ZHCSCK8H May   2014  – April 2025 LP8860-Q1

PRODUCTION DATA  

  1.   1
  2. 1 特性
  3. 2 应用
  4. 3 说明
  5.   Device Comparison Table
  6. 4 Pin Configuration and Functions
    1.     Pin Functions
  7. 5 Specifications
    1. 5.1  Absolute Maximum Ratings
    2. 5.2  ESD Ratings
    3. 5.3  Recommended Operating Conditions
    4. 5.4  Thermal Information
    5. 5.5  Electrical Characteristics
    6. 5.6  Current Sinks Electrical Characteristics
    7. 5.7  Boost Converter Characteristics
    8. 5.8  Logic Interface Characteristics
    9. 5.9  VIN Undervoltage Protection (VIN_UVLO)
    10. 5.10 VDD Undervoltage Protection (VDD_UVLO)
    11. 5.11 VIN Overvoltage Protection (VIN_OVP)
    12. 5.12 VIN Overcurrent Protection (VIN_OCP)
    13. 5.13 Power-Line FET Control Electrical Characteristics
    14. 5.14 External Temp Sensor Control Electrical Characteristics
    15. 5.15 I2C Serial Bus Timing Parameters (SDA, SCLK)
    16. 5.16 SPI Timing Requirements
    17. 5.17 Typical Characteristics
  8. 6 Detailed Description
    1. 6.1 Overview
      1. 6.1.1 Boost Controller
      2. 6.1.2 LED Output Configurations
      3. 6.1.3 Display Mode
      4. 6.1.4 Cluster Mode
      5. 6.1.5 Hybrid Dimming
      6. 6.1.6 Charge Pump and Square Waveform (SQW) Output
      7. 6.1.7 Power-Line FET
      8. 6.1.8 Protection Features
      9. 6.1.9 Advanced Thermal Protection Features
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Clock Generation
        1. 6.3.1.1 LED PWM Clock Generation With VSYNC
        2. 6.3.1.2 LED PWM Frequency and Resolution
      2. 6.3.2 Brightness Control (Display Mode)
        1. 6.3.2.1 PWM Input Duty Cycle Based Control
        2. 6.3.2.2 Brightness Register Control
        3. 6.3.2.3 PWM Input Duty × Brightness Register
        4. 6.3.2.4 PWM-Input Direct Control
        5. 6.3.2.5 Brightness Slope
        6. 6.3.2.6 LED Dimming Methods
        7. 6.3.2.7 PWM Calculation Data Flow for Display Mode
      3. 6.3.3 LED Output Modes and Phase Shift PWM (PSPWM) Scheme
      4. 6.3.4 LED Current Setting
      5. 6.3.5 Cluster Mode
      6. 6.3.6 Boost Controller
      7. 6.3.7 Charge Pump
      8. 6.3.8 Powerline Control FET
      9. 6.3.9 Protection and Fault Detection Modes
        1. 6.3.9.1 LED Fault Comparators and Adaptive Boost Control
        2. 6.3.9.2 LED Current Dimming With Internal Temperature Sensor
        3. 6.3.9.3 LED Current Limitation With External NTC Sensor
        4. 6.3.9.4 LED Current Dimming With External NTC Sensor
        5. 6.3.9.5 Protection Feature and Fault Summary
    4. 6.4 Device Functional Modes
      1. 6.4.1 Standby Mode
      2. 6.4.2 Active Mode
      3. 6.4.3 Fault Recovery State
      4. 6.4.4 Start-Up and Shutdown Sequences
    5. 6.5 Programming
      1. 6.5.1 EEPROM
      2. 6.5.2 Serial Interface
        1. 6.5.2.1 SPI Interface
        2. 6.5.2.2 I2C Serial Bus Interface
          1. 6.5.2.2.1 Interface Bus Overview
          2. 6.5.2.2.2 Data Transactions
          3. 6.5.2.2.3 Acknowledge Cycle
          4. 6.5.2.2.4 Acknowledge After Every Byte Rule
          5. 6.5.2.2.5 Addressing Transfer Formats
          6. 6.5.2.2.6 Control Register Write Cycle
          7. 6.5.2.2.7 Control Register Read Cycle
    6. 6.6 Register Maps
      1. 6.6.1 Register Bit Explanations
        1. 6.6.1.1  Display/Cluster1 Brightness Control MSB
        2. 6.6.1.2  Display/Cluster1 Brightness Control LSB
        3. 6.6.1.3  Display/Cluster1 Output Current MSB
        4. 6.6.1.4  Display/Cluster1 Output Current LSB
        5. 6.6.1.5  Cluster2 Brightness Control MSB
        6. 6.6.1.6  Cluster2 Brightness Control LSB
        7. 6.6.1.7  Cluster2 Output Current
        8. 6.6.1.8  Cluster3 Brightness Control MSB
        9. 6.6.1.9  Cluster3 Brightness Control LSB
        10. 6.6.1.10 Cluster3 Output Current
        11. 6.6.1.11 Cluster4 Brightness Control MSB
        12. 6.6.1.12 Cluster4 Brightness Control LSB
        13. 6.6.1.13 Cluster4 Output Current
        14. 6.6.1.14 Configuration
        15. 6.6.1.15 Status
        16. 6.6.1.16 Fault
        17. 6.6.1.17 LED Fault
        18. 6.6.1.18 Fault Clear
        19. 6.6.1.19 Identification
        20. 6.6.1.20 Temp MSB
        21. 6.6.1.21 Temp LSB
        22. 6.6.1.22 Display LED Current MSB
        23. 6.6.1.23 Display LED Current LSB
        24. 6.6.1.24 Display LED PWM MSB
        25. 6.6.1.25 Display LED PWM LSB
        26. 6.6.1.26 EEPROM Control
        27. 6.6.1.27 EEPROM Unlock Code
      2. 6.6.2 EEPROM Bit Explanations
        1. 6.6.2.1  EEPROM Register 0
        2. 6.6.2.2  EEPROM Register 1
        3. 6.6.2.3  EEPROM Register 2
        4. 6.6.2.4  EEPROM Register 3
        5. 6.6.2.5  EEPROM Register 4
        6. 6.6.2.6  EEPROM Register 5
        7. 6.6.2.7  EEPROM Register 6
        8. 6.6.2.8  EEPROM Register 7
        9. 6.6.2.9  EEPROM Register 8
        10. 6.6.2.10 EEPROM Register 9
        11. 6.6.2.11 EEPROM Register 10
        12. 6.6.2.12 EEPROM Register 11
        13. 6.6.2.13 EEPROM Register 12
        14. 6.6.2.14 EEPROM Register 13
        15. 6.6.2.15 EEPROM Register 14
        16. 6.6.2.16 EEPROM Register 15
        17. 6.6.2.17 EEPROM Register 16
        18. 6.6.2.18 EEPROM Register 17
        19. 6.6.2.19 EEPROM Register 18
        20. 6.6.2.20 EEPROM Register 19
        21. 6.6.2.21 EEPROM Register 20
        22. 6.6.2.22 EEPROM Register 21
        23. 6.6.2.23 EEPROM Register 22
        24. 6.6.2.24 EEPROM Register 23
        25. 6.6.2.25 EEPROM Register 24
  9. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Applications
      1. 7.2.1 Typical Application for Display Backlight
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1  Inductor Selection
          2. 7.2.1.2.2  Output Capacitor Selection
          3. 7.2.1.2.3  Input Capacitor Selection
          4. 7.2.1.2.4  Charge Pump Output Capacitor
          5. 7.2.1.2.5  Charge Pump Flying Capacitor
          6. 7.2.1.2.6  Diode
          7. 7.2.1.2.7  Boost Converter Transistor
          8. 7.2.1.2.8  Boost Sense Resistor
          9. 7.2.1.2.9  Power Line Transistor
          10. 7.2.1.2.10 Input Current Sense Resistor
          11. 7.2.1.2.11 Filter Component Values
            1. 7.2.1.2.11.1 Critical Components for Design
        3. 7.2.1.3 Application Performance Plots
      2. 7.2.2 Low VDD Voltage and Combined Output Mode Application
        1. 7.2.2.1 Design Requirements
        2. 7.2.2.2 Detailed Design Procedure
        3. 7.2.2.3 Application Performance Plots
      3. 7.2.3 High Output Voltage Application
        1. 7.2.3.1 Design Requirements
        2. 7.2.3.2 Detailed Design Procedure
        3. 7.2.3.3 Application Performance Plots
      4. 7.2.4 High Output Current Application
        1. 7.2.4.1 Design Requirements
        2. 7.2.4.2 Detailed Design Procedure
        3. 7.2.4.3 Application Performance Plots
      5. 7.2.5 Three-Channel Configuration Without Serial Interface
        1. 7.2.5.1 Design Requirements
        2. 7.2.5.2 Detailed Design Procedure
        3. 7.2.5.3 Application Performance Plots
      6. 7.2.6 Solution With Minimum External Components
        1. 7.2.6.1 Design Requirements
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  10. 8 Device and Documentation Support
    1. 8.1 Device Support
    2. 8.2 Documentation Support
      1. 8.2.1 Related Documentation
    3. 8.3 Receiving Notification of Documentation Updates
    4. 8.4 Community Resources
    5. 8.5 Trademarks
  11. 9 Revision History
  12. 10Mechanical, Packaging, and Orderable Information

6.3.4 LED Current Setting

LP8860-Q1 LED Current SettingFigure 6-11 LED Current Setting

The output LED current can be set by a register. Maximum output LED current can be set by an external resistor when that option is enabled. For strings in cluster mode current for every LED output can be set independently. For more details regarding electrical overstress analysis options, see TI Application Note LP8860-Q1 Electrical Overstress Analysis and Recommendation (SNVA843).

The maximum current for the LED outputs in display mode are controlled with <DISP_CL1_CURRENT [11:0]> bits. Current for the outputs in the cluster mode are controlled separately by the register bits <DISP_CL1_CURRENT[11:0]>, <CL2_CURRENT[7:0]>, <CL3_CURRENT[7:0]>, and <CL4_CURRENT[7:0]> respectively. In the display mode resolution for current control is 12 bits. In the cluster mode resolution is 8 bits for all outputs except OUT1. For OUT1 maximum current resolution is always 12 bits.

Additionally, current for every output current can be scaled with <DRV_LED_CURRENT_SCALE[2:0]> bits (see Table 6-11) and can be corrected by <DRV_OUTx_CORR[3:0]> EEPROM bits. The adjustment range is shown in Table 6-12 Maximum current settings are effective for display and cluster modes.

Table 6-11 LED Current Scaling
DRV_LED_CURRENT_SCALE[2:0]MAXIMUM CURRENT
00025 mA
00130 mA
01050 mA
01160 mA
10080 mA
101100 mA
110120 mA
111150 mA

When maximum current is controlled by anexternal resistor RISET (<DRV_EN_EXT_LED_CUR_CTRL>=1), current for outputs in display mode or for OUT1 in cluster mode can be calculated as follows:

Equation 2. LP8860-Q1

Where VBG = 1.2 V.

For example, if <DISP_CL1_CURRENT[11:0]> is 0xFFF, <DRV_LED_CURRENT_SCALE[0:2]> is 111, and a 24-kΩ RISET resistor is used, then the LED maximum current is 150 mA.

When current control with external resistor is disabled (<DRV_EN_EXT_LED_CUR_CTRL>=0) LED current for outputs in display mode or for OUT1 in cluster mode can be calculated as follow:

Equation 3. LP8860-Q1

When maximum current control with external resistor is enabled, LED current for OUT2…OUT4 outputs in cluster mode is defined as:  

Equation 4. LP8860-Q1

Otherwise, when current control with external resistor is disabled:

Equation 5. LP8860-Q1

Correction value is defined by <DRV_OUTx_CORR[3:0]> shown in Table 6-12:

Table 6-12 Individual Current Correction
DRV_OUTx_CORR[3:0]CORRECTION
00006.50%
00015.60%
00104.70%
00113.70%
01002.80%
01011.90%
01100.90%
01110.00%
1000–0.9%
1001–1.90%
1010–2.80%
1011–3.70%
1100–4.70%
1101–5.60%
1110–6.50%
1111–7.40%
Note:

Formulas are only approximation for the actual current.

The <DISP_CL1_CURRENT[11:0]> register is initialized during start-up by the <LED_CURRENT_CTRL[11:0]> EEPROM bits. <DRV_LED_CURRENT_SCALE[2:0]> are initialized by the <DRV_LED_CURRENT_SCALE[2:0]> EEPROM bits. Cluster mode current registers for outputs OUT2 and OUT3 are initialized by 0 during power on reset.

Current register value must be not written to 0 if brightness is not zero – it may cause LED faults and adaptive voltage control instability.