LM723Adjustable precision regulator

Set the output voltage and current limit with external resistors.

Manufacturer-referenced

STMicroelectronics · LM723CN

PDIP-14LM723 / LM723C · September 2003

LM723 combines a voltage reference, error amplifier, internal series pass transistor and adjustable current-limit circuit. External resistors determine the regulated output rather than a fixed internal voltage setting. This page covers the commercial LM723C grade in ST’s DIP14 and SO14 packages. The reference is nominally 7.15 V. For a lower output, divide that reference before applying it to the non-inverting input and feed the regulated output back to the inverting input. The pass-stage collector and control-circuit supply are separate pins; both must be connected correctly. The example uses a 12 V input and an approximately 5 V output, with a 10 Ω current-sense resistor and a small 1 kΩ load. All unused contacts remain unconnected. The published ST reference is an archived manufacturer document; check availability and the exact package before sourcing a legacy part.

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LM723CN black PDIP-14 package with silver contacts and readable marking.

Pinout

LM723CNPDIP-14Top view

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14Physical pins LM723CNPDIP-14 Manufacturer-referencedSTMicroelectronics

Pin diagram

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Package map

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LM723CNPDIP-14Top view

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PIN 1 · Not connected

NC

No connection

Function

Unused contact

How to connect

Leave unconnected.

Key specifications

Set the output voltage and current limit with external resistors.

Supply9.5–40 V

Output range2–37 V · circuit dependent

Commercial ambient0–70 °C

Reference7.15 V typical

Package details

LM723CN · PDIP-14

Selected package

Selected LM723 physical package
Property	Details
Manufacturer	STMicroelectronics
Part number	LM723CN
Package	PDIP-14
Connections	14 pins
Mounting	Through-hole
Lead pitch	2.54 mm
Package code	PDIP-14
Thermal reference	See operating and package limits

Operating reference

ST LM723C selected grade

Manufacturer specifications 5 parameters

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Parameter	Value	Conditions / notes
Supply range	9.5–40 V	Maintain input/output headroom
Output range	2–37 V	Appropriate external circuit required
Ambient	0–70°C	LM723C; not extended-grade LM723
Reference	6.8–7.5 V; 7.15 V typical	IREF = 160 µA
Internal output capability	Up to 150 mA	Package dissipation and headroom limit actual use

Do not substitute extended-grade limits for the commercial parts.

Regulation and reference

25°C, manufacturer test circuit

Manufacturer specifications 6 parameters

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Parameter	Value	Conditions / notes
Line regulation	0.01% typical; 0.1% max	12–15 V input
Wide-range line regulation	0.1% typical; 0.5% max	12–40 V input
Load regulation	0.03% typical; 0.2% max	1–50 mA
Quiescent current	2.3 mA typical; 4 mA max	30 V input; no load
Ripple rejection	74 dB typical	100 Hz–10 kHz; no reference bypass
Current limit	65 mA typical	RSC = 10 Ω; output shorted

Regulation values exclude changing junction temperature.

Five-volt circuit

Nominal calculation

Manufacturer specifications 7 parameters

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Parameter	Value	Conditions / notes
Input	12 V	V+12 and VC11
Reference divider	4.3 kΩ / 10 kΩ	VREF6 → 4.3k → IN+5 → 10k → GND
Nominal output	7.15 × 10 / 14.3 = 5 V	Reference and resistor tolerances remain
Current sense	10 Ω	OUT10/CL2 → resistor → regulated output/CS3
Feedback	3 kΩ to IN−4	From the regulated output
Compensation	100 pF	COMP13 to IN−4
Load	1 kΩ	About 5 mA and 25 mW

No external pass transistor is needed for this small example.

Thermal and stress limits

LM723CN · PDIP-14

Manufacturer specifications 6 parameters

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Parameter	Value	Conditions / notes
Lead pitch	2.54 mm	Through-hole
Input stress ceiling	40 V	Do not exceed
Reference output stress current	25 mA	LM723C absolute maximum; avoid designing at it
Maximum junction	125°C	Selected commercial grade
θJA reference	200°C/W DIP; 160°C/W SO14	Manufacturer reference mounting
Storage	−65 to +150°C	Unpowered

A headline current limit does not remove the package power limit.

External connections

Physical package contacts

Manufacturer specifications 14 parameters

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Parameter	Value	Conditions / notes
1 · NC	Unused contact	Leave unconnected.
2 · CL	Current-limit transistor base	Connect to OUT10 before the 10 Ω sense resistor.
3 · CS	Current-sense transistor emitter	Connect to the regulated output after the sense resistor.
4 · IN−	Error amplifier feedback	Connect to the regulated output through 3 kΩ; connect compensation capacitor here.
5 · IN+	Error amplifier reference input	Connect to the 4.3 kΩ / 10 kΩ reference-divider junction.
6 · VREF	Nominal 7.15 V reference	Connect 4.3 kΩ to IN+5; 10 kΩ from IN+5 to ground.
7 · V−	Control-circuit return	Connect to ground.
8 · NC	Unused contact	Leave unconnected.
9 · VZ	Internal zener connection	Leave open in this positive-output example.
10 · OUT	Internal pass emitter	Connect CL2 and the input side of the 10 Ω sense resistor.
11 · VC	Pass-transistor collector	Connect to +12 V.
12 · V+	Control-circuit positive supply	Connect to +12 V; bypass locally to ground.
13 · COMP	Frequency compensation	Connect 100 pF between COMP13 and IN−4.
14 · NC	Unused contact	Leave unconnected.

Connect all supply and return contacts; leave only explicitly unused contacts open.

Connections by function

Select a pin for its function, connection guidance and electrical notes.

Not connected3 pins

Control3 pins

Inputs2 pins

Reference2 pins

Supply3 pins

Outputs1 pin

LM723 working principle: illustrated functional stages, basic circuit and connections — Select the diagram to read it at full resolution.

How it works

3 stages · Explore one step at a time

Step 1 / 3

Input and reference

Divide the reference to the intended output level.

Step 2 / 3

Internal control

Compare that level against the sensed regulated output.

Step 3 / 3

Output behavior

Adjust pass current; the sense resistor activates current limiting.

LM723 reviewed circuit; pin numbers, supply returns and external components are labeled. — All matching node labels connect. Values illustrate the reference configuration.

Connect it, step by step

Follow the component values and pin connections

Power

Connect every specified supply and return contact.

External network

Fit the external components at the numbered pins shown.

Check

Compare the nominal calculation with device and component tolerances.

LM723 functional cutaway with REFERENCE, ERROR AMPLIFIER, PASS TRANSISTOR, CURRENT LIMIT. — Functional explanation, not a transistor-level schematic or physical die layout.

Explore the circuit

Select a stage to see its role and connections

Input

Divide the reference to the intended output level.

Control

Compare that level against the sensed regulated output.

Output

Adjust pass current; the sense resistor activates current limiting.

Selected packagePDIP-14LM723CN

Physical connections14 pinsPackage-specific numbering

Reference collection6 tables38 parameters & pin functions