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19-0239; Rev 2; 4/03
50mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
_______________General Description
The MAX860/MAX861 charge-pump voltage converters
invert input voltages ranging from +1.5V to +5.5V, or
double input voltages ranging from +2.5V to +5.5V.
Because of their high switching frequencies, these
devices use only two small, low-cost capacitors. Their
50mA output makes switching regulators unnecessary,
eliminating inductors and their associated cost, size,
and EMI. Greater than 90% efficiency over most of the
load-current range, combined with a typical operating
current of only 200µA (MAX860), provides ideal perfor-
mance for both battery-powered and board-level volt-
age-conversion applications.
A frequency-control (FC) pin provides three switching-
frequencies to optimize capacitor size and quiescent
current and to prevent interference with sensitive cir-
cuitry. Each device has a unique set of three available
— —
— –
frequencies. A shutdown (SHDN) pin reduces current
consumption to less than 1µA. The MAX860/MAX861
are suitable for use in applications where the ICL7660
and MAX660's switching frequencies are too low. The
MAX860/MAX861 are available in 8-pin µMAX and
SO packages.
____________________________Features
o
8-Pin, 1.11mm High µMAX Package
o
Invert or Double the Input Supply Voltage
o
Three Selectable Switching Frequencies
o
High Frequency Reduces Capacitor Size
o
87% Efficiency at 50mA
o
200µA Quiescent Current (MAX860)
o
1µA Shutdown Supply Current
o
600mV Voltage Drop at 50mA Load
o
12Ω Output Resistance
MAX860/MAX861
______________Ordering Information
PART
MAX860ISA
MAX860IUA
MAX860C/D
MAX860ESA
MAX860MJA
MAX861ISA
MAX861IUA
MAX861C/D
MAX861ESA
MAX861MJA
TEMP RANGE
-25°C to +85°C
-25°C to +85°C
0°C to +70°C
-40°C to +85°C
-55°C to +125°C
-25°C to +85°C
-25°C to +85°C
0°C to +70°C
-40°C to +85°C
-55°C to +125°C
PIN-PACKAGE
8 SO
8 µMAX
Dice*
8 SO
8 CERDIP
†
8 SO
8 µMAX
Dice*
8 SO
8 CERDIP
†
________________________Applications
Portable Computers
Medical Instruments
Interface Power Supplies
Hand-Held Instruments
Operational-Amplifier Power Supplies
__________Typical Operating Circuit
1
2
3
C1 10µF
4
FC
MAX860
V
DD
8
7
6
5
INPUT
VOLTAGE
+1.5V TO +5.5V
*Dice
are tested at T
A
= +25°C, DC parameters only.
†Contact
factory for availability.
MAX861
C1+
GND
C1-
SHDN
LV
OUT
__________________Pin Configuration
INVERTED
NEGATIVE
OUTPUT
10µF
C2
TOP VIEW
VOLTAGE INVERTER
FC
1
INPUT
VOLTAGE
+2.5V TO +5.5V
1
2
3
C1
10µF
4
8
FC
MAX860
V
DD
MAX861
C1+
GND
C1-
SHDN
LV
OUT
7
6
5
DOUBLED
POSITIVE
OUTPUT
10µF
C2
8
7
V
DD
SHDN
LV
OUT
C1+
2
GND
3
C1-
4
MAX860
MAX861
6
5
SO/µMAX
POSITIVE VOLTAGE DOUBLER
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
50mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
MAX860/MAX861
ABSOLUTE MAXIMUM RATINGS
Supply Voltage (V
DD
to GND or GND to OUT) ...................+6.0V
—
– ——–
Input Voltage Range (LV, FC, S H D N ) ...................(OUT - 0.3V)
to (V
DD
+ 0.3V)
Continuous Output Current (OUT, V
DD
) .............................60mA
Output Short-Circuit to GND (Note 1).......................................1s
Continuous Power Dissipation (T
A
= +70°C)
SO (derate 5.88mW/°C above +70°C) .........................471mW
µMAX (derate 4.10mW/°C above +70°C) ....................330mW
CERDIP (derate 8.00mW/°C above +70°C) .................640mW
Note 1:
Operating Temperature Ranges
MAX86_I_A ......................................................-25°C to +85°C
MAX86_ESA.....................................................-40°C to +85°C
MAX86_MJA ..................................................-55°C to +125°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
OUT may be shorted to GND for 1sec without damage, but shorting OUT to V
DD
may damage the device and should be
avoided. Also, for temperatures above +85°C, OUT must not be shorted to GND or V
DD
, even instantaneously, or device
damage may result.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
— —
–— –
(Typical Operating Circuit (Inverter), V
DD
= +5V, SHDN = V
DD
, FC = LV = GND, C1 = C2 = 10µF (Note 2), T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Supply Voltage
SYMBOL
V
DD
R
L
= 1kΩ
CONDITIONS
Inverter, LV = GND
Doubler, LV = OUT
FC = V
DD
= 5V
MAX860I/E
FC = V
DD
= 3V
FC = GND
FC = OUT
FC = V
DD
MAX860M
No-Load Supply Current
(Note 3)
I
DD
MAX861I/E
FC = GND
FC = OUT
FC = V
DD
FC = GND
FC = OUT
FC = V
DD
MAX861M
FC = GND
FC = OUT
V
DD
= 5V, V
OUT
more negative than -3.75V
Output Current
I
OUT
V
DD
= 3V, V
OUT
more negative than -2.5V
Output Resistance
(Note 4)
R
OUT
I
L
= 50mA
I
L
= 10mA, V
DD
= 2V
10
30
12
20
25
35
Ω
50
100
mA
0.3
1.1
2.5
MIN
1.5
2.5
0.2
0.07
0.6
1.4
1.0
2.5
0.4
1.3
3.3
0.4
2.0
5.0
0.5
2.6
6.5
mA
TYP
MAX
5.5
5.5
0.3
UNITS
V
ELECTRICAL CHARACTERISTICS
2
_______________________________________________________________________________________
50mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
ELECTRICAL CHARACTERISTICS (continued)
PARAMETER
SYMBOL
MAX860
Switching Frequency
(Note 5)
f
S
MAX861
FC Current (from V
DD
)
I
FC
FC < 4V
MAX860,
FC = V
DD
R
L
= 2kΩ from V
DD
to OUT
R
L
= 1kΩ from OUT
to GND
R
L
= 2kΩ from V
DD
to OUT
R
L
= 1kΩ from OUT
to GND
93
90
93
88
MAX860/MAX861
— —
–— –
(Typical Operating Circuit (Inverter), V
DD
= +5V, SHDN = V
DD
, FC = LV = GND, C1 = C2 = 10µF (Note 2), T
A
= T
MIN
to T
MAX
, unless
otherwise noted. Typical values are at T
A
= +25°C.)
CONDITIONS
FC = V
DD
FC = GND
FC = OUT
FC = V
DD
FC = GND
FC = OUT
MIN
3
30
80
8
60
160
TYP
6
50
130
13
100
250
-2
96
93
96
92
87
99
1.2
0.3
—
– ——–
S H D N < 0.3V
No load, V
OUT
= -4V
MAX86_I/E
MAX86_M
500
1
10
99.9
%
V
µA
µs
%
-4
µA
kHz
MAX
UNITS
Power Efficiency (Note 6)
MAX861,
FC = V
DD
MAX860/MAX861, FC = V
DD
,
I
L
= 50mA to GND, C1 = C2 = 68µF
Voltage-Conversion Efficiency
— —
–— –
SHDN Threshold
Shutdown Supply Current
Time to Exit Shutdown
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
V
IH
V
IL
No load
LV = GND
C1 and C2 are low-ESR (<0.2Ω) aluminum electrolytics. Capacitor ESR adds to the circuit’s output resistance. Using
capacitors with higher ESR may reduce output voltage and efficiency.
MAX860/MAX861 may draw high supply current during startup, up to the minimum operating supply voltage. To guaran-
tee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current.
Specified output resistance includes the effect of the 0.2Ω ESR of the test circuit’s capacitors.
The switches are driven directly at the oscillator frequency, without any division.
At lowest frequencies, using 10µF capacitors gives worse efficiency figures than using the recommended capacitor
values in Table 3, due to larger 1 ⁄ (f
s
x C1) term in R
OUT
.
_______________________________________________________________________________________
3
50mA, Frequency-Selectable,
Switched-Capacitor Voltage Converters
MAX860/MAX861
__________________________________________Typical Operating Characteristics
(All curves generated using the inverter circuit shown in the
Typical Operating Circuits
with LV = GND and T
A
= +25°C, unless other-
wise noted. Test results also valid for doubler mode with LV = OUT and T
A
= +25°C. All capacitor values used are those recom-
mended in Table 3, unless otherwise noted. The output resistance curves represent the resistance of the device itself, which is R
O
in
the equation for R
OUT
shown in the
Capacitor Selection
section.)
OUTPUT VOLTAGE DROP FROM
SUPPLY VOLTAGE vs. LOAD CURRENT
MAX860-01
PERCENTAGE FREQUENCY CHANGE (%)
(FROM FREQUENCY MEASURED WITH V
DD
= +5V)
OSCILLATOR FREQUENCY vs.
SUPPLY VOLTAGE
MAX860-02
OUTPUT SOURCE RESISTANCE (R
O
) vs.
SUPPLY VOLTAGE
OUTPUT SOURCE RESISTANCE (Ω)
18
16
14
12
10
8
6
4
2
0
ALL FREQUENCIES
0
1
2
3
4
5
MAX860-03
0.8
0.7
0.6
V
OUT
DROP (V)
0.5
0.4
0.3
0.2
0.1
0
0
2
0
-2
-4
-6
-8
ALL FREQUENCIES
V
DD
= +1.5V
V
DD
= +2.5V
20
V
DD
= +3.5V
V
DD
= +4.5V, +5.0V
V
DD
= +5.5V
10
20
30
40
50
-10
-12
ALL FREQUENCIES,
LV CONNECTED TO GND
(INVERTER) OR OUT (DOUBLER)
-14
1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
OUTPUT SOURCE RESISTANCE (R
O
) vs.
TEMPERATURE
OUTPUT SOURCE RESISTANCE (Ω)
ALL FREQUENCIES
28
24
20
16
12
8
4
0
-60 -40 -20 0
20 40 60 80 100 120 140
TEMPERATURE (°C)
V
DD
= +5V
V
DD
= +1.5V
V
DD
= +3V
EFFICIENCY (%)
MAX860-04
MAX860
EFFICIENCY vs. LOAD CURRENT
MAX860-05
MAX860 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
FC = V
DD
400
DOUBLER, LV = OUT
SUPPLY CURRENT (µA)
MAX860-06
32
100
90
80
70
60
50
40
30
20
10
0
0.01
0.1
1
10
INVERTER
FC = V
DD
V
DD
= +1.5V
V
DD
= +3V
V
DD
= +5V
500
300
INVERTER, LV = GND
(V
DD
> 3V)
200
100
0
100
0
1
2
3
4
5
6
LOAD CURRENT (mA)
SUPPLY VOLTAGE (V)
MAX861 SUPPLY CURRENT
vs. SUPPLY VOLTAGE
MAX860-07
MAX860 OUTPUT CURRENT vs. CAPACITANCE
HIGH-FREQUENCY MODE
MAX860-08
MAX860 OUTPUT CURRENT vs. CAPACITANCE
MEDIUM-FREQUENCY MODE
70
OUTPUT CURRENT (mA)
60
50
40
30
V
IN
= +4.5V, V
OUT
= -4V
20
10
0
V
IN
= +3V, V
OUT
= -2.7V
f
OSC
= 50kHz
FC = GND
LV = GND
INVERTER MODE
V
IN
= +4.5V, V
OUT
= -3.5V
V
IN
= +3V, V
OUT
= -2.4V
MAX860-09
500
FC = V
DD
400
SUPPLY CURRENT (µA)
DOUBLER, LV = OUT
70
60
OUTPUT CURRENT (mA)
50
40
30
20
10
0
300
INVERTER, LV = GND
200
f
OSC
= 130kHz
FC = OUT
LV = GND
INVERTER MODE
V
IN
= +4.5V, V
OUT
= -3.5V
V
IN
= +4.5V, V
OUT
= -4V
80
V
IN
= +3V, V
OUT
= -2.4V
100
V
IN
= +3V, V
OUT
= -2.7V
0
0
1
2
3
4
5
6
SUPPLY VOLTAGE (V)
0.33
1
2.2
4.7
10
22
0.33
1
2.2
4.7
10
22
CAPACITANCE (µF)
CAPACITANCE (µF)
4
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