AS1374 datasheet(10/14 Pages) AMSCO

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AS1374

Datasheet - D e t a i l e d D e s c r i p t i o n

Current Limit

The AS1374 include a current limiting circuitry to monitor and control the P-channel MOSFET pass transistor’s gate

voltage, thus limiting the device output current to 300mA.

Note:

See Table 3 on page 4 for the recommended min and max current limits. The output can be shorted to ground

indefinitely without causing damage to the device.

Thermal Protection

Integrated thermal protection circuitry limits total power dissipation in the AS1374. When the junction temperature (TJ)

exceeds +160ºC, the thermal sensor signals the shutdown logic, turning off the P-channel MOSFET pass transistor

and allowing the device to cool down. The thermal sensor turns the pass transistor on again after the device’s junction

temperature drops by 15ºC, resulting in a pulsed output during continuous thermal-overload conditions.

Note:

Thermal protection is designed to protect the devices in the event of fault conditions. For continuous operation,

do not exceed the absolute maximum junction temperature rating of +150ºC.

Operating Region and Power Dissipation

The AS1374 maximum power dissipation is dependant on the thermal resistance of the case and PCB, the tempera-

ture difference between the die junction and TAMB, and airflow rate.

Power dissipation across the device is calculated as:

PD = IOUT (VIN - VOUT)(EQ 1)

The maximum power dissipation is calculated:

PDMAX = (TJ - TAMB)/

θJA

(EQ 2)

Where:

TJ - TAMB is the temperature difference between the AS1374 die junction and the surrounding air;

θJA is the thermal resistance through the circuit board, copper traces, and other materials to the surrounding.

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