SLUSFM1 December   2024 TPS4812-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Device Comparison
  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, GATE, BST, SRC)
      2. 8.3.2 Capacitive Load Driving
        1. 8.3.2.1 Using Low-Power Bypass FET (G Drive) for Load Capacitor Charging
        2. 8.3.2.2 Using Main FET (GATE Drive) Gate Slew Rate Control
      3. 8.3.3 Overcurrent and Short-Circuit Protection
        1. 8.3.3.1 I2t-Based Overcurrent Protection
          1. 8.3.3.1.1 I2t-Based Overcurrent Protection With Auto-Retry
          2. 8.3.3.1.2 I2t-Based Overcurrent Protection With Latch-Off
        2. 8.3.3.2 Short-Circuit Protection
      4. 8.3.4 Analog Current Monitor Output (IMON)
      5. 8.3.5 NTC-Based Temperature Sensing (TMP) and Analog Monitor Output (ITMPO)
      6. 8.3.6 Fault Indication and Diagnosis (FLT)
      7. 8.3.7 Reverse Polarity Protection
      8. 8.3.8 Undervoltage Protection (UVLO)
    4. 8.4 Device Functional Modes
      1. 8.4.1 State Diagram
      2. 8.4.2 State Transition Timing Diagram
      3. 8.4.3 Power Down
      4. 8.4.4 Shutdown Mode
      5. 8.4.5 Low Power Mode (LPM)
      6. 8.4.6 Active Mode (AM)
  10. 9 Application and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical Application 1: Driving Power at all times (PAAT) Loads With Automatic Load Wakeup
      1. 9.2.1 Design Requirements
      2. 9.2.2 Detailed Design Procedure
      3. 9.2.3 Application Curves
    3. 9.3 Typical Application 2: Driving Power at all times (PAAT) Loads With Automatic Load Wakeup and Output Bulk Capacitor Charging
      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

Package Options

Refer to the PDF data sheet for device specific package drawings

Mechanical Data (Package|Pins)
  • RGE|23
Thermal pad, mechanical data (Package|Pins)
Orderable Information

8.3.3.1 I2t-Based Overcurrent Protection

The I2t profile for TPS4812-Q1 is set by two parameters which are I2t start overcurrent threshold, IOC and I2t ampere squared second factor (melting point or breaking point). The overcurrent protection time tOC is determined based on set I2t factor when load current is higher than set IOC threshold.

Setting I2t Protection Starting Threshold, RIOC

The I2t protection starting threshold IOC is set using an external resistor RIOC across IOC and GND pins.

Use Equation 9 to calculate the required RIOC value:

Equation 9. R I O C   ( Ω ) = V ( R E F _ O C ) K   ×   I O C 2  

Where,

V(REF_OC) is internal reference voltage of 200mV.

IOC is the overcurrent level.

The scaling factor, K can be calculated by Equation 10:

Equation 10. S c a l i n g   f a c t o r   ( K ) = 0.1   × R S N S R S E T   2 I B I A S

Where,

IBIAS is internal reference current of 5µA.

RSET is the resistor connected across CS1+ and input battery supply.

RSNS is the current sense resistor.

Setting I2t Profile, CI2t

The device senses the voltage across the external current sense resistor (RSNS) through CS1+ and CS1–. When sensed voltage across RSNS exceeds IOC threshold set by RIOC resistor, CI2t capacitor starts charging with current proportional to ILOAD2 – IOC2 current.

The time to turn OFF the gate drive at maximum overcurrent limit (IOC_MAX) can be determined using Equation 11:

Equation 11. t O C _ M I N   ( s ) = I 2 T   f a c t o r I O C _ M A X   ×   I O C _ M A X  
Note: The maximum overcurrent limit (IOC_MAX) can 5% to 10% below short-circuit protection threshold (ISC).

Use Equation 12 to calculate the required CI2t value.

Equation 12. C I 2 t   ( F ) = K   ×   t O C _ M I N V ( I 2 t _ O C )   -   V ( I 2 t _ O F F S E T )   ×   I O C _ M A X 2   -   I O C 2

Where,

V(I2t_OC) is I2t trip threshold voltage of 2V (typ).

V(I2t_OFFSET) is offset voltage of 500mV (typ) on I2t pin during normal operation.

tOC_MIN is the desired overcurrent response time at maximum overcurrent threshold IOC_MAX.