8.3.2.1 Reverse Battery Protection (A, C, DGATE)

A, C, DGATE comprises of Ideal Diode stage. Connect the Source of the external MOSFET to A, Drain to C and

Gate to DGATE. The LM74810 has integrated reverse input protection down to –65 V.

Before the DGATE driver is enabled, following conditions must be achieved:

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

• The CAP to VS voltage must be greater than the undervoltage lockout voltage.

• Voltage at A pin must be greater than VA POR Rising threshold.

• Voltage at Vs pin must be greater than Vs POR Rising thershold.

If the above conditions are not achieved, then the DGATE pin is internally connected to the A pin, assuring that

the external MOSFET is disabled.

In LM74810 the voltage drop across the MOSFET is continuously monitored between the A and C pins, and the

DGATE to A voltage is adjusted as needed to regulate the forward voltage drop at 9.1 mV (typ). This closed loop

regulation scheme enables graceful turn off of the MOSFET during a reverse current event and ensures zero DC

reverse current flow. This scheme ensures robust performance during slow input voltage ramp down tests. Along

with the linear regulation amplifier scheme, the LM74810 also integrates a fast reverse voltage comparator.

When the voltage drop across A and C reaches V(AC_REV) threshold then the DGATE goes low within 0.5-µs

(typ). This fast reverse voltage comparator scheme ensures robust performance during fast input voltage ramp

down tests such as input micro-shorts. The external MOSFET is turned ON back when the voltage across A and

C hits V(AC_FWD) threshold within 0.85 µs (typ).

For Ideal Diode only designs, connect LM74810 as shown in Figure 8-2.

GND

DGATE

A

HGATE

OUT

C

EN/UVLO

VBATT

12 V

VOUT

LM74810

CAP VS

ON OFF

Q1

D1

SMBJ36CA

SW

R2

R1

OV

VSNS

BATT_MON

Figure 8-2. Configuring LM74810 for Ideal Diode Only

8.3.2.2 Load Disconnect Switch Control (HGATE, OUT)

HGATE and OUT comprises of Load disconnect switch control stage. Connect the Source of the external

MOSFET to OUT and Gate to HGATE.

Before the HGATE driver is enabled, following conditions must be achieved:

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

• The CAP to VS voltage must be greater than the undervoltage lockout voltage.

• Voltage at Vs pin must be greater than Vs POR Rising thershold.

If the above conditions are not achieved, then the HGATE pin is internally connected to the OUT pin, assuring

that the external MOSFET is disabled.

For Inrush Current limiting, connect CdVdT capacitor and R1 as shown in Figure 8-3.

www.ti.com

LM7481

SNOSDD9 – DECEMBER 2022

Copyright © 2022 Texas Instruments Incorporated

Submit Document Feedback

13

Product Folder Links: LM7481