SNVSCE4A may   2023  – august 2023 LP5861T

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  6. 5 Device Comparison
  7. 6 Pin Configuration and Functions
  8. 7 Specifications
    1. 7.1 Absolute Maximum Ratings
    2. 7.2 ESD Ratings
    3. 7.3 Recommended Operating Conditions
    4. 7.4 Thermal Information
    5. 7.5 Electrical Characteristics
    6. 7.6 Timing Requirements
    7.     15
    8. 7.7 Typical Characteristics
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Analog Dimming (Current Gain Control)
      2. 8.3.2 PWM Dimming
      3. 8.3.3 ON and OFF Control
      4. 8.3.4 Data Refresh Mode
      5. 8.3.5 Full Addressable SRAM
      6. 8.3.6 Protections and Diagnostics
    4. 8.4 Device Functional Modes
    5. 8.5 Programming
    6. 8.6 Register Maps
      1. 8.6.1 CONFIG Registers
      2. 8.6.2 GROUP Registers
      3. 8.6.3 DOTGROUP Registers
      4. 8.6.4 DOTONOFF Registers
      5. 8.6.5 FAULT Registers
      6. 8.6.6 RESET Registers
      7. 8.6.7 DC Registers
      8. 8.6.8 PWM Registers
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 Application
      2. 9.2.2 Design Requirements
      3. 9.2.3 Detailed Design Procedure
        1. 9.2.3.1 Program Procedure
      4. 9.2.4 Application Performance Plots
    3. 9.3 Power Supply Recommendations
    4. 9.4 Layout
      1. 9.4.1 Layout Guidelines
      2. 9.4.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.1 Analog Dimming (Current Gain Control)

Analog dimming of LP5861T is achieved by configuring the current gain control. There are several methods to control the current gain of each LED.

  • Global 3-bits Maximum Current (MC) setting without external resistor
  • 3 Groups of 7-bits Color Current (CC) setting
  • Individual 8-bit Dot Current (DC) setting
Note:

When setting to small output current in low brightness situation, adjusting MC to a small value firstly can get smaller output saturation voltage.

Global 3-Bits Maximum Current (MC) Setting

The MC is used to set the maximum current IOUT_MAX for each current sink and this current is the maximum peak current for each LED dot. The MC can be set with 3-bit (8 steps) from 7.5 mA to 125 mA. When the device is powered on, the MC data is set to default value 37.5 mA.

For data refresh Mode 1, MC data is effective immediately after new data updated. For Mode 2 and Mode 3, to avoid unexpected MC data change during high speed data refreshing, MC data must be changed when all channels are off and new MC data is only be updated when the 'Chip_EN' bit in Chip_en register is set to 0, and after the 'Chip_EN' returns to 1, the new MC data is effective. 'Down_Deghost' and 'Up_Deghost' in Dev_config3 work in the similar way with MC.

Table 8-1 Maximum Current (MC) Register Setting
3-BITS MAXIMUM_CURRENT REGISTERIOUT_MAX
BinaryDecimalmA
00007.5
001112.5
010225
011 (default)3 (default)37.5 (default)
100450
101575
1106100
1117125
3 Groups of 7-Bits Color Current (CC) Setting

The LP5861T device is able to adjust the output current of three color groups separately. For each color, the device has 7-bits data in 'CC_Group1', 'CC_Group2', and 'CC_Group3'. Thus, all color group currents can be adjusted in 128 steps from 0% to 100% of the maximum output current, IOUT_MAX.

The 18 current sinks have fixed mapping to the three color groups:

  • CC-Group 1: CS0, CS3, CS6, CS9, CS12, CS15
  • CC-Group 2: CS1, CS4, CS7, CS10, CS13, CS16
  • CC-Group 3: CS2, CS5, CS8, CS11, CS14, CS17

Table 8-2 3 Groups of 7-bits Color Current (CC) Setting
7-BITS CC_GROUP1/CC_GROUP2/CC_GROUP3 REGISTERRATIO OF OUTPUT CURRENT TO IOUT_MAX
BinaryDecimal%
000 000000
000 000110.79
000 001021.57
- - -- - -- - -
100 0000 (default)64 (default)50.4 (default)
- - -- - -- - -
111 110112598.4
111 111012699.2
111 1111127100
Individual 8-bit Dot Current (DC) Setting
The LP5861T can individually adjust the output current of each LED by using dot current function through DC setting. The device allows the brightness deviations of the LEDs to adjusted be individually. Each output DC is programmed with a 8-bit depth, so the value can be adjusted with 256 steps within the range from 0% to 100% of (IOUT_MAX × CC/127).

Table 8-3 Individual 8-bit Dot Current (DC) Setting
8-BIT DC REGISTERRATIO OF OUTPUT CURRENT TO IOUT_MAX × CC/127
BinaryDecimal%
0000 000000
0000 000110.39
0000 001020.78
- - -- - -- - -
1000 0000 (default)128 (default)50.2 (default)
- - -- - -- - -
1111 110125399.2
1111 111025499.6
1111 1111255100

In summary, the current gain of each current sink can be calculated as below:

Equation 1. IOUT (mA) = IOUT_MAX × (CC/127) × (DC/255)