AIC1650
3-Cell, High-Efficiency, Inverting DC/DC
Converter
Analog Integrations Corporation 4F, 9, Industry E. 9th Rd, Science Based Industrial Park, Hsinchu Taiwan, ROC www.analog.com.tw
DS-1650-02 Dec 27, 00 TEL: 886-3-5772500 FAX: 886-3-5772510 1
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FEATURES
tensans 4V to 20V Input Voltage Operation.
tensans Adjustable Output Voltage up to -40V.
tensans Low Quiescent Current at 100µA.
tensans Pulse Frequency Modulation Maintains High
Efficiency (max. 90%).
tensans 100KHz to 320KHz Switching Frequency.
tensans Power-Saving Shutdown Mode (8µA Typical).
tensans High Efficiency with Low Cost External PNP
Bipolar Transistor.
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APPLICATIONS
tensans Negative LCD Contrast Bias for
1. Notebook & Palmtop Computers.
2. Pen-Based Data System.
3. Portable Data Collection Terminals.
4. Personal Digital Assistants.
tensans Negative Voltage Supply.
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DESCRIPTION
The AIC1650 is a high performance inverting
DC/DC converter, designed to drive an external
power switch to generate programmable nega-
tive voltages. In the particularly suitable LCD
bias contrast application, maximum efficiency of
90% can be achieved with low cost PNP bipolar
transistor drivers. 4V to 20V input operation
range allows the AIC1650 to be powered di-
rectly by the battery pack in most battery-
operated applications for greater efficiency.
Output voltage can be scaled to -40V or greater
by two external resistors. A pulse frequency
modulation scheme is employed to maintain
high efficiency conversion under wide input
voltage range. Quiescent current is about
100µA and can be reduced to 8µA in shutdown
mode. Switching frequency being around
100KHz to 320KHz range, small size switching
components are ideal for battery powered port-
able equipments, like notebook and palmtop
computers.
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TYPICAL APPLICATION CIRCUIT
D1 1N5819
AIC1650
CL
DHI
DLOW
FB GND
SHDN
VIN
VREF
C3
10nF
C4
0.047µF
*L
150µH
Q1
2N2907A
RB
1.5K~12K
R1
1M
C2
C1
VIN
+4V ~ 20V
VOUT
-12V~ -40V
5V
100µF
* Sumida CD-54 SERIES
VOUT = -1.22V x R1/R2
100
µ
F
+
+
R2
100K
Negative LCD Contrast Bias Power Supply