Preliminary Datasheet
150mA RF ULDO REGULATOR
AP2202
Typical Application
VIN=3.8V
AP2202-2.8V
V
OUT=2.8V
V
V
V
V
OUT
IN
EN
GND
OUT
IN
+
C
C
OUT
IN
BYP
C
1.0µF
2.2µF
tantalum
BYP
470pF
AP2202-ADJ
IN
V
V
V
V
OUT
OUT
IN
R1
R2
+
C
C
EN
GND
ADJ
C
IN
OUT
1.0 µF
2.2 µF
tantalum
BYP
optional
VOUT=1.25* (1+R2/R1)
Figure 15. Typical Application of AP2202
Application Information
External Capacitors
In most cases, tantalum or aluminium electrolytic
capacitors are adequate.
Regarding good performance of regulator stability,
external capacitors required by the AP2202 should
be prudently selected.
Noise Bypass Capacitor
Bypass capacitor is connected to the internal voltage
reference. A 680pF capacitor connected from BYP to
GND leads reference to be quiet which results in a
significant reduction in output noise. When using
Input Capacitor
If there is more than 10 inches of wire between the
input and the AC filter, or if a battery is used as the
input, a 1µF capacitor should be placed from IN to
GND.
C
output capacitors of 2.2µF or greater are
BYP,
required for better stability.
Output Capacitor
It is required to prevent oscillation. 1.0µF minimum
is recommended when C
The start-up speed of the AP2202 is inversely
proportional to the value of reference bypass
capacitor. In some cases, if output noise is not a
major concern and rapid turn-on is necessary, omit
is unused. 2.2µF mini-
BYP
mum is recommended when C
is 470pF. The out-
BYP
C
and leave BYP open.
put capacitor may be increased without limit for
large values to improve transient response.
BYP
BCD Semiconductor Manufacturing Limited
Aug. 2005 Rev. 1. 3
11
BCDSEMI [ BCD SEMICONDUCTOR MANUFACTURING LIMITED ]
