Linear Regulators with POK

6

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Reverse Battery Protection

The MAX8880/MAX8881 have a unique protection

scheme that limits the reverse supply current to less

monitors the polarity of IN, disconnecting the internal

circuitry and parasitic diodes when the battery is

reversed. This feature prevents the device from electri-

cal stress and damage when the battery is connected

backwards. If reverse battery protection is needed,

drive SHDN through a 100k

Ω resistor.

Current Limiting

The MAX8880/MAX8881 include a current limiter. When

the output is shorted to ground, drive to the output

PMOS is limited. The output can be shorted to ground

without damage to the part.

Thermal Overload Protection

Thermal overload protection limits total power dissipa-

tion in the MAX8880/MAX8881. When the internal junc-

sensor signals the shutdown logic, turning off the pass

transistor and allowing the IC to cool. The thermal sen-

sor turns the pass transistor on again after the IC’s

junction temperature cools by 15°C, resulting in a

pulsed output during continuous thermal-overload con-

ditions.

Thermal-overload protection is designed to protect the

MAX8880/MAX8881 in the event of fault conditions. For

continuous operation, do not exceed the absolute maxi-

Operating Region and Power Dissipation

The MAX8880/MAX8881’s maximum power dissipation

depends on the thermal resistance of the case and cir-

cuit board, the temperature difference between the die

junction and ambient air, and the rate of airflow. The

IN

OUT

FB

GND

C2

4.7

μF

C1

1

μF

SHDN

2.5V TO 12V

UP TO 200mA

R3

R4

REGULATION OK

POK

MAX8880

1.25V TO 5.5V

Figure 3. Adjustable Output Using External Feedback Resistors

SHUTDOWN

LOGIC

ERROR

AMP

1.25V

REF

91%

REF

P

OUT

POK

GND

IN

SHDN

MAX8881

THERMAL

SENSOR

REVERSE

BATTERY

PROTECTION

MOS DRIVER

POK

FB

Figure 2. Functional Diagram