TC1263

DS21374B-page 4

© 2002 Microchip Technology Inc.

3.0

DETAILED DESCRIPTION

The TC1263 is a precision, fixed output LDO. Unlike

bipolar regulators, the TC1263’s supply current does

remains stable and within regulation over the entire

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

A1

The output capacitor should have an effective series

resistance greater than 0.1

Ω and less than 5Ω, and a

resonant frequency above 1MHz. A 1

µF capacitor

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 canbeimprovedbyincreasingthe value of

the input and output capacitors and employing passive

filtering techniques.

3.2

ERROR Output

regulation by more than – 5% (typical). This condition

may be caused by low input voltage, output current

limiting, or thermal limiting. The ERROR threshold is

(typ.) for a 5.0V regulator and 2.85V (typ.) for a 3.0V

regulator). ERROR output operation is shown in

Figure 3-2.

As shown in Figure 3-1, ERROR canbe usedas a

battery low flag, or as a processor RESET signal (with

the addition of timing capacitor C3). R1 x C3 should be

RESET input for at least 200 msec to allow time for the

system to stabilize. Pull-up resistor R1 can be tied to

FIGURE 3-2:

ERROR OUTPUT

OPERATION

1

µF

C1

0.2

µF

R1

1M

C3 Required Only

if ERROR is used as a

Processor RESET Signal

(See Text)

Shutdown Control

(to CMOS Logic or Tie

BATTLOW

or RESET

TC1263

Battery

ERROR

SHDN

GND

1

µF

C2

C3

+

+

+

+

ERROR