SLUSEW1 January   2024 TPS4810-Q1

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 Switching Characteristics
  7. 6 Parameter Measurement Information
  8. 7 Detailed Description
    1. 7.1 Overview
    2. 7.2 Functional Block Diagram
    3. 7.3 Feature Description
      1. 7.3.1 Charge Pump and Gate Driver Output (VS, G1PU, G1PD, G2, BST, SRC)
      2. 7.3.2 Capacitive Load Driving Using FET Gate (G1PU, G1PD) Slew Rate Control
      3. 7.3.3 Short-Circuit Protection
        1. 7.3.3.1 Short-Circuit Protection With Auto-Retry
        2. 7.3.3.2 Short-Circuit Protection With Latch-Off
      4. 7.3.4 Undervoltage Protection (UVLO)
      5. 7.3.5 Reverse Polarity Protection
      6. 7.3.6 Short-Circuit Protection Diagnosis (SCP_TEST)
      7. 7.3.7 TPS48100-Q1 as a Simple Gate Driver
    4. 7.4 Device Functional Modes
  9. 8 Application and Implementation
    1. 8.1 Application Information
      1. 8.1.1 Application Limitations
        1. 8.1.1.1 Short-Circuit Protection Delay
        2. 8.1.1.2 Short-Circuit Protection Threshold
    2. 8.2 Typical Application: Circuit Breaker in Battery Management System (BMS) using Low Side Current Sense
      1. 8.2.1 Design Requirements
      2. 8.2.2 Detailed Design Procedure
      3. 8.2.3 Application Curves
    3. 8.3 Power Supply Recommendations
    4. 8.4 Layout
      1. 8.4.1 Layout Guidelines
      2. 8.4.2 Layout Example
  10. 9 Device and Documentation Support
    1. 9.1 Receiving Notification of Documentation Updates
    2. 9.2 Support Resources
    3. 9.3 Trademarks
    4. 9.4 Electrostatic Discharge Caution
    5. 9.5 Glossary
  11. 10Revision History
  12. 11Mechanical, Packaging, and Orderable Information

Package Options

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

7.3.2 Capacitive Load Driving Using FET Gate (G1PU, G1PD) Slew Rate Control

For limiting inrush current during turn-ON of the external FET (Q1) with capacitive loads, use R1, R2, C1 as shown in Figure 7-4. The R1 and C1 components slow down the voltage ramp rate at the gate of Q1 FET. The FET source follows the gate voltage resulting in a controlled voltage ramp across the output capacitors.

GUID-20230423-SS0I-FTBT-NSHS-0DK07LBCVM08-low.svgFigure 7-4 Inrush Current Limiting Using G1 Gate Drive

Use the Equation 2 to calculate the inrush current during turn-ON of the FET.

Equation 2. IINRUSH= CLOAD× VBATTTcharge
Equation 3. C1= 0.63 × V(BST - SRC) × CLOADR1 × IINRUSH

Where,

CLOAD is the load capacitance.

VBATT is the input voltage and Tcharge is the charge time.

V(BST-SRC) is the charge pump voltage (11V),

Use a damping resistor R2 (approximately 10Ω) in series with C1. Equation 3 can be used to compute required C1 value for a target inrush current. A 100kΩ resistor for R1 can be a good starting point for calculations.

Connecting G1PD pin of TPS48100-Q1 directly to the gate of the Q1 FET ensures fast turn-OFF without any impact of R1 and C1 components.

C1 results in an additional loading on CBST to charge during turn-ON. Use below equation to calculate the required CBST value:

Equation 4. CBST = Qg(total)∆VBST+ 10 × C1

Where,

Qg(total) is the total gate charge of the FET,

ΔVBST (1V typical) is the ripple voltage across BST to SRC pins.