SLUSEI6 November   2021 UCC28781-Q1

PRODUCTION DATA  

  1. Features
  2. Applications
  3. Description
  4. Revision History
  5. Pin Configuration and 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 Detailed Pin Description
      1. 7.3.1  BUR Pin (Programmable Burst Mode)
      2. 7.3.2  FB Pin (Feedback Pin)
      3. 7.3.3  REF Pin (Internal 5-V Bias)
      4. 7.3.4  VDD Pin (Device Bias Supply)
      5. 7.3.5  P13 and SWS Pins
      6. 7.3.6  S13 Pin
      7. 7.3.7  IPC Pin (Intelligent Power Control Pin)
      8. 7.3.8  RUN Pin (Driver and Bias Source for Isolator)
      9. 7.3.9  PWMH and AGND Pins
      10. 7.3.10 PWML and PGND Pins
      11. 7.3.11 SET Pin
      12. 7.3.12 RTZ Pin (Sets Delay for Transition Time to Zero)
      13. 7.3.13 RDM Pin (Sets Synthesized Demagnetization Time for ZVS Tuning)
      14. 7.3.14 XCD Pin
      15. 7.3.15 CS, VS, and FLT Pins
    4. 7.4 Device Functional Modes
      1. 7.4.1  Adaptive ZVS Control with Auto-Tuning
      2. 7.4.2  Dead-Time Optimization
      3. 7.4.3  EMI Dither and Dither Fading Function
      4. 7.4.4  Control Law Across Entire Load Range
      5. 7.4.5  Adaptive Amplitude Modulation (AAM)
      6. 7.4.6  Adaptive Burst Mode (ABM)
      7. 7.4.7  Low Power Mode (LPM)
      8. 7.4.8  First Standby Power Mode (SBP1)
      9. 7.4.9  Second Standby Power Mode (SBP2)
      10. 7.4.10 Startup Sequence
      11. 7.4.11 Survival Mode of VDD (INT_STOP)
      12. 7.4.12 System Fault Protections
        1. 7.4.12.1  Brown-In and Brown-Out
        2. 7.4.12.2  Output Over-Voltage Protection (OVP)
        3. 7.4.12.3  Input Over Voltage Protection (IOVP)
        4. 7.4.12.4  Over-Temperature Protection (OTP) on FLT Pin
        5. 7.4.12.5  Over-Temperature Protection (OTP) on CS Pin
        6. 7.4.12.6  Programmable Over-Power Protection (OPP)
        7. 7.4.12.7  Peak Power Limit (PPL)
        8. 7.4.12.8  Output Short-Circuit Protection (SCP)
        9. 7.4.12.9  Over-Current Protection (OCP)
        10. 7.4.12.10 External Shutdown
        11. 7.4.12.11 Internal Thermal Shutdown
      13. 7.4.13 Pin Open/Short Protections
        1. 7.4.13.1 Protections on CS pin Fault
        2. 7.4.13.2 Protections on P13 pin Fault
        3. 7.4.13.3 Protections on RDM and RTZ pin Faults
  8. Application and Implementation
    1. 8.1 Application Information
    2. 8.2 Typical Application Circuit
      1. 8.2.1 Design Requirements for a 60-W, 15-V ZVSF Bias Supply Application with a DC Input
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Input Bulk Capacitance and Minimum Bulk Voltage
        2. 8.2.2.2 Transformer Calculations
          1. 8.2.2.2.1 Primary-to-Secondary Turns Ratio (NPS)
          2. 8.2.2.2.2 Primary Magnetizing Inductance (LM)
          3. 8.2.2.2.3 Primary Winding Turns (NP)
          4. 8.2.2.2.4 Secondary Winding Turns (NS)
          5. 8.2.2.2.5 Auxiliary Winding Turns (NA)
          6. 8.2.2.2.6 Winding and Magnetic Core Materials
        3. 8.2.2.3 Calculation of ZVS Sensing Network
        4. 8.2.2.4 Calculation of BUR Pin Resistances
        5. 8.2.2.5 Calculation of Compensation Network
      3. 8.2.3 Application Curves
  9. Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
      1. 10.1.1  General Considerations
      2. 10.1.2  RDM and RTZ Pins
      3. 10.1.3  SWS Pin
      4. 10.1.4  VS Pin
      5. 10.1.5  BUR Pin
      6. 10.1.6  FB Pin
      7. 10.1.7  CS Pin
      8. 10.1.8  AGND Pin
      9. 10.1.9  PGND Pin
      10. 10.1.10 Thermal Pad
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Receiving Notification of Documentation Updates
    2. 11.2 Support Resources
    3. 11.3 Trademarks
    4. 11.4 Electrostatic Discharge Caution
    5. 11.5 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

RUN Pin (Driver and Bias Source for Isolator)

The RUN pin is a logic-level output signal which enables PWM switching when active high. When RUN is low, all PWML and PWMH switching is disabled and the controller enters a low-current wait state.

In addition to enabling switching, RUN is capable of sourcing considerable current to bias an external gate driver and perform a power management function on the primary side of a digital isolator. It generates a 5-V logic output when the driver should be active, and pulls down to less than 0.5 V when the driver should be disabled. During the off-time of any burst mode, the RUN pin serves as a power-management function to dynamically reduce the static bias current of the isolator/ driver, so light-load efficiency can be further improved and stand-by power can be minimized.

As RUN goes high, while its voltage is less than 3 V, a 44-mA peak pull-up current is supplied from the internal P13 regulator. With this current, the RUN driver can quickly charge the primary-side decoupling capacitor of a digital isolator above its UVLO(ON) threshold. A Schottky diode can block discharge of this capacitor when RUN goes low. When the RUN voltage goes above 3 V, P13 stops providing current and the pull-up is supplied from the REF regulator, so the peak driving capability will be limited in order to avoid triggering the over-current protection of the REF regulator. When RUN is low for a long burst off-time, the decoupling capacitor of the digital isolator will be gradually discharged below its UVLO(OFF) threshold, so the isolator power loss can be minimized.

There are three delays between RUN going high to the first PWML pulse going high in each burst packet. The first delay is a fixed 2.2-μs delay time, intended to provide an appropriate "wake-up" time for the controller and the gate driver to transition from a wait state to a run state. The second delay is gated by the 10-V power-good threshold of the S13 pin. PWML will not go high until S13 voltage exceeds 10 V. The third delay is another 2.2-μs timeout, tZC in the electrical table, intended to turn on the low-side switch of the first switching cycle per burst packet around the valley point of DCM ringing by waiting for the zero-crossing detection (ZCD) on the auxiliary winding voltage (VAUX). If ZCD is detected (on the VS input) before the tZC timeout elapses, PWML is immediately driven. If no ZCD is detected, PWML is driven when tZC elapses. The first two delays can be concurrent; the third delay is sequential.

Therefore, the minimum total delay time is 2.2 μs typically if VS13 > 10 V and ZCD is detected immediately after the 2.2-μs wake-up time. If VS13 < 10 V, the total delay time with tolerance over temperature is listed as tD(RUN-PWML) in the electrical table.

Figure 7-12 Power Management Circuit
Figure 7-13 Power Management Waveform