SNVSB79A November   2018  – July 2019 LM25180

PRODUCTION DATA.  

  1. Features
  2. Applications
  3. Description
    1.     Device Images
      1.      Typical Application
      2.      Typical Efficiency, VOUT = 5 V
  4. Revision History
  5. Pin Configuration and Functions
    1.     Pin Functions
  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 Typical Characteristics
  7. Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Integrated Power MOSFET
      2. 7.3.2  PSR Flyback Modes of Operation
      3. 7.3.3  Setting the Output Voltage
        1. 7.3.3.1 Diode Thermal Compensation
      4. 7.3.4  Control Loop Error Amplifier
      5. 7.3.5  Precision Enable
      6. 7.3.6  Configurable Soft Start
      7. 7.3.7  External Bias Supply
      8. 7.3.8  Minimum On-Time and Off-Time
      9. 7.3.9  Overcurrent Protection
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Shutdown Mode
      2. 7.4.2 Standby Mode
      3. 7.4.3 Active Mode
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Applications
      1. 8.2.1 Design 1: Wide VIN, Low IQ PSR Flyback Converter Rated at 5 V, 1 A
        1. 8.2.1.1 Design Requirements
        2. 8.2.1.2 Detailed Design Procedure
          1. 8.2.1.2.1  Custom Design With WEBENCH® Tools
          2. 8.2.1.2.2  Custom Design With Excel Quickstart Tool
          3. 8.2.1.2.3  Flyback Transformer – T1
          4. 8.2.1.2.4  Flyback Diode – DFLY
          5. 8.2.1.2.5  Zener Clamp Circuit – DF, DCLAMP
          6. 8.2.1.2.6  Output Capacitor – COUT
          7. 8.2.1.2.7  Input Capacitor – CIN
          8. 8.2.1.2.8  Feedback Resistor – RFB
          9. 8.2.1.2.9  Thermal Compensation Resistor – RTC
          10. 8.2.1.2.10 UVLO Resistors – RUV1, RUV2
          11. 8.2.1.2.11 Soft-Start Capacitor – CSS
        3. 8.2.1.3 Application Curves
      2. 8.2.2 Design 2: PSR Flyback Converter With Dual Outputs of 15 V and –7.7 V at 200 mA
        1. 8.2.2.1 Design Requirements
        2. 8.2.2.2 Detailed Design Procedure
          1. 8.2.2.2.1 Flyback Transformer – T1
          2. 8.2.2.2.2 Flyback Diodes – DFLY1 and DFLY2
          3. 8.2.2.2.3 Input Capacitor – CIN
          4. 8.2.2.2.4 Feedback Resistor – RFB
          5. 8.2.2.2.5 UVLO Resistors – RUV1, RUV2
        3. 8.2.2.3 Application Curves
      3. 8.2.3 Design 3: PSR Flyback Converter With Stacked Dual Outputs of 24 V and 5 V
        1. 8.2.3.1 Design Requirements
        2. 8.2.3.2 Detailed Design Procedure
          1. 8.2.3.2.1 Flyback Transformer – T1
          2. 8.2.3.2.2 Feedback Resistor – RFB
          3. 8.2.3.2.3 UVLO Resistors – RUV1, RUV2
        3. 8.2.3.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Examples
  11. 11Device and Documentation Support
    1. 11.1 Device Support
      1. 11.1.1 Third-Party Products Disclaimer
      2. 11.1.2 Development Support
      3. 11.1.3 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • NGU|8
Thermal pad, mechanical data (Package|Pins)
Orderable Information

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 36 V
Input UVLO thresholds 9.5 V on, 6.5 V off
Output voltage 5 V
Rated load current, VIN = 24 V 1 A
Output voltage regulation ±1.5%
Output voltage ripple < 100 mV

The target full-load efficiency is 86% based on a nominal input voltage of 24 V and an isolated output voltage of 5 V. The LM25180 is chosen to deliver a fixed 5-V output voltage set by resistor RFB connected between the SW and FB pins. The input voltage turn-on and turn-off thresholds are established by RUV1 and RUV2. The required components are listed in Table 2.

Table 2. List of Components for Design 1

REF DES QTY SPECIFICATION VENDOR PART NUMBER
CIN 1 10 µF, 50 V, X7R, 1210, ceramic Taiyo Yuden UMK325AB7106KM-T
COUT 1 100 µF, 6.3 V, X7S, 1210, ceramic Murata GRM32EC70J107ME15
Taiyo Yuden JMK325AC7107MM-P
100 µF, 6.3 V, X5R, 1210, ceramic TDK C3225X5R0J107M250AC
Würth Electronik 885012109004
CSS 1 47 nF, 16 V, X7R, 0402 Std Std
DCLAMP 1 Zener, 24 V, 1 W, PowerDI-123 DFLZ24-7 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 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 30 µH, 2 A, turns ratio 3 : 1, 9.3 × 10.2 mm Coilcraft YA8779-BLD
Würth Electronik 750317605
30 µH, 2.6 A, turns ratio 3 : 1, 12.5 × 15.5 mm Sumida 12387-T151
40 µH, 2 A, turns ratio 3 : 1, 13.3 × 15.2 mm Würth Electronik 750313974
U1 1 LM25180 PSR flyback converter, VSON-8 Texas Instruments LM25180NGUR