Switched-Capacitor Voltage Converters
Paralleling Devices
1
2
C1
3
4
8
V+
MAX1044/ICL7660
MAX1044
ICL7660
7
6
5
Paralleling multiple MAX1044/ICL7660s reduces output
resistance and increases current capability. As illus-
trated in Figure 13, each device requires its own pump
capacitor C1, but the reservoir capacitor C2 serves all
devices. The equation for calculating output resistance is:
R
OUT
=
R
OUT
(of MAX1044 or ICL7660)
n (number of devices)
1
Shutdown Schemes
1
2
C1
3
4
8
MAX1044
ICL7660
7
6
5
V
OUT
=
-(V+)
C2
n
Figures 14a–14c illustrate three ways of adding shut-
down capability to the MAX1044/ICL7660. When using
these circuits, be aware that the additional capacitive
loading on the OSC pin will reduce the oscillator fre-
quency. The first circuit has the least loading on the
OSC pin and has the added advantage of controlling
shutdown with a high or low logic level, depending on
the orientation of the switching diode.
Figure 13. Paralleling MAX1044/ICL7660 to Reduce Output
Resistance
V+
1
2
10µF
3
4
8
1N4148
_Ordering Information (continued)
10kΩ REQUIRED FOR TTL
V+ CMOS or
TTL GATE
PART
MAX1044ESA
MAX1044MJA
ICL7660CPA
ICL7660CSA
ICL7660CUA
ICL7660C/D
ICL7660EPA
ICL7660ESA
ICL7660AMJA
†
ICL7660AMTV
†
TEMP. RANGE
-40°C to +85°C
-55°C to +125°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
0°C to +70°C
-40°C to +85°C
-40°C to +85°C
-55°C to +125°C
-55°C to +125°C
PIN-PACKAGE
8 SO
8 CERDIP**
8 Plastic DIP
8 SO
8 µMAX
Dice*
8 Plastic DIP
8 SO
8 CERDIP**
8 TO-99**
MAX1044
ICL7660
7
6
5
V
OUT
=
-(V+)
10µF
a)
V+
74HC03
OPEN-DRAIN OR
74LS03
OPEN-COLLECTOR
NAND GATES
MAX1044
ICL7660
7
* Contact factory for dice specifications.
** Contact factory for availability.
†
The Maxim ICL7660 meets or exceeds all “A” and “S”
specifications.
b)
V+
OUTPUT
ENABLE
74HC126 OR
74LS126
TRI-STATE BUFFER
MAX1044
ICL7660
7
c)
Figure 14a-14c. Shutdown Schemes for MAX1044/ICL7660
______________________________________________________________________________________
11
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
