ZHCSLM3B August 2020 – May 2024 LP8864-Q1
PRODUCTION DATA
- 1
- 1 特性
- 2 應(yīng)用
- 3 說(shuō)明
- 4 Pin Configuration and Functions
- 5 Specifications
-
6 Detailed Description
- 6.1 Overview
- 6.2 Functional Block Diagram
- 6.3
Feature Description
- 6.3.1 Control Interface
- 6.3.2 Function Setting
- 6.3.3 Device Supply (VDD)
- 6.3.4 Enable (EN)
- 6.3.5 Charge Pump
- 6.3.6 Boost Controller
- 6.3.7 LED Current Sinks
- 6.3.8 Brightness Control
- 6.3.9
Protection and Fault Detections
- 6.3.9.1 Supply Faults
- 6.3.9.2
Boost Faults
- 6.3.9.2.1 Boost Overvoltage Faults (BSTOVPL, BSTOVPH)
- 6.3.9.2.2 Boost Overcurrent Faults (BSTOCP)
- 6.3.9.2.3 LEDSET Resistor Missing Faults (LEDSET)
- 6.3.9.2.4 MODE Resistor Missing Faults (MODESEL)
- 6.3.9.2.5 FSET Resistor Missing Faults (FSET)
- 6.3.9.2.6 ISET Resistor Out of Range Faults (ISET)
- 6.3.9.2.7 Thermal Shutdown Faults (TSD)
- 6.3.9.3 LED Faults
- 6.3.9.4 Overview of the Fault and Protection Schemes
- 6.4 Device Functional Modes
- 6.5 Programming
-
7 Application and Implementation
- 7.1 Application Information
- 7.2
Typical Applications
- 7.2.1
Full Feature 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 Output Diode
- 7.2.1.2.7 Switching FET
- 7.2.1.2.8 Boost Sense Resistor
- 7.2.1.2.9 Power-Line FET
- 7.2.1.2.10 Input Current Sense Resistor
- 7.2.1.2.11 Feedback Resistor Divider
- 7.2.1.2.12 Critical Components for Design
- 7.2.1.3 Application Curves
- 7.2.2 Application with Basic/Minimal Operation
- 7.2.3
SEPIC Mode Application
- 7.2.3.1 Design Requirements
- 7.2.3.2
Detailed Design Procedure
- 7.2.3.2.1 Inductor Selection
- 7.2.3.2.2 Coupling Capacitor Selection
- 7.2.3.2.3 Output Capacitor Selection
- 7.2.3.2.4 Input Capacitor Selection
- 7.2.3.2.5 Charge Pump Output Capacitor
- 7.2.3.2.6 Charge Pump Flying Capacitor
- 7.2.3.2.7 Switching FET
- 7.2.3.2.8 Output Diode
- 7.2.3.2.9 Switching Sense Resistor
- 7.2.3.2.10 Power-Line FET
- 7.2.3.2.11 Input Current Sense Resistor
- 7.2.3.2.12 Feedback Resistor Divider
- 7.2.3.2.13 Critical Components for Design
- 7.2.3.3 Application Curves
- 7.2.1
Full Feature Application for Display Backlight
- 7.3 Power Supply Recommendations
- 7.4 Layout
- 8 Register Maps
- 9 Device and Documentation Support
- 10Revision History
- 11Mechanical, Packaging, and Orderable Information
封裝選項(xiàng)
機(jī)械數(shù)據(jù) (封裝 | 引腳)
散熱焊盤機(jī)械數(shù)據(jù) (封裝 | 引腳)
訂購(gòu)信息
7.2.1.2.1 Inductor Selection
There are a few things to consider when choosing an inductor: inductance, current rating, and DC resistance (DCR). Table 7-2 shows recommended inductor values for each operating frequency. The LP8864-Q1 device automatically sets internal boost compensation controls depending on the selected switching frequency.
| SW FREQUENCY (kHz) | INDUCTANCE (μH) |
|---|---|
| 100 | 47 |
| 200 | 33 |
| 303 | 22 |
| 400 | 22 |
| 500 | 22 |
| 1818 | 10 |
| 2000 | 10 |
| 2222 | 10 |
The current rating of inductor must be at least 25% higher than maximum boost switching current ISW(max), which can be calculated with Equation 21. TI recommends to use an inductor with low DCR to achieve good efficiency. Efficiency varies with load condition, switching frequency, and components. 80% can be used as a typical estimation. 65% efficiency needs to take into account in extreme condition.
where
- ΔIL = VIN(min) × D / ?SW × L
- D = 1 – VIN(min) × η / VOUT
- ISW(max): Maximum switching current
- ΔIL: Inductor ripple current
- IOUT(max): Maximum output current
- D: Boost duty cycle
- VIN(min): Minimum input voltage
- ?SW: Minimum switching frequency of the converter
- L: Inductance
- VOUT: Output voltage
- η: Efficiency of boost converter