SLVSI14 March   2026 TPS922152

ADVANCE INFORMATION  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Pin Configuration and Functions
  6. 5 Specifications
    1. 5.1 Absolute Maximum Ratings
    2. 5.2 ESD Ratings
    3. 5.3 Recommended Operating Conditions
    4. 5.4 Thermal Information
    5. 5.5 Electrical Characteristics
    6. 5.6 Typical Characteristics
  7. 6 Detailed Description
    1. 6.1 Overview
    2. 6.2 Functional Block Diagram
    3. 6.3 Feature Description
      1. 6.3.1 Adaptive Off-Time Mode
      2. 6.3.2 Setting LED Current
      3. 6.3.3 VIN UVLO & Clamping
      4. 6.3.4 Dimming Mode
        1. 6.3.4.1 PWM Dimming
        2. 6.3.4.2 Analog Dimming
        3. 6.3.4.3 External Shunt Dimming
      5. 6.3.5 Fault Protection
  8. 7 Application and Implementation
    1. 7.1 Application Information
    2. 7.2 Typical Application
      1. 7.2.1 TPS922152 60V Input Bus, 5A Output, 16-piece WLED With Analog and PWM Dimming
        1. 7.2.1.1 Design Requirements
        2. 7.2.1.2 Detailed Design Procedure
          1. 7.2.1.2.1 Inductor Selection
          2. 7.2.1.2.2 Input Capacitor Selection
          3. 7.2.1.2.3 Output Capacitor Selection
          4. 7.2.1.2.4 Sense Resistor Selection
          5. 7.2.1.2.5 Other External Components Selection
        3. 7.2.1.3 Application Curves
    3. 7.3 Power Supply Recommendations
    4. 7.4 Layout
      1. 7.4.1 Layout Guidelines
      2. 7.4.2 Layout Example
  9. 8 Device and Documentation Support
    1. 8.1 Receiving Notification of Documentation Updates
    2. 8.2 Support Resources
    3. 8.3 Trademarks
    4. 8.4 Electrostatic Discharge Caution
    5. 8.5 Glossary
  10. 9 Revision History
  11. 10Mechanical, Packaging, and Orderable Information

6.3.1 Adaptive Off-Time Mode

The TPS922152 device operates in AOT mode average-current control with constant frequency to support accurate current regulation and fast transient response over a wide load range.

For average output current regulation, the sensed voltage across the sensing resistor between the CSZCD pin and ground is averaged and compared with the internal voltage reference, VREF , through the error amplifier. VREF is controllable through the analog input voltage at ADIM pin. During each switching cycle, when the switching FET is turned on, the current rising edge is sensed through the CSZCD pin. The output of the error amplifier, VCOMP, passes through an internal compensation network and is then compared with the current rising edge. When the sensed current reaches VCOMP at the input of PWM comparator, the switching FET is turned off to generate the peak current.

An off-time counter starts counting after the switching FET is turned off. The counting off time corresponding to a switching frequency is determined by the external resistor connected to the FSET pin. Once the off-time counter stops counting, the counter is reset until when the switching FET stays off. Thus, the device is able to maintain a nearly constant switching frequency at steady state CCM and DCM. By connecting an external resistor between FSET pin and ground, the switching frequency is set in the range of 50kHz to 1MHz. The resistor value and the corresponding switching frequency can be calculated using Equation 7

Equation 1. F S W = 1 R F S E T × C F S E T

where

  • CFSET = 100pF

At light load, the off time continuously increases by pulse frequency modulation for accurate light load control. The minimum switching frequency is clamped at 20kHz.

TPS922152 AOT mode average-current control Figure 6-1 AOT mode average-current control