ZHCSCK8H May 2014 – April 2025 LP8860-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 應用
- 3 說明
- Device Comparison Table
- 4 Pin Configuration and Functions
-
5 Specifications
- 5.1 Absolute Maximum Ratings
- 5.2 ESD Ratings
- 5.3 Recommended Operating Conditions
- 5.4 Thermal Information
- 5.5 Electrical Characteristics
- 5.6 Current Sinks Electrical Characteristics
- 5.7 Boost Converter Characteristics
- 5.8 Logic Interface Characteristics
- 5.9 VIN Undervoltage Protection (VIN_UVLO)
- 5.10 VDD Undervoltage Protection (VDD_UVLO)
- 5.11 VIN Overvoltage Protection (VIN_OVP)
- 5.12 VIN Overcurrent Protection (VIN_OCP)
- 5.13 Power-Line FET Control Electrical Characteristics
- 5.14 External Temp Sensor Control Electrical Characteristics
- 5.15 I2C Serial Bus Timing Parameters (SDA, SCLK)
- 5.16 SPI Timing Requirements
- 5.17 Typical Characteristics
-
6 Detailed Description
- 6.1 Overview
- 6.2 Functional Block Diagram
- 6.3 Feature Description
- 6.4 Device Functional Modes
- 6.5 Programming
- 6.6
Register Maps
- 6.6.1
Register Bit Explanations
- 6.6.1.1 Display/Cluster1 Brightness Control MSB
- 6.6.1.2 Display/Cluster1 Brightness Control LSB
- 6.6.1.3 Display/Cluster1 Output Current MSB
- 6.6.1.4 Display/Cluster1 Output Current LSB
- 6.6.1.5 Cluster2 Brightness Control MSB
- 6.6.1.6 Cluster2 Brightness Control LSB
- 6.6.1.7 Cluster2 Output Current
- 6.6.1.8 Cluster3 Brightness Control MSB
- 6.6.1.9 Cluster3 Brightness Control LSB
- 6.6.1.10 Cluster3 Output Current
- 6.6.1.11 Cluster4 Brightness Control MSB
- 6.6.1.12 Cluster4 Brightness Control LSB
- 6.6.1.13 Cluster4 Output Current
- 6.6.1.14 Configuration
- 6.6.1.15 Status
- 6.6.1.16 Fault
- 6.6.1.17 LED Fault
- 6.6.1.18 Fault Clear
- 6.6.1.19 Identification
- 6.6.1.20 Temp MSB
- 6.6.1.21 Temp LSB
- 6.6.1.22 Display LED Current MSB
- 6.6.1.23 Display LED Current LSB
- 6.6.1.24 Display LED PWM MSB
- 6.6.1.25 Display LED PWM LSB
- 6.6.1.26 EEPROM Control
- 6.6.1.27 EEPROM Unlock Code
- 6.6.2
EEPROM Bit Explanations
- 6.6.2.1 EEPROM Register 0
- 6.6.2.2 EEPROM Register 1
- 6.6.2.3 EEPROM Register 2
- 6.6.2.4 EEPROM Register 3
- 6.6.2.5 EEPROM Register 4
- 6.6.2.6 EEPROM Register 5
- 6.6.2.7 EEPROM Register 6
- 6.6.2.8 EEPROM Register 7
- 6.6.2.9 EEPROM Register 8
- 6.6.2.10 EEPROM Register 9
- 6.6.2.11 EEPROM Register 10
- 6.6.2.12 EEPROM Register 11
- 6.6.2.13 EEPROM Register 12
- 6.6.2.14 EEPROM Register 13
- 6.6.2.15 EEPROM Register 14
- 6.6.2.16 EEPROM Register 15
- 6.6.2.17 EEPROM Register 16
- 6.6.2.18 EEPROM Register 17
- 6.6.2.19 EEPROM Register 18
- 6.6.2.20 EEPROM Register 19
- 6.6.2.21 EEPROM Register 20
- 6.6.2.22 EEPROM Register 21
- 6.6.2.23 EEPROM Register 22
- 6.6.2.24 EEPROM Register 23
- 6.6.2.25 EEPROM Register 24
- 6.6.1
Register Bit Explanations
-
7 Application and Implementation
- 7.1 Application Information
- 7.2
Typical Applications
- 7.2.1
Typical Application for Display Backlight
- 7.2.1.1 Design Requirements
- 7.2.1.2
Detailed Design Procedure
- 7.2.1.2.1 Inductor Selection
- 7.2.1.2.2 Output Capacitor Selection
- 7.2.1.2.3 Input Capacitor Selection
- 7.2.1.2.4 Charge Pump Output Capacitor
- 7.2.1.2.5 Charge Pump Flying Capacitor
- 7.2.1.2.6 Diode
- 7.2.1.2.7 Boost Converter Transistor
- 7.2.1.2.8 Boost Sense Resistor
- 7.2.1.2.9 Power Line Transistor
- 7.2.1.2.10 Input Current Sense Resistor
- 7.2.1.2.11 Filter Component Values
- 7.2.1.3 Application Performance Plots
- 7.2.2 Low VDD Voltage and Combined Output Mode Application
- 7.2.3 High Output Voltage Application
- 7.2.4 High Output Current Application
- 7.2.5 Three-Channel Configuration Without Serial Interface
- 7.2.6 Solution With Minimum External Components
- 7.2.1
Typical Application for Display Backlight
- 7.3 Power Supply Recommendations
- 7.4 Layout
- 8 Device and Documentation Support
- 9 Revision History
- 10Mechanical, Packaging, and Orderable Information
6.3.9.4 LED Current Dimming With External NTC Sensor
When an external resistor for maximum current control is used, current dimming for LED current can be used also. In this case LED current can be de-rated when ambient temperature is high. This option must be enabled by <EXT_TEMP_I_DIMMING_EN> and <EXT_TEMP_COMP_EN> EEPROM bits.
Knee point and slope are defined by <EXT_TEMP_MINUS[1:0]> and <EXT_TEMP_GAIN[3:0]> EEPROM bits respectively. LED shutdown temperature is defined by <EXT_TEMP_LEVEL_HIGH[3:0]> bits. Serial and parallel resistors R1 and R2 affect the slope and knee point and can be used for the thermal curve adjustment and NTC linearization.
Figure 6-25 Current Dimming for High Ambient Temperature
Figure 6-26 NTC LinearizationFigure 6-27 and Figure 6-28 show the block diagrams for current dimming.
Figure 6-27 Temperature-Dependent NTC Current (Subtracted from ISET Current)
Figure 6-28 NTC Current Processing — Scaling, Shift, and LimitationCurrent dimming by external NTC sensor for 150-mA scale can be defined by formulas:
Equation 6. 
Equation 7. 
ITEMP cannot be negative; if ITEMP < 0, then ITEMP must be 0.
Equation 8. ILED = (ISET – ITEMP) × 150 mA
ILED cannot go below a 5-mA level; if calculated ILED < 5 mA, then ILED = 5 mA.
where
- ISET: Maximum current setting with external resistor RISET, μA
- ITEMP: Temperature compensation, μA
- RISET: External resistor, kΩ
- R1, R2: Resistors for adjustment, kΩ
- ILED: Output current per channel, mA
- EXT_TEMP_MINUS[1:0]: 1, 5, 9, 13 μA
- EXT_TEMP_GAIN[[3:0]: 50/n, n = 16 to 1
- VBG: 1.2 V