SLUSCG2A March   2016  – March 2016 UCC24636

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Device Comparison Table
  6. 6 Pin Configuration and 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 Timing Requirements
    7. 7.7 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 Start Up and UVLO
      2. 8.3.2 Volt-Sec SR Driver On-Time Control
      3. 8.3.3 Standby Operation
      4. 8.3.4 Pin Fault Protection
        1. 8.3.4.1 VPC Pin Overvoltage
        2. 8.3.4.2 VPC Pin Open
        3. 8.3.4.3 VSC Pin Open
        4. 8.3.4.4 TBLK Pin Open
        5. 8.3.4.5 VPC and VSC Short to Ground
        6. 8.3.4.6 TBLK Pin Short to Ground
    4. 8.4 Device Functional Modes
      1. 8.4.1 Start-Up
      2. 8.4.2 Normal Operation
      3. 8.4.3 Standby Operation
      4. 8.4.4 Conditions to Stop Operation
  9. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application
      1. 9.2.1 AC-to-DC Adapter, 5 V, 15 W
      2. 9.2.2 Design Requirements
      3. 9.2.3 Calculation of Component Values
        1. 9.2.3.1 VPC Input
        2. 9.2.3.2 VSC Input
        3. 9.2.3.3 TBLK Input
      4. 9.2.4 Application Waveforms And Curves
    3. 9.3 Do's and Don'ts
  10. 10Power Supply Recommendations
  11. 11Layout
    1. 11.1 Layout Guidelines
      1. 11.1.1 VDD Pin
      2. 11.1.2 VPC Pin
      3. 11.1.3 VSC Pin
      4. 11.1.4 GND Pin
      5. 11.1.5 TBLK Pin
      6. 11.1.6 DRV Pin
    2. 11.2 Layout Example
  12. 12Device and Documentation Support
    1. 12.1 Device Support
      1. 12.1.1 Device Nomenclature
        1. 12.1.1.1 Definition of Terms (For Design Example)
    2. 12.2 Documentation Support
      1. 12.2.1 Related Documentation
    3. 12.3 Trademarks
    4. 12.4 Electrostatic Discharge Caution
    5. 12.5 Glossary
  13. 13Mechanical, Packaging, and Orderable Information

Package Options

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

1 Features

  • Secondary-Side SR Controller Optimized for 5-V to 24-V Output Discontinuous/Transition Mode Only Flyback Converters
  • Volt-Second Balance Control Enables Highest Rectifier Efficiency
  • Compatible with PSR and SSR Flyback Controllers
  • Ultra Low 110-µA Standby Current Consumption
  • Auto-Detect Standby Mode Disables SR Switching for Lower No-Load Power Consumption
  • SR Turn-Off Independent of RDSON and Parasitic Inductance
  • Operating Frequency Up to 130 kHz
  • Wide VDD Range from 3.6 V to 28 V
  • Adaptive Gate Drive Clamp
  • Open and Short Pin Fault Protection

2 Applications

  • AC/DC Adapters For Smartphones and Tablets
  • USB Chargers with Type-C Connectors
  • Notebook and Ultrabook Adapters
  • High Efficiency Flyback Converters in Industrial SMPS
  • High Efficiency Auxilliary Power In Server and Desktop Applications

3 Description

The UCC24636 SR is a compact, 6-pin secondary-side synchronous rectifier MOSFET controller and driver for high efficiency Flyback converters operating in Discontinuous (DCM) and Transition mode (TM). Unlike traditional SR controllers which measure the SR MOSFET drain voltage, UCC24636 implements a volt-second balance control method to determine the turn off transition of the SR MOSFET; hence, SR conduction time is independent of the MOSFET RDSON, parasitic inductance or ringing allowing flexibility to designers in component slelction and PCB layout. This control method enables maximum SR conduction time and highest rectifier efficiency for a given MOSFET.

The controller has built in intelligence to detect converter no load operation and automatically enters standby mode. While in standby mode, it disables the SR MOSFET and lowers its bias supply current to 110uA to further reduce overall system standby power consumption. The wide VDD operating range for the controller allows direct bias from the converter output for fixed or variable output voltage designs. This eliminates the need for an auxilliary winding on the main transformer, which simplifies the circuit design and reduces the cost.

Device Information(1)

PART NUMBER PACKAGE BODY SIZE (NOM)
UCC24636 SOT23 (6) 2.92 mm x 1.30 mm
  1. For all available packages, see the orderable addendum at the end of the data sheet.

Simplified Schematic

UCC24636 alt_lusc82.gif

Gate-Drive Timing vs VDS Sensing SR Driver

UCC24636 alt2_lusc82.gif