ZHCSBB6H April   2012  – November 2017 LM34927

PRODUCTION DATA.  

  1. 1 特性
  2. 2 应用
  3. 3 说明
    1.     Device Images
      1.      典型应用
  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 Switching Characteristics
    7. 6.7 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Control Overview
      2. 7.3.2  VCC Regulator
      3. 7.3.3  Regulation Comparator
      4. 7.3.4  Overvoltage Comparator
      5. 7.3.5  On-Time Generator
      6. 7.3.6  Current Limit
      7. 7.3.7  N-Channel Buck Switch and Driver
      8. 7.3.8  Synchronous Rectifier
      9. 7.3.9  Undervoltage Detector
      10. 7.3.10 Thermal Protection
      11. 7.3.11 Ripple Configuration
      12. 7.3.12 Soft Start
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Application Circuit: 20-V to 95-V Input and 10-V, 300-mA Output Isolated Fly-Buck Converter
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Transformer Turns Ratio
          2. 8.2.1.2.2  Total IOUT
          3. 8.2.1.2.3  RFB1, RFB2
          4. 8.2.1.2.4  Frequency Selection
          5. 8.2.1.2.5  Transformer Selection
          6. 8.2.1.2.6  Primary Output Capacitor
          7. 8.2.1.2.7  Secondary Output Capacitor
          8. 8.2.1.2.8  Type III Feedback Ripple Circuit
          9. 8.2.1.2.9  Secondary Diode
          10. 8.2.1.2.10 VCC and Bootstrap Capacitor
          11. 8.2.1.2.11 Input Capacitor
          12. 8.2.1.2.12 UVLO Resistors
          13. 8.2.1.2.13 VCC Diode
        3. 8.2.1.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Curves
  11. 11器件和文档支持
    1. 11.1 接收文档更新通知
    2. 11.2 社区资源
    3. 11.3 商标
    4. 11.4 静电放电警告
    5. 11.5 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

6.5 Electrical Characteristics

Typical values correspond to TJ = 25°C. Minimum and maximum limits apply over –40°C to 125°C junction temperature range, unless otherwise stated. VIN = 48 V unless otherwise stated. See(1).
PARAMETERTEST CONDITIONSMINTYPMAXUNIT
VCC SUPPLY
VCC Reg VCC Regulator Output VIN = 48 V, ICC = 20 mA 6.25 7.6 8.55 V
VCC Current Limit VIN = 48 V(2) 26 mA
VCC UVLO Threshold (VCC increasing) 4.15 4.5 4.9 V
VCC UVLO Hysteresis 300 mV
VCC Dropout Voltage VIN = 8 V, ICC = 20 mA 2.3 V
IIN Operating Current Non-switching, FB = 3 V 1.75 mA
IIN Shutdown Current UVLO = 0 V 50 225 µA
UNDERVOLTAGE SENSING FUNCTION
UV Threshold UV Rising 1.19 1.225 1.26 V
UV Hysteresis Input Current UV = 2.5 V –10 –20 –29 µA
Remote Shutdown Threshold Voltage at UVLO Falling 0.32 0.66 V
Remote Shutdown Hysteresis 110 mV
REGULATION AND OVERVOLTAGE COMPARATORS
FB Regulation Level Internal Reference Trip Point for Switch ON 1.2 1.225 1.25 V
FB Overvoltage Threshold Trip Point for Switch OFF 1.62 V
FB Bias Current 60 nA
SWITCH CHARACTERISTICS
Buck Switch RDS(ON) ITEST = 200 mA, BST-SW = 7 V 0.8 1.8 Ω
Synchronous RDS(ON) ITEST = 200 mA 0.45 1 Ω
Gate Drive UVLO VBST − VSW Rising 2.4 3 3.6 V
Gate Drive UVLO Hysteresis 260 mV
CURRENT LIMIT
Current Limit Threshold 0.7 1.02 1.3 A
Current Limit Response Time Time to switch off 150 ns
OFF-Time Generator (Test 1) FB = 0.1 V, VIN = 48 V 12 µs
OFF-Time Generator (Test 2) FB = 1.0 V, VIN = 48 V 2.5 µs
THERMAL SHUTDOWN
Tsd Thermal Shutdown Temperature 165 °C
Thermal Shutdown Hysteresis 20 °C
(1) All limits are specified by design. All electrical characteristics having room temperature limits are tested during production at TA = 25°C. All hot and cold limits are specified by correlating the electrical characteristics to process and temperature variations and applying statistical process control.
(2) VCC provides self bias for the internal gate drive and control circuits. Device thermal limitations limit external loading.