TC1070(2002) 查看數據表（PDF） - Microchip Technology

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TC1070
(Rev.:2002)

50mA, 100mA and 150mA Adjustable CMOS LDOs with Shutdown

Microchip Technology 

TC1070/TC1071/TC1187

3.0 DETAILED DESCRIPTION

The TC1070, TC1071 and TC1187 are adjustable fixed

output voltage regulators. (If a fixed version is desired,

please see the TC1014/TC1015/TC1185 data sheet.)

Unlike bipolar regulators, the TC1070, TC1071 and

TC1187 supply current does not increase with load

current. In addition, VOUT remains stable and within

regulation over the entire 0mA to IOUTMAX operating

load current range, (an important consideration in RTC

and CMOS RAM battery back-up applications).

Figure 3-1 shows a typical application circuit. The

regulator is enabled any time the shutdown input

(SHDN) is at or above VIH, and shutdown (disabled)

when SHDN is at or below VIL. SHDN may be

controlled by a CMOS logic gate, 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 0.05µA

(typical), VOUT falls to zero volts.

FIGURE 3-1:

BATTERY-OPERATED

SUPPLY

3.0V +

Battery

1

+ C1

1µF

VIN

VOUT

TC1070

TC1071

TC1187

5

C2 +

1µF

2

GND

+2.45V

R1

470K

3

SHDN

Shutdown Control

(from Power

Control Logic)

4

ADJ

C3

100pF

to 0.01µF

(Optional)

R2

470K

3.1 Adjust Input

The output voltage setting is determined by the values

of R1 and R2 (Figure 3-1). The ohmic values of these

resistors should be between 470K and 3M to minimize

bleeder current.

The output voltage setting is calculated using the

following equation.

EQUATION 3-1:

[ ] VOUT = VREF x

R1

R2

+1

The voltage adjustment range of the TC1070, TC1071

and TC1187 is from VREF to (VIN – 0.05V). If so desired,

a small capacitor (100pF to 0.01µF) may be added to

the ADJ input to further reduce output noise.

3.2 Output Capacitor

A 1µF (min) capacitor from VOUT to ground is

recommended. The output capacitor should have an

effective series resistance greater than 0.1Ω and less

than 5.0Ω, and a resonant frequency above 1MHz. A

1µF capacitor should be connected from VIN 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 capacitor types can be used. (Since many

aluminum electrolytic capacitors freeze at approxi-

mately -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.

© 2002 Microchip Technology Inc.

DS21353B-page 5

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