TC1014

3

PRELIMINARY INFORMATION

TC1014-01-6/5/97

50mA CMOS LDO WITH SHUTDOWN

AND REFERENCE BYPASS

Pin No.

Unregulated supply input.

2

GND

Ground terminal.

3

SHDN

Shutdown control input. The regulator is fully enabled when a logic high is applied to this

input. The regulator enters shutdown when a logic low is applied to this input. During

shutdown, output voltage falls to zero, and supply current is reduced to under 1 microamp

(typical).

4

Bypass

Reference bypass input. Connecting a 470pF to this input further reduces output noise.

Regulated voltage output.

PIN DESCRIPTION

(SOT-23A-5)

Symbol

Description

DETAILED DESCRIPTION

The TC1014 is a precision fixed output voltage regula-

tor. (If an adjustable version is desired, please see the

TC1070 or TC1071 data sheets.) Unlike the bipolar regula-

tors, the TC1014 supply current does not increase with load

tion at very low load currents (an important consideration in

RTC and CMOS RAM battery back-up applications).

Figure 1 shows a typical application circuit. The regula-

tor is enabled any time the shutdown input (SHDN) is at or

or I/O port of a microcontroller. If the SHDN input is not

required, it should be connected directly to the input supply.

While in shutdown, supply current decreases to 0.05

µA

Bypass Input

A 470pF capacitor connected from the Bypass input to

ground reduces noise present on the internal reference,

which in turn significantly reduces output noise. If output

noise is not a concern, this input may be left unconnected.

Larger capacitor values may be used, but results in a longer

time period to rated output voltage when power is initially

applied.

Output Capacitor

A 1

mended. The output capacitor should have an effective

series resistance of 5

Ω or less, and a resonant frequency

above 1MHz. A 1

to GND if there 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 capaci-

tor 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.

Thermal Considerations

Thermal Shutdown

Integrated thermal protection circuitry shuts the regula-

tor off when die temperature exceeds 160

°C. The regulator

remains off until the die temperature drops to approximately

150

°C.

Power Dissipation

The amount of power the regulator dissipates is prima-

rily a function of input and output voltage, and output current.

The following equation is used to calculate worst case

actual power dissipation:

Figure 1. Typical Application Circuit

1

µF

470pF

Reference

Bypass Cap

(Optional)

Shutdown Control

(to CMOS Logic or Tie to V

TC1014

BATTERY

Bypass

SHDN

GND

1

µF