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© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
SWITCHED CAPACITOR
VOLTAGE CONVERTER
SC1660
January 30, 1998
Note:
(1) Add suffix ‘TR’ for tape and reel.
FEATURES
• Improved direct replacement for 7660
• Easy to use
• 1.5V to 9V operation
• No external diode required
• Simple conversion of +5V to ±5V
• Low quiescent current
• High power efficiency
• Boost pin for higher switching frequency
DESCRIPTION
The SC1660 is a monolithic CMOS switched capacitor
voltage converter. Designed to be an improved direct
replacement for the popular 7660, the SC1660
provides performance superior to previous designs by
combining low quiescent current with high efficiency,
and by eliminating diode drop voltage losses. The only
required external components are two low cost
electrolytic capacitors.
TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com
TEST CIRCUIT APPLICATIONS
• RS-232 power supplies
• Handheld instruments
• Data acquisition systems
• Supply splitter, V
OUT
= ±VS/2
• Operational amplifier supplies
DEVICE
(1)
PACKAGE
SC1660CN 8-Pin DIP
SC1660CS SO-8
ORDERING INFORMATION
ABSOLUTE MAXIMUM RATINGS
Parameter Symbol Maximum Units
Supply Voltage
V
+
9.0 V
Operating
Temperature Range
T
A
-40 to 85 °C
Storage
Temperature Range
T
STG
-65 to 125 °C
PIN CONFIGURATION
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© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
SWITCHED CAPACITOR
VOLTAGE CONVERTER
SC1660
January 30, 1998
ELECTRICAL CHARACTERISTICS
Unless otherwise specified, TA = 25°C, V+ = 5V, OSC = free running
Parameter Symbol Conditions Min Typ Max Units
Input Voltage
V
+
RL=∞
1.5 9 V
Supply Current I
S
RL=∞
35 70 µA
Output Resistance R
OUT
IL=20mA, f
OSC
= 10kHz 45 90
Ω
Oscillator Frequency
Pin 1=V
+
f
OSC
RL=∞
10
50
kHz
Efficiency
η
R
L
= 5K, f
OSC
= 10kHz 96 98 %
Voltage Conversion
Efficiency
η
VOUT
RL=∞
98 99.9 %
TYPICAL APPLICATIONS
• Negative Voltage Converter
Figure 1 shows a typical connection which will
provide a negative supply from an available positive supply without the need for any external
diodes. The LV pin should be connected to ground
for V
+
≤ 3V; for V+ > 3V it may be left floating.
• Voltage Doubling
Figure 2 shows a method of voltage doubling.
Doubling is achieved by simply rearranging the
connection of the two external capacitors. An
external 500kΩ resistor is required to ensure the
oscillator will start.
• Ultra Precision Voltage Divider
An ultra precision voltage divider is shown in Figure 3. To achieve the 0.0002% accuracy indicated,
the load current should be kept below 100nA.
However, with a slight loss in accuracy, the load
current can be increased.
• Battery Splitter
A common need in many systems is to obtain
positive and negative supplies from a single battery
or power supply system. Where current requirements are small, the circuit shown in Figure 4 is a
simple solution.
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© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
SWITCHED CAPACITOR
VOLTAGE CONVERTER
SC1660
January 30, 1998
TYPICAL PERFORMANCE CHARACTERISTICS
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© 1997 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
SWITCHED CAPACITOR
VOLTAGE CONVERTER
SC1660
January 30, 1998
OUTLINE DRAWING - SO-8
TYPICAL PERFORMANCE CHARACTERISTICS (cont.)
OUTLINE DRAWING - 8-PIN DIP
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