TC1220 Microchip Technology, TC1220 Datasheet - Page 7

• Manufacturer Part Number: TC1220
• Description: (TC1219) Switched Capacitor Voltage Converters with Shutdown in SOT Packages
• Manufacturer: Microchip Technology

4.7
Two or more TC1219/TC1220 can be cascaded to
increase output voltage (Figure 4-4). If the output is
lightly loaded, it will be close to (-2 x V
at least by R
of the second. It can be seen that the output resistance
rises rapidly for multiple cascaded devices.
FIGURE 4-4:
FIGURE 4-5:
 2002 Microchip Technology Inc.
Cascading Devices
OUT
of the first device multiplied by the I
C1
Shutdown
Control
CASCADING MULTIPLE DEVICES TO INCREASE OUTPUT VOLTAGE
PARALLELING MULTIPLE DEVICES TO REDUCE OUTPUT RESISTANCE
+
V
C1
IN
+
3
4
6
5
SHDN
TC1219
TC1220
3
4
6
5
IN
SHDN
"1"
) but will droop
TC1219
TC1220
"1"
2
1
C1
V
Q
IN
2
1
R
C1
+
. . .
. . .
V
+
OUT
IN
C2
+
= R
3
4
6
5
V
4.8
To reduce the value of R
TC1220’s can be connected in parallel (Figure 4-5).
The output resistance will be reduced by a factor of N
where N is the number of TC1219/TC1220. Each
device will require its own pump capacitor (C1), but all
devices may share one reservoir capacitor (C2).
However, to preserve ripple performance the value of
C2 should be scaled according to the number of
paralleled TC1219/TC1220.
SHDN
OUT
. . .
. . .
OUT
NUMBER OF DEVICES
TC1219
TC1220
3
4
6
5
= -nV
OF SINGLE DEVICE
SHDN
"n"
V
TC1219
TC1220
OUT
Paralleling Devices
IN
"n"
= -V
TC1219/TC1220
2
1
IN
+
C2
2
1
V
+
OUT
C2
V
V
IN
OUT
OUT
, multiple TC1219/
DS21366B-page 7