Datasheet LM389N Datasheet (NSC)

LM389 Low Voltage Audio Power Amplifier
with NPN Transistor Array

Y

General Description

The LM389 is an array of three NPN transistors on the same
substrate with an audio power amplifier similar to the
LM386.

The amplifier inputs are ground referenced while the output
is automatically biased to one half the supply voltage. The
gain is internally set at 20 to minimize external parts, but the
addition of an external resistor and capacitor between pins
4 and 12 will increase the gain to any value up to 200.

The three transistors have high gain and excellent matching
characteristics. They are well suited to a wide variety of ap­plications in DC through VHF systems.

Features

Amplifier

Y

Battery operation

Y

Minimum external parts

Y

Wide supply voltage range

Equivalent Schematic and Connection Diagrams

Low quiescent current drain

Y

Voltage gains from 20 to 200

Y

Ground referenced input

Y

Self-centering output quiescent voltage

Y

Low distortion

Transistors

Y

Operation from 1 mAto25mA

Y

Frequency range from DC to 100 MHz

Y

Excellent matching

Applications

Y

AM-FM radios

Y

Portable tape recorders

Y

Intercoms

Y

Toys and games

Y

Walkie-talkies

Y

Portable phonographs

Y

Power converters

LM389 Low Voltage Audio Power Amplifier with NPN Transistor Array

December 1994

TL/H/7847– 1

Dual-In-Line Package

Order Number LM389N

TL/H/7847– 2

See NS Package Number N18A

C

1995 National Semiconductor Corporation RRD-B30M115/Printed in U. S. A.

TL/H/7847

Absolute Maximum Ratings

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

Supply Voltage 15V
Package Dissipation (Note 1) 1.89W

Ctoa70§C

§

e

25§C

A

g

0.4V

§

§

12V

Input Voltage
Storage Temperature

b

65§Ctoa150§C
Operating Temperature 0
Junction Temperature 150
Lead Temperature (Soldering, 10 sec.) 260
Collector to Emitter Voltage, V

CEO

Electrical Characteristics T

Symbol Parameter Conditions Min Typ Max Units

AMPLIFIER

V

S

I

Q

P

OUT

A

V

BW Bandwidth V

THD Total Harmonic Distortion V

PSRR Power Supply Rejection Ratio V

R

IN

I

BIAS

Operating Supply Voltage 4 12 V

Quiescent Current V

Output Power (Note 3)

Voltage Gain V

e

S

e

THD

e

S

10 mF from Pins 4 to 12 46 dB

e

S

e

S

e

1 kHz, Pins 4 and 12 Open

f

e

S

Pins 4 and 12 Open, Referred to Output

Input Resistance 10 50 kX

Input Bias Current V

e

S

TRANSISTORS

V

CEO

V

CBO

V

CIO

V

EBO

H

FE

h

oe

V

BE

V

l

BE1–VBE2

V

CESAT

C

EB

C

CB

C

CI

h

fe

Note 1: For operation in ambient temperatures above 25§C, the device must be derated based on a 150§C maximum junction temperature and a thermal resistance

C/W junction to ambient.

of 66

§

Note 2: The collector of each transistor is isolated from the substrate by an integral diode. Therefore, the collector voltage should remain positive with respect to
pin 17 at all times.

Note 3: If oscillation exists under some load conditions, add 2.7X and 0.05 m F series network from pin 1 to ground.

Collector to Emitter I
Breakdown Voltage

Collector to Base I
Breakdown Voltage

Collector to Substrate I
Breakdown Voltage

Emitter to Base I
Breakdown Voltage

Static Forward Current I
Transfer Ratio (Static Beta) I

Open-Circuit Output Admittance I

Base to Emitter Voltage I

Base to Emitter Voltage Offset I

l

Collector to Emitter I
Saturation Voltage

Emitter to Base Capacitance V

Collector to Base Capacitance V

Collector to Substrate V
Capacitance

High Frequency Current Gain I

e

1 mA, I

C

e

10 mA, I

C

e

10 mA, I

C

e

10 mA, I

E

e

10 mA 100

C

e

1 mA 100 275

C

e

10 mA 275

I

C

e

1 mA, V

C

e

1 mA 0.7 0.85 V

E

e

1mA 1 5 mV

E

e

10 mA, I

C

e

EB

e

CB

e

CI

e

10 mA, V

C

Collector to Base Voltage, V
Collector to Substrate Voltage, V

(Note 2) 15V
Collector Current, I
Emitter Current, I
Base Current, I
Power Dissipation (Each Transistor) T

B

Thermal Resistance

C
C

6V, V

i

JC

i

JA

e

0V 6 12 mA

IN

10%

e

6V, R

V

S

e

9V, R

V

S

E

L
L

CBO

CIO

C

s

a

70§C 150 mW

A

e

8X 250 325 mW

e

16X 500 mW

25 mA
25 mA

5mA

24§C/W
70§C/W

6V, fe1 kHz 23 26 30 dB

6V, Pins 4 and 12 Open 250 kHz

e

6V, R

8X,P

L

6V, fe1 kHz, C

OUT

BYPASS

e

125 mW,

e

10 mF,

0.2 3.0 %

30 50 dB

6V, Pins 5 and 16 Open 250 nA

e

0

B

e

0

E

e

e

I

E

C

CE

B

0

B

e

0

e

5V, fe1.0 kHz 20 mmho

e

1mA

12 20 V

15 40 V

15 40 V

6.4 7.1 7.8 V

0.15 0.5 V

3V 1.5 pF

3V 2 pF

3V

e

5V, fe100 MHz 1.5 5.5

CE

3.5 pF

2

15V

Typical Amplifier Performance Characteristics

Quiescent Supply Current
vs Supply Voltage

Voltage Gain vs Frequency Distortion vs Frequency Distortion vs Output Power

Device Dissipation vs Output
PowerÐ4X Load

Power Supply Rejection Ratio
(Referred to the Output)
vs Frequency

Device Dissipation vs Output
PowerÐ8X Load

Peak-to-Peak Output Voltage
Swing vs Supply Voltage

Device Dissipation vs Output
PowerÐ16X Load

TL/H/7847– 3

3

Typical Transistor Performance Characteristics

Forward Current Transfer Ratio
vs Collector Current

Saturation Voltage vs
Collector Current

Open Circuit Output Admittance
vs Collector Current

High Frequency Current Gain

Noise Voltage vs Frequency Noise Current vs Frequency vs Collector Current

and Coevs Collector

g

oe

Current

goeand Coevs Collector
Current

Contours of Constant Noise
Figure

TL/H/7847– 4

TL/H/7847– 5

4

Application Hints

Gain Control

To make the LM389 a more versatile amplifier, two pins (4
and 12) are provided for gain control. With pins 4 and 12
open, the 1.35 kX resistor sets the gain at 20 (26 dB). If a
capacitor is put from pin 4 to 12, bypassing the 1.35 kX
resistor, the gain will go up to 200 (46 dB). If a resistor is
placed in series with the capacitor, the gain can be set to
any value from 20 to 200. A low frequency pole in the gain
response is caused by the capacitor working against the
external resistor in series with the 150X internal resistor. If
the capacitor is eliminated and a resistor connects pin 4 to
12, then the output dc level may shift due to the additional
dc gain. Gain control can also be done by capacitively cou­pling a resistor (or FET) from pin 12 to ground.

Additional external components can be placed in parallel
with the internal feedback resistors to tailor the gain and
frequency response for individual applications. For example,
we can compensate poor speaker bass response by fre­quency shaping the feedback path. This is done with a se­ries RC from pin 1 to 12 (paralleling the internal 15 kX resis­tor). For 6 dB effective bass boost: Rj15 kX, the lowest
value for good stable operation is R
open. If pins 4 and 12 are bypassed then R as low as 2 kX
can be used. This restriction is because the amplifier is only
compensated for closed-loop gains greater than 9V/V.

Input Biasing

The schematic shows that both inputs are biased to ground
witha50kXresistor. The base current of the input transis-
tors is about 250 nA, so the inputs are at about 12.5 mV
when left open. If the dc source resistance driving the
LM389 is higher than 250 kX it will contribute very little
additional offset (about 2.5 mV at the input, 50 mV at the
output). If the dc source resistance is less than 10 kX, then
shorting the unused input to ground will keep the offset low
(about 2.5 mV at the input, 50 mV at the output). For dc
source resistances between these values we can eliminate
excess offset by putting a resistor from the unused input to
ground, equal in value to the dc source resistance. Of
course all offset problems are eliminated if the input is ca­pacitively coupled.

When using the LM389 with higher gains (bypassing the

1.35 kX resistor between pins 4 and 12) it is necessary to

e

10 kX if pin 4 is

bypass the unused input, preventing degradation of gain
and possible instabilities. This is done with a 0.1 mF capaci­tor or a short to ground depending on the dc source resist­ance of the driven input.

Supplies and Grounds

The LM389 has excellent supply rejection and does not re­quire a well regulated supply. However, to eliminate possi­ble high frequency stability problems, the supply should be
decoupled to ground with a 0.1 mF capacitor. The high cur­rent ground of the output transistor, pin 18, is brought out
separately from small signal ground, pin 17. If the two
ground leads are returned separately to supply then the par­asitic resistance in the power ground lead will not cause
stability problems. The parasitic resistance in the signal
ground can cause stability problems and it should be mini­mized. Care should also be taken to insure that the power
dissipation does not exceed the maximum dissipation of the
package for a given temperature. There are two ways to
mute the LM389 amplifier. Shorting pin 3 to the supply volt­age, or shorting pin 12 to ground will turn the amplifier off
without affecting the input signal.

Transistors

The three transistors on the LM389 are general purpose
devices that can be used the same as other small signal
transistors. As long as the currents and voltages are kept
within the absolute maximum limitations, and the collectors
are never at a negative potential with respect to pin 17,
there is no limit on the way they can be used.

For example, the emitter-base breakdown voltage of 7.1V
can be used as a zener diode at currents from 1 mAto
5 mA. These transistors make good LED driver devices,
V

is only 150 mV when sinking 10 mA.

SAT

In the linear region, these transistors have been used in AM
and FM radios, tape recorders, phonographs and many oth­er applications. Using the characteristic curves on noise
voltage and noise current, the level of the collector current
can be set to optimize noise performance for a given source
impedance. Some of the circuits that have been built are
shown in

Figures 1–7

of applications, since that is limited only by the designers
imagination.

. This is by no means a complete list

FIGURE 1. AM Radio

5

TL/H/7847– 6

Application Hints (Continued)

All switches in record mode

Head characteristic 280 mH/300X

FIGURE 2. Tape Recorder

FIGURE 3. Ceramic Phono Amplifier with Tone Controls

TL/H/7847– 7

TL/H/7847– 8

6

Application Hints (Continued)

e

f

0.69R1C1

FIGURE 4. FM Scanner Noise Squelch Circuit

TL/H/7847– 9

1

TL/H/7847– 10

FIGURE 5. Siren

FIGURE 6. Voltage-Controlled Amplifier or Tremolo Circuit

7

* Tremolo freq.

s

2q (Ra10k)C

TL/H/7847– 11

1

Application Hints (Continued)

FIGURE 7. Noise Generator Using Zener Diode

TL/H/7847– 12

Physical Dimensions inches (millimeters)

Molded Dual-In-Line Package (N)

Order Number LM389N

NS Package Number N18A

LIFE SUPPORT POLICY

LM389 Low Voltage Audio Power Amplifier with NPN Transistor Array

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT
DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF NATIONAL
SEMICONDUCTOR CORPORATION. As used herein:

1. Life support devices or systems are devices or 2. A critical component is any component of a life
systems which, (a) are intended for surgical implant support device or system whose failure to perform can
into the body, or (b) support or sustain life, and whose be reasonably expected to cause the failure of the life
failure to perform, when properly used in accordance support device or system, or to affect its safety or
with instructions for use provided in the labeling, can effectiveness.
be reasonably expected to result in a significant injury
to the user.

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