SLVSGU5A April   2022  – July 2022 TPS22811

PRODUCTION DATA  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
  6. 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 Timing Requirements
    7. 6.7 Switching Characteristics
      1.      14
    8. 6.8 Typical Characteristics
  7. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Undervoltage Lockout (UVLO and UVP)
      2. 7.3.2 Overvoltage Lockout (OVLO)
      3. 7.3.3 Inrush Current, Overcurrent, and Short-Circuit Protection
        1. 7.3.3.1 Slew Rate (dVdt) and Inrush Current Control
        2. 7.3.3.2 Short-Circuit Protection
        3. 7.3.3.3 Active Current Limiting During Start-Up
      4. 7.3.4 Analog Load Current Monitor
      5. 7.3.5 Overtemperature Protection (OTP)
      6. 7.3.6 Fault Response
      7. 7.3.7 Power-Good Indication (PG)
      8. 7.3.8 Quick Output Discharge (QOD)
    4. 7.4 Device Functional Modes
  8. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Single Device, Self-Controlled
      2. 8.1.2 Parallel Operation
    2. 8.2 Typical Application
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
        1. 8.2.2.1 Setting Undervoltage and Overvoltage Thresholds
        2. 8.2.2.2 Setting Output Voltage Rise Time (tR)
        3. 8.2.2.3 Setting Power-Good Assertion Threshold
        4. 8.2.2.4 Setting Analog Current Monitor Voltage (IMON) Range
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
    1. 9.1 Transient Protection
    2. 9.2 Output Short-Circuit Measurements
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Related Documentation
    2. 11.2 Receiving Notification of Documentation Updates
    3. 11.3 Support Resources
    4. 11.4 Trademarks
    5. 11.5 Electrostatic Discharge Caution
    6. 11.6 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

9.1 Transient Protection

In the case of a short-circuit or device turn off during steady-state when the device interrupts current flow, the input inductance generates a positive voltage spike on the input, and the output inductance generates a negative voltage spike on the output. The peak amplitude of voltage spikes (transients) is dependent on the value of inductance in series to the input or output of the device. Such transients can exceed the absolute maximum ratings of the device if steps are not taken to address the issue. Typical methods for addressing transients include:

  • Minimize lead length and inductance into and out of the device.
  • Use a large PCB GND plane.
  • Connect a Schottky diode from the OUT pin ground to absorb negative spikes.
  • Connect a low ESR capacitor larger than 1 μF at the OUT pin very close to the device.
  • Use a low-value ceramic capacitor CIN = 1 μF to absorb the energy and dampen the transients. The capacitor voltage rating must be at least twice the input supply voltage to be able to withstand the positive voltage excursion during inductive ringing.

    Use Equation 15 to estimate the approximate value of input capacitance:

    Equation 15. VSPIKEAbsolute = VIN+ ILOAD  × LINCIN

    where

    • VIN is the nominal supply voltage.
    • ILOAD is the load current.
    • LIN equals the effective inductance seen looking into the source.
    • CIN is the capacitance present at the input.
  • Some applications can require the addition of a Transient Voltage Suppressor (TVS) to prevent transients from exceeding the absolute maximum ratings of the device. In some cases, even if the maximum amplitude of the transients is below the absolute maximum rating of the device, a TVS can help to absorb the excessive energy dump and prevent it from creating very fast transient voltages on the input supply pin of the IC, which can couple to the internal control circuits and cause unexpected behavior.

Figure 9-1 shows the circuit implementation with optional protection components.

GUID-20220321-SS0I-TCSM-JMBB-4DR42CGJJ81X-low.gifFigure 9-1 Circuit Implementation with Optional Protection Components