ZHCSGN9D February   2016  – March 2018 LM36274

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
    1.     简化原理图
  3. 3 说明
    1.     背光效率，4P6S
  4. 4 修订历史记录
  5. 5 Pin Configuration and Functions
    1.     Pin Functions
  6. 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 I2C Timing Requirements (Fast Mode)
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Features Description
      1. 7.3.1 Enabling the LM36274
      2. 7.3.2 Backlight
        1. 7.3.2.1 Current Sink Enable
        2. 7.3.2.2 Brightness Mapping
          1. 7.3.2.2.1 Linear Mapping
          2. 7.3.2.2.2 Exponential Mapping
        3. 7.3.2.3 Backlight Brightness Control Modes
          1. 7.3.2.3.1 I2C Brightness Control (PWM Pin Disabled)
          2. 7.3.2.3.2 I2C × PWM Brightness Control (PWM Pin Enabled)
            1. 7.3.2.3.2.1 PWM Ramper
        4. 7.3.2.4 Boost Switching Frequency
          1. 7.3.2.4.1 Minimum Inductor Select
        5. 7.3.2.5 Boost Feedback Gain Select
        6. 7.3.2.6 Auto Switching Frequency
        7. 7.3.2.7 PWM Input
          1. 7.3.2.7.1 PWM Sample Frequency
            1. 7.3.2.7.1.1 PWM Resolution and Input Frequency Range
            2. 7.3.2.7.1.2 PWM Sample Rate and Efficiency
              1. 7.3.2.7.1.2.1 PWM Sample Rate Example
          2. 7.3.2.7.2 PWM Hysteresis
          3. 7.3.2.7.3 PWM Step Response
          4. 7.3.2.7.4 PWM Timeout
          5. 7.3.2.7.5 PWM-to-Digital Code Readback
        8. 7.3.2.8 Regulated Headroom Voltage
        9. 7.3.2.9 Backlight Fault Protection and Faults
          1. 7.3.2.9.1 Backlight Overvoltage Protection (OVP)
          2. 7.3.2.9.2 Backlight Overcurrent Protection (OCP)
      3. 7.3.3 LCM Bias
        1. 7.3.3.1 Display Bias Boost Converter (VVPOS, VVNEG)
        2. 7.3.3.2 Auto Sequence Mode
        3. 7.3.3.3 Wake-up Mode
          1. 7.3.3.3.1 Wake1 Mode
          2. 7.3.3.3.2 Wake2 Mode
        4. 7.3.3.4 Active Discharge
        5. 7.3.3.5 LCM Bias Protection and Faults
          1. 7.3.3.5.1 LCM Overvoltage (OVP) Protection
          2. 7.3.3.5.2 VPOS Short-Circuit Protection
          3. 7.3.3.5.3 VNEG Short-Circuit Protection
      4. 7.3.4 Software Reset
      5. 7.3.5 HWEN Input
      6. 7.3.6 Thermal Shutdown (TSD)
    4. 7.4 Device Functional Modes
      1. 7.4.1 Modes of Operation
    5. 7.5 Programming
      1. 7.5.1 I2C-Compatible Serial Bus Interface
        1. 7.5.1.1 Interface Bus Overview
        2. 7.5.1.2 Data Transactions
        3. 7.5.1.3 Acknowledge Cycle
        4. 7.5.1.4 Acknowledge After Every Byte Rule
        5. 7.5.1.5 Addressing Transfer Formats
        6. 7.5.1.6 Register Programming
    6. 7.6 Register Maps
      1. 7.6.1  Revision Register (Address = 0x01)[Reset = 0x01]
        1. Table 11. Revision Register Field Descriptions
      2. 7.6.2  Backlight Configuration1 Register (Address = 0x02)[Reset = 0x28]
        1. Table 12. Backlight Configuration 1 Register Field Descriptions
      3. 7.6.3  Backlight Configuration 2 Register (Address = 0x03)[Reset = 0x8D]
        1. Table 13. Backlight Configuration 2 Register Field Descriptions
      4. 7.6.4  Backlight Brightness LSB Register (Address = 0x04)[Reset = 0x07]
        1. Table 14. Backlight Brightness LSB Register Field Descriptions
      5. 7.6.5  Backlight Brightness MSB Register (Address = 0x05)[Reset = 0xFF]
        1. Table 15. Backlight Brightness MSB Register Field Descriptions
      6. 7.6.6  Backlight Auto-Frequency Low Threshold Register (Address = 0x06)[Reset = 0x00]
        1. Table 16. Backlight Auto-Frequency Low Threshold Field Descriptions
      7. 7.6.7  Backlight Auto-Frequency High Threshold Register (Address = 0x07)[Reset = 0x00]
        1. Table 17. Backlight Auto-Frequency High Threshold Field Descriptions
      8. 7.6.8  Backlight Enable Register (Address = 0x08)[Reset = 0x00]
        1. Table 18. Backlight Enable Register Field Descriptions
      9. 7.6.9  Bias Configuration 1 Register (Address = 0x09)[Reset = 0x18]
        1. Table 19. Bias Configuration 1 Register Field Descriptions
      10. 7.6.10 Bias Configuration 2 register (Address = 0x0A)[Reset = 0x11]
        1. Table 20. Bias Configuration 2 Register Field Descriptions
      11. 7.6.11 Bias Configuration 3 Register (Address = 0x0B)[Reset = 0x00]
        1. Table 21. Bias Configuration 3 Register Field Descriptions
      12. 7.6.12 LCM Boost Bias Register (Address = 0x0C)[Reset = 0x28]
        1. Table 22. LCM Boost Bias Register Field Descriptions
      13. 7.6.13 VPOS Bias Register (Address = 0x0D)[Reset = 0x1E]
        1. Table 23. VPOS Bias Register Field Descriptions
      14. 7.6.14 VNEG Bias Register (Address = 0x0E)[Reset = 0x1C]
        1. Table 24. VNEG Bias Register Field Descriptions
      15. 7.6.15 Flags Register (Address = 0x0F)[Reset = 0x00]
        1. Table 25. Flags Register Field Descriptions
      16. 7.6.16 Option 1 Register (Address = 0x10)[Reset = 0x06]
        1. Table 26. Option 1 Register Field Descriptions
      17. 7.6.17 Option 2 Register (Address = 0x11)[Reset = 0x35]
        1. Table 27. Option 2 Register Field Descriptions
      18. 7.6.18 PWM-to-Digital Code Readback LSB Register (Address = 0x12)[Reset = 0x00]
        1. Table 28. PWM-to-Digital Code Readback LSB Register Field Descriptions
      19. 7.6.19 PWM-to-Digital Code Readback MSB Register (Address = 0x13)[Reset = 0x00]
        1. Table 29. PWM-to-Digital Code Readback MSB Register Field Descriptions
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Component Selection
          1. 8.2.2.1.1 Inductor Selection
          2. 8.2.2.1.2 Boost Output Capacitor Selection
          3. 8.2.2.1.3 Input Capacitor Selection
      3. 8.2.3 Application Curves
        1. 8.2.3.1 Backlight Curves
          1. 8.2.3.1.1 Two LED Strings
          2. 8.2.3.1.2 Three LED Strings
          3. 8.2.3.1.3 Four LED Strings
        2. 8.2.3.2 LCM Bias Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11器件和文档支持
    1. 11.1 器件支持
      1. 11.1.1 第三方产品免责声明
      2. 11.1.2 开发支持
    2. 11.2 文档支持
      1. 11.2.1 相关文档
    3. 11.3 接收文档更新通知
    4. 11.4 社区资源
    5. 11.5 商标
    6. 11.6 静电放电警告
    7. 11.7 Glossary
  12. 12机械、封装和可订购信息

封装选项

机械数据 (封装 | 引脚)
散热焊盘机械数据 (封装 | 引脚)
订购信息

7.3.3.1 Display Bias Boost Converter (VVPOS, VVNEG)

A single high-efficiency boost converter provides a positive voltage rail, VLCM_OUT, which serves as the power rail for the LCM VPOS and VNEG outputs.

  • The VVPOS output LDO has a programmable range from 4 V up to 6.5 V with 50-mV steps and can supply up to 80 mA.
  • The VVNEG output is generated from a regulated, inverting charge pump and has an adjustable range of –6.5 V up to –4 V with 50-mV steps and a maximum load of 80 mA.

Boost voltage also has a programmable range from 4 V up to 7.15 V with 50-mV steps. Refer to Table 22, Table 23 and Table 24 for VLCM_OUT, VVPOS and VVNEG voltage settings. When selecting a suitable boost-output voltage, the following estimation can be used: VLCM_OUT = max(VVPOS, |VVNEG|) + VHR, where VHR ≥ 200 mV for lower currents and VHR ≥ 300 mV for higher currents. When the device input voltage (VIN) is greater than the programmed LCM boost output voltage, the boost voltage is regulated to VIN + 100 mV. VVPOS and VVNEG voltage settings cannot be changed while they are enabled. VVPOS and VVNEG register setting targets take effect only after the outputs are disabled and re-enabled. However, the VLCM_OUT target changes immediately upon a register write.

LM36274 LM36274_LCMBoost.gifFigure 40. LCM Boost Block Diagram

The LCM Bias outputs can be controlled either by pins LCM_EN1 and LCM_EN2 or register bits VPOS_EN and VNEG_EN, register 0x09 bits[2:1]. Setting bit EXT_EN, register 0x09 bit[0], to 1 allows pins LCM_EN1 and LCM_EN2 to control VPOS and VNEG, respectively, while setting this bit to 0 yields control to bits VPOS_EN and VNEG_EN. Refer to Table 8 for LCM bias control information.

Table 8. LCM Operating Modes

HWEN LCM_EN2
INPUT		 LCM_EN1
INPUT		 LCM_EN MODE
0x09[7:5] 		VPOS_EN
0x09[2] 		VNEG_EN
0x09[1] 		EXT_EN
0x09[0]		 ACTION
0 X X XXX X X X Device shutdown
1 0 0 000 X X 1 Standby(1)
1 X X 100 0 0 0 Standby(1)
1 0 1 100 X X 1 VPOS enabled via external input
1 1 0 100 X X 1 VNEG enabled via external input
1 1 1 100 X X 1 VPOS and VNEG enabled via external input
1 X X 100 1 0 0 VPOS enabled via I2C
1 X X 100 0 1 0 VNEG enabled via I2C
1 X X 100 1 1 0 VPOS and VNEG enabled via I2C
1 X X 101 1 1 0 VPOS and VNEG enabled via I2C with auto-sequencing
1 1 X 101 X X 1 VPOS and VNEG enabled via LCM_EN2 with auto-sequencing
1 1 X 110 1 0 X WAKE1
VVPOS = VIN
VVNEG = GND
1 1 X 110 0 1 X WAKE1
VVPOS = GND
VVNEG = –VIN
1 1 X 110 1 1 X WAKE1
VVPOS = VIN
VVNEG = –VIN
1 0 X 110 1 1 X WAKE1
Standby(1)
1 1 X 110 0 0 X WAKE1
Standby(1)
1 1 X 111 1 0 X WAKE2
VVPOS = programmed target
VVNEG = disabled
1 1 X 111 0 1 X WAKE2
VVPOS = disabled
VVNEG = programmed target
1 1 X 111 1 1 X WAKE2
VVPOS = programmed target
VVNEG = programmed target
1 1 X 111 0 0 X WAKE2
Standby(1)
1 0 X 111 1 1 X WAKE2
Standby(1)
(1) Standby implies that VPOS and VNEG are either high impedance or being internally pulled low via the active pulldown, and that the LCM boost is off. Shutdown implies that the device is in reset and no I2C communication is possible.