TC1121_06 MICROCHIP [Microchip Technology], TC1121_06 Datasheet - Page 6

• Manufacturer Part Number: TC1121_06
• Description: 100mA Charge Pump Voltage Converter with Shutdown
• Manufacturer: MICROCHIP [Microchip Technology]

TC1121
3.4
To produce greater negative magnitudes of the initial
supply voltage, the TC1121 may be cascaded (see
Figure 3-2). Resulting output resistance is approxi-
mately equal to the sum of individual TC1121 R
values. The output voltage (where n is an integer
representing the number of devices cascaded) is
defined by V
FIGURE 3-2:
FIGURE 3-3:
DS21358C-page 6
Cascading Devices
OUT
*SHDN should be tied to V
R
OUT
C1
= -n (V
C1
*SHDN should be tied to V
= R
+
Cascading TC1121s to Increase Output Voltage
Paralleling TC1121s to Reduce Output Resistance
OUT
IN
+
).
2
3
4
(of TC1121)/n(number of devices)
FC
CAP
GND
CAP
3
4
2
TC1121
+
–
FC
CAP
GND
CAP
“1”
TC1121
IN if
+
–
SHDN
V
OSC
“1”
OUT
V
not used.
IN if
IN
SHDN
V
OSC
OUT
V
not used.
8
7
5
IN
V +
5
8
IN
SHDN*
V
OSC
OUT
+
IN
SHDN*
C1n
C1n
+
+
+
3.5
To reduce output resistance, multiple TC1121s may be
paralleled (see Figure 3-3). Each device needs a pump
capacitor C1, but the reservoir capacitor C2 serves all
devices. The value of C2 should be increased by a
factor of n (the number of devices).
C2
2
3
4
3
2
4
FC
CAP
GND
CAP
FC
CAP
GND
CAP
Paralleling Devices
TC1121
+
–
TC1121
+
–
“n”
“n”
SHDN
V
SHDN
OSC
V
OUT
OSC
V
OUT
V
IN
IN
8
7
5
8
7
5
© 2006 Microchip Technology Inc.
+
+
SHDN*
SHDN*
C2
C2n
V
OUT