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 3.

Table 3. Design Parameters

DESIGN PARAMETER VALUE
Input voltage range (steady state) 9.5 V to 36 V
Output 1 voltage and current 15 V, 0.2 A
Output 2 voltage and current –7.7 V, –0.2 A
Input UVLO thresholds 9 V on, 7 V off
Output voltage regulation ±2%

The target full-load efficiency of this LM25180 design is 88% based on a nominal input voltage of 24 V and isolated output voltages of 15 V and –7.7 V sharing a common return. The selected flyback converter components are cited in Table 4, including multi-winding flyback transformer, input and output capacitors, rectifying diodes and flyback converter IC.

Table 4. List of Components for Design 2

REF DES QTY SPECIFICATION VENDOR PART NUMBER
CIN 1 10 µF, 50 V, X7R, 1210, ceramic Taiyo Yuden UMK325AB7106KM-T
COUT1 1 22 µF, 25 V, X7R, 1210, ceramic TDK C3225X7R1E226M
Murata GRM32ER71E226KE15L
Taiyo Yuden TMK325B7226MM-TR
COUT2 1 47 µF, 10 V, X7R, 1210, ceramic TDK C3225X7R1A476M
Murata GRM32ER71A476ME15L
Taiyo Yuden LMK325B7476MM-TR
DFLY1 1 Schottky diode, 100 V, 1 A, PowerDI-123 DFLS1100-7 Diodes Inc.
DFLY2 1 Schottky diode, 60 V, 1 A, PowerDI-123 DFLS160-7 Diodes Inc.
DCLAMP 1 Zener, 24 V, 1 W, PowerDI-123 DFLZ24-7 Diodes Inc.
DF 1 Switching diode, 75 V, 0.3 A, SOD323 1N4148WS Diodes Inc.
DOUT1 1 Zener, 18 V, 5%, SOD523 BZX585-C18 Nexperia
DOUT2 1 Zener, 8.2 V, 2%, SOD523 BZX585-B8V2 Nexperia
RFB 1 154 kΩ, 1%, 0402 Std Std
RSET 1 12.1 kΩ, 1%, 0402 Std Std
RTC 1 200 kΩ, 1%, 0402 Std Std
RUV1 1 340 kΩ, 1%, 0603 Std Std
RUV2 1 68.1 kΩ, 1%, 0402 Std Std
T1 1 30 µH, 2 A, turns ratio 1 : 1: 0.52, 9 × 10 mm, SMT Coilcraft YA8916-BLD
Würth Electronik 750317595
U1 1 LM25180 PSR flyback converter, VSON-8 Texas Instruments LM25180NGUR