Rainbow Electronics ICL7660 - Manual (Page 11)

Paralleling Devices
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:
Shutdown Schemes
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.
R
R (of MAX1044 or ICL7660)
n (number of devices)
OUT
OUT =
MAX1044/ICL7660
Switched-Capacitor Voltage Converters
______________________________________________________________________________________ 11
MAX1044
ICL7660
4
3
V
OUT
= -(V+)
2
1
5
6
7
8
C2
C1
V+
MAX1044
ICL7660
4
3
2
1
5
6
7
8
C1
1
n
Figure 13. Paralleling MAX1044/ICL7660 to Reduce Output
Resistance
MAX1044
ICL7660
4
3
10µF
V OUT
= -(V+)
10µF
CMOS or
TTL GATE
1N4148
V+
2
1
5
6
7
8
V+
10k Ω REQUIRED FOR TTL
Figure 14a-14c. Shutdown Schemes for MAX1044/ICL7660
OUTPUT
ENABLE
74HC126 OR
74LS126
TRI-STATE BUFFER
V+
7 MAX1044
ICL7660
74HC03
OPEN-DRAIN OR
74LS03
OPEN-COLLECTOR
NAND GATES
V+
MAX1044
ICL7660
7
a)
b)
c)
8 CERDIP**
8 SO
PIN-PACKAGE TEMP. RANGE
-40°C to +85°C
-55°C to +125°C MAX1044MJA
MAX1044ESA
PART
8 Plastic DIP 0°C to +70°C ICL7660 CPA
8 SO 0°C to +70°C ICL7660CSA
8 µMAX 0°C to +70°C ICL7660CUA
Dice* 0°C to +70°C ICL7660C/D
8 Plastic DIP -40°C to +85°C ICL7660EPA
8 SO -40°C to +85°C ICL7660ESA
8 CERDIP** -55°C to +125°C ICL7660AMJA †
8 TO-99** -55°C to +125°C ICL7660AMTV †
_Ordering Information (continued)
* Contact factory for dice specifications.
** Contact factory for availability.
† The Maxim ICL7660 meets or exceeds all “A” and “S”
specifications.