Fairchild RC0431A service manual

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RC0431A (RC431A)

Low-Voltage Adjustable Precision Shunt Regulator

Features

•Low voltage operation to 1.24V

• 1% reference voltage tolerance

• Output voltage adjustable from V

•Low 80µA operational cathode current

• 0.25Ω typical output impedance

•TO-92, SOT23-3 and SOT23-5 packages

to 12V

ref

Applications

•Voltage reference for discrete power circuits

Description

The RC0431A is a low-voltage 3-terminal adjustable
precision voltage reference regulator. It has an excellent
thermal stability over the standard commercial temperature
range. The output voltage can be set to any value between
Vref (1.24V) and 12V using two external resistors. The
RC0431A operates from a lower voltage (1.24V) than the
traditional shunt regulator references which operate from

2.5V. When used with an optocoupler, the RC0431A will be
an ideal voltage reference in an isolated feedback circuit for
use in switched-mode power supplies and modular DC-DC
converters. The RC0431A has a low output impedance of
active output circuitry offering a very sharp turn-on
characteristic. The RC0431A will be an excellent
replacement for low-voltage zener diodes in many
applications such as on-board regulation and adjustable
power supplies.

Symbol Block Diagram

REF

Anode Cathode

65-431A-01

REF

V

= 1.24V

ref

CATHODE

+

_

65-431A-02

ANODE

REV. 1.0.7 8/5/03

RC0431A (RC431A) PRODUCT SPECIFICATION

Pin Assignments

SOT-23 PACKAGE (3-Lead)

(TOP VIEW)

REF

1

3

CATHODE

2

Equivalent Schematic

CATHODE

REF

ANODE

SOT-23 PACKAGE (5-Lead)

(TOP VIEW)

1

5

NC

2

NC

CATHODE

NC = No internal connection

34

ANODE

REF

TO-92 PACKAGE

(TOP VIEW)

CATHODE

ANODE

REF

65-431A-03

A

ANODE

65-431A-04

Absolute Maximum Ratings

Ratings are over full operating free-air temperature range unless otherwise noted.

Cathode voltage, V

KA

Continuous cathode current I

Reference current, I

ref

K

13.2V

–20mA to 20mA

–0.05mA to 3mA

Power dissipation See Dissipation Rating Table
Storage temperature range -65° to 150°C

Notes:

1. Functional operation under these conditions is not implied. Permanent damage may occur if the device is subjected to
conditions outside these ratings.

Recommended Operating Conditions

Parameter Min. Max. Units

Cathode voltage, V

Cathode current, I

Operating temperature range in free-air, T

V

KA

K

A

REF

0.1 15 mA

070°C

12 V

2 REV. 1.0.7 8/5/03

PRODUCT SPECIFICATION RC0431A (RC431A)

Dissipation Rating Table

Package

Power Rating

TA ≤ 25°C

Derating Factor

TA ≥ 25°C

Power Rating

TA = 70°C

TO-92 775mW 6.2mW/OC 496mW

o

SOT23-5 150mW 1.2mW/

C 96mW

Electrical Specifications

TA = 25°C (unless otherwise noted), at free-air

Symbol Parameters Conditions Min. Typ. Max. Units

V

ref

V

ref (dev)

∆V

ref

∆V

KA

I

ref

I

ref(dev)

I

K(min)

I

off

|ZKA| Dynamic impedance (see note 3) VKA = V

Reference Voltage VKA = V

ref

IK = 10mA,
TA = 0 to 70°C

V

deviation over full temperature

ref

range (see note 2)

Ratio of V

change in cathode

ref

voltage change

VKA = V

ref

See note 2 and Figure 1.

IK = 10mA,
∆VKA = V

ref

See figure 2.

Reference terminal current IK = 10mA,

R1 = 10KΩ, R2 = ∞
See figure 2.

I

deviation over full temperature

ref

range (see note 2)

IK = 10mA,
R1 = 10KΩ, R2 = ∞
See note 1 & figure 2.

Minimum cathode current for
regulation

VKA = V

ref

See figure 1.

Off-state cathode current VKA = 6V, V

See figure 3.

IK = 0.1mA to 15mA,

ref

See figure 1.

, TA = 25°C 1.228 1.24 1.252 V

1.221 1.259

, IK = 10mA,

412mV

-1.5 -2.7 mV

to 6V.

0.15 0.5 µA

0.05 0.3 µA

= 0

ref

, f ≤ 1KHz

55 80 µA

0.001 0.1 µA

0.25 0.4 Ω

V

Notes:

1. Functional operation under these conditions is not implied. Permanent damage may occur if the device is subjected to
conditions outside these ratings.

2. Full temperature range is 0°C to 70°C.

3. The deviation parameters V
obtained over the rated temperature range. The average full-range temperature coefficient of the reference input voltage,
∞V

, is defined as:

ref

V

ref dev()VrefTA

----------------------------------------------------------------------------------------------

∞V

where ∆T
∞V

temperature.

4. The dynamic impedance is defined as: Z

When the device is operating with two external resistors (see Figure 2), the total dynamic impedance of the circuit is given
by:

Z

REV. 1.0.7 8/5/03 3

ppm/°C〈〉

ref

is the rated operating free-air temperature range of the device.

A

can be positive or negative depending on whether minimum V

ref

∆V

--------

KA

∆I

=

×≈=

Z

KA



1



ref(dev)

R

1

-------+
R

2

and I

are defined as the differences between the maximum and minimum values

ref(dev)

25°C=〈〉⁄{}106×

∆T

A

= ∆VKA/ ∆I

KA

or maximum V

ref

K

, respectively, occurs at the lower

ref