National Semiconductor LM3876 Technical data

August 2000

LM3876 Overture Audio Power Amplifier Series

High-Performance 56W Audio Power Amplifier w/Mute

LM3876 Overture

™

Audio Power Amplifier Series
High-Performance 56W Audio Power Amplifier w/Mute

General Description

The LM3876 is a high-performance audio power amplifier
capable of delivering 56W of continuous average power to
an 8Ω load with 0.1% THD+N from 20Hz–20kHz.

The performance of the LM3876, utilizing its Self Peak In­stantaneous Temperature (˚Ke) (SPiKe
cuitry, puts it in a class above discrete and hybrid amplifiers
by providing an inherently, dynamically protected Safe Op­erating Area (SOA). SPiKe protection means that these
parts are completely safeguarded at the output against ov­ervoltage, undervoltage, overloads, including shorts to the
supplies, thermal runaway, and instantaneous temperature
peaks.

The LM3876 maintains an excellent signal-to-noise ratio of
greater than 95dB (min) with a typical low noise floor of

2.0µV. It exhibits extremely low THD+N values of 0.06% at
the rated output into the rated load over the audio spectrum,
and provides excellent linearity with an IMD (SMPTE) typical
rating of 0.004%.

™

) protection cir-

Features

n 56W continuous average output power into 8Ω
n 100W instantaneous peak output power capability
n Signal-to-Noise Ratio ≥ 95 dB(min)
n An input mute function
n Output protection from a short to ground or to the

supplies via internal current limiting circuitry

n Output over-voltage protection against transients from

inductive loads

n Supply under-voltage protection, not allowing internal

biasing to occur when |V
eliminating turn-on and turn-off transients

n 11-lead TO-220 package
n Wide supply range 20V - 94V

|+|VCC| ≤ 12V, thus

EE

Applications

n Component stereo
n Compact stereo
n Self-powered speakers
n Surround-sound amplifiers
n High-end stereo TVs

Typical Application

*Optional components dependent upon specific design requirements. Refer to the External Components Description section for a component functional
description.

FIGURE 1. Typical Audio Amplifier Application Circuit

01183201

Overture™and SPiKe™Protection are trademarks of National Semiconductor Corporation.

© 2004 National Semiconductor Corporation DS011832 www.national.com

Connection Diagram

LM3876

Plastic Package (Note 11)

†

Connect Pin 5 to V+for Compatibility with LM3886.

Top View Order Number LM3876Tor LM3876TFSee NS Package Number TA11B forStaggered Lead

Non-IsolatedPackage or TF11B forStaggered Lead Isolated Package

01183202

www.national.com 2

LM3876

Absolute Maximum Ratings (Notes 4,

5)

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

+

Supply Voltage |V

Supply Voltage |V

Common Mode Input Voltage (V

Differential Input Voltage 60V

Output Current Internally Limited

Power Dissipation (Note 6) 125W

ESD Susceptibility (Note 7) 3000V

Junction Temperature (Note 8) 150˚C

Soldering Information

|+|V−| (No Signal) 94V

+

|+|V−| (Input Signal) 84V

+

or V−) and

+

|V

|+|V−| ≤80V

Storage Temperature −40˚C to +150˚C

Thermal Resistance

θ

JC

θ

JA

1˚C/W

43˚C/W

Operating Ratings (Notes 4, 5)

Temperature Range

T

≤ TA≤ T

MIN

Supply Voltage |V

Note 1: Operation is guaranteed up to 84V, however, distortion may be
introduced from SPiKe Protection Circuitry when operating above 70V if
proper thermal considerations are not taken into account. Refer to the
Thermal Considerations section for more information.

(See SPiKe Protection Response)

MAX

+

|+|V−| 24V to 84V

−20˚C ≤ TA≤
+85˚C

T Package (10 seconds) 260˚C

Electrical Characteristics (Notes 4, 5)

The following specifications apply for V+= +35V, V−= −35V, I
apply for T

= 25˚C.

A

Symbol Parameter Conditions LM3876 Units

+

|+|V−| Power Supply Voltage (Note 13) V

|V

A

M

Mute Attenuation Pin 8 Open or at 0V, Mute: On

−V−≥ 9V 18 24 V (min)

pin7

Current out of Pin 8

Mute: Off

P

(Note 3) Output Power (Continuous Average) THD+N=0.1% (max) 56 40 W (min)

O

f=1kHz;f=20kHz

Peak P

Instantaneous Peak Output Power 100 W

O

THD + N Total Harmonic Distortion Plus Noise 40W, 20 Hz ≤ f ≤ 20 kHz 0.06 %

A

=26dB

V

SR (Note 3) Slew Rate (Note 12) V

= 1.2 Vrms,f=10kHz, 11 5 V/µs (min)

IN

Square-Wave, R

+

I

(Note 2) Total Quiescent Power Supply Current VCM= 0V, Vo= 0V, Io= 0A, I

V

OS

Input Offset Voltage V

= 0V, Io= 0 mA 1 15 mV (max)

CM

(Note 2)

I

B

I

OS

I

o

V

od

(Note 2)

PSRR
(Note 2)

CMRR
(Note 2)

A

VOL

Input Bias Current VCM= 0V, Io= 0 mA 0.2 1 µA (max)

Input Offset Current VCM= 0V, Io= 0 mA 0.01 0.2 µA (max)

Output Current Limit |V+|=|V−| = 12V, tON= 10 ms, VO= 0V 6 4 A (min)

Output Dropout Voltage (Note 14) |V

Power Supply Rejection Ratio V

Common Mode Rejection Ratio V

Open Loop Voltage Gain |V

+

–VO|, V+= 20V, Io= +100 mA 1.6 5 V (max)

|V

–V−|, V−= −20V, Io= −100 mA 2.7 5 V (max)

O

+

= 40V to 20V, V−= −40V, 120 85 dB (min)

V

= 0V, Io=0mA

CM
+

V

= 40V, V−= −40V to −20V, 120 85 dB (min)

V

= 0V, Io=0mA

CM
+

= 60V to 20V, V−= −20V to −60V, 120 80 dB (min)

V

= 20V to −20V, Io=0mA

CM

+

|=|V−| = 40V, RL=2kΩ, ∆VO= 60V 120 90 dB (min)

(Note 2)

= −0.5 mA with RL=8Ω unless otherwise specified. Limits

MUTE

Typical Limit

(Note 9) (Note 10)

84 V (max)

>

0.5 mA, 120 80 dB (min)

=2kΩ

L

= 0A 30 70 mA (max)

mute

(Limits)

www.national.com3

Electrical Characteristics (Notes 4, 5) (Continued)

The following specifications apply for V+= +35V, V−= −35V, I

LM3876

apply for T

= 25˚C.

A

Symbol Parameter Conditions LM3876 Units

+

GBWP Gain-Bandwidth Product |V

e

(Note 3) Input Noise IHF — A Weighting Filter 2.0 8 µV (max)

IN

SNR Signal-to-Noise Ratio P

|=|V−| = 40V 8 2 MHz (min)

f

= 100 kHz, VIN= 50 mVrms

O

R

= 600Ω (Input Referred)

IN

= 1W, A-Weighted, 98 dB

O

Measured at 1 kHz, R

P

= 40W, A-Weighted, 114 dB

O

Measured at 1 kHz, R

Ppk= 100W, A-Weighted, 122 dB

Measured at 1 kHz, R

IMD Intermodulation Distortion Test 60 Hz, 7 kHz, 4:1 (SMPTE) 0.004 %

60 Hz, 7 kHz, 1:1 (SMPTE) 0.006

Note 2: DC Electrical Test; refer to Test Circuit #1.

Note 3: AC Electrical Test; refer to Test Circuit #2.

Note 4: All voltages are measured with respect to the GND pin (pin 7), unless otherwise specified.

Note 5: 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. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which
guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit
is given, however, the typical value is a good indication of device performance.

Note 6: For operating at case temperatures above 25˚C, the device must be derated based on a 150˚C maximum junction temperature and a thermal resistance
of θ

= 1.0 ˚C/W (junction to case). Refer to the Thermal Resistance figure in the Application Information section under Thermal Considerations.

JC

Note 7: Human body model, 100 pF discharged through a 1.5 kΩ resistor.

Note 8: The operating junction temperature maximum is 150˚C, however, the instantaneous Safe Operating Area temperature is 250˚C.

Note 9: Typicals are measured at 25˚C and represent the parametric norm.

Note 10: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 11: The LM3876T package TA11B is a non-isolated package, setting the tab of the device and the heat sink at V

mounted to the heat sink using only thermal compound. If a mica washer is used in addition to thermal compound, θ
will be isolated from V

Note 12: The feedback compensation network limits the bandwidth of the closed-loop response and so the slew rate will be reduced due to the high frequency
roll-off. Without feedback compensation, the slew rate is typically 16V/µs.

Note 13: V

Note 14: The output dropout voltage is the supply voltage minus the clipping voltage. Refer to the Clipping Voltage vs Supply Voltage graph in the Typical

Performance Characteristics section.

−

−

.

must have at least −9V at its pin with reference to ground in order for the under-voltage protection circuitry to be disabled.

= −0.5 mA with RL=8Ω unless otherwise specified. Limits

MUTE

Typical Limit

(Note 9) (Note 10)

=25Ω

S

=25Ω

S

=25Ω

S

−

potential when the LM3876 is directly

(case to sink) is increased, but the heat sink

CS

(Limits)

www.national.com 4

Test Circuit #1 (DC Electrical Test Circuit)

Test Circuit #2 (AC Electrical Test Circuit)

LM3876

01183203

01183204

www.national.com5

Single Supply Application Circuit

LM3876

*Optional components dependent upon specific design requirements. Refer to the External

Components Description section for a component functional description.

FIGURE 2. Typical Single Supply Audio Amplifier Application Circuit

01183205

www.national.com 6

Equivalent Schematic (excluding active protection circuitry)

LM3876

01183206

www.national.com7