Part Number: LM74700QDBVRQ1

Manufacturer: Texas Instruments

Description: Hot Swap Voltage Controllers

Shipped from: Shenzhen/HK Warehouse

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The LM74700-Q1 is a low-loss reverse polarity protector that uses an external N-channel MOSFET and a forward voltage drop of only 20 mV. It is an ideal diode controller that has passed the automotive equivalent of the AEC Q100 standard. Many common DC bus voltages may be managed, including those found in 12-V, 24-V, and 48-V automotive battery systems, thanks to the supply input range of 3.2 V to 65 V. To meet the stringent cold crank requirements of automotive systems, the 3.2-V input voltage support is ideal.

Negative supply voltages of up to -65 V are tolerated, and the device shields the loads. It maintains a forward voltage drop of 20 mV by controlling the MOSFET’s GATE. The MOSFET is gracefully shut down, and no DC reverse current flows thanks to the control technique. The device’s fast response to Reverse Current Blocking ( 0.75 s) makes it ideally suited for systems that need to maintain an output voltage during power failure and input micro-short testing per ISO7637 pulses. As a charge pump gate drives for an external N-channel MOSFET, the LM74700-Q1 controller is a useful piece of hardware. This is especially true in the automotive industry, where the LM74700-Q1’s high voltage rating simplifies ISO7637 protection system design. When the enable pin is low, the controller is disabled and consumes about 1 A of power.

LM74700QDBVRQ1 Features

  • It is an ideal diode controller that has achieved the following results after passing the automotive version of the AEC Q100 standard: Devices with a working temperature range of 40°C to +125°C, a CDM ESD classification level C4B, and an HBM ESD classification level 2 are considered to be devices with device temperature grade 1.
  • The device can withstand negative supply voltages of up to -65 V, and the loads are insulated.
  • The device is perfect for systems that need to maintain an output voltage during a power outage and input micro-short testing by ISO7637 pulses due to its quick response to reverse current blocking (0.75 s).
  • It has a 3.2-V to 65-V input range (3.9-V start-up)
  • It features a 65-V reverse voltage rating
  • It uses an external N-channel MOSFET and a forward voltage drop of only 20 mV
  • It is available in 6-pin and 8-pin SOT-23 Package 2.90 mm × 1.60 mm

LM74700QDBVRQ1 Applications

  • It is used in Automotive ADAS systems – camera
  • It is used in Automotive infotainment systems – digital clusters,
  • It is used in Industrial factory automation – PLC
  • It is used in Enterprise power supplies

Detailed description

LM74700QDBVRQ1 Applications

The LM74700-Q1 is a perfect diode controller that can be utilized in an ORing arrangement or to construct a fast and efficient reverse polarity protection circuit with a minimum of external components. This user-friendly ideal diode controller is used in place of more complex reverse polarity methods, such as a  a Schottky diode or P-channel MOSFET , combined with an external N-channel MOSFET. A built-in charge pump powers the external N-Channel MOSFET, which can drive its gates up to around 15 V at their highest potential.  Continuous monitoring of the ANODE and CATHODE pins allows the forward voltage drop across the MOSFET to be maintained at 20 mV by adjusting the GATE to ANODE voltage as needed.

This closed-loop regulation approach ensures no DC reverse current flow by gracefully shutting off the MOSFET during a reverse current incident. When the voltage between the anode and cathode pins drops below -11 mV, the fast reverse current condition is detected, the N-channel MOSFET is turned off, and the body diode is used to block the reverse current. The N-Channel MOSFET in the LM74700-Q1 can be disabled, and the quiescent current can be reduced using the EN enable pin.

Device Functional Modes

Conduction Mode

The gate driver is enabled when the conducting mode is on. Based on the LM74700-Q1’s ANODE to CATHODE voltage, conduction mode operation may be divided into three areas. The sections on Full Conduction Mode, Regulated Conduction Mode, and Reverse Current Protection Mode each provide descriptions of one of the three modes.

Regulated Conduction Mode

The LM74700-Q1 can only operate in regulated type of conduction mode if the source-to-drain current of the external MOSFET falls within a range that results in an ANODE-to-CATHODE voltage drop between -11 mV and 50 mV.  In forward regulation mode, the GATE to ANODE voltage is changed to regulate the ANODE to CATHODE voltage to 20 mV. This closed-loop regulation system assures no DC reverse current flow and allows the MOSFET to be turned off gracefully under very light loads.

Full Conduction Mode

The LM74700-Q1 needs to have the gate driver enabled as described in the Gate Driver section in order to operate in full conduction mode. The external MOSFET’s source-to-drain current must be sufficient to cause a typical voltage drop from the anode to the cathode of more than 50 mV. The GATE to ANODE voltage will be almost the same as the VCAP to ANODE voltage if these conditions are met, as the GATE pin is internally coupled to the VCAP pin. When VCAP is connected to GATE, the MOSFET’s RDS(ON) is decreased, which lowers the external MOSFET’s power loss in events that forward currents are high.

Reverse Current Protection Mode

The gate driver must be activated as per the instructions in the Gate Driver section for the LM74700-Q1 to function in reverse current protection mode, and the external MOSFET’s current flow must be from the drain to the source. Reverse current protection mode enters when the ANODE to CATHODE voltage is normally less than -11 mV, and the GATE pin is then internally connected to the ANODE pin. The external MOSFET is turned off when the GATE pin is connected to the ANODE pin. The MOSFET’s body diode prevents reverse current flow from the drain to the source.


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