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.1.1 May.27, 2004
1/5
Features
- Input voltage range:2.2V~8V（VOUT type）
- Adjustable version（±2.5%）
- Oscillator frequency: 270KHz（±15%）
- High Efficiency: 92%（typ .）
- Stand-by capability: ISTB＝2µA.（max .）
- Soft-start time set-up externally type possible
- 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 270KHz 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.
In relation to soft-start time external capacitor
regulated types.
During stand-by time （CE pin “LOW”）,current
consumption is reduced to less than 0.5µA.
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
Soft-start capacitor connection
5 3 FB Feedback pin
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw
Rev.1.1 May.27, 2004
2/5
Ordering Information
AP1621X 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
Block Diagrams
Phase
Compensation
Vref with
Soft Start
CE
+
-
PWM/PFM
Controller
+
-
Ramp Wave
Generator,
OSC
Buffer,
Driver V
out
CE GND
V
DD
PWM
Comparator
FB
Absolute Maximum Ratings
Ta=25°C
Parameter Symbol Rating Unit
VIN Pin Voltage VDD -0.3 ~ 8.5 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.1.1 May.27, 2004
3/5
Electrical Characteristics
AP1621 （VOUT＝3.3V, FOSC＝270kHz） Ta=25°C
Parameter Symbol Conditions Min. Typ. Max. Unit
FB VFB 1.17 1.2 1.23 V
Maximum Input Voltage VIN 8 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 230 270 310 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”
0.5 Vcc
CE”Low” Voltage VCEL Same as VCEH, determine
EXT/”High” 0.20 V
Efficiency EFFI 92 %
Soft-Start Time Tss Use a 33 nF Capacitor 5 15 msec
Measuring conditions: Unless otherwise specified, connect external components. VIN=5.0V,LOUT=220mA
Series Amendment:
AP1621
External Components: Css ＝0.033µF, Rss＝470kΩ
The Following Parameter Applies:
Soft Start Time（Tss）:Connect Rss,CSS. CE, 0V→3.0V（When VIN<3.0V, VIN＝3.0V）
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw
Rev.1.1 May.27, 2004
4/5
Typical Application Circuit
AP1621
V
DD
CE FB
GND
R
L
V
OUT
+C
L
L
SD
PMOS
V
IN
+C
IN
C
FB
R
FB1
R
FB2
V
OUT
R
SS
C
SS
Marking Information
SOT23-5L
XX
: Identification code
(See Appendix)
Y
: Year: 0-9
M
: Month: A~L
X
: Blank: normal
L: Lead Free Package
SOT23-5L
XX Y M X
7
12
3
45
Appendix
Part Number Package Identification
Code
AP1621A SOT23-5 EX
AP1621B SOT23-5 EU
AP1621
PWM/PFM Dual Mode Step-down DC/DC Controller
Anachip Corp.
www.anachip.com.tw
Rev.1.1 May.27, 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 0o 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
