www.austriamicrosystems.com

Revision 1.00

9 - 13

AS1361/AS1362

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

Power-OK

The power-ok circuitry is built around an N-channel MOSFET. The circuitry monitors the output voltage and if the volt-

age goes out of regulation (e.g. during dropout, current limit, or thermal shutdown) pin POK goes low.

The power-OK feature is not active during shutdown and provides a power-on-reset (POR) function that can operate

To obtain a logic-level output, connect a pull-up resistor from pin POK to pin OUT. Larger values for this resistor will

help minimize current consumption; a 100k

Ω resistor is perfect for most applications (see Figure 1 on page 1).

Current Limit

The AS1361/AS1362 include a current limiting circuitry to monitor and control the P-channel MOSFET pass transis-

tor’s gate voltage, thus limiting the device output current to 270mA (AS1361) and 510mA (AS1362).

Note: See Table 4 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 AS1361/AS1362. When the junction temper-

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 10ºC, resulting in a pulsed output during continuous thermal-overload condi-

tions.

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 AS1361/AS1362 maximum power dissipation is dependant on the thermal resistance of the case and PCB, the

Power dissipation across the device is calculated as:

The maximum power dissipation is calculated:

Where:

Note: Pin GND of the AS1361/AS1362 provides the electrical connection to system ground and also serves as a heat

sink. Connect pin GND to the system ground using a large pad or ground plane.

Noise Reduction

The AS1361/AS1362 noise bypass circuitry dramatically reduces output noise, exhibiting 9µVRMS of output voltage

OUT (see Figure 1 on page 1).