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AS1371

Datasheet - A p p l i c a t i o n I n f o r m a t i o n

9 Application Information

Capacitor Selection and Regulator Stability

Ceramic capacitors are highly recommended as they offer distinct advantages over their tantalum and aluminum

electrolytic components. For stable operation with load currents up to 400mA over the entire device temperature

range, use a 1µF (min) ceramic output capacitor with an ESR <0.2

Ω. Use large output capacitor values (e.g. 10µF) to

reduce noise and improve load transient-response, stability and power-supply rejection.

Note: Some ceramic capacitors exhibit large capacitance and ESR variations with variations in temperature.

Power Supply Rejection Ratio

The AS1371 is designed to deliver low dropout voltages and low quiescent currents. Power-supply rejection is typically

50dB at 10kHz. To improve power supply-noise rejection and transient response, increase the values of the input and

output bypass capacitors, which are shown in Figure 14.

The Section 6 Electrical Characteristics on page 4 show also the device line- and load-transient responses.

Dropout Voltage

differential (dropout voltage) determines the lowest usable supply voltage. This determines the useful end-of-life

battery voltage in battery-powered systems. The dropout voltage is a function of the P-MOSFET drain-to-source on-

resistance multiplied by the load current, and is calculated by:

Where:

Figure 14. Application Diagrams

(EQ 4)

V

DROPOUT

V

IN

V

OUT

–

R

DS ON

()

I

OUT

×

==

Input

1.2V to 3.6V

1

ON /

OFF

1µF

Output

0.6V to 3.3V

IN

EN

GND

SENSE

OUT

AS1371

POK

Input

1.2V to 3.6V

1

ON /

OFF

1µF

Output

0.6V to 3.3V

IN

EN

GND

SENSE

OUT

AS1371

POK

External Voltage Level Detection

(Input Monitoring)

Internal Voltage Level Detection

(Output Monitoring)

100k

Ω

100k

Ω