JAJSOY2B May   2023  – November 2023 LP5860T

PRODUCTION DATA  

  1.   1
  2. 1 特長
  3. 2 アプリケーション
  4. 3 概要
  5. 4 Device Comparison
  6. 5 Pin Configuration and Functions
  7. 6 Specifications
    1. 6.1 Absolute Maximum Ratings
    2. 6.2 ESD Ratings
    3. 6.3 Recommended Operating Conditions
    4. 6.4 Thermal Information
    5. 6.5 Electrical Characteristics
    6. 6.6 Timing Requirements
    7.     14
    8. 6.7 Typical Characteristics
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Time-Multiplexing Matrix
      2. 7.3.2 Analog Dimming (Current Gain Control)
      3. 7.3.3 PWM Dimming
      4. 7.3.4 ON and OFF Control
      5. 7.3.5 Data Refresh Mode
      6. 7.3.6 Full Addressable SRAM
      7. 7.3.7 Protections and Diagnostics
    4. 7.4 Device Functional Modes
    5. 7.5 Programming
    6. 7.6 Register Maps
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Application
      2. 8.2.2 Design Requirements
      3. 8.2.3 Detailed Design Procedure
        1. 8.2.3.1 Program Procedure
      4. 8.2.4 Application Performance Plots
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 ドキュメントの更新通知を受け取る方法
    2. 9.2 サポート・リソース
    3. 9.3 Trademarks
    4. 9.4 静電気放電に関する注意事項
    5. 9.5 用語集
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

パッケージ・オプション

メカニカル・データ（パッケージ｜ピン）
サーマルパッド・メカニカル・データ
発注情報

7.3.2 Analog Dimming (Current Gain Control)

Analog dimming of LP5860T 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 7 steps from 7.5 mA to 100 mA. When the device is powered on, the MC data is set to default value, which is 37.5 mA.

For data refresh Mode 1, MC data is effective immediately after new data is 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 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 7-1 Maximum Current (MC) Register Setting
3-BITS MAXIMUM_CURRENT REGISTER IOUT_MAX
Binary Decimal mA
000 0 7.5
001 1 12.5
010 2 25
011 (Default) 3 (Default) 37.5 (Default)
100 4 50
101 5 75
110 6 100
3 Groups of 7-Bits Color Current (CC) Setting

The LP5860T 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 7-2 3 Groups of 7-bits Color Current (CC) Setting
7-BITS CC_GROUP1/CC_GROUP2/CC_GROUP3 REGISTER RATIO OF OUTPUT CURRENT TO IOUT_MAX
Binary Decimal %
000 0000 0 0
000 0001 1 0.79
000 0010 2 1.57
- - - - - - - - -
100 0000 (default) 64 (default) 50.4 (default)
- - - - - - - - -
111 1101 125 98.4
111 1110 126 99.2
111 1111 127 100
Individual 8-bit Dot Current (DC) Setting

The LP5860T 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 an 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 7-3 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 3. IOUT (mA) = IOUT_MAX × (CC/127) × (DC/255)

For time-multiplexing scan scheme, if the scan number is N, each LED dot's average current IAVG is shown as below:

Equation 4. IAVG (mA) = IOUT/N = IOUT_MAX × (CC/127) × (DC/255)/N