SLUS161G April   1999  – April 2025 UCC2813-0 , UCC2813-1 , UCC2813-2 , UCC2813-3 , UCC2813-4 , UCC2813-5 , UCC3813-0 , UCC3813-1 , UCC3813-2 , UCC3813-3 , UCC3813-4 , UCC3813-5

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison Table
  6. 5 Pin Configuration and Functions
  7. 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
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1  Detailed Pin Descriptions
        1. 7.3.1.1 COMP
        2. 7.3.1.2 CS
        3. 7.3.1.3 FB
        4. 7.3.1.4 GND
        5. 7.3.1.5 OUT
        6. 7.3.1.6 RC
        7. 7.3.1.7 REF
        8. 7.3.1.8 VCC
      2. 7.3.2  Undervoltage Lockout (UVLO)
      3. 7.3.3  Self-Biasing, Active Low Output
      4. 7.3.4  Reference Voltage
      5. 7.3.5  Oscillator
      6. 7.3.6  Synchronization
      7. 7.3.7  PWM Generator
      8. 7.3.8  Minimum Off-Time Adjustment (Dead-Time Control)
      9. 7.3.9  Leading Edge Blanking
      10. 7.3.10 Minimum Pulse Width
      11. 7.3.11 Current Limiting
      12. 7.3.12 Overcurrent Protection and Full-Cycle Restart
      13. 7.3.13 Soft Start
      14. 7.3.14 Slope Compensation
    4. 7.4 Device Functional Modes
      1. 7.4.1 Normal Operation
      2. 7.4.2 UVLO Mode
      3. 7.4.3 Soft-Start Mode
      4. 7.4.4 Fault Mode
  9. 8 Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1  Bulk Capacitor Calculation
        2. 8.2.2.2  Transformer Design
        3. 8.2.2.3  MOSFET and Output Diode Selection
        4. 8.2.2.4  Output Capacitor Calculation
        5. 8.2.2.5  Current Sensing Network
        6. 8.2.2.6  Gate Drive Resistor
        7. 8.2.2.7  REF Bypass Capacitor
        8. 8.2.2.8  RT and CT
        9. 8.2.2.9  Start-Up Circuit
        10. 8.2.2.10 Voltage Feedback Compensation Procedure
          1. 8.2.2.10.1 Power Stage Gain, Zeroes, and Poles
          2. 8.2.2.10.2 Compensating the Loop
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Documentation Support
      1. 9.1.1 Related Documentation
    2. 9.2 Related Links
    3. 9.3 Receiving Notification of Documentation Updates
    4. 9.4 Support Resources
    5. 9.5 Trademarks
    6. 9.6 Electrostatic Discharge Caution
    7. 9.7 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

Refer to the PDF data sheet for device specific package drawings

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

7.3.2 Undervoltage Lockout (UVLO)

The UCCx813-[2,4] devices feature undervoltage lockout protection circuits for controlled operation during power-up and power-down sequences. Both the supply voltage (VVCC) and the reference voltage (VREF) are monitored by the UVLO circuitry. During UVLO, an active-low, self-biasing totem-pole output structure is also incorporated for enhanced power switch protection.

Undervoltage lockout thresholds for the UCCx813-[2,3,4,5] devices are different from the previous generation of UCx84[2,3,4,5] PWM controllers. The thresholds are optimized for two groups of applications: off-line power supplies and DC-DC converters. See Table 7-1 for the specific thresholds for each device.

Table 7-1 UVLO Level Comparison Table
DEVICEVON (V)VOFF (V)
UCCx813-07.26.9
UCCx813-19.47.4
UCCx813-[2,4]12.58.3
UCCx813-[3,5]4.13.6

The UCCx813-[2,4] feature typical UVLO thresholds of 12.5 V for turnon and 8.3 V for turnoff, providing 4.3 V of hysteresis.

For low voltage inputs, which include battery and 5-V applications, the UCCx813-[3,5] turn on at 4.1 V and turn off at 3.6 V with 0.5 V of hysteresis.

The UCCx813-[0,1] have UVLO thresholds optimized for automotive and battery applications.

During UVLO, the device draws approximately 100 µA of supply current. Once VCC crosses the turnon threshold, the IC supply current increases typically to about 500 µA, over an order of magnitude lower than bipolar counterparts. Figure 7-1 indicates the supply current behavior at the relative UVLO turnon and turnoff thresholds, not including average OUT current.

UCC2813-0 UCC2813-1 UCC2813-2 UCC2813-3 UCC2813-4 UCC2813-5 UCC3813-0 UCC3813-1 UCC3813-2 UCC3813-3 UCC3813-4 UCC3813-5 IC Supply Current at UVLOFigure 7-1 IC Supply Current at UVLO