AP1605 ANACHIP [Anachip Corp], AP1605 Datasheet - Page 4

• Manufacturer Part Number: AP1605
• Description: PWM/PFM Dual-mode Step-Down Switching Regulator
• Manufacturer: ANACHIP [Anachip Corp]

PWM/PFM Dual-mode Step-Down Switching Regulator
（2） Application with Short Circuit Protection
PWM/PFM Control (AP1605 Series)
The AP1605 consists of DC/DC converters that employ a PWM/PFM auto-switch system.
In converters of the AP1605, the PFM mode varies in a range of duty cycle from 0% to 25%, and the PWM
mode varies in a range of duty cycle from 25% to 100% according to the load current, and yet ripple voltage
produced by the switching can easily be removed through a filter because the switching frequency remains
constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load
current.
Anachip Corp.
www.anachip.com.tw
Typical Application Circuit (Continued)
V
Test Circuit
Function Description
IN :
2.5V~7V
C
100 uF
PVCC
C
0.1uF
D
1N4148 for above 5V Vin and
Schottky for below 5V Vin
VCC
VCC
+
-
R
ON /OFF
3.5M
R
10M
A
Bias
CE
Vcc
PVcc
CE
PVcc
Vcc
R
1M
C
0.2uF
SENCE
ON /OFF
Vss
Vss
SW
SW
open
PV
CE
V
FB
FB
CC
CC
V
open
SS
AP 1605
+
-
4/6
SW
V
FB
+
-
D1
A
C
C
Vcc
PVcc
CE
=~10K
R
R
A
B
Vss
SW
V
OUT :
+
-
Vo
C
100 uF
FB
1.8V
OUTPUT
Rev. 1.1 Jan 18, 2005
=
AP1605
Vref
×
(1
+
R
R
A
B
)