AS1362 austriamicrosystems AG, AS1362 Datasheet - Page 9

• Manufacturer Part Number: AS1362
• Description: (AS1361 / AS1362) High-PSRR Low Dropout Regulators
• Manufacturer: austriamicrosystems AG

www.datasheet4u.com
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
down to V
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 100kΩ resistor is perfect for most applications
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
Thermal Protection
Integrated thermal protection circuitry limits total power dissipation in the AS1361/AS1362. When the junction temper-
ature (T
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,
Operating Region and Power Dissipation
The AS1361/AS1362 maximum power dissipation is dependant on the thermal resistance of the case and PCB, the
temperature difference between the die junction and T
Power dissipation across the device is calculated as:
The maximum power dissipation is calculated:
Where:
T
θ
θ
Note: Pin GND of the AS1361/AS1362 provides the electrical connection to system ground and also serves as a heat
Noise Reduction
The AS1361/AS1362 noise bypass circuitry dramatically reduces output noise, exhibiting 9µVRMS of output voltage
noise with C
OUT
Note: Startup time is minimized by internal power-on circuitry which pre-charges C
www.austriamicrosystems.com
JC
CA
J
- T
is the thermal resistance of the package;
is the thermal resistance through the PC board/copper traces/other materials to the surrounding air.
(see Figure 1 on page
AMB
indefinitely without causing damage to the device.
J
do not exceed the absolute maximum junction temperature rating of +150ºC.
sink. Connect pin GND to the system ground using a large pad or ground plane.
) exceeds +160ºC, the thermal sensor signals the shutdown logic, turning off the P-channel MOSFET pass
IN
is the temperature difference between the AS1361/AS1362 die junction and the surrounding air;
BYPASS
= 1V. A capacitor to GND may be added to generate a POR delay.
Table 4 on page 4
= 0.01µF and C
1).
for the recommended min and max current limits. The output can be shorted to ground
OUT
PDMAX = (T
= 1µF. Use an external 0.01µF bypass capacitor between pin BYPASS and pin
PD = I
OUT
J
Revision 1.00
- T
AMB
(V
AMB
IN
, and airflow rate.
- V
)/(
θ
OUT
JC
+
)
θ
CA
)
BYPASS
(see Figure 1 on page
.
1).
(EQ 1)
(EQ 2)
9 - 13