ZHCSE41C August   2015  – May 2017 LP8861-Q1

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
    1.     系统效率
  3. 3 说明
    1.     简化原理图
  4. 4 修订历史记录
  5. 5 器件比较表
  6. 6 Pin Configuration and Functions
    1.     Pin Functions
  7. 7 Specifications
    1. 7.1  Absolute Maximum Ratings
    2. 7.2  ESD Ratings
    3. 7.3  Recommended Operating Conditions
    4. 7.4  Thermal Information
    5. 7.5  Electrical Characteristics
    6. 7.6  Internal LDO Electrical Characteristics
    7. 7.7  Protection Electrical Characteristics
    8. 7.8  Power Line FET Control Electrical Characteristics
    9. 7.9  Current Sinks Electrical Characteristics
    10. 7.10 PWM Brightness Control Electrical Characteristics
    11. 7.11 Boost/SEPIC Converter Characteristics
    12. 7.12 Logic Interface Characteristics
    13. 7.13 Typical Characteristics
  8. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Integrated Boost/SEPIC Converter
      2. 8.3.2 Internal LDO
      3. 8.3.3 LED Current Sinks
        1. 8.3.3.1 Current Sink Configuration
        2. 8.3.3.2 Current Setting
        3. 8.3.3.3 Brightness Control
      4. 8.3.4 Power-Line FET Control
      5. 8.3.5 LED Current Dimming With External Temperature Sensor
      6. 8.3.6 Protection and Fault Detection
        1. 8.3.6.1 Adaptive Boost Control and Functionality of LED Fault Comparators
        2. 8.3.6.2 Overview of the Fault/Protection Schemes
    4. 8.4 Device Functional Modes
      1. 8.4.1 Device States
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Typical Application for 4 LED Strings
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1 Inductor Selection
          2. 9.2.1.2.2 Output Capacitor Selection
          3. 9.2.1.2.3 Input Capacitor Selection
          4. 9.2.1.2.4 LDO Output Capacitor
          5. 9.2.1.2.5 Diode
          6. 9.2.1.2.6 Power Line Transistor
          7. 9.2.1.2.7 Input Current Sense Resistor
        3. 9.2.1.3 Application Curves
      2. 9.2.2 High Output Current Application
        1. 9.2.2.1 Design Requirements
        2. 9.2.2.2 Detailed Design Procedure
        3. 9.2.2.3 Application Curves
      3. 9.2.3 SEPIC Mode Application
        1. 9.2.3.1 Design Requirements
        2. 9.2.3.2 Detailed Design Procedure
          1. 9.2.3.2.1 Diode
          2. 9.2.3.2.2 Inductor
        3. 9.2.3.3 Application Curves
      4. 9.2.4 Application with Temperature Based LED Current De-rating
        1. 9.2.4.1 Design Requirements
        2. 9.2.4.2 Detailed Design Procedure
        3. 9.2.4.3 Application Curve
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Example
  12. 12器件和文档支持
    1. 12.1 器件支持
      1. 12.1.1 第三方产品免责声明
    2. 12.2 文档支持
      1. 12.2.1 相关文档
    3. 12.3 接收文档更新通知
    4. 12.4 社区资源
    5. 12.5 商标
    6. 12.6 静电放电警告
    7. 12.7 术语表
  13. 13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

8.3.6.2 Overview of the Fault/Protection Schemes

The LP8861-Q1 fault detection behavior is described in Table 3. Detected faults (excluding LED faults) cause the device to enter FAULT_RECOVERY state. In FAULT_RECOVERY the boost and LED outputs of LP8861-Q1 are disabled, power-line FET is turned off, and the FAULT pin is pulled low. Device recovers automatically and enters normal operating mode (ACTIVE) after a recovery time of 100 ms if the fault condition has disappeared. When recovery is successful, the FAULT pin is released.

In case a LED fault is detected, device continues normal operation and only the faulty string is disabled. Fault is indicated via FAULT pin which can be released by toggling VDDIO/EN pin low for a short period of 2…20 µs. LEDs are turned off for this period but device stays in ACTIVE mode. If VDDIO/EN is low longer, device goes to STANDBY and restarts when EN goes high again.

Table 3. Fault/Protection Schemes

FAULT/
PROTECTION 		FAULT NAME THRESHOLD CONNECTED TO
FAULT PIN 		FAULT_
RECOVERY
STATE		 ACTION
VIN overvoltage protection VIN_OVP 1. VIN > 42 V
2. VBOOST > VSET_BOOST + (6...10) V
VSET_BOOST is voltage value defined by logic during adaptation 		Yes Yes 1. Overvoltage is monitored from the beginning of soft start. Fault is detected if the duration of overvoltage condition is 100 µs minimum.
2. Overvoltage is monitored from the beginning of normal operation (ACTIVE mode). Fault is detected if overvoltage condition duration is 560 ms minimum (tfilter). After the first fault detection filter time is reduced to 50 ms for following recovery cycles. When device recovers and has been in ACTIVE mode for 160 ms, filter is increased back to 560 ms.
VIN undervoltage lockout VIN_UVLO Falling 3.9 V
Rising 4 V 		Yes Yes Detects undervoltage condition at VIN pin. Sensed from the beginning of soft start. Fault is detected if undervoltage condition duration is 100 µs minimum.
VIN overcurrent protection VIN_OCP 3 A (50-mΩ current sensor resistor) Yes Yes Detects overcurrent by measuring voltage of the SENSE resistor connected between VIN and VSENSE_N pins. Sensed from the beginning of soft start. Fault is detected if undervoltage condition duration is 10 µs minimum.
Open LED fault OPEN_LED LOW_COMP threshold Yes No Detected if one or more outputs are below threshold level, and boost adaptive control has reached maximum voltage. Open string(s) is removed from voltage control loop and PWM is disabled.
Fault pin is cleaned by toggling VDDIO/EN pin. If VDDIO/EN is low for a short period of 2…20 µs, LEDs are turned off for this period but device stays ACTIVE. If VDDIO/EN is low longer, device goes to STANDBY and restarts when EN goes high again.
Shorted LED fault SHORT_LED Shorted string detection level 6 V Yes No Detected if one or more outputs voltages are above shorted string detection level and at least one LED output voltage is within headroom window. Shorted string(s) are removed from the boost voltage control loop and outputs PWM(s) are disabled.
Fault pin is cleaned by toggling VDDIO/EN pin. If VDDIO/EN is low for a short period of 2…20 µs, LEDs are turned off for this period but device stays ACTIVE. If VDDIO/EN is low longer, device goes to STANDBY and restarts when EN goes high again.
Thermal protection TSD 165ºC
Thermal Shutdown Hysteresis 20ºC 		Yes Yes Thermal shutdown is monitored from the beginning of soft start. Die temperature must decrease by 20ºC for device to recover.
LP8861-Q1 boost_OVP_SNVSA50.gifFigure 16. VIN Overvoltage Protection (Boost OVP)
LP8861-Q1 VIN_OVP_SNVSA50.gifFigure 17. VIN Overvoltage Protection (VIN OVP)
LP8861-Q1 VIN_UVLO_SNVSA50.gifFigure 18. VIN Undervoltage Lockout
LP8861-Q1 VIN_OCP_SNVSA50.gifFigure 19. Input Voltage Overcurrent Protection
LP8861-Q1 LED_open_fault_SNVSA50.gifFigure 20. LED Open Fault
LP8861-Q1 LED_short_fault_SNVSA50.gifFigure 21. LED Short Fault