TC682

DS21453C-page 6

© 2006 Microchip Technology Inc.

4.3

Paralleling Devices

Paralleling

multiple

TC682s

reduces

the

output

resistance of the converter. The effective output

resistance is the output resistance of a single device

divided by the number of devices. As illustrated in

4.4

-5V Regulated Supply From A

Single 3V Battery

Figure 4-3 shows a -5V power supply using one 3V

regulated to -5V by the negative LDO. The input to the

TC682 can vary from 3V to 5.5V without affecting

regulation appreciably. A TC54 device is connected to

the battery to detect undervoltage. This unit is set to

detect at 2.7V. With higher input voltage, more current

can be drawn from the outputs of the TC682. With 5V

Assuming 150

Ω source resistance for the converter,

FIGURE 4-2:

Paralleling TC682 for Lower Output Source Resistance

FIGURE 4-3:

Negative Supply Derived from 3V Battery

10

μF

10

μF

10

μF

10

μF

22

μF

GND

GND

Negative

Supply

TC682

TC682

GND

+

–

+

–

+

–

+

–

+

–

GND

TC682

3V

Ground

-5 Supply

LOW BATTERY

Negative LDO

Regulator

TC54VC2702Exx

1

μF

+

–

+

–

+

–

+

–

+

–

10

μF

22

μF

10

μF