TC2054 Datasheet, PDF(4/16 Page) Microchip Technology – 50mA, 100mA, and 150mA CMOS LDOs with Shutdown and Error Output

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TC2054 Datasheet, PDF (4/16 Pages) Microchip Technology – 50mA, 100mA, and 150mA CMOS LDOs with Shutdown and Error Output

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TC2054/2055/2186

3.0 DETAILED DESCRIPTION

The TC2054, TC2055 and TC2186 are precision fixed

output voltage regulators. (If an adjustable version is

desired, please see the TC1070, TC1071 or TC1187

data sheets.) Unlike bipolar regulators, the TC2054,

TC2055 and TC2186 supply current does not increase

with load current. In addition, VOUT remains stable and

within regulation over the entire 0mA to maximum out-

put current operating load range.

Figure 3-1 shows a typical application circuit. The reg-

ulator 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 0.05ÂµA (typical), VOUT falls to

zero volts, and ERROR is open-circuited.

FIGURE 3-1: TYPICAL APPLICATION CIRCUIT

1ÂµF

BATTERY

VIN

VOUT

TC2054

GND TC2055

TC2186

Shutdown Control

(to CMOS Logic or Tie

to VIN if unused)

SHDN

ERROR

C2 Required Only

if ERROR is used as a

Processor RESET Signal

(See Text)

VOUT

1ÂµF

V+

0.2ÂµF

BATTLOW

or RESET

3.1 ERROR Open Drain Output

ERROR is driven low whenever VOUT falls out of regu-

lation by more than -5% (typical). This condition may be

caused by low input voltage, output current limiting or

thermal limiting. The ERROR threshold is 5% below

rated VOUT regardless of the programmed output volt-

age value (e.g. ERROR = VOL at 4.75V (typ.) for a 5.0V

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

ERROR output operation is shown in Figure 4-2.

Note that ERROR is active when VOUT falls to VTH, and

inactive when VOUT rises above VTH by VHYS.

As shown in Figure 3-1, ERROR can be used as a bat-

tery low flag or as a processor RESET signal (with the

addition of timing capacitor C2). R1 x C2 should be

chosen to maintain ERROR below VIH of the processor

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

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

VOUT, VIN or any other voltage less than (VIN + 0.3V).

The ERROR pin sink current is self-limiting to approxi-

mately 18mA.

FIGURE 3-2: ERROR OUTPUT OPERATION

VOUT

VTH

HYSTERESIS (VHYS)

ERROR

VIH

VOL

3.2 Output Capacitor

A 1ÂµF (min) capacitor from VOUT to ground is required.

The output capacitor should have an effective series

resistance of 0.01â¦. to 5â¦ for VOUT = 2.5V, and 0.05â¦.

to 5â¦ for VOUT < 2.5V. A 1ÂµF capacitor should be con-

nected from VIN to GND if there is more than 10 inches

of wire between the regulator and the AC filter capaci-

tor, or if a battery is used as the power source. Ceramic,

tantalum and aluminum electrolytic capacitors can be

used. (Since many aluminum electrolytic capacitors

freeze at approximately -30Â°C, solid tantalums are rec-

ommended for applications operating below -25Â°C).

When operating from sources other than batteries, sup-

ply-noise rejection and transient response can be

improved by increasing the value of the input and out-

put capacitors and employing passive filtering tech-

niques.

DS21663B-page 4

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