Fairchild Semiconductor RC2951 Datasheet

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RC2951

Adjustable Micropower Voltage Regulator

Features

• High accuracy output voltage

• Guaranteed 100 mA output current

• Extremely low quiescent current

• Extremely tight load and line regulation

• Requires only a 1.0µF output capacitor for stability

• Internal Current and Thermal Limiting

• Error flag warns of output dropout

• Logic-controlled electronic shutdown

• Output programmable from 1.24 to 29V

• Fixed 3.3V version available

• -25°C to +85°C operating range

• 8 lead SOIC package

Block Diagram

Description

The RC2951 is a voltage regulator specifically designed to
maintain proper regulation with a very low dropout voltage
(Typ. 40mV at light loads and 380 mV at 100mA). It has a
low quiescent bias current of 75µA and is capable of supply­ing output currents in excess of 100mA. It has internal cur­rent and thermal limiting protection. The output can be
programmed from 1.24V to 29V with two external resistors.
A fixed output voltage (3.3V) is also available.

The error flag output can be used as power-on reset for
warning of a low output voltage. The Shutdown input feature
allows a logic level signal to turn on and off the regulator
output. The RC2951 is ideally suited for battery powered
computer, consumer, and industrial equipment where an
extension of useful battery life is desirable. The RC2951 is
available in an 8-pin SOIC package.

V

Unregulated DC

+

From
CMOS
or TTL

PRELIMINARY INFORMATION describes products that are not in full production at the time of printing. Specifications are based on design goals
and limited characterization. They may change without notice. Contact Raytheon for current information.

3

Shut

Down

781

Feed-

Back

60 mV

+

1.23V
Reference

Error Detection Comparator

Input Output

+

–

Error
Amplifier

+

+

–

Sense

V

Error

Ground

IL ≤ 100 mA

2

6

TAP

5

4

OUT

+

See Application

Discussion

330kΩ

To CMOS
or TTL

REV. 1.0.1 4/8/02

RC2951 PRODUCT SPECIFICATION

Pin Assignments

8 Lead SOIC Package

Output

Sense

Shutdown

Ground

1

2

3

4

Input

8

Feedback

7

V

6

5

TA P

Error

Top View

Absolute Maximum Ratings

Power Dissipation Internally Limited
Lead Temp. (Soldering, 5 seconds) 260°C
Storage Temperature Range –65° to +150°C

Operating Junction Temperature Range

Input Supply/Voltage –0.3 to +30V

Feedback Input Voltage

Shutdown Input Voltage

2,3

2

Error Comparator Output Voltage

Notes:

1. Junction to ambient thermal resistance for the S.O. (M) package is 160°C/W.
2 May exceed input supply voltage.

3. When used in dual-supply systems where the output terminal sees loads returned to a negative supply, the output voltage
should be diode-clamped to ground.

1

–55° to +150°C

–1.5 to +30V

–0.3 to +30V

2

–0.3 to +30V

Electrical Characteristics

The • denotes that the limits apply at temperature extremes.

Parameter Conditions

Output Voltage

TJ = 25°C 5.0 5.025

(RC2951M)

-25°C ≤ TJ ≤ 85°C •

Output Voltage
(RC2951M)

Output Voltage

100µA ≤ IL ≤ 100mA
TJ ≤ T

TJ = 25°C 3.3 3.317

(RC2951M-3.3)

-25°C ≤ TJ ≤ 85°C •

Output Voltage
(RC2951M-3.3)

Output Voltage Temperature
Coefficient

Line Regulation

Load Regulation

7

9, 10

9

100µA ≤ IL ≤ 100mA
TJ ≤ T

(VONOM + 1)V ≤ Vin ≤ 20V

100 µA ≤ IL ≤ 100 mA

1

JMAX

JMAX

Typ. Tested Limit

2

Units

V max

5.0 5.06

•

•

5.0 5.075

•

4.975

4.94

4.925

V min

V max

V min

V max

V min

V max

3.3 3.340

•

•

3.3 3.346

•

3.284

3.260

3.254

V min

V max

V min

V max

V min

• 20 120 ppm/°C

0.03 0.1

•

0.08 0.2

•

0.5

0.4

% max
% max

% max
% max

2 REV. 1.0.1 4/8/02

PRODUCT SPECIFICATION RC2951

Electrical Characteristics (continued)

The • denotes that the limits apply at temperature extremes.

Parameter Conditions

Dropout Voltage

Ground Current I

Dropout Ground Current V

3

IL = 100 µA

= 100 mA

I

L

= 100 µA

L

= 100 mA

I

L

= (VONOM - 0.5)V

in

IL = 100 µA •

Current Limit V

Thermal Regulation

8

Output Noise,
10 Hz to
100 KHz

= 0

out

CL = 1 µF (5V Only) 430 µV rms

CL = 200 µF 160 µV rms

CL = 3.3 µF
(Bypass = 0.01 µF
Pins 7 to 1 (RC2951)

Reference Voltage

Reference Voltage

5

Feedback Pin Bias Current

Reference Voltage
Temperature Coefficient

7

Feedback Pin Bias Current
Temperature Coefficient

Error Comparator

Output Leakage Current VOH = 30V

Output Low Voltage V

= (VONOM - 0.5)V

in

IOL = 400 µA •

Upper Threshold Voltage

Lower Threshold Voltage

Hysteresis

4

4

4

1

Typ. Tested Limit

50 80

•

150

380 500

•

700

75 120

•

140

81415mA max

•

110 250

300

160 200

•

220

0.05 0.2 %/W max

100 µV rms

1.235 1.25

•

1.26

1.22

•

•

•

1.2

1.27

1.19

20 40

•

60

20 ppm/°C

0.1 nA/°C

0.01 1

•

150 250

400

60 40

•

25

75 95

•

140

15 mV

2

Units

mV max
mV max

mV max
mV max

µA max
µA max

mA max

µA max
µA max

mA max
mA max

V max
V max

V min
V min

V max

V min

nA max
nA max

µA max

2

µA max

mV max
mV max

mV min
mV min

mV max
mV max

REV. 1.0.1 4/8/02 3

RC2951 PRODUCT SPECIFICATION

Electrical Characteristics (continued)

The • denotes that the limits apply at temperature extremes.

Parameter Conditions

1

Typ. Tested Limit

Shutdown Input

Input Logic Voltage

Low (Regulator ON)
High (Regulator OFF)

Shutdown Pin Input Current V

Regulator Output
Current in Shutdown

Notes:

1. Unless otherwise specified all limits guaranteed for T
versions, and 2.2 µF for 3V and 3.3V versions. Additional conditions for the 8-pin versions are Feedback tied to V
Output tied to Output Sense and V

2. Guaranteed and 100% production tested.

3. Dropout Voltage is defined as the input to output differential at which the output voltage drops 100 mV below its nominal value
measured at 1V differential. At very low values of programmed output voltage, the minimum input supply voltage of 2V (2.3V
over temperature) must be taken into account.

4. Comparator thresholds are expressed in terms of a voltage differential at the Feedback terminal below the nominal
reference voltage measured at V
by the error amplifier gain = V
is guaranteed to go low when the output drops by 95 mV x 5V/1.235V = 384 mV. Thresholds remain constant as a percent
of V

as V

out

out

5. V

< V

ref

6. V

shutdown

7. Output or reference voltage temperature coefficient is defined as the worst case voltage change divided by the total
temperature range.

8. Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied,
excluding load or line regulation effects. Specifications are for a 50 mA load pulse at V
T = 10 ms.

9. Regulation is measured at constant junction temperature, using pulse testing with a low duty cycle. Changes in output voltage
due to heating effects are covered under the specification for thermal regulation.

10. Line regulation for the RC2951 is tested at 150°C for I
by design to 0.2%. See Typical Performance Characteristics for line regulation versus temperature and load current.

≤ (V

out

≥ 2V, Vin ≤ 30V, V

6

is varied, with the dropout warning occurring at typically 5% below nominal, 7.5% guaranteed.

– 1V), 2.3V ≤ Vin ≤ 30V, 100µA ≤ IL ≤ 100 mA, TJ ≤ T

in

shutdown

V

shutdown

shutdown

= (VONOM + 1)V. To express these thresholds in terms of output voltage change, multiply

in

out/Vref

= 0, Feedback pin tied to V

out

= 2.4V

= 30V

= 25°C, Vin = (VONOM + 1)V, IL = 100µA and CL = 1 µF for 5V

J

< 0.8V.

= (R1 + R2)/R2. For example, at a programmed output voltage of 5V, the Error output

JMAX

.

TAP

= 1 mA. For IL = 100 µA and TJ = 125°C, line regulation is guaranteed

L

1.3

•

•

30 50

•

450 600

•

31020µA max

•

.

0.6

2.0

100

750

= 30V (1.25W pulse) for

IN

2

Units

V

V max

V min

µA max
µA max

µA max
µA max

µA max

,

TAP

4 REV. 1.0.1 4/8/02