 2002 Microchip Technology Inc.

DS21367B-page 7

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

of the second. It can be seen that the output resistance

rises rapidly for multiple cascaded devices.

4.8

Paralleling Devices

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

FIGURE 4-5:

PARALLELING MULTIPLE DEVICES TO REDUCE OUTPUT RESISTANCE

C1

C1

C2

6

6

4

3

4

1

2

2

1

3

C2

TC1221

TC1222

TC1221

TC1222

...

...

SHDN

SHDN

5

5

"1"

"n"

+

+

+

+

C1

C1

6

5

4

3

4

1

2

2

1

3

C2

NUMBER OF DEVICES

TC1221

TC1222

TC1221

TC1222

...

...

SHDN

SHDN

Shutdown

Control

5

6

+

+

+

"1"

"n"