LM7480 datasheet(16/43 Pages) TI

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For Inrush Current limiting, connect CdVdT capacitor and R1 as shown in Figure 9-3.

HGATE

OUT

LM7480x

dVdT

Figure 9-3. Inrush Current Limiting

The CdVdT capacitor is required for slowing down the HGATE voltage ramp during power up for inrush current

limiting. Use Equation 2 to calculate CdVdT capacitance value.

HGATE

DRV

dVdT

OUT

INRUSH

(2)

where IHATE_DRV is 55 μA (typ), IINRUSH is the inrush current and COUT is the output load capacitance. An extra

resistor, R1, in series with the CdVdT capacitor improves the turn off time.

9.3.3 Overvoltage Protection and Battery Voltage Sensing (VSNS, SW, OV)

Connect a resistor ladder as shown in Figure 9-4 for overvoltage threshold programming.

LM7480x

VIN_MON

VIN

HGATE_OFF

1.23 V

1.13 V

VSNS

Figure 9-4. Programming Overvoltage Threshold and Battery Sensing

A disconnect switch is integrated between VSNS and SW pins. This switch is turned OFF when EN/UVLO pin is

pulled low. This helps to reduce the leakage current through the resistor divider network during system shutdown

state (IGN_OFF state).

LM7480-Q1 OV pin can also be used as a control input to turn off HGATE drive to achieve load disconnect

functionality. When OV pin is driven high (VOV > VOVR), device pulls down HGATE to OUT thus turning off the

load disconnect MOSFET. When OV pin is pulled low (VOV < VOVF) HGATE drive is again enabled to trun on

the load disconnect MOSFET. When OV pin is used as a control input to turn on/off load disconnect MOSFET,

ensure device EN/UVLO pin is high (VEN/UVLO > VENR) and SW/VSNS pin voltage is higher than OV pin voltage.

9.3.4 Low Iq Shutdown and Under Voltage Lockout (EN/UVLO)

The enable pin allows for the gate driver to be either enabled or disabled by an external signal. If the EN/UVLO

pin voltage is greater than the rising threshold, the gate driver and charge pump operates as described in

Charge Pump section. If EN/UVLO pin voltage is less than the input low threshold, V(ENF), the charge pump

LM7480

SNOSDD8 – DECEMBER 2022

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