanks Robin for your response.

    I will look into LP8556 option and try to come back asap.

    Best Regards,

    Rajesh Kumar

  • 0 in reply to Rajesh Kumar72
    Intellectual 500 points

    Hi Robin,

    I have few queries regarding configuration of LP8556TME-E05/NOPB.

    I have selected above part as we are trying to evaluate the BL driver functionality on our proto board.

    Please clarify the below:

    1. E05 version chip - what is typical no. of erase/write cycles for the in-built EEPROM? Because in actual application, based on brightness requirement, LED current need to be set alternatively different values., for ex - we would like to set driver current as 50mA and 5mA alternatively. Similarly, we would try configuring VBOOST voltage accordingly based on actual backlight LED module.

    2. Does the eval board LP8556TM-EVM come with programmed EEPROM?

    Thanks & Regards,

    Rajesh Kumar

  • 0 in reply to Rajesh Kumar72
    TI__Genius 13001 points

    Hi Rajesh,

    1.LP8556 uses EPROM, so you can only burn it once. But if you can control the device on time by configuring registers, you don't need to burn EPROM.

    2.LP8556-E05 has un-configured EPROM settings, so you need configure the related register first.

    BR,

    Robin 

  • 0 in reply to Yuting Shao
    Intellectual 500 points

    Hi Robin,

    Thanks for the clarifications.

    I have got confused with usage of EEPROM terminologies used in the datasheet.

    We are planning to consider new devices.

    Regards,

    Rajesh