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Charge Pump DC-DC Voltage Converter
CE7660
Charge Pump DC-DC Voltage Converter
CE7660
CE7660 is a charge pump dc-to-dc
voltage converter using Si-gate CMOS technology and optimization design. It converters a +2.5V to +10V input to a corresponding -2.5V to -10V output using only two external capacitors, eliminating inductors and their associated cost, size and EMI. The on-board oscillator operates at a nominal frequency of 10KHz. Operation below 10 KHz (for lower supply current applications) is possible by connecting an external capacitor from OSC to ground.
Features
• Wide input voltage range: 2.5V~10V • Efficient voltage conversion:99.9% • Good power efficiency: 98% • Low power supply: 50uA @5V input • Easy to use: only two external
capacitors required • Compatible with RS232 negative
power supply standard • High ESD protection: up to 4KV • No Dx diode needed for high voltage
operation • Package : SOP8, DIP8
Applications
• LCD Display Module • Specially designed for LCD module • Instrument product • RS-232 Power supply • Operation amplifier supply • On board negative supply for dynamic
RAMS
Pin Configuration
NC CAP+
GND CAP-
1 2 3 4
8 VDD 7 OSC 6 LV 5 Vout
CE7660 DIP8 / SOP8
Pin Description
PIN Number 1 2 3 4 5 6 7 8
PIN NAME
NC CAP+
GND CAP-
Vout
LV
OSC
VDD
FUNCTION No connection Connecting external capacitor(+) pin Ground pin Connecting external capacitor(-) pin Voltage output pin Low voltage selection pin Connecting oscillation capacitor pin Power supply pin
Nanjing Chipower Electronics Inc.
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Charge Pump DC-DC Voltage Converter
Block Diagram
CE7660
Absolute Maximum Ratings
PARAMETER
Input voltage
LV PIN input voltage
OSC PIN input voltage
Output Short Duration (Vsupply ≤5.5V)
ContinuousTotal Power
Dissipation (TA≤75℃)
SOP8 DIP8
Operating Ambient Temperature
Storage Temperature
Soldering temperature and time
SYMBOL VIN VLX VOSC
Pd
Pd TOpr Tstg Tsolder
RATINGS +13V
-0.3~(V++0.3)(if V+<5.5V) (V+-5.5V)~(V++0.3V)(if V+>5.5V)
∞
470
730
-40~+85 -65~+150 260℃, 10s
UNITS V V
mW mW ℃ ℃
Electrical Characteristics(VDD=5V,COSC=0)
Symbol
Item
Conditions
Min
Typ
Max Unit
I+ Supply Current
RL=∞
— 50 100 µA
VDD
Supply Voltage
2.5 —
10 V
ROUT
Output Resistance
IOUT=20mA TA=25℃
60
Ω
FOSC PEFF
Oscillator Frequency Power Efficiency
Pin 7 open RL=5kΩ
— 95
10 98
— kHz —%
VOUTEFF Voltage Conversion Efficiency
RL=∞
98 99.9 — %
Nanjing Chipower Electronics Inc.
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Charge Pump DC-DC Voltage Converter
Test Circuits
CE7660
Type Characteristics
1.Vout VS Iout:
Vout VS Iout (Vin=5V)
-6
-5
-4
Vout(V) -3
Vout
-2
-1
0 0 1 2 3 4 5 6 7 8 9 10 15 20 30 40 50 Iout(mA)
2.η VS Iout:
Efficiency VS Io(utVin=5V)
120
100
80 (%) Efficiency60
40
Efficiency
20
0 1 2 3 4 5 6 7 8 9 10 15 20 30 40 50 Iout(mA)
Nanjing Chipower Electronics Inc.
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Charge Pump DC-DC Voltage Converter
CE7660
Operation
CE7660 together with two external capacitors C1、C2 complement a voltage Inverter. Capacitor C1 is charged to a voltage V+, for the first half cycle when switches S1 and S3 are closed ( while switches S2 and S4 are open during this half cycle); During the second half cycle of operation, switches S2 and S4 are closed, with S1 and S3 open, thereby shifting capacitor C2 negatively to -V+.
Theoretical Power Efficiency Considerations
In theory, a capacitive charge pump can approach 100% efficiency if certain conditions are met: 1、 The drive circuitry consumes no power. 2、 The output switches have extremely low ON resistance and no offset when operation. 3、 The impedances of the pump and reservoir capacitors are negligible at the pump frequency.
Notes:
1、Supply voltage should not exceed maximum rating; 2、Do not short the output to VDD supply for voltages above 5.5V for extended periods; 3、Polarized capacitors should be connected as the figure above.
Nanjing Chipower Electronics Inc.
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Charge Pump DC-DC Voltage Converter
Typical Application
CE7660
Above figure is the basic application circuit to provide a negative supply from -2.5V~ -10V while a positive supply from +2.5V ~ +10V is available. When VDD=+5V, the output resistance is about 60Ω; The output voltage is –4.5V while the load current is 10mA.
CE7660 may be paralleled to reduce output resistance (see the above figure) Rout(Paralleled)=Rout/N
CE7660 may be cascaded as shown above to produce larger negative output voltage (-10V). However, The output resistance is approximately double that of a single chip resistance.
CE7660 may be cascaded as shown above to produce larger negative output voltage (-15V). However, The output resistance is approximately double that of a single chip resistance.
Nanjing Chipower Electronics Inc.
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Charge Pump DC-DC Voltage Converter
CE7660
VDD
+ 10uF
1 NC 2 CAP+ 3 GND 4 CAP-
VDD 8 OSC 7 LV 6 Vout 5
Cosc Vout
CE7660
10uF +
To increase the conversion efficiency, the oscillator frequency may be lowered by connecting a capacitor from pin 7 and pin 8 as shown above.
CE7660 m.