MAX4945BELA-T データシートの表示（PDF） - Maxim Integrated

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MAX4945BELA-T

Overvoltage-Protection Controllers with Internal FET

Maxim Integrated 

PIN

1, 2

3

4

5

6, 7, 8

Overvoltage-Protection Controllers with

Internal FET

NAME

IN

GP

ACOK

GND

OUT

Pin Description

FUNCTION

Voltage Input. IN powers the charge pump required to turn on the internal switch. When the correct

adapter is plugged in, a 15ms (typ) debouncer prevents false turn-on of the internal switch. Bypass

IN to GND with a 1µF ceramic capacitor as close as possible to the device to enable ±15kV (HBM)

ESD protection on IN.

pFET Gate-Drive Output. GP pulls the external pFET gate down when the input is above ground.

Active-Low Open-Drain Adapter-Voltage Indicator Output. ACOK is driven low after the adapter

voltage is stable between VUVLO and VOVLO for 30ms (typ). Connect a pullup resistor from ACOK to

the logic I/O voltage of the host system.

Ground

Output Voltage. Output of internal switch. Short all pins together for proper operation.

IN

GP

GND

ACOK

+

VOVLO

-

VUVLO

+

-

OUT

CHARGE

PUMP

CHARGE-PUMP

ENABLED

15ms (typ)

DEBOUNCE

TIMER AND

RETRY TIME

RESET

OVERCURRENT

OR

THERMAL

FAULTS

OSCILLATOR

RESET

30ms (typ)

TIMER

MAX4943–MAX4946/MAX4944L/

MAX4945L/MAX4949

Figure 1. Functional Diagram

Detailed Description

The MAX4943–MAX4946/MAX4949 overvoltage-protec-

tion devices feature a low RON internal FET and protect

low-voltage systems against voltage faults up to +28V. If

the input voltage exceeds the overvoltage threshold, the

internal MOSFET is turned off to prevent damage to the

protected components. These devices also drive an

optional external pFET to protect down to -28V. If the

adapter voltage drops below ground, the pFET turns off

to prevent damage to the protected components due to

negative voltage exposure. The internal charge pump’s

15ms (typ) debounce time prevents false turn-on of the

internal switch during startup. An open-drain, active-low

logic output is available to signal that a successful

power-up has occurred.

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