PL0501

Quick Charging Mode

The

reference up very quickly by charging the BYP capacitor

with very high current when the chip comes out of shut

down. This quick charge block stops charging the BYP

capacitor when the reference reaches 95% of its nominal

value and then the chip switches out of quick charging

mode to normal operating mode.

Over Temperature Protection

July 2007

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© 2007 Power IC. All Rights Reserved.

8

Over temperature protection limits the total power

dissipation

in

the

signals the shutdown logic and turns off the pass

transistor. The thermal sensor turns the pass transistor

on again after the IC’s junction temperature drops by

20

°C, resulting in a pulsed output during continuous

thermal-overload conditions.

Thermal-overload protection is designed to protect the

operation, do not exceed the absolute maximum junction

Operating Region and Power Dissipation

The

(1) the thermal resistance of the case and circuit board,

(2) the temperature difference between the die junction

and ambient and (3) the rate of airflow. The power

dissipation across the device is:

The maximum power dissipation is:

the

the thermal resistance of the package and

thermal resistance through the PC board, copper traces

and other materials to the surrounding air.

The GND pin of the

of providing an electrical connection to ground and

channeling heat away. Connect the GND pin to ground

using a large pad or ground plane.

Noise Reduction

For the

between BYP and GND with innovative noise bypass

scheme reduces the output noises dramatically, exhibiting

100

APPLICATION INFORMATION

Capacitor Selection And Regulator Stability

Use a 1.0

μF capacitor on the

capacitor on the output. Large input capacitor values and

lower ESR provide better noise rejection and line-

transient response.

Reduce output noise and improve load-transient

response, stability and power-supply rejection by using

large output capacitors. Note that some ceramic

dielectrics exhibit large capacitance and ESR variation

with temperature. With dielectrics such as Z5U and Y5V,

it may be necessary to use a 2.2

μF or larger output

capacitor to ensure stability at temperatures below -10

°C.

With X7R or X5R dielectrics, 1

μF is sufficient at all

operating temperatures.

Use a 0.01

μF bypass capacitor at BYP (

low-output voltage noise. The leakage current going into

the BYP pin should be less than 10nA.

Noise, PSRR and Transient Response

The

high PSRR, as well as low dropout and low quiescent

currents in battery-powered systems. The

is 75dB at 100Hz and 70dB at 10KHz.

When operating from sources other than batteries,

improved supply-noise rejection and transient response

can be achieved by increasing the values of the input and

output bypass capacitors and through passive filtering

techniques.

Dropout Voltage

A regulator’s minimum dropout voltage determines the

lowest usable supply voltage. In battery-powered

systems, this determines the useful end-of-life battery

voltage. Because the PL0501 uses a P-channel MOSFET

pass transistor, its dropout voltage is a function of drain-

current.