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DS21357C-page 3

TC1108

2.0

PIN DESCRIPTIONS

The descriptions of the pins are listed in Table 2-1.

TABLE 2-1:

PIN FUNCTION TABLE

3.0

DETAILED DESCRIPTION

The TC1108 is a precision, fixed output LDO. Unlike

bipolar regulators, the TC1108’s supply current does

remains stable and within regulation over the entire

important consideration in RTC and CMOS RAM

battery back-up applications).

Figure 3-1 shows a typical application circuit.

FIGURE 3-1:

TYPICAL APPLICATION

CIRCUIT

3.1

Output Capacitor

A 1

F (min) capacitor from V

The output capacitor should have an effective series

resistance greater than 0.1

 and less than 5.0. A 1F

is more than 10 inches of wire between the regulator

and the AC filter capacitor, or if a battery is used as the

power source. Aluminum electrolytic or tantalum

capacitor types can be used. (Since many aluminum

electrolytic capacitors freeze at approximately -30°C,

solid tantalums are recommended for applications

operating below -25°C.) When operating from sources

other

than batteries, supply-noise rejection and

transient response can be improved by increasing the

value of the input and output capacitors and employing

passive filtering techniques.

Pin No.

(3-Pin SOT-223)

Symbol

Description

Unregulated supply input.

2

GND

Ground terminal.

Regulated voltage output.

C1

1

μF

Battery

TC1108

1

2

3

C2

1

μF

GND

+

–

+

+