SP682
Corporation
Micro Power Inverting Charge Pump
■ Low Power Voltage Conversion
■ +2.4V to +5.5V Input Range
■ 99% Voltage Conversion Efficiency
■ Typical 60µA Supply Current
■ Requires Only Three External Capacitors
■ Includes Low Power Shutdown Option
■ Ideal in Portable Applications Such As
Handheld Instruments
Cellular Phones
Personal Digital Assistants
Laptops and Notebooks
■ Pin Compatible Upgrade to Microchip's
TC682
C1- 1
8 SD
C2+ 2
SP682
7 C1+
C2- 3
8 Pin MSOP
6 VCC
5 GND
VOUT 4
APPLICATIONS
■ LCD Display
■ Negative bias supply for op amps
■ Serial interface protocol circuits
DESCRIPTION
The SP682 is a monolithic charge pump voltage converter that produces a doubled, negative
voltage from a single positive supply. The SP682 charge pump outputs a –10V voltage from
a +5V input. Three external charge pump capacitors are required to support the voltage
conversion and voltage doubling process. An internal oscillator generates a 12kHz clock
which cycles the internal switching that charges the storage and transfer capacitors. The
charge pump architecture is fabricated using a low power BiCMOS process technology.
The SP682 charge pump is ideal for low power applications requiring a typical +3V battery
source such as a lithium cell. Typical applications are handheld instruments, notebook and
laptop computers, cellular phones, and data acquisition or GP systems. The SP682 is
packaged in either 8-pin NSOIC, 8-pin MSOP for surface mount applications, and 8 Pin PDIP.
TYPICAL APPLICATION CIRCUIT
+2.4V to +5V
1µF
+
6
7
C1+
VCC
VOUT
C1
1
2
C2
3
COUT
C1–
C2+
SP682
C2–
SD
GND
5
Date: 5/20/04
- VOUT
4
8
SP682 Micro Power Inverting Charge Pump
1
© Copyright 2004 Sipex Corporation
ABSOLUTE MAXIMUM RATINGS
These are stress ratings only and functional operation
of the device at these ratings or any other above those
indicated in the operation sections of the specifications
below is not implied. Exposure to absolute maximum
rating conditions for extended periods of time may
affect reliability.
Power Dissipation:
8-pin NSOIC......................................500mW
8-pin MSOP......................................320mW
8-pin PDIP......................................750mW
Package Derating:
8-pin NSOIC:
øJA..................................................128 °C/W
8-pin MSOP:
øJA..................................................216°C/W
8-pin PDIP:
øJA..................................................97°C/W
VCC...........................................................................+7V
VOUT........................................................................–11V
Storage Temperature..........................-65˚C to +150˚C
ELECTRICAL CHARACTERISTICS
TA = TMIN to TMAX and VCC = +5V. Charge pump cap = 3.3µF, unless otherwise noted.
MIN.
SUPPLY CURRENT
ICC
TYP.
60
99
90
SHUTDOWN TIMING
Shutdown to VOUT Delay
Operating Temperature Range
-C
-E
Date: 5/20/04
120
200
1
–9.99
–9.5
140
OSCILLATOR FREQUENCY
fOSC
SUPPLY VOLTAGE
VCC
CONDITIONS
µA
µA
µA
RL = ∞, TA = +25°C
RL = ∞
TA = +25 C, SD = +5V
O
CHARGE PUMP CAPACITORS: 3.3µF
–9.9
–9.0
SOURCE RESISTANCE
ROUT
CONVERSION EFFICIENCY
VOUT EFF
VOUT EFF
START-UP TIMING
VOUT Power On Delay
UNITS
CHARGE PUMP CAPACITORS: 3.3µF
in shutdown
CHARGE PUMP OUTPUT
VOUT
MAX.
Volts
Volts
380
180
230
450
Ω
Ω
Ω
12
20
kHz
RL = ∞
RL = 2kΩ
IL = 10mA, TA = +25°C
IL = 10mA
IL = 5mA, VCC = +2.8V
fosc = 2 X fC1+
99.9
95
%
%
RL = ∞
RL = 2kΩ
12
ms
RL = 2kΩ
5
ms
RL = 2kΩ
+2.4
+5.5
Volts
0
-40
+70
+85
oC
oC
SP682 Micro Power Inverting Charge Pump
2
© Copyright 2004 Sipex Corporation
THEORY OF OPERATION
about 12kHz (20kHz maximum) which conserves power as opposed to higher frequency
which operation typically draws more power
from VCC. The external charge pump capacitors
specified are 3.3µF but the absolute minimum
should be 1µF.
The SP682's charge pump design is a simplified version of Sipex's original patented charge
pump design (5,306,954) except that it only
generates a negative output. The charge pump
utilizes external capacitors to store the charge.
Figure 1 shows the waveform found on the
negative side of capacitor C2. There is a free–
running oscillator, running at 12kHz, that controls the two phases of the voltage shifting. A
description of each phase follows.
EFFICIENCY INFORMATION
A charge pump theoretically produces a doubled
voltage at 100% efficiency. However in the real
world, there is a small voltage drop on the output
which reduces the output efficiency. The SP682
can usually run 99.9% efficient without driving
a load. While driving a 1kΩ load, the SP682
remains over 90% efficiency.
Phase 1
VOUT charge storage — During this phase of
the clock cycle, the positive side of capacitors
C1 and C2 are initially charged to +5V. Cl+ is
then switched to ground and the charge on C1–
is transferred to C2–. Since C2+ is connected to
+5V, the voltage potential across capacitor C2
is now 10V.
Output Voltage Efficiency = VOUT / (–2*VCC);
VOUT = –2*VCC + VDROP
VDROP = (IOUT)*(ROUT)
Phase 2
VOUT transfer — Phase two of the clock connects the negative terminal of C2 to the VOUT
storage capacitor and the positive terminal of
C2 to ground, and transfers the generated –l0V
to C3. Simultaneously, the positive side of
capacitor C 1 is switched to +5V and the negative side is connected to ground.
Power Loss = IOUT*(VDROP)
The efficiency changes as the external charge
pump capacitors are varied. Larger capacitor
values will strengthen the output and reduce
output ripple. Although smaller capacitors will
cost less and save board space, lower values will
reduce the output drive capability and also increase the output ripple.
The oscillator frequency or clock rate for the
charge pump is designed for low power operation. The oscillator operates at a frequency of
VCC = +5V
+5V
C1
+
C2
–
+
–
VOUT Storage Capacitor
–5V
+
–
C3
–5V
Figure 2. Charge Pump Phase 1
VCC = +5V
C1
+
–
C2
+
–
VOUT Storage Capacitor
–
–10V
Figure 3. Charge Pump Phase 2
Figure 1. Charge Pump Waveform
Date: 5/20/04
+
C3
SP682 Micro Power Inverting Charge Pump
3
© Copyright 2004 Sipex Corporation
THEORY OF OPERATION
The ESR of the charge pump capacitors also
determine the output resistance. Assuming that
switch resistances are approximately equal, the
output resistance can be derived as shown below:
SHUTDOWN FEATURE
The SP682 charge pump includes a shutdown
feature (pin 8) which disables the charge pump
when the VOUT is not needed. A logic "1" will
activate the shutdown mode. If shutdown is not
needed, it can be left open where an internal
pull-down resistor will always keep the charge
pump active. Typical input current for the
shutdown pin is 3µA. The shutdown feature is
another option for conserving power in portable
applications, reducing current to only 1µA.
ROUT = 16*(RSW1-4) + 4*( ESRC1+ ESRC2) + ESRC3
+ 1 / (fOSC * C1) + 1 / (fOSC * C2)
ROUT is typically 140Ω at +25°C with VCC at
+5V using 3.3µF capacitors. The total internal
switch resistance (16*RSW) is approximately
90Ω. The table below shows the comparison of
ROUT versus C1&C2.
C1, C2 (µF)
0.05
0.10
0.47
1.00
3.30
4.70
10.00
22.00
PARALLEL DEVICES
Multiple SP682 charge pumps can be connected
in parallel. However, the effective output resistance now is the output resistance of a single
device divided by the number of devices. Connecting multiple pumps allows the user to save
on the storage capacitor. The charge pump
capacitors still must be separate for each device.
ROUT (Ω)
4085
2084
510
285
140
125
105
94
APPLICATIONS INFORMATION
The SP682 charge pump produces a doubled,
inverted voltage from the VCC input. As such, it
can serve in many applications where a negative
–5V to –10V output is needed. Typical applications include powering analog switches, and
biasing LCD displays and panels.
Table 1. ROUT .vs. C1, C2
The output voltage ripple is also affected by the
capacitors, specifically COUT. Larger values
will reduce the output ripple for a given output
current load of current. The formula representation is:
VRIPPLE = {1 / [2 * (fOSC * C3)] + 2 * (ESRC3)} * IOUT
To minimize the output ripple, the COUT storage
capacitor can be increased to over 10µF whereas
the pump capacitors can range from 1µF to 5µF.
Table 2 shows the typical VRIPPLE for given
COUT values.
COUT (µF)
0.50
1.00
3.30
4.70
10.00
22.00
VRIPPLE (mV)
1020
520
172
120
70
43
Table 2. C3 .vs. VRIPPLE
Date: 5/20/04
SP682 Micro Power Inverting Charge Pump
4
© Copyright 2004 Sipex Corporation
PACKAGE: 8 PIN NSOIC
D
e
E/2
E1
E
SEE VIEW C
E1/2
1
b
INDEX AREA
(D/2 X E1/2)
Ø1
A
TOP VIEW
Gauge Plane
L2
Seating Plane
Ø1
Ø
L
L1
VIEW C
A2
A
SEATING PLANE
A1
SIDE VIEW
DIMENSIONS
Minimum/Maximum
(mm)
b
WITH PLATING
8 Pin NSOIC
(JEDEC MS-012,
AA - VARIATION)
COMMON HEIGHT DIMENSION
SYMBOL
A
A1
A2
b
c
D
E
E1
e
L
L1
L2
Ø
Ø1
Date: 5/20/04
MIN NOM MAX
1.75
1.35
0.25
0.10 1.25
1.65
0.31
0.51
0.17
0.25
4.90 BSC
6.00 BSC
3.90 BSC
1.27 BSC
0.40 1.27
1.04 REF
0.25 BSC
0º
8º
5º
15º
c
BASE METAL
CONTACT AREA
PACKAGE: 8 PIN NSOIC
SP682 Micro Power Inverting Charge Pump
5
© Copyright 2004 Sipex Corporation
PACKAGE: 8 PIN MSOP
D
e1
Ø1
E/2
R1
R
E1
E
Gauge Plane
L2
Ø1
Seating Plane
Ø
L
L1
1
2
e
Pin #1 indentifier must be indicated within this shaded area (D/2 * E1/2)
8-PIN MSOP
JEDEC MO-187
(AA) Variation
Dimensions in (mm)
MIN
A
-
A1
0
-
0.15
A2
0.75
0.85
0.95
b
0.22
-
0.38
c
0.08
-
0.23
D
B
NOM MAX
-
1.10
B
A2
3.00 BSC
E
4.90 BSC
E1
3.00 BSC
e
0.65 BSC
e1
1.95 BSC
L
0.40
L1
0.60
b
A1
(b)
WITH PLATING
0.80
0.95 REF
0.25 BSC
L2
N
-
8
R
0.07
-
R1
0.07
-
Ø
0º
Ø1
0º
c
-
Section B-B
BASE METAL
8º
-
15º
8-PIN MSOP
1
Date: 5/20/04
A
SP682 Micro Power Inverting Charge Pump
6
© Copyright 2004 Sipex Corporation
PACKAGE: 8 PIN PDIP
N
INDEX
AREA
E1 E
1 2 3
N/2
A1
D
A
A2
D1
8 PIN PDIP
JEDEC MS-001
(BA) Variation
A
b3
b2
b
e
Dimensions in inches
MIN
-
E
NOM MAX
-
.210
A1
.015
-
-
A2
.115
.130
.195
b
.014
.018
.022
b2
.045
.060
.070
b3
.030
.039
.045
c
.008
.010
.014
eA
D
.355
.365
.400
eB
D1
.005
-
-
E
.300
.310
.325
E1
.240
.250
.280
L
c
b
.100 BSC
e
eA
.300 BSC
eB
-
-
.430
L
.115
.130
.150
c
8 PIN PDIP
Date: 5/20/04
SP682 Micro Power Inverting Charge Pump
7
© Copyright 2004 Sipex Corporation
ORDERING IFORMATION
Part Number
Temperature Range
Package Types
SP682CN ............................................. -0°C to +70°C ................................................................. 8-pin NSOIC
SP682CN/TR ....................................... -0°C to +70°C ................................................................. 8-pin NSOIC
SP682CP ............................................. -0°C to +70°C .................................................................... 8-pin PDIP
SP682CU ............................................. -0°C to +70°C .................................................................. 8-pin MSOP
SP682CU/TR ....................................... -0°C to +70°C .................................................................. 8-pin MSOP
SP682EN ........................................... -40°C to +85°C ................................................................. 8-pin NSOIC
SP682EN/TR ..................................... -40°C to +85°C ................................................................. 8-pin NSOIC
SP682EP ........................................... -40°C to +85°C .................................................................... 8-pin PDIP
SP682EU ........................................... -40°C to +85°C .................................................................. 8-pin MSOP
SP682EU/TR ..................................... -40°C to +85°C .................................................................. 8-pin MSOP
/TR = Tape and Reel
Pack quantity is 2,500 for NSOIC and MSOP.
Corporation
ANALOG EXCELLENCE
Sipex Corporation
Headquarters and
Sales Office
233 South Hillview Drive
Milpitas, CA 95035
TEL: (408) 934-7500
FAX: (408) 935-7600
Sipex Corporation reserves the right to make changes to any products described herein. Sipex does not assume any liability arising out of the
application or use of any product or circuit described hereing; neither does it convey any license under its patent rights nor the rights of others.
Date: 5/20/04
SP682 Micro Power Inverting Charge Pump
8
© Copyright 2004 Sipex Corporation