0V

VIN

6.5 V

11.6 V

12.4 V

GATE DRIVER

ENABLE

Figure 8-1. Charge Pump Operation

8.3.3 Gate Driver

The gate driver is used to control the external N-Channel MOSFET by setting the GATE to ANODE voltage

to the corresponding mode of operation. There are three defined modes of operation that the gate driver

operates under forward regulation, full conduction mode and reverse current protection, according to the ANODE

to CATHODE voltage. Forward regulation mode, full conduction mode and reverse current protection mode

are described in more detail in the Regulated Conduction Mode, Full Conduction Mode and Reverse Current

Production Mode sections. Figure 8-2 depicts how the modes of operation vary according to the ANODE to

CATHODE voltage of the LM74700-EP. The threshold between forward regulation mode and conduction mode is

when the ANODE to CATHODE voltage is 50 mV. The threshold between forward regulation mode and reverse

current protection mode is when the ANODE to CATHODE voltage is –11 mV.

GATE connected

to ANODE

GATE to ANODE Voltage Regulated

0 mV

20 mV

50 mV

-11 mV

Regulated Conduction Mode

Reverse Current

Protection Mode

Full Conduction Mode

GATE connected

to VCAP

Figure 8-2. Gate Driver Mode Transitions

Before the gate driver is enabled. the following three conditions must be achieved:

• The EN pin voltage must be greater than the specified input high voltage.

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LM74700-EP

SNOSDD6 – SEPTEMBER 2021

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