MAX4959EUB 查看數據表（PDF） - Maxim Integrated

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MAX4959EUB

High-Voltage OVP with Battery Switchover

Maxim Integrated 

High-Voltage OVP with Battery Switchover

Functional Diagrams (continued)

Functional Diagram for the MAX4960

IN

SOURCE1

GATE1

VSG

+

BANDGAP

N

VDD

-

N1

ANALOG

SUPPLY

DIGITAL

SUPPLY

GATE2

N2

CB

+

-

VREF2 = 0.7V

+

-

POWER

ON

VDD

UVLO

POWER-ON

RESET AND

OFF STORAGE

LOGIC

VREF1 = 2V

OVS

UVS

MAX4960

GND

+

UVLOINT

-

+

OVLO

-

+

UVLO

-

only if the backup capacitor on VDD is large enough to

maintain power for greater than the 10ms blanking time.

The detection that the adapter is unplugged and

plugged in again is implemented by monitoring the VIN

signal. The adapter is unplugged when VIN drops below

VIN =~ 0.75V, and it is plugged in when VIN becomes

greater than VIN =~ 0.75V. To ensure the monitoring of

this lower threshold, an external storage capacitor at the

VDD pin is necessary. When the input voltage VIN drops

below 4V, power for some internal VIN monitoring circuit-

ry is supplied by the external capacitor at the VDD pin.

This capacitor is supplied by VIN through a diode and is

internally limited to 5.5V.

Adapter Not Present (VIN < VUVLO)

When the input voltage VIN drops below 4.4V, P1 is

turned off automatically and P1 does not turn on again

until the adapter is unplugged (VIN<~0.75V) and

plugged in again. When the adapter is not present, P1 is

kept off with the gate-source resistor (which is internal for

the MAX4960 and external for the MAX4959), and the

CB pin controls the battery switchover pFET P2.

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