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APL5301

Low IQ, Low Dropout 300mA Fixed Voltage Regulator

Anpec Electronics 

APL5301/2

Application Information

Capacitor Selection and Regulator

Stability

The APL5301/2 use at least a 1uF capacitor on the

input, and this capacitor can be Aluminum, Tantalum

or Ceramic capacitor. The input capacitor with larger

value and lower ESR provides better PSRR and line-

transient response. The output capacitor also can use

Aluminum, Tantalum or Ceramic capacitor, and a mini-

mum value of 1uF and ESR above 0.06Ω is

recommended. The curve of the stable region in typi-

cal characteristics shows the appropriate output ca-

pacitor ESR for different load current stable operation.

A larger output capacitor can reduce noise and im-

prove load-transient response, stability, and PSRR.

Note that some ceramic dielectrics exhibit large ca-

pacitance and ESR variation with temperature. When

using this capacitor, a minimum 2.2uF or more may

be required to ensure the stability at low temperature

operation. Use a bypass capacitor at BP pin for low

output noise. Increasing the capacitance will slightly

decrease the output noise, but increase the start-up

time. (See Shutdown Exit Delay and Output Noise

vs.Bypass Capacitor graph in the typical

characteristics)

tery-powered systems, this will determine the useful

end-of-life battery voltage. Because the APL5301/2

use a p-channel MOSFET pass transistor, the drop-

out voltage is a function of drain-to-source on-resis-

tance (RDS(ON)) multiplied by the load current.

Reverse Current Protection

The APL5301/2 have an internal reverse protection, it

does not need an external schottky diode to connect

the regulator input and output. If the output voltage is

forced above the input voltage by more than 11mV,

the IC will be shutdown and the ground pin current is

below 0.1uA.

Shutdown/Enable

The APL5301/2 have an active high enable function.

Force EN high (>1.6V) enables the regulator, EN low

(<0.4V) disables the regulator and enter the shutdown

mode. In shutdown mode, the quiescent current can

reduce below 1uA. The EN pin cannot be floating, a

floating EN pin may cause an indeterminate state on

the output. If it is no use, connect to VIN for normal

operation.

Load-Transient Considerations

The APL5301/2 load-transient response graphs in typi-

cal characteristics show the transient response. A

step change in the load current from 1mA to 50mA at

1us will cause a 60mV transient spike. Larger output

capacitor and lower ESR can reduce transient spike.

Input-Output (Dropout)Voltage

The minimum input-output voltage difference (dropout)

determines the lowest usable supply voltage. In bat

Current Limit

The APL5301/2 have a current limit protection. The

ouptut voltage will drop close to zero volt, when load

current reaches the limit, and then the load current

will be limited at 50mA after output voltage is below 0.

7V. When the load current back to the value where

limiting started, the output voltage and current will re-

turn to normal value. When output is shorted to

ground, the APL5301/2 will keep short circuit current

at 150mA .

Copyright  ANPEC Electronics Corp.

10

Rev. B.1 - Mar., 2004

www.anpec.com.tw

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