SLUSBP9C SEPTEMBER   2013  – June 2018 TPS53513

PRODUCTION DATA.  

  1. 1 Features
  2. 2 Applications
  3. 3 Description
    1.     Device Images
      1.      Simplified Schematic
      2.      Efficiency
  4. 4 Revision History
  5. 5 Pin Configuration and Functions
    1.     Pin 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 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  5-V LDO and VREG Start-Up
      2. 7.3.2  Enable, Soft Start, and Mode Selection
      3. 7.3.3  Frequency Selection
      4. 7.3.4  D-CAP3 Control and Mode Selection
        1. 7.3.4.1 D-CAP3 Mode
        2. 7.3.4.2 Sample and Hold Circuitry
        3. 7.3.4.3 Adaptive Zero-Crossing
      5. 7.3.5  Power-Good
      6. 7.3.6  Current Sense and Overcurrent Protection
      7. 7.3.7  Overvoltage and Undervoltage Protection
      8. 7.3.8  Out-Of-Bounds Operation
      9. 7.3.9  UVLO Protection
      10. 7.3.10 Thermal Shutdown
    4. 7.4 Device Functional Modes
      1. 7.4.1 Auto-Skip Eco-mode Light Load Operation
      2. 7.4.2 Forced Continuous-Conduction Mode
  8. 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 Choose the Switching Frequency
        2. 8.2.2.2 Choose the Operation Mode
        3. 8.2.2.3 Choose the Inductor
        4. 8.2.2.4 Choose the Output Capacitor
        5. 8.2.2.5 Determine the Value of R1 and R2
      3. 8.2.3 Application Curves
  9. 9 Power Supply Recommendations
  10. 10Layout
    1. 10.1 Layout Guidelines
    2. 10.2 Layout Example
    3. 10.3 Thermal Performance
  11. 11Device and Documentation Support
    1. 11.1 Documentation Support
      1. 11.1.1 Custom Design With WEBENCH® Tools
    2. 11.2 Documentation Support
      1. 11.2.1 Related Documentation
    3. 11.3 Receiving Notification of Documentation Updates
    4. 11.4 Community Resources
    5. 11.5 Trademarks
    6. 11.6 Electrostatic Discharge Caution
    7. 11.7 Glossary
  12. 12Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.6 Current Sense and Overcurrent Protection

The TPS53513 device has cycle-by-cycle overcurrent limiting control. The inductor current is monitored during the OFF state and the controller maintains the OFF state during the period that the inductor current is larger than the overcurrent trip level. To provide good accuracy and a cost-effective solution, the TPS53513 device supports temperature compensated MOSFET RDS(on) sensing. Connect the TRIP pin to GND through the trip-voltage setting resistor, RTRIP. The TRIP pin sources ITRIP current, which is 10 μA typically at room temperature, and the trip level is set to the OCL trip voltage VTRIP as shown in Equation 4.

Equation 4. TPS53513 eq2_ocl_trip_slusbn5.gif

where

  • VTRIP is in mV
  • RTRIP is in kΩ
  • ITRIP is in µA

The inductor current is monitored by the voltage between the GND pin and SW pin so that the SW pin is properly connected to the drain pin of the low-side MOSFET. ITRIP has a 3000-ppm/°C temperature slope to compensate the temperature dependency of RDS(on). The GND pin acts as the positive current-sensing node. Connect the GND pin to the proper current sensing device, (for example, the source pin of the low-side MOSFET.)

Because the comparison occurs during the OFF state, VTRIP sets the valley level of the inductor current. Thus, the load current at the overcurrent threshold, IOCP, is calculated as shown in Equation 5.

Equation 5. TPS53513 q_iocp_slusbn5.gif

where

  • RDS(on)L is the on-resistance of the low-side MOSFET
  • RTRIP is in kΩ

Equation 5 calculates the typical DC OCP level (typical low-side on-resistance [RDS(on)] of 5.9 mΩ should be used); to design for worst case minimum OCP, maximum low-side on-resistance value of 8 mΩ should be used.

During an overcurrent condition, the current to the load exceeds the current to the output capacitor thus the output voltage tends to decrease. Eventually, the output voltage crosses the undervoltage-protection threshold and shuts down.

For the TPS53513 device, the overcurrent protection maximum is recommended up to 12 A only.