TC1222 Ver la hoja de datos (PDF) - Microchip Technology
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TC1222
Microchip Technology
TC1222 Datasheet PDF : 16 Pages
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TC1221/TC1222
4.7 Cascading Devices
Two or more TC1221/TC1222 can be cascaded to
increase output voltage (Figure 4-4). If the output is
lightly loaded, it will be close to (-2 x VIN) but will droop
at least by ROUT of the first device multiplied by the IQ
of the second. It can be seen that the output resistance
rises rapidly for multiple cascaded devices.
4.8 Paralleling Devices
To reduce the value of ROUT, multiple TC1221/
TC1222’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 TC1221/TC1222. 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 TC1221/TC1222.
FIGURE 4-4:
CASCADING MULTIPLE DEVICES TO INCREASE OUTPUT VOLTAGE
C1
+
VIN
3
TC1221
4 TC1222
6
"1"
5 SHDN
...
VIN
2
C1
1
3
TC1221
4 TC1222
+
6
"n"
. . . 5 SHDN
C2
+
VOUT = -nVIN
2
1
VOUT
C2
+
FIGURE 4-5:
PARALLELING MULTIPLE DEVICES TO REDUCE OUTPUT RESISTANCE
ROUT = ROUT OF SINGLE DEVICE
NUMBER OF DEVICES
VIN
...
VIN
C1
+
Shutdown
Control
3
TC1221
4 TC1222
6
"1"
5 SHDN
2
2
3
C1
+
TC1221
4 TC1222
1
6
"n"
5 SHDN
1
VOUT
...
VOUT = -VIN
C2
+
2002 Microchip Technology Inc.
DS21367B-page 7
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