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零件编号 | AIC1639 | ||
描述 | 3-PIN ONE-CELL STEP-UP DC/DC CONVERTER | ||
制造商 | aic | ||
LOGO | |||
1 Page
AIC1639
FEATURES
l Guaranteed Start-Up from Below 0.9 V.
l High Efficiency.
l Low Quiescent Current.
l Few Number of External Components needed.
l Low Ripple and Low Noise.
l Fixed Output Voltage: 2.7, 3.0V, 3.3V, and 5V.
l Driver for External Transistor.
l Space Saving SOT-89 and TO-92 Packages.
APPLICATIONS
l Pagers.
l Cameras.
l Wireless Microphones.
l Pocket Organizers.
l Battery Backup Suppliers.
l Portable Instruments.
3-PIN ONE-CELL STEP-UP DC/DC CONVERTER
SPEC NO: DS-1639-00 05/26/00
DESCRIPTION
The AIC1639 is a high efficiency step-up DC/DC
converter for applications using 1 to 4 battery cells.
Only three external components are required to de-
liver a fixed output voltage of 2.7, 3.0V, 3.3V, or 5V.
The AIC1639 starts up from below 0.9V input with
1mA load. Pulse Frequency Modulation scheme
brings optimized performance for applications with
light output loading and low input voltages. The out-
put ripple and noise are lower compared with the
circuits operating in PSM mode.
The PFM control circuit operating in 100KHz (max.)
switching rate results in smaller passive compo-
nents. The space saving SOT-89 and TO-92 pack-
ages make the AIC1639 an ideal choice of DC/DC
converter for space conscious applications, like
pagers, electronic cameras, and wireless micro-
phones.
Provided with an external transistor driver pin (EXT),
the AIC1639 is recommended for applications re-
quiring current as large as several tens to several
hundreds of milli-amperes.
TYPICAL APPLICATION CIRCUIT
VIN
+ C2
47µF
L1
33 µH
Q1
2SD1803
R1 300
EXT
10nF
D1
AIC1639-27
AIC1639-30
AIC1639-3 3
AIC1639-50
VOUT
+
GND
VOUT
C2
100µF
100mA Load Current Step-Up Converter
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F,9IndustryE.9thRoad,Science-basedIndustrialPark,Hsinchu,Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
1
FreeDatasheethttp://www.Datasheet4U.com
AIC1639
3-PIN ONE-CELL STEP-UP DC/DC CONVERTER
SPEC NO: DS-1639-00 05/26/00
APPLICATION INFORMATION
GENERAL DESCRIPTION
AIC1639 PFM (pluse frequency modulation) controller
ICs combine a switch mode regulator, push pull driver
(AIC1639), precision voltage reference, and voltage
detector in a single monolithic device. They offer both
extreme low quescient current, high efficiency, and
very low gate threshold voltage to ensure start-up with
low battery voltage ( 0.8V typ.). Designed to maxi-
mize battery life in protable products, and minimize
switching losses by only switching as needed service
the load.
PFM controllers transfer a discreate amount of energy
per cycle and regulate the output voltage by modulat-
ing switching frequency with the constant turn-on time.
Switching frequency depends on load, input voltage,
and inductor value, and it can range up to 100KHz.
mode. Continuous conduction mode means that the
inductor current does not ramp to zero during each
cycle.
VIN
IIN
SW
EXT
Isw
ID IOUT
+ VOUT
Ico
VEXT
IIN
I PK
When the output voltage drops, the error comparator
enable 100kHz oscillator that turns on the MOSFET
around 7.5us and 2.5us off time. Turning on the
MOSFET allows inductor current to ramp up, storing
energy in a magnetic field. When MOSFET turns off
that forces inductor current through diode to the out-
put capacitor and load. As the stored energy is de-
pleted, the current ramp down until the diode turns off.
At this point, inductor may ring due to residual energy
and stray capacitance. The output capacitor stores
charge when current flowing through the diode is high,
and release it when current is low, thereby maintain-
ing a steady voltage across the load.
ISW
Charge Co.
ID IOUT
TDIS Discharge Co.
VSW
t
Discontinuous Conduction Mode
As the load increases, the output capacitor dis-
charges faster and the error comparator initiates cy-
cles sooner, increasing the switching frequency. The
maximum duty cycle ensure adequate time for energy
tranfer to output during the second half each cycle.
Depending on circuit, PFM controller can operate in
either discontinuous mode or continuous conduction
ANALOG INTEGRATIONS CORPORATION
www.analog.com.tw
4F,9IndustryE.9thRoad,Science-basedIndustrialPark,Hsinchu,Taiwan, R.O.C. TEL: (8863)577-2500 FAX:(8863)577-2510
8
Free Datasheet http://www.Datasheet4U.com
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页数 | 11 页 | ||
下载 | [ AIC1639.PDF 数据手册 ] |
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