NSC LM334Z, LM334SMX, LM334SM, LM334MX, LM334M Datasheet

LM134/LM234/LM334
3-Terminal Adjustable Current Sources

General Description

The LM134/LM234/LM334 are 3-terminal adjustable current
sources featuring10,000:1 range in operating current, excel­lent current regulation and a wide dynamic voltage range of
1V to 40V. Current is established with one external resistor
and no other parts are required. Initial current accuracy is

±

3%. The LM134/LM234/LM334 are true floating current
sources with no separate power supply connections. Inaddi­tion, reverse applied voltages of up to 20V will draw only a
few dozen microamperes of current, allowing the devices to
act as both a rectifier and current source in AC applications.

The sense voltage used to establish operating current in the
LM134 is 64mV at 25˚C and is directly proportional to abso­lute temperature (˚K). The simplest one external resistor
connection, then, generates a current with ≈+0.33%/˚C tem­perature dependence. Zero drift operation can be obtained
by adding one extra resistor and a diode.

Applications for the current sources include bias networks,
surge protection, low power reference, ramp generation,

LED driver, and temperature sensing. The LM234-3 and
LM234-6 are specified as true temperature sensors with
guaranteed initial accuracy of

±

3˚C and±6˚C, respectively.
These devices are ideal in remote sense applications be­cause series resistance in long wire runs does not affect ac­curacy. In addition, only 2 wires are required.

The LM134 is guaranteed over a temperature range of

−55˚C to +125˚C, the LM234 from −25˚C to +100˚C and the
LM334 from 0˚C to +70˚C. These devices are available in
TO-46 hermetic, TO-92 and SO-8 plastic packages.

Features

n Operates from 1V to 40V
n 0.02%/V current regulation
n Programmable from 1µA to 10mA
n True 2-terminal operation
n Available as fully specified temperature sensor

n

±

3% initial accuracy

Connection Diagrams

SO-8

Surface Mount Package

DS005697-24

Order Number LM334M or

LM334MX

See NS Package Number M08A

SO-8 Alternative Pinout
Surface Mount Package

DS005697-25

Order Number LM334SM or

LM334SMX

See NS Package Number M08A

TO-46

Metal Can Package

DS005697-12

V−Pin is electrically connected to case.

Bottom View

Order Number LM134H,

LM234H or LM334H

See NS Package

Number H03H

TO-92 Plastic Package

DS005697-10

Bottom View

Order Number LM334Z, LM234Z-3 or LM234Z-6

See NS Package Number Z03A

March 2000

LM134/LM234/LM334 3-Terminal Adjustable Current Sources

© 2000 National Semiconductor Corporation DS005697 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

V

+

to V−Forward Voltage
LM134/LM234/LM334 40V
LM234-3/LM234-6 30V

V

+

to V−Reverse Voltage 20V

R Pin to V

−

Voltage 5V
Set Current 10 mA
Power Dissipation 400 mW
ESD Susceptibility (Note 6) 2000V
Operating Temperature Range (Note 5)

LM134 −55˚C to +125˚C

LM234/LM234-3/LM234-6 −25˚C to +100˚C
LM334 0˚C to +70˚C

Soldering Information

TO-92 Package (10 sec.) 260˚C
TO-46 Package (10 sec.) 300˚C
SO Package

Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C

See AN-450 “Surface Mounting Methods and Their Effect on
Product Reliability” (Appendix D) for other methods of sol­dering surface mount devices.

Electrical Characteristics (Note 2)

Parameter Conditions LM134/LM234 LM334 Units

Min Typ Max Min Typ Max

Set Current Error, V

+

=2.5V, 10µA ≤ I

SET

≤ 1mA 3 6 %

(Note 3) 1mA

<

I

SET

≤ 5mA 5 8 %

2µA ≤ I

SET

<

10µA 8 12 %

Ratio of Set Current to 100µA ≤ I

SET

≤ 1mA 14 18 23 14 18 26

Bias Current 1mA ≤ I

SET

≤ 5mA 14 14

2µA≤I

SET

≤100 µA 18 23 18 26

Minimum Operating Voltage 2µA ≤ I

SET

≤ 100µA 0.8 0.8 V

100µA

<

I

SET

≤

1mA

0.9 0.9 V

1mA

<

I

SET

≤ 5mA 1.0 1.0 V

Average Change in Set Current 2µA ≤ I

SET

≤ 1mA

with Input Voltage 1.5 ≤ V

+

≤ 5V 0.02 0.05 0.02 0.1 %/V

5V ≤ V

+

≤ 40V 0.01 0.03 0.01 0.05 %/V

1mA

<

I

SET

≤ 5mA

1.5V ≤ V ≤ 5V 0.03 0.03 %/V
5V ≤ V ≤ 40V 0.02 0.02 %/V

Temperature Dependence of 25µA ≤ I

SET

≤ 1mA 0.96T T 1.04T 0.96T T 1.04T
Set Current (Note 4)
Effective Shunt Capacitance 15 15 pF

Note 1: .“Absolute Maximum Ratings” indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is
functional, but do not guarantee specific performance limits.

Note 2: Unless otherwise specified, tests are performed at T

j

= 25˚C with pulse testing so that junction temperature does not change during test

Note 3: Set current is thecurrentflowingintotheV

+

pin. For the Basic 2-TerminalCurrentSourcecircuitshownonthefirst page of this data sheet. I

SET

is determined

by the following formula: I

SET

= 67.7 mV/R

SET

(@25˚C). Set current error is expressed as a percent deviation from this amount. I

SET

increases at 0.336%/˚C@T

j

= 25˚C (227 µV/˚C).
Note 4: I

SET

is directly proportional to absolute temperature (˚K). I

SET

at any temperature can be calculated from: I

SET=Io

(T/To) where Iois I

SET

measured at T

o

(˚K).
Note 5: For elevated temperature operation, T

J

max is:

LM134 150˚C
LM234 125˚C
LM334 100˚C

Thermal Resistance TO-92 TO-46 SO-8

θ

ja

(Junction to Ambient) 180˚C/W (0.4" leads) 440˚C/W 165˚C/W

160˚C/W (0.125" leads)

θ

jc

(Junction to Case) N/A 32˚C/W 80˚C/W

Note 6: Human body model, 100pF discharged through a 1.5kΩ resistor.

LM134/LM234/LM334

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Electrical Characteristics (Note 2)

Parameter Conditions LM234-3 LM234-6 Units

Min Typ Max Min Typ Max

Set Current Error, V

+

=2.5V, 100µA ≤ I

SET

≤

1mA

±

1

±

2%

(Note 3) T

J

= 25˚

Equivalent Temperature Error

±

3

±

6˚C

Ratio of Set Current to 100µA ≤ I

SET

≤

1mA

14 18 26 14 18 26

Bias Current
Minimum Operating Voltage 100µA I

SET

≤ 1mA 0.9 0.9 V

Average Change in Set Current 100µA ≤ I

SET

≤

1mA

with Input Voltage 1.5 ≤ V

+

≤ 5V 0.02 0.05 0.02 0.01 %/V

5V ≤ V

+

≤ 30V 0.01 0.03 0.01 0.05 %/V

Temperature Dependence of 100µA ≤ I

SET

≤

1mA

0.98T T 1.02T 0.97T T 1.03T

Set Current (Note 4) and
Equivalent Slope Error

±

2

±

3%

Effective Shunt Capacitance 15 15 pF

LM134/LM234/LM334

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Typical Performance Characteristics

Output Impedance

DS005697-30

Maximum Slew Rate
Linear Operation

DS005697-31

Start-Up

DS005697-32

Transient Response

DS005697-33

Voltage Across R

SET(VR

)

DS005697-34

Current Noise

DS005697-35

LM134/LM234/LM334

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Typical Performance Characteristics (Continued)

Application Hints

The LM134 has been designed for ease of application, but a
general discussion of design features is presented here to
familiarize the designer with device characteristics which
may not be immediately obvious. These include the effects
of slewing, power dissipation, capacitance, noise, and con­tact resistance.

CALCULATING R

SET

The total current through the LM134 (I

SET

) is the sum of the

current going through the SET resistor (I

R

) and the LM134’s

bias current (I

BIAS

), as shown in

Figure 1

.

A graph showing the ratio of these two currents is supplied
under Ratio of I

SET

to I

BIAS

in the Typical Performance

Characteristics section. The current flowing through R

SET

is

determined by V

R

, which is approximately 214µV/˚K (64 mV/

298˚K ∼ 214µV/˚K).

Since (for a given set current) I

BIAS

is simply a percentage of

I

SET

, the equation can be rewritten

where n is the ratio of I

SET

to I

BIAS

as specified in the Elec­trical Characteristics Section and shown in the graph. Since
n is typically 18 for 2µA ≤ I

SET

≤ 1mA, the equation can be

further simplified to

for most set currents.

SLEW RATE

At slew rates above a given threshold (see curve), the
LM134 may exhibit non-linear current shifts. The slewing
rate at which this occurs is directly proportional to I

SET

.At

I

SET

= 10µA, maximum dV/dt is 0.01V/µs; at I

SET

= 1mA, the
limit is 1V/µs. Slew rates above the limit do not harm the
LM134, or cause large currents to flow.

THERMAL EFFECTS

Internal heating can have a significant effecton currentregu­lation for I

SET

greater than 100µA. For example, each 1V in-

crease across the LM134 at I

SET

= 1 mA will increase junc-

tion temperature by ≈0.4˚C in still air. Output current (I

SET

)
has a temperature coefficient of≈0.33%/˚C, sothe changein
current due to temperature rise will be (0.4) (0.33) = 0.132%.
This is a 10:1 degradation in regulation compared to true
electrical effects. Thermal effects, therefore, must be taken
into account when DC regulation is critical and I

SET

exceeds
100µA. Heat sinking of the TO-46 package or the TO-92
leads can reduce this effect by more than 3:1.

SHUNT CAPACITANCE

In certain applications, the 15 pF shunt capacitance of the
LM134 may have to be reduced, either because of loading
problems or because it limitsthe AC outputimpedance of the
current source. This can be easily accomplished by buffering
the LM134 with an FET as shown in the applications. This
can reduce capacitance to less than 3 pF and improve regu­lation by at least an order of magnitude. DC characteristics
(with the exception of minimum input voltage), are not af­fected.

Turn-On Voltage

DS005697-29

Ratio of I

SET

to I

BIAS

DS005697-3

DS005697-27

FIGURE 1. Basic Current Source

LM134/LM234/LM334

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