TC1121 Microchip, TC1121 Datasheet - Page 6

• Manufacturer Part Number: TC1121
• Description: 100mA Charge Pump Voltage Converter with Shutdown
• Manufacturer: Microchip

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:
DS21358B-page 6
Cascading Devices
OUT
C1
= -n (V
UT
= R
SHDN should be tied to V
1
CASCADING TC1121s TO INCREASE OUTPUT VOLTAGE
PARALLELING TC1121s TO REDUCE OUTPUT RESISTANCE
IN
UT
).
2
of TC1121)/n(number of devices)
FC
CAP
AP
ND
+
C1121
C
AP
AP
ND
1"
IN if
C1121
HDN
1"
SC
not used.
IN if
UT
N
HDN
SC
UT
ot used.
N
N
OUT
HDN*
N
SC
HDN*
1n
1n
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).
2
C
AP
ND
AP
Paralleling Devices
C
AP
AP
ND
C1121
C1121
n"
n"
HDN
HDN
SC
UT
V
SC
UT
IN
8
7
 2002 Microchip Technology Inc.
HDN*
HDN*
2
2n
UT