FN3179 Rev 7.00 Page 1 of 13
January 23, 2013
FN3179
Rev 7.00
January 23, 2013
ICL7660S, ICL7660A
Super Voltage Converters
DATASHEET
The ICL7660S and ICL7660A Super Voltage Converters are
monolithic CMOS voltage conversion ICs that guarantee
significant performance advantages over other similar
devices. They are direct replacements for the industry
standard ICL7660 offering an extended operating supply
voltage range up to 12V, with lower supply current. A
Frequency Boost pin has been incorporated to enable the
user to achieve lower output impedance despite using smaller
capacitors. All improvements are highlighted in the “Electrical
Specifications” section on page 3. Critical parameters are
guaranteed over the entire commercial and industrial
temperature ranges.
The ICL7660S and ICL7660A perform supply voltage
conversions from positive to negative for an input range of
1.5V to 12V, resulting in complementary output voltages of
-1.5V to -12V. Only two non-critical external capacitors are
needed, for the charge pump and charge reservoir functions.
The ICL7660S and ICL7660A can be connected to function
as a voltage doubler and will generate up to 22.8V with a
12V input. They can also be used as a voltage multipliers or
voltage dividers.
Each chip contains a series DC power supply regulator, RC
oscillator, voltage level translator, and four output power
MOS switches. The oscillator, when unloaded, oscillates at a
nominal frequency of 10kHz for an input supply voltage of
5.0V. This frequency can be lowered by the addition of an
external capacitor to the “OSC” terminal, or the oscillator
may be over-driven by an external clock.
The “LV” terminal may be tied to GND to bypass the internal
series regulator and improve low voltage (LV) operation. At
medium to high voltages (3.5V to 12V), the LV pin is left
floating to prevent device latchup.
In some applications, an external Schottky diode from VOUT
to CAP- is needed to guarantee latchup free operation (see
Do’s and Dont’s section on page 8).
Features
• Guaranteed Lower Max Supply Current for All
Temperature Ranges
• Wide Operating Voltage Range: 1.5V to 12V
• 100% Tested at 3V
• Boost Pin (Pin 1) for Higher Switching Frequency
• Guaranteed Minimum Power Efficiency of 96%
• Improved Minimum Open Circuit Voltage Conversion
Efficiency of 99%
• Improved SCR Latchup Protection
• Simple Conversion of +5V Logic Supply to ±5V Supplies
• Simple Voltage Multiplication VOUT = (-)nVIN
• Easy to Use; Requires Only Two External Non-Critical
Passive Components
• Improved Direct Replacement for Industry Standard
ICL7660 and Other Second Source Devices
• Pb-Free Available (RoHS Compliant)
Applications
• Simple Conversion of +5V to ±5V Supplies
• Voltage Multiplication VOUT = ±nVIN
• Negative Supplies for Data Acquisition Systems and
Instrumentation
• RS232 Power Supplies
• Supply Splitter, VOUT = ±VS
Pin Configurations
ICL7660S
(8 LD PDIP, SOIC)
TOP VIEW
ICL7660A
(8 LD PDIP, SOIC)
TOP VIEW
BOOST
CAP+
GND
CAP-
1
2
3
4
8
7
6
5
V+
OSC
LV
VOUT
NC
CAP+
GND
CAP-
1
2
3
4
8
7
6
5
V+
OSC
LV
VOUT
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 2 of 13
January 23, 2013
Ordering Information
PART NUMBER
(NOTE 3) PART MARKING
TEMP. RANGE
(°C) PACKAGE PKG. DWG. #
ICL7660SCBA (Note 1) 7660 SCBA 0 to +70 8 Ld SOIC M8.15
ICL7660SCBAZ
(Notes 1, 2)
7660 SCBAZ 0 to +70 8 Ld SOIC (Pb-free) M8.15
ICL7660SCPA 7660S CPA 0 to +70 8 Ld PDIP E8.3
ICL7660SCPAZ (Note 2) 7660S CPAZ 0 to +70 8 Ld PDIP (Pb-free; Note 4) E8.3
ICL7660SIBA (Note 1) 7660 SIBA -40 to +85 8 Ld SOIC M8.15
ICL7660SIBAZ
(Notes 1, 2)
7660 SIBAZ -40 to +85 8 Ld SOIC (Pb-free) M8.15
ICL7660SIPA 7660 SIPA -40 to +85 8 Ld PDIP E8.3
ICL7660SIPAZ
(Note 2)
7660S IPAZ -40 to +85 8 Ld PDIP (Pb-free; Note 4) E8.3
ICL7660ACBA (Note 1) 7660ACBA 0 to 70 8 Ld SOIC (N) M8.15
ICL7660ACBAZA
(Notes 1, 2)
7660ACBAZ 0 to 70 8 Ld SOIC (N) (Pb-free) M8.15
ICL7660ACPA 7660ACPA 0 to 70 8 Ld PDIP E8.3
ICL7660ACPAZ (Note 2) 7660ACPAZ 0 to 70 8 Ld PDIP (Pb-free; Note 4) E8.3
ICL7660AIBA (Note 1) 7660AIBA -40 to 85 8 Ld SOIC (N) M8.15
ICL7660AIBAZA
(Notes 1, 2)
7660AIBAZ -40 to 85 8 Ld SOIC (N) (Pb-free) M8.15
NOTES:
1. Add “-T*” suffix for tape and reel. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte
tin plate plus anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil
Pb-free products are MSL classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of
IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ICL7660S, ICL7660A. For more information on MSL, please see
Te ch B ri ef TB363.
4. Pb-free PDIPs can be used for through-hole wave solder processing only. They are not intended for use in reflow solder processing applications.
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 3 of 13
January 23, 2013
Absolute Maximum Ratings Thermal Information
Supply Voltage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . +13.0V
LV and OSC Input Voltage (Note 5)
V+ < 5.5V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to V+ + 0.3V
V+ > 5.5V . . . . . . . . . . . . . . . . . . . . . . . . . . . V+ -5.5V to V+ +0.3V
Current into LV (Note 5)
V+ > 3.5V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20µA
Output Short Duration
VSUPPLY 5.5V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .Continuous
Operating Conditions
Temperature Range
ICL7660SI, ICL7660AI . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
ICL7660SC, ICL7660AC . . . . . . . . . . . . . . . . . . . . . 0°C to +70°C
Thermal Resistance (Typical, Notes 6, 7) JA (°C/W) JC (°C/W)
8 Ld PDIP* . . . . . . . . . . . . . . . . . . . . . . 110 59
8 Ld Plastic SOIC. . . . . . . . . . . . . . . . . 160 48
Storage Temperature Range . . . . . . . . . . . . . . . . . .-65°C to +150°C
Pb-free reflow profile . . . . . . . . . . . . . . . . . . . . . . . . . .see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
*Pb-free PDIPs can be used for through-hole wave solder
processing only. They are not intended for use in reflow solder
processing applications.
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product reliability and
result in failures not covered by warranty.
NOTES:
5. Connecting any terminal to voltages greater than V+ or less than GND may cause destructive latchup. It is recommended that no inputs from
sources operating from external supplies be applied prior to “power up” of ICL7660S and ICL7660A.
6. JA is measured with the component mounted on a low effective thermal conductivity test board in free air. See Tech Brief TB379 for details.
7. For JC, the “case temp” location is taken at the package top center.
8. Pb-free PDIPs can be used for through-hole wave solder processing only. They are not intended for use in reflow solder processing applications.
Electrical Specifications ICL7660S and ICL7660A, V+ = 5V, TA = +25°C, OSC = Free running (see Figure 12, “ICL7660S Test Circuit”
on page 7 and Figure 13 “ICL7660A Test Circuit” on page 7), unless otherwise specified.
PARAMETER SYMBOL TEST CONDITIONS
MIN
(Note 9) TYP
MAX
(Note 9) UNITS
Supply Current (Note 11) I+ RL = , +25°C - 80 160 µA
0°C < TA < +70°C - - 180 µA
-40°C < TA < +85°C - - 180 µA
-55°C < TA < +125°C - - 200 µA
Supply Voltage Range - High
(Note 12)
V+HRL = 10k, LV Open, TMIN < TA < TMAX 3.0 - 12 V
Supply Voltage Range - Low V+LRL = 10k, LV to GND, TMIN < TA < TMAX 1.5 - 3.5 V
Output Source Resistance ROUT IOUT = 20mA - 60 100
IOUT = 20mA, 0°C < TA < +70°C - - 120
IOUT = 20mA, -25°C < TA < +85°C - - 120
IOUT = 20mA, -55°C < TA < +125°C - - 150
IOUT = 3mA, V+ = 2V, LV = GND,
0°C < TA < +70°C
- - 250
IOUT = 3mA, V+ = 2V, LV = GND,
-40°C < TA < +85°C
- - 300
IOUT = 3mA, V+ = 2V, LV = GND,
-55°C < TA < +125°C
- - 400
Oscillator Frequency (Note 10) fOSC COSC = 0, Pin 1 Open or GND 5 10 - kHz
COSC = 0, Pin 1 = V+ - 35 - kHz
Power Efficiency PEFF RL = 5k96 98 - %
TMIN < TA < TMAX RL = 5k95 97 - -
Voltage Conversion Efficiency VOUTEFF RL = 99 99.9 - %
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 4 of 13
January 23, 2013
Oscillator Impedance ZOSC V+ = 2V - 1 - M
V+ = 5V - 100 - k
ICL7660A, V+ = 3V, TA = 25°C, OSC = Free running, Test Circuit Figure 13, unless otherwise specified
Supply Current (Note 13) I+ V+ = 3V, RL = , +25°C - 26 100 A
0°C < TA < +70°C - - 125 A
-40°C < TA < +85°C - - 125 A
Output Source Resistance ROUT V+ = 3V, IOUT = 10mA - 97 150
0°C < TA < +70°C - - 200
-40°C < TA < +85°C - - 200
Oscillator Frequency (Note 13) fOSC V+ = 3V (same as 5V conditions) 5.0 8 - kHz
0°C < TA < +70°C 3.0 - - kHz
-40°C < TA < +85°C 3.0 - - kHz
NOTES:
9. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization
and are not production tested.
10. In the test circuit, there is no external capacitor applied to pin 7. However, when the device is plugged into a test socket, there is usually a very
small but finite stray capacitance present, on the order of 5pF.
11. The Intersil ICL7660S and ICL7660A can operate without an external diode over the full temperature and voltage range. This device will function
in existing designs that incorporate an external diode with no degradation in overall circuit performance.
12. All significant improvements over the industry standard ICL7660 are highlighted.
13. Derate linearly above 50°C by 5.5mW/°C.
Electrical Specifications ICL7660S and ICL7660A, V+ = 5V, TA = +25°C, OSC = Free running (see Figure 12, “ICL7660S Test Circuit”
on page 7 and Figure 13 “ICL7660A Test Circuit” on page 7), unless otherwise specified. (Continued)
PARAMETER SYMBOL TEST CONDITIONS
MIN
(Note 9) TYP
MAX
(Note 9) UNITS
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 5 of 13
January 23, 2013
Functional Block Diagram
VOLTAGE
LEVEL
TRANSLATOR
SUBSTRATE
NETWORK
OSC
LV
V+
CAP+
CAP-
7
OSCILLATOR
AND DIVIDE-BY-
2 COUNTER
6
INTERNAL SUPPLY
REGULATOR
3
LOGIC
Q3
3
Q1
VOUT
3
8
2
Q2
3
4
5
Q4
GND
Typical Performance Curves
See Figure 12, “ICL7660S Test Circuit” on page 7) and Figure 13 “ICL7660A Test Circuit” on page 7
FIGURE 1. OPERATING VOLTAGE AS A
FUNCTION OF TEMPERATURE
FIGURE 2. OUTPUT SOURCE RESISTANCE AS A
FUNCTION OF SUPPLY VOLTAGE
FIGURE 3. OUTPUT SOURCE RESISTANCE AS A
FUNCTION OF TEMPERATURE
FIGURE 4. POWER CONVERSION EFFICIENCY AS A
FUNCTION OF OSCILLATOR FREQUENCY
-55 -25 0 25 50 100 125
12
10
8
6
4
2
0
SUPPLY VOLTAGE (V)
TEMPERATURE (°C)
SUPPLY VOLTAGE RANGE
(NO DIODE REQUIRED)
250
200
150
100
50
0
02 4681012
SUPPLY VOLTAGE (V)
OUTPUT SOURCE RESISTANCE (Ω)
TA = +125°C
TA = +25°C
TA = -55°C
350
300
250
200
150
100
50
0
OUTPUT SOURCE RESISTANCE (Ω)
-50 -25 0 25 50 75 100 125
TEMPERATURE (°C)
IOUT = 20mA,
V+ = 12V
IOUT = 20mA,
V+ = 5V
IOUT = 20mA,
V+ = 5V
IOUT = 3mA,
V+ = 2V
98
96
94
92
90
88
86
84
82
80
POWER CONVERSION EFFICIENCY (%)
100 1k 10k 50k
OSC FREQUENCY fOSC (Hz)
V+ = 5V
TA = +25°C
IOUT = 1mA
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 6 of 13
January 23, 2013
FIGURE 5. FREQUENCY OF OSCILLATION AS A FUNCTION
OF EXTERNAL OSCILLATOR CAPACITANCE
FIGURE 6. UNLOADED OSCILLATOR FREQUENCY AS A
FUNCTION OF TEMPERATURE
FIGURE 7. OUTPUT VOLTAGE AS A FUNCTION
OF OUTPUT CURRENT
FIGURE 8. SUPPLY CURRENT AND POWER CONVERSION
EFFICIENCY AS A FUNCTION OF LOAD
CURRENT
FIGURE 9. OUTPUT VOLTAGE AS A FUNCTION OF OUTPUT
CURRENT
FIGURE 10. SUPPLY CURRENT AND POWER CONVERSION
EFFICIENCY AS A FUNCTION OF LOAD CURRENT
Typical Performance Curves
See Figure 12, “ICL7660S Test Circuit” on page 7) and Figure 13 “ICL7660A Test Circuit” on page 7 (Continued)
1 10 100 1k
OSCILLATOR FREQUENCY fOSC (kHz)
10
9
8
7
6
5
4
3
2
1
0
COSC (pF)
V+ = 5V
TA = +25°C
OSCILLATOR FREQUENCY fOSC (kHz)
20
18
16
14
12
10
8
-55 -25 0 25 50 75 100 125
TEMPERATURE (°C)
V+ = 10V
V+ = 5V
OUTPUT VOLTAGE (V)
1
0
-1
-2
-3
-4
-5
010203040
LOAD CURRENT (mA)
V+ = 5V
TA = +25°C
POWER CONVERSION EFFICIENCY (%)
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
LOAD CURRENT (mA)
0102030 40 5060
V+ = 5V
TA = +25°C
SUPPLY CURRENT (mA)
OUTPUT VOLTAGE (V)
2
1
0
-1
-2
012 345 6789
LOAD CURRENT (mA)
TA = +25°C
V+ = 2V
100
90
80
70
60
50
40
30
20
10
0
16
14
12
10
8
6
4
2
0
0 1.5 3.0 4.5 6.0 7.5 9.0
LOAD CURRENT (mA)
V+ = 2V
TA = +25°C
POWER CONVERSION
EFFICIENCY (%)
SUPPLY CURRENT (mA) (NOTE 12)
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 7 of 13
January 23, 2013
FIGURE 11. OUTPUT SOURCE RESISTANCE AS A FUNCTION OF OSCILLATOR FREQUENCY
NOTE:
14. These curves include, in the supply current, that current fed directly into the load RL from the V+ (see Figure 12). Thus, approximately half the
supply current goes directly to the positive side of the load, and the other half, through the ICL7660S and ICL7660A, goes to the negative side
of the load. Ideally, VOUT 2VIN, IS 2IL, so VIN x IS VOUT x IL.
Typical Performance Curves
See Figure 12, “ICL7660S Test Circuit” on page 7) and Figure 13 “ICL7660A Test Circuit” on page 7 (Continued)
OUTPUT RESISTANCE (Ω)
400
300
200
100
0
100 1k 10k 100k
OSCILLATOR FREQUENCY (Hz)
V+ = 5V
TA = +25°C
I = 10mA
C1 = C2 = 10mF
C1 = C2 = 1mF
C1 = C2 = 100mF
1
2
3
4
8
7
6
5
+
-
C1
10µF
ISV+
(+5V)
IL
RL
-VOUT
C2
10µF
ICL7660S
V+
+
-
NOTE: For large values of COSC (>1000pF), the values of C1 and C2
should be increased to 100µF.
FIGURE 12. ICL7660S TEST CIRCUIT
NOTE: For large values of COSC (>1000pF) the values of C1 and C2
should be increased to 100F.
FIGURE 13. ICL7660A TEST CIRCUIT
1
2
3
4
8
7
6
5
+
-
C1
10µF
ISV+
(+5V)
IL
RL
-VOUT
C2
10µF
ICL7660A
COSC
+
-
(NOTE)
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 8 of 13
January 23, 2013
Detailed Description
The ICL7660S and ICL7660A contain all the necessary
circuitry to complete a negative voltage converter, with the
exception of two external capacitors, which may be
inexpensive 10µF polarized electrolytic types. The mode of
operation of the device may best be understood by
considering Figure 14, which shows an idealized negative
voltage converter. Capacitor C1 is charged to a voltage, V+,
for the half cycle, when switches S1 and S3 are closed.
(Note: 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 C1 to C2 such that the voltage on C2 is exactly V+,
assuming ideal switches and no load on C2. The ICL7660S
and ICL7660A approach this ideal situation more closely
than existing non-mechanical circuits.
In the ICL7660S and ICL7660A, the four switches of
Figure 14 are MOS power switches; S1 is a P-Channel
device; and S2, S3 and S4 are N-Channel devices. The main
difficulty with this approach is that in integrating the switches,
the substrates of S3 and S4 must always remain reverse
biased with respect to their sources, but not so much as to
degrade their “ON” resistances. In addition, at circuit start-
up, and under output short circuit conditions (VOUT = V+),
the output voltage must be sensed and the substrate bias
adjusted accordingly. Failure to accomplish this would result
in high power losses and probable device latch-up.
This problem is eliminated in the ICL7660S and ICL7660A by
a logic network that senses the output voltage (VOUT)
together with the level translators, and switches the
substrates of S3 and S4 to the correct level to maintain
necessary reverse bias.
The voltage regulator portion of the ICL7660S and
ICL7660A is an integral part of the anti-latchup circuitry;
however, its inherent voltage drop can degrade operation at
low voltages. Therefore, to improve low voltage operation,
the “LV” pin should be connected to GND, thus disabling the
regulator. For supply voltages greater than 3.5V, the LV
terminal must be left open to ensure latchup-proof operation
and to prevent device damage.
Theoretical Power Efficiency
Considerations
In theory, a voltage converter can approach 100% efficiency
if certain conditions are met:
1. The drive circuitry consumes minimal power.
2. The output switches have extremely low ON resistance
and virtually no offset.
3. The impedance of the pump and reservoir capacitors are
negligible at the pump frequency.
The ICL7660S and ICL7660A approach these conditions for
negative voltage conversion if large values of C1 and C2 are
used. ENERGY IS LOST ONLY IN THE TRANSFER OF
CHARGE BETWEEN CAPACITORS IF A CHANGE IN
VOLTAGE OCCURS. The energy lost is defined as shown in
Equation 1:
where V1 and V2 are the voltages on C1 during the pump
and transfer cycles. If the impedances of C1 and C2 are
relatively high at the pump frequency (see Figure 14)
compared to the value of RL, there will be a substantial
difference in the voltages, V1 and V2. Therefore it is not only
desirable to make C2 as large as possible to eliminate output
voltage ripple, but also to employ a correspondingly large
value for C1 in order to achieve maximum efficiency of
operation.
Do’s and Don’ts
1. Do not exceed maximum supply voltages.
2. Do not connect LV terminal to GND for supply voltage
greater than 3.5V.
3. Do not short circuit the output to V+ supply for supply
voltages above 5.5V for extended periods; however,
transient conditions including start-up are okay.
4. When using polarized capacitors, the + terminal of C1 must
be connected to pin 2 of the ICL7660S and ICL7660A, and
the + terminal of C2 must be connected to GND.
5. If the voltage supply driving the ICL7660S and ICL7660A
has a large source impedance (25 to 30), then a
2.2µF capacitor from pin 8 to ground may be required to
limit the rate of rise of input voltage to less than 2V/µs.
6. If the input voltage is higher than 5V and it has a rise rate
more than 2V/µs, an external Schottky diode from VOUT
to CAP- is needed to prevent latchup (triggered by
forward biasing Q4’s body diode) by keeping the output
(pin 5) from going more positive than CAP- (pin 4).
7. User should ensure that the output (pin 5) does not go
more positive than GND (pin 3). Device latch-up will
occur under these conditions. To provide additional
protection, a 1N914 or similar diode placed in parallel
with C2 will prevent the device from latching up under
these conditions, when the load on VOUT creates a path
to pull up VOUT before the IC is active (anode pin 5,
cathode pin 3).
VOUT = -VIN
C2
VIN
C1
S3S4
S1S2
82
4
33
5
7
FIGURE 14. IDEALIZED NEGATIVE VOLTAGE CONVERTER
E1
2
---C1V12V22
–=(EQ. 1)
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 9 of 13
January 23, 2013
Typical Applications
Simple Negative Voltage Converter
The majority of applications will undoubtedly utilize the
ICL7660S and ICL7660A for generation of negative supply
voltages. Figure 15 shows typical connections to provide a
negative supply where a positive supply of +1.5V to +12V is
available. Keep in mind that pin 6 (LV) is tied to the supply
negative (GND) for supply voltage below 3.5V.
The output characteristics of the circuit in Figure 15 can be
approximated by an ideal voltage source in series with a
resistance as shown in Figure 15B. The voltage source has
a value of -(V+). The output impedance (RO) is a function of
the ON resistance of the internal MOS switches (shown in
Figure 14), the switching frequency, the value of C1 and C2,
and the ESR (equivalent series resistance) of C1 and C2. A
good first order approximation for RO is shown in
Equation 2:
Combining the four RSWX terms as RSW, we see in
Equation 3 that:
RSW, the total switch resistance, is a function of supply
voltage and temperature (see the output source resistance
graphs, Figures 2, 3, and 11), typically 23 at +25°C and 5V.
Careful selection of C1 and C2 will reduce the remaining
terms, minimizing the output impedance. High value
capacitors will reduce the 1/(fPUMP x C1) component, and low
ESR capacitors will lower the ESR term. Increasing the
oscillator frequency will reduce the 1/(fPUMP x C1) term, but
may have the side effect of a net increase in output
impedance when C1 > 10µF and is not long enough to fully
charge the capacitors every cycle. Equation 4 shows a typical
application where fOSC = 10kHz and C = C1 = C2 = 10µF:
Since the ESRs of the capacitors are reflected in the output
impedance multiplied by a factor of 5, a high value could
potentially swamp out a low 1/fPUMP x C1 term, rendering an
increase in switching frequency or filter capacitance
ineffective. Typical electrolytic capacitors may have ESRs as
high as 10.
Output Ripple
ESR also affects the ripple voltage seen at the output. The
peak-to-peak output ripple voltage is given by Equation 5:
A low ESR capacitor will result in a higher performance
output.
Paralleling Devices
Any number of ICL7660S and ICL7660A voltage converters
may be paralleled to reduce output resistance. The reservoir
capacitor, C2, serves all devices, while each device requires
its own pump capacitor, C1. The resultant output resistance
is approximated in Equation 6:
Cascading De vices
The ICL7660S and ICL7660A may be cascaded as shown to
produce larger negative multiplication of the initial supply
voltage. However, due to the finite efficiency of each device,
the practical limit is 10 devices for light loads. The output
voltage is defined as shown in Equation 7:
where n is an integer representing the number of devices
cascaded. The resulting output resistance would be
approximately the weighted sum of the individual ICL7660S
and ICL7660A ROUT values.
Changing the ICL7660S and ICL7660A Oscillato r
Frequency
It may be desirable in some applications, due to noise or other
considerations, to alter the oscillator frequency. This can be
achieved simply by one of several methods.
By connecting the Boost Pin (Pin 1) to V+, the oscillator
charge and discharge current is increased and, hence, the
oscillator frequency is increased by approximately 3.5 times.
The result is a decrease in the output impedance and ripple.
1
2
3
4
8
7
6
5
+
-
10µF
10µF
ICL7660S
VOUT = -V+ V+
+
-
ROVOUT
V+
+
-
15A. 15B.
FIGURE 15. SIMPLE NEGATIVE CONVERTER AND ITS
OUTPUT EQUIVALENT
ICL7660A
R02R
SW1 RSW3 ESRC1
++2R
SW2 RSW4 ESRC1
+++
(EQ. 2)
1
fPUMP C1
--------------------------------ESRC2
+
fPUMP
fOSC
2
--------------
=RSWX MOSFET Switch Resistance=
R02xRSW
1
fPUMP C1
--------------------------------4xESRC1 ESRC2
+++(EQ. 3)
R02x23 1
510
3
1010 6–
---------------------------------------------------4xESRC1 ESRC2
+++
(EQ. 4)
R046 20 5++ ESRC
VRIPPLE
1
2f
PUMP
C2
----------------------------------------- 2ESRC2 IOUT
+
(EQ. 5)
ROUT
ROUT of ICL7660S
n number of devices
---------------------------------------------------------
=(EQ. 6)
VOUT nV
IN
–= (EQ. 7)
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 10 of 13
January 23, 2013
This is of major importance for surface mount applications
where capacitor size and cost are critical. Smaller
capacitors, such as 0.1µF, can be used in conjunction with
the Boost Pin to achieve similar output currents compared to
the device free running with C1 = C2 = 10µF or 100µF. (see
Figure 11).
Increasing the oscillator frequency can also be achieved by
overdriving the oscillator from an external clock, as shown in
Figure 16. In order to prevent device latchup, a 1k resistor
must be used in series with the clock output. In a situation
where the designer has generated the external clock
frequency using TTL logic, the addition of a 10k pull-up
resistor to V+ supply is required. Note that the pump
frequency with external clocking, as with internal clocking,
will be one-half of the clock frequency. Output transitions
occur on the positive going edge of the clock.
It is also possible to increase the conversion efficiency of the
ICL7660S and ICL7660A at low load levels by lowering the
oscillator frequency. This reduces the switching losses, and
is shown in Figure 17. However, lowering the oscillator
frequency will cause an undesirable increase in the
impedance of the pump (C1) and reservoir (C2) capacitors;
this is overcome by increasing the values of C1 and C2 by
the same factor by which the frequency has been reduced.
For example, the addition of a 100pF capacitor between pin
7 (OSC and V+) will lower the oscillator frequency to 1kHz
from its nominal frequency of 10kHz (a multiple of 10), and
thereby necessitate a corresponding increase in the value of
C1 and C2 (from 10µF to 100µF).
Positive Voltage Doubling
The ICL7660S and ICL7660A may be employed to achieve
positive voltage doubling using the circuit shown in Figure
18. In this application, the pump inverter switches of the
ICL7660S and ICL7660A are used to charge C1 to a voltage
level of V+ -VF
, where V+ is the supply voltage and VF is the
forward voltage on C1, plus the supply voltage (V+) is
applied through diode D2 to capacitor C2. The voltage thus
created on C2 becomes (2V+) - (2VF) or twice the supply
voltage minus the combined forward voltage drops of diodes
D1 and D2.
The source impedance of the output (VOUT) will depend on
the output current, but for V+ = 5V and an output current of
10mA, it will be approximately 60.
Combined Negative Voltage Conversion and
Positive Supply Doubling
Figure 19 combines the functions shown in Figure 15 and
Figure 18 to provide negative voltage conversion and
positive voltage doubling simultaneously. This approach
would be suitable, for example, for generating +9V and -5V
from an existing +5V supply. In this instance, capacitors C1
and C3 perform the pump and reservoir functions,
respectively, for negative voltage generation, while
capacitors C2 and C4 are pump and reservoir, respectively,
for the doubled positive voltage. There is a penalty in this
configuration which combines both functions, however, in
that the source impedances of the generated supplies will be
somewhat higher, due to the finite impedance of the
common charge pump driver at pin 2 of the device.
1
2
3
4
8
7
6
5
+
-
10µF
ICL7660S
VOUT
V+
+
-10µF
V+
CMOS
GATE
1kΩ
FIGURE 16. EXTERNAL CLOCKING
ICL7660A
1
2
3
4
8
7
6
5
+
-
ICL7660S
VOUT
V+
+
-C2
C1
COSC
FIGURE 17. LOWERING OSCILLATOR FREQUENCY
ICL7660A
1
2
3
4
8
7
6
5
ICL7660S
V+
D1
D2
C1
C2
VOUT =
(2V+) - (2VF)
+
-
+
-
FIGURE 18. POSITIVE VOLTAGE DOUBLER
NOTE: D1 AND D2 CAN BE ANY SUITABLE DIODE.
ICL7660A
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 11 of 13
January 23, 2013
Voltage Splitting
The bidirectional characteristics can also be used to split a
high supply in half, as shown in Figure 20. The combined load
will be evenly shared between the two sides, and a high value
resistor to the LV pin ensures start-up. Because the switches
share the load in parallel, the output impedance is much lower
than in the standard circuits, and higher currents can be drawn
from the device. By using this circuit, and then the circuit of
Figure 15, +15V can be converted, via +7.5 and -7.5, to a
nominal -15V, although with rather high series output
resistance (250).
Regulated Negative Voltage Supply
In some cases, the output impedance of the ICL7660S and
ICL7660A can be a problem, particularly if the load current
varies substantially. The circuit of Figure 21 can be used to
overcome this by controlling the input voltage, via an ICL7611
low-power CMOS op amp, in such a way as to maintain a
nearly constant output voltage. Direct feedback is inadvisable,
since the ICL7660S’s and ICL7660A’s output does not respond
instantaneously to change in input, but only after the switching
delay. The circuit shown supplies enough delay to
accommodate the ICL7660S and ICL7660A, while maintaining
adequate feedback. An increase in pump and storage
capacitors is desirable, and the values shown provide an
output impedance of less than 5 to a load of 10mA.
Other Applications
Further information on the operation and use of the ICL7660S
and ICL7660A may be found in application note AN051,
“Principles and Applications of the ICL7660 CMOS Voltage
Converter”.
1
2
3
4
8
7
6
5
ICL7660S
V+
D1
D2
C4
VOUT = (2V+) -
(VFD1) - (VFD2)
+
-
C2
+
-
C3
+
-
VOUT = -VIN
C1
+
-
FIGURE 19. COMBINED NEGATIVE VOLTAGE CONVERTER
AND POSITIVE DOUBLER
D3
ICL7660A
1
2
3
4
8
7
6
5
+
-
+
-
50µF
50µF
+
-
50µF
RL1
VOUT = V+ - V-
2ICL7660S
V+
V-
RL2
FIGURE 20. SPLITTING A SUPPLY IN HALF
ICL7660A
1
2
3
4
8
7
6
5
+
-
100µF
ICL7660S
100µF
VOUT
+
-10µF
ICL7611
+
-
100
50k
+8V
100k
50k
ICL8069
56k
+8V
800k 250k
VOLTAGE
ADJUST
+
-
FIGURE 21. REGULATING THE OUTPUT VOLTAGE
ICL7660A
FN3179 Rev 7.00 Page 12 of 13
January 23, 2013
ICL7660S, ICL7660A
Intersil products are manufactured, assembled and tested utilizing ISO9001 quality systems as noted
in the quality certifications found at www.intersil.com/en/support/qualandreliability.html
Intersil products are sold by description only. Intersil may modify the circuit design and/or specifications of products at any time without notice, provided that such
modification does not, in Intersil's sole judgment, affect the form, fit or function of the product. Accordingly, the reader is cautioned to verify that datasheets are
current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its
subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Intersil or its subsidiaries.
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For additional products, see www.intersil.com/en/products.html
© Copyright Intersil Americas LLC 1999-2013. All Rights Reserved.
All trademarks and registered trademarks are the property of their respective owners.
Dual-In-Line Plastic Packages (PDIP)
C
L
E
eA
C
eB
eC
-B-
E1
INDEX 12 3 N/2
N
AREA
SEATING
BASE
PLANE
PLANE
-C-
D1
B1
B
e
D
D1
A
A2
L
A1
-A-
0.010 (0.25) C AMBS
NOTES:
1. Controlling Dimensions: INCH. In case of conflict between
English and Metric dimensions, the inch dimensions control.
2. Dimensioning and tolerancing per ANSI Y14.5M-1982.
3. Symbols are defined in the “MO Series Symbol List” in Section
2.2 of Publication No. 95.
4. Dimensions A, A1 and L are measured with the package seated
in JEDEC seating plane gauge GS-3.
5. D, D1, and E1 dimensions do not include mold flash or protru-
sions. Mold flash or protrusions shall not exceed 0.010 inch
(0.25mm).
6. E and are measured with the leads constrained to be per-
pendicular to datum .
7. eB and eC are measured at the lead tips with the leads uncon-
strained. eC must be zero or greater.
8. B1 maximum dimensions do not include dambar protrusions.
Dambar protrusions shall not exceed 0.010 inch (0.25mm).
9. N is the maximum number of terminal positions.
10. Corner leads (1, N, N/2 and N/2 + 1) for E8.3, E16.3, E18.3,
E28.3, E42.6 will have a B1 dimension of 0.030 - 0.045 inch
(0.76 - 1.14mm).
eA
-C-
E8.3 (JEDEC MS-001-BA ISSUE D)
8 LEAD DUAL-IN-LINE PLASTIC PACKAGE
SYMBOL
INCHES MILLIMETERS
NOTESMIN MAX MIN MAX
A - 0.210 - 5.33 4
A1 0.015 - 0.39 - 4
A2 0.115 0.195 2.93 4.95 -
B 0.014 0.022 0.356 0.558 -
B1 0.045 0.070 1.15 1.77 8, 10
C 0.008 0.014 0.204 0.355 -
D 0.355 0.400 9.01 10.16 5
D1 0.005 - 0.13 - 5
E 0.300 0.325 7.62 8.25 6
E1 0.240 0.280 6.10 7.11 5
e 0.100 BSC 2.54 BSC -
eA0.300 BSC 7.62 BSC 6
eB- 0.430 - 10.92 7
L 0.115 0.150 2.93 3.81 4
N8 89
Rev. 0 12/93
ICL7660S, ICL7660A
FN3179 Rev 7.00 Page 13 of 13
January 23, 2013
Package Outline Drawing
M8.15
8 LEAD NARROW BODY SMALL OUTLINE PLASTIC PACKAGE
Rev 4, 1/12
DETAIL "A"
TOP VIEW
INDEX
AREA
123
-C-
SEATING PLANE
x 45°
NOTES:
1. Dimensioning and tolerancing per ANSI Y14.5M-1994.
2. Package length does not include mold flash, protrusions or gate burrs.
Mold flash, protrusion and gate burrs shall not exceed 0.15mm (0.006
inch) per side.
3. Package width does not include interlead flash or protrusions. Interlead
flash and protrusions shall not exceed 0.25mm (0.010 inch) per side.
4. The chamfer on the body is optional. If it is not present, a visual index
feature must be located within the crosshatched area.
5. Terminal numbers are shown for reference only.
6. The lead width as measured 0.36mm (0.014 inch) or greater above the
seating plane, shall not exceed a maximum value of 0.61mm (0.024 inch).
7. Controlling dimension: MILLIMETER. Converted inch dimensions are not
necessarily exact.
8. This outline conforms to JEDEC publication MS-012-AA ISSUE C.
SIDE VIEW “A
SIDE VIEW “B”
1.27 (0.050)
6.20 (0.244)
5.80 (0.228)
4.00 (0.157)
3.80 (0.150)
0.50 (0.20)
0.25 (0.01)
5.00 (0.197)
4.80 (0.189)
1.75 (0.069)
1.35 (0.053)
0.25(0.010)
0.10(0.004)
0.51(0.020)
0.33(0.013)
8°
0°
0.25 (0.010)
0.19 (0.008)
1.27 (0.050)
0.40 (0.016)
1.27 (0.050)
5.20(0.205)
1
2
3
45
6
7
8
TYPICAL RECOMMENDED LAND PATTERN
2.20 (0.087)
0.60 (0.023)
