SNOSDE8A July   2023  – September 2023 LM74912-Q1

PRODUCTION DATA  

  1.   1
  2. 1 Features
  3. 2 Applications
  4. 3 Description
  5. 4 Revision History
  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
      2. 8.3.2 Dual Gate Control (DGATE, HGATE)
        1. 8.3.2.1 Reverse Battery Protection (A, C, DGATE)
        2. 8.3.2.2 Load Disconnect Switch Control (HGATE, OUT)
      3. 8.3.3 Short Circuit Protection (CS+, CS-, ISCP)
      4. 8.3.4 Overvoltage Protection and Battery Voltage Sensing (SW, OV, UVLO)
      5. 8.3.5 Low IQ SLEEP Mode (SLEEP, SLEEP_OV)
    4. 8.4 Device Functional Modes
  10. 9 Applications and Implementation
    1. 9.1 Application Information
    2. 9.2 Typical 12-V Reverse Battery Protection Application
      1. 9.2.1 Design Requirements for 12-V Battery Protection
      2. 9.2.2 Automotive Reverse Battery Protection
        1. 9.2.2.1 Input Transient Protection: ISO 7637-2 Pulse 1
        2. 9.2.2.2 AC Super Imposed Input Rectification: ISO 16750-2 and LV124 E-06
        3. 9.2.2.3 Input Micro-Short Protection: LV124 E-10
      3. 9.2.3 Detailed Design Procedure
        1. 9.2.3.1 Design Considerations
        2. 9.2.3.2 Charge Pump Capacitance VCAP
        3. 9.2.3.3 Input , Supply and Output Capacitance
        4. 9.2.3.4 Hold-Up Capacitance
        5. 9.2.3.5 Overvoltage Protection and Battery Monitor
        6. 9.2.3.6 Selecting Short Circuit Current Threshold
          1. 9.2.3.6.1 Selection of Scaling Resistor RSET and RISCP for Short Circuit Protection
      4. 9.2.4 MOSFET Selection: Blocking MOSFET Q1
      5. 9.2.5 MOSFET Selection: Hot-Swap MOSFET Q2
      6. 9.2.6 TVS Selection
      7. 9.2.7 Application Curves
    3. 9.3 Best Design Practices
    4. 9.4 Power Supply Recommendations
      1. 9.4.1 Transient Protection
      2. 9.4.2 TVS Selection for 12-V Battery Systems
      3. 9.4.3 TVS Selection for 24-V Battery Systems
    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. 11Mechanical, Packaging, and Orderable Information

Package Options

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

8.1 Overview

The LM74912-Q1 Ideal Diode controller drive back-to-back external N-Channel MOSFETs to realize low loss power path protection with short circuit, under and overvoltage protection functionality.

The wide input supply of 3 V to 65 V allows protection and control of 12-V and 24-V automotive battery powered ECUs. The device can withstand and protect the loads from negative supply voltages down to –65 V. An integrated ideal diode controller (DGATE) drives the first MOSFET to replace a Schottky diode for reverse input protection and output voltage holdup. With a second MOSFET in the power path the device allows load disconnect (ON/OFF control) and overvoltage protection using HGATE control. The device features an adjustable overvoltage cut-off protection feature. With common drain configuration of the power MOSFETs, the mid-point can be utilized for OR-ing designs using another ideal diode. The LM74912-Q1 has a maximum voltage rating of 65 V.

It has integrated current sense amplifier which monitors external MOSFET (Q2) VDS voltage to provide short circuit protection. The device has default short circuit comparator threshold- at 50-mV with complete flexibility to shift this threshold using external components (RISCP and RSET). Once short circuit condition is detected then device latches off MOSFET Q2 until either the EN, SLEEP or the VS pin is toggled from low to high.

The device offers adjustable overvoltage and undervoltage protection, providing robust load disconnect in case of voltage transient events.

LM74912-Q1 features two different low power modes based on status of EN and SLEEP pin. In SLEEP mode (SLEEP=Low, EN=High) the device consumes only 5.5-μA current by turning off both the external MOSFET gate drives and internal charge pump but at the same time providing internal bypass path to power up always ON loads with limited current capacity. With the enable pin low, device enters into ultra low power mode by completely cutting off loads with typical current consumption of 2.5 μA. The high voltage rating of LM74912-Q1 helps to simplify the system designs for automotive ISO7637 protection. The LM74912-Q1 is also suitable for ORing applications.