AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of
this product. No rights under any patent accompany the sale of the product.
Rev.1.2 Dec. 23, 2004
1/5
Features
- Input voltage range:2.2V~7V（VOUT type）
- Adjustable version（±2.5%）
- Oscillator frequency: 300KHz（±20%）
- High Efficiency: 92%（typ .）
- Stand-by capability: ISTB＝2µA.（Max .）
- Output voltage type possible（FB）
- Package: SOT23-5
Applications
● Electronic Information Organizers
● Palmtops
● Cellular and portable phones
● Portable Audio Systems
● Various Multi-function Power Supplies
General Descriptions
The AP1621 series are multi-functional step-down
DC/DC converters with built-in speed, low ON
resistance drivers. A more than 1A output current is
possible using an externally connected transistor,
coil, diode and capacitor.
Output voltage is set-up by external resistor.（±2.5%
accuracy）.
With a 300KHz switching frequency, the size of the
external components can be reduced.
Control switches from PWM to PFM during light
loads with the AP1621（PWM/PFM switchable）and
the series is highly efficient from light loads to large
output currents.
During stand-by time （CE pin “LOW”）,current
consumption is reduced to less than 2µA.
With U.V.L.O internal, the external MOSFET. Will
be forcibly switched off if used below the stipulated
voltage.
Pin Assignment
1 32
5 4
CE
V
OUT
V
DD
GND
FB
AP1621A
1 32
5 4
CE
V
OUT
V
DD
GND
SOT23-5
FB
(Top View)
AP1621B
Pin Descriptions
Pin No.
A B
Pin
Name Function
14V
OUT External PMOSFET Connection
2 2 GND Ground
35 V
DD Power Supply
41 CE
Chip Enable:
H: Enable
L: Disable
5 3 FB Feedback pin
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw Rev. 1.2 Dec 23, 2004
2/5
Ordering Information
AP1621X X X X X
W : SOT23-5
Packing
A : Taping
Package Lead Free
Blank : Normal
L : Lead Free Package
Version
A : A version
B : B version
Blank: Adjustable
-33: 3.3V
Vout
Block Diagrams
Phase
Compensation
Vref with
CE
+
-
PWM/PFM
Controller
+
-
Ramp Wave
Generator,
OSC
Buffer,
Driver Vout
CE GND
VDD
PWM
Comparator
FB
Absolute Maximum Ratings
Ta=25°C
Parameter Symbol Rating Unit
VIN Pin Voltage VDD -0.3 ~ 8 V
VOUT Pin Voltage VOUT -0.3 ~ V
IN+0.3 V
FB Pin Voltage VFB -0.3 ~ V
IN+0.3 V
CE Pin Voltage VCE -0.3 ~ V
IN+0.3 V
VOUT Pin Current VOUT ±100 mA
Continuous Total
Power Dissipation Pd 250 mW
Operating Ambient
Temperature Topr -30 ~ +80 °C
Storage Temperature Tstg -40 ~ +125 °C
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw Rev. 1.2 Dec 23, 2004
3/5
Electrical Characteristics
AP1621 （VOUT＝3.3V, FOSC＝300kHz） Ta=25°C
Parameter Symbol Conditions Min. Typ. Max. Unit
FB Voltage VFB 1.1625 1.2 1.2375 V
Output Voltage VOUT AP1621-33 only 3.2 3.3 3.4 V
Maximum Input Voltage VIN 7 - - V
UVLO Voltage（Min.
Operating Voltage） VUVLO Same as IDD, voltage required to
maintain H at VOUT - - 2.2 V
Supply Current IDD No external components,
CE=VIN, VOUT=0V - 35 102 µA
Stand-by Current ISTB No external components,
CE=VIN, VOUT=0V - - 2 µA
Oscillator Frequency Fosc Measuring of EXT/waveform,
VIN=output voltage+0.3V 240 300 360 KHz
Maximum Duty Ratio MAXDTY 100 - - %
PFM Duty Ratio PFMDTY No load (AP1621 only) 15 25 35 %
CE ”High” Voltage VCEH
No external components, VFB=0V,
apply 0.65V (min.) to CE, determine
VOUT”Low”
0.65 - - *Vcc
CE ”Low” Voltage VCEL Same as VCEH, determine
EXT/”High” - - 0.20 *Vcc
Efficiency EFFI - 92 - %
Measuring conditions: Unless otherwise specified, connect external components. VIN=5.0V,LOUT=220mA
Series Amendment:
AP1621
External Components: CCE ＝0.1µF, RCE＝100kΩ
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw Rev. 1.2 Dec 23, 2004
4/5
Typical Application Circuit
(1) AP1621-Adj
+
-
C
FB
R
A
R
B
D1
OUT
V
SS
FB
V
CC
R
VCC
C
VCC
AP1621
=~200K
PMOS
V
OUT
L
CE
R
CE
C
CE
)
R
R
(1VrefVo
B
A
+×=
100K
0.1uF
(2) AP1621-33 Only
+
-
D1
OUT
V
SS
FB
V
CC
R
VCC
C
VCC
CE
AP1621
PMOS
V
OUT
R
CE
C
CE
L
100K
0.1uF
Marking Information
XX : Identification code
(See Appendix)
Y : Year: 0-9
M : Month: A~L
X : Blank: normal
L: Lead Free Package
SOT23-5L
XX YM X
7
12
3
45
Appendix
Part Number
Output
version AP1621A AP1621B
ADJ EX EU
3.3V EZ ET
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw Rev. 1.2 Dec 23, 2004
5/5
Package Information
Package Type: SOT23-5L
θ
Gauge Plane
0.25 mm
L
L1
E1 E
e1
D
123
4
5
b
e
b1
b
CC1
Base
Metal
With
Plating
A2
A1
A
Seating Plane
0.10 C
5x
2(4x)
θ
1(4x)
θ
Dimensions In Millimeters Dimensions In Inches
Symbol Min. Nom. Max. Min. Nom. Max.
A 1.05 1.20 1.35 0.041 0.047 0.053
A1 0.05 0.10 0.15 0.002 0.004 0.006
A2 1.00 1.10 1.20 0.039 0.043 0.047
b 0.25 - 0.55 0.010 - 0.022
b1 0.25 0.40 0.45 0.010 0.016 0.018
c 0.08 - 0.20 0.003 - 0.008
c1 0.08 0.11 0.15 0.003 0.004 0.006
D 2.70 2.85 3.00 0.106 0.112 0.118
E 2.60 2.80 3.00 0.102 0.110 0.118
E1 1.50 1.60 1.70 0.059 0.063 0.067
L 0.35 0.45 0.55 0.014 0.018 0.022
L1 0.60 Ref. 0.024 Ref.
e 0.95 Bsc. 0.037 Bsc.
e1 1.90 Bsc. 0.075 Bsc.
θ 0
o 5
o 10o 0
o 5
o 10o
θ1 3o 5
o 7
o 3
o 5
o 7
o
θ2 6o 8
o 10o 6
o 8
o 10o
