AP7167

1.2A LOW DROPOUT REGULATOR WITH POK

AP7167 Rev. 2

8 of 11

JANUARY 2008

www.diodes.com

Typical Performance Characteristics

(Continued)

Current Limit vs. Temperature

1.4

1.5

1.6

1.7

1.8

-50

-25

0

25

50

75

100

Temperature (

VIN =2.8V,Vout=1.8V

VIN =3.3V,Vout=1.8V

Application Note

Input Capacitor

A 1

μF ceramic capacitor is recommended to connect

between IN and GND pins to decouple input power

supply glitch and noise. The amount of the capacitance

may be increased without limit. A lower ESR (Equivalent

Series Resistance) capacitor allows the use of less

capacitance, while higher ESR type requires more

capacitance. This input capacitor should be located as

close as possible to the device to assure input stability

and less noise. For PCB layout, a wide copper trace is

required for both IN and GND.

Output Capacitor

The output capacitor is required to stabilize and help the

transient response of the LDO. The AP7167 is designed

to

have

excellent

transient

response

for

most

applications with a small amount of output capacitance.

The AP7167 is stable for all available types and values

of output capacitors

≥ 4.7μF. The device is also stable

with multiple capacitors in parallel, which can be of any

type of value. Additional capacitance helps to reduce

undershoot

and

overshoot

during

transient.

This

capacitor should be placed as close as possible to OUT

and GND pins for optimum performance.

Adjustable Operation

The AP7167 provides output voltage from 0.8V to 5.0V

through external resistor divider as shown below.

IN

GND

EN

OUT

Enable

FB

POK

100kOhm

AP7167

The output voltage is calculated by:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

+

=

2

1

1

R

R

V

V

REF

OUT

Rearranging

the equation will give the following

equation to find the approximate resistor divider values:

⎟⎟

⎠

⎞

⎜⎜

⎝

⎛

−

=

1

2

1

REF

OUT

V

V

R

R

To maintain the stability of the internal reference voltage,