9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification,

and TI does not warrant its accuracy or completeness. TI’s customers are responsible for

determining suitability of components for their purposes, as well as validating and testing their design

implementation to confirm system functionality.

9.1 Application Information

The LM74700-EP is used with N-Channel MOSFET controller in a typical reverse polarity protection application.

The schematic for the 12-V battery protection application is shown in Figure 9-1, where the LM74700-EP is used

in series with a battery to drive the MOSFET Q1. The TVS is not required for the LM74700-EP to operate, but

protect the immediate output voltage collapse as a result of line disturbance.

9.2 Typical Application

LM74700

GATE

CATHODE

EN

ANODE

VCAP

GND

TVS

Voltage

Regulator

VCAP

Q1

Figure 9-1. Typical Application Circuit

9.2.1 Design Requirements

A design example, with system design parameters, is listed in Table 9-1.

Table 9-1. Design Parameters

DESIGN PARAMETER

EXAMPLE VALUE

Input voltage range

12-V battery, 12-V nominal with 3.2-V cold crank and 35-V load

dump

Output voltage

3.2 V during cold crank to 35-V load dump

Output current range

3-A nominal, 6-A maximum

Output capacitance

1-µF minimum, 220-µF typical hold up capacitance

Automotive EMC compliance

ISO 7637-2 and ISO 16750-2

9.2.2 Detailed Design Procedure

9.2.2.1 Design Considerations

• Input operating voltage range, including cold crank and load dump conditions

• Nominal load current and maximum load current

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LM74700-EP

SNOSDD6 – SEPTEMBER 2021

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