SNVSBN6 April   2020 LM5181-Q1

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Typical Application
      2.      Typical Efficiency, VOUT = 5 V
  4. 4 Revision History
  5. 5 Description (continued)
  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 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 Power MOSFET
      2. 8.3.2  PSR Flyback Modes of Operation
      3. 8.3.3  Setting the Output Voltage
        1. 8.3.3.1 Diode Thermal Compensation
      4. 8.3.4  Control Loop Error Amplifier
      5. 8.3.5  Precision Enable
      6. 8.3.6  Configurable Soft Start
      7. 8.3.7  External Bias Supply
      8. 8.3.8  Minimum On-Time and Off-Time
      9. 8.3.9  Overcurrent Protection
      10. 8.3.10 Thermal Shutdown
    4. 8.4 Device Functional Modes
      1. 8.4.1 Shutdown Mode
      2. 8.4.2 Standby Mode
      3. 8.4.3 Active Mode
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Applications
      1. 9.2.1 Design 1: Wide VIN, Low IQ PSR Flyback Converter Rated at 5 V, 0.5 A
        1. 9.2.1.1 Design Requirements
        2. 9.2.1.2 Detailed Design Procedure
          1. 9.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 9.2.1.2.2  Custom Design With Excel Quickstart Tool
          3. 9.2.1.2.3  Flyback Transformer – T1
          4. 9.2.1.2.4  Flyback Diode – DFLY
          5. 9.2.1.2.5  Zener Clamp Circuit – DF, DCLAMP
          6. 9.2.1.2.6  Output Capacitor – COUT
          7. 9.2.1.2.7  Input Capacitor – CIN
          8. 9.2.1.2.8  Feedback Resistor – RFB
          9. 9.2.1.2.9  Thermal Compensation Resistor – RTC
          10. 9.2.1.2.10 UVLO Resistors – RUV1, RUV2
          11. 9.2.1.2.11 Soft-Start Capacitor – CSS
      2. 9.2.2 Application Curves
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
    2. 11.2 Layout Examples
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Third-Party Products Disclaimer
      2. 12.1.2 Development Support
      3. 12.1.3 Custom Design With WEBENCH® Tools
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Receiving Notification of Documentation Updates
    4. 12.4 Support Resources
    5. 12.5 Trademarks
    6. 12.6 Electrostatic Discharge Caution
    7. 12.7 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

Mechanical Data (Package|Pins)
Thermal pad, mechanical data (Package|Pins)
Orderable Information

9.2.1.1 Design Requirements

The required input, output, and performance parameters for this application example are shown in Table 1.

Table 1. Design Parameters

DESIGN PARAMETER VALUE
Input voltage range 10 V to 65 V
Input UVLO thresholds 9.5 V on, 6.5 V off
Output voltage 5 V
Rated load current, VIN = 24 V 0.5 A
Output voltage regulation ±1.5%
Output voltage ripple < 100 mV

The target full-load efficiency is 87.5% based on a nominal input voltage of 24 V and an isolated output voltage of 5 V. The LM5181-Q1 is chosen to deliver a fixed 5-V output voltage set by resistor RFB connected between the SW and FB pins. The input voltage turnon and turnoff thresholds are established by RUV1 and RUV2. The required components are listed in Table 2. Transformers for other designs are listed in Table 3.

Table 2. List of Components for Design 1

REF DES QTY SPECIFICATION VENDOR PART NUMBER
CIN 1 2.2 µF, 100 V, X7R, 1206, ceramic AVX 12061C225K4T2A
2.2 µF, 100 V, X7R, 1210, ceramic, AEC-Q200 TDK CGA6N3X7R2A225K230AB
Murata GCJ32DR72A225KA01L
Taiyo Yuden HMK325B7225KMHP
COUT 1 47 µF, 10 V, X7S, 1210, ceramic, AEC-Q200 TDK CGA6P1X7S1A476M250AC
47 µF, 10 V, X7R, 1210, ceramic Murata GRM32ER71A476KE15L
Taiyo Yuden LMK325B7476MM-TR
CSS 1 47 nF, 16 V, X7R, 0402 Std Std
DCLAMP 1 Zener, 24 V, 1 W, PowerDI-123, AEC-Q101 DFLZ24Q-7 Diodes Inc.
DF 1 Switching diode, 75 V, 0.25 A, SOD-323 CMDD4448 Central Semi
DFLY 1 Schottky diode, 40 V, 2 A, SOD-123 FSV340FP Onsemi
DOUT 1 Zener, 5.6 V, 5%, SOD-523, AEC-Q101 BZX585-C5V6 Nexperia
RFB 1 158 kΩ, 1%, 0402 Std Std
RSET 1 12.1 kΩ, 1%, 0402 Std Std
RTC 1 130 kΩ, 1%, 0402 Std Std
RUV1 1 536 kΩ, 1%, 0603 Std Std
RUV2 1 100 kΩ, 1%, 0402 Std Std
T1 1 44 µH, 1.4 A, 3 : 1, 8.2 × 8.6 × 9.6 mm Würth Electronik 750318633
U1 1 LM5181-Q1 PSR flyback converter, AEC-Q100, VSON-8 Texas Instruments LM5181QNGURQ1

Table 3. Magnetic Components for Various Output Voltages

OUTPUT VOLTAGE (RANGE) TURNS RATIO LMAG, ISAT DIMENSIONS VENDOR PART NUMBER
3.3 V (up to 4 V) 4 : 1 40 µH, 1 A 8.6 × 8.26 × 9.65 mm Würth Electronik 750319117
5 V (4 V to 5.5 V) 3 : 1 44 µH, 1 A 750318633
12 V (5.5 V to 16 V) 1 : 1 750318737
24 V (16 V to 32 V) 1 : 2 750318738
48 V (32 V to 50 V) 1 : 3 750319118
15 V and –7.5 V dual 1 : 1.5 : 0.8 30 µH, 1 A 750319119