SLUSEQ9D July   2022  – April 2024 TPS1211-Q1

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 Switching Characteristics
    7. 6.7 Typical Characteristics
  8. 7 Parameter Measurement Information
  9. 8 Detailed Description
    1. 8.1 Overview
    2. 8.2 Functional Block Diagram
    3. 8.3 Feature Description
      1. 8.3.1 Charge Pump and Gate Driver Output (VS, PU, PD, BST, SRC)
      2. 8.3.2 Capacitive Load Driving
        1. 8.3.2.1 FET Gate Slew Rate Control
        2. 8.3.2.2 Using Precharge FET - (with TPS12111-Q1 Only)
      3. 8.3.3 Overcurrent and Short-Circuit Protection
        1. 8.3.3.1 Overcurrent Protection with Auto-Retry
        2. 8.3.3.2 Overcurrent Protection with Latch-Off
        3. 8.3.3.3 Short-Circuit Protection
      4. 8.3.4 Analog Current Monitor Output (IMON)
      5. 8.3.5 Overvoltage (OV) and Undervoltage Protection (UVLO)
      6. 8.3.6 Remote Temperature Sensing and Protection (DIODE)
      7. 8.3.7 Output Reverse Polarity Protection
      8. 8.3.8 TPS1211x-Q1 as a Simple Gate Driver
    4. 8.4 Device Functional Modes
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application: Driving Zonal Controller Loads on 12-V Line in Power Distribution Unit
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application: Reverse Polarity Protection with TPS12110-Q1
      1. 9.3.1 Design Requirements
      2. 9.3.2 External Component Selection
      3. 9.3.3 Application Curves
    4. 9.4 Power Supply Recommendations
    5. 9.5 Layout
      1. 9.5.1 Layout Guidelines
      2. 9.5.2 Layout Example
  11. 10Device and Documentation Support
    1. 10.1 Receiving Notification of Documentation Updates
    2. 10.2 Support Resources
    3. 10.3 Trademarks
    4. 10.4 Electrostatic Discharge Caution
    5. 10.5 Glossary
  12. 11Revision History
  13. 12Mechanical, Packaging, and Orderable Information

8.3.2.2 Using Precharge FET - (with TPS12111-Q1 Only)

In high-current applications where several FETs are connected in parallel, the gate slew rate control for the main FETs is not recommended due to unequal distribution of inrush currents among the FETs. This action makes FET selection complex and results in over sizing of the FETs.

The TPS12111-Q1 integrates precharge gate driver (G) with a dedicated control input (INP_G). This feature can be used to drive a separate FET that can be used to precharge the capacitive load. Figure 8-7 shows the precharge FET implementation for capacitive load charging using TPS12111-Q1. An external capacitor Cg reduces the gate turn-ON slew rate and controls the inrush current.

GUID-20220722-SS0I-JWQG-TSLB-CSGZ2FDFFV4S-low.svg Figure 8-7 Capacitor Charging Using Gate Slew Rate Control of Precharge FET

During power up with EN/UVLO high and CBST voltage above V(BST_UVLOR) threshold, INP and INP_G controls are active. For the precharge functionality, drive INP low to keep the main FETs OFF and drive INP_G high. G output gets pulled up to BST with I(G). Use Equation 5 to calculate the required Cg value.

Equation 5. C g   =   C L O A D   ×   I ( G ) I I N R U S H

Where,

I(G) is 100 µA (typical),

Use Equation 2 to calculate the IINRUSH.

A series resistor Rg must be used in conjunction with Cg to limit the discharge current from Cg during turn-off . The recommended value for Rg is between 220 Ω to 470 Ω. After the output capacitor is charged, turn OFF the precharge FET by driving INP_G low. G gets pulled low to SRC with an internal 135-mA pulldown switch. The main FETs can be turned ON by driving INP high.

Figure 8-18 shows other system design approaches to charge large output capacitors in high current applications. The designs involve an additional power resistor in series in series with precharge FET. The back-to-back FET topology shown is typically used in bi-directional power control applications like battery management systems.

GUID-20221208-SS0I-S4XR-B9TD-41MNBJHBW3BV-low.svg Figure 8-8 TPS12111-Q1 application Circuits for Capacitive Load Driving Using Precharge FET and a Series Power Resistor