National Semiconductor LM3886 Technical data

October 2003

LM3886 Overture™Audio Power Amplifier Series High-Performance 68W Audio Power Amplifier w/Mute

General Description

The LM3886 is a high-performance audio power amplifier capable of delivering 68W of continuous average power to a 4Ω load and 38W into 8Ω with 0.1% THD+N from 20Hz–20kHz.

The performance of the LM3886, 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 LM3886 maintains an excellent signal-to-noise ratio of greater than 92dB with a typical low noise floor of 2.0µV. It exhibits extremely low THD+N values of 0.03% 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-

n 135W instantaneous peak output power capability n Signal-to-Noise Ratio ≥ 92dB 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

Applications

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

LM3886 Overture Audio Power Amplifier Series High-Performance 68W Audio Power Amplifier

w/Mute

Features

n 68W cont. avg. output power into 4Ω at VCC=±28V n 38W cont. avg. output power into 8Ω at V n 50W cont. avg. output power into 8Ω at V

=±28V =±35V

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

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

01183301

Connection Diagram

LM3886

Plastic Package (Note 12)

Note 1: Preliminary: call you local National Sales Rep. or distributor for availability

Top View

Order Number LM3886T

or LM3886TF

See NS Package Number TA11B for

Staggered Lead Non-Isolated

Package or TF11B (Note 1) for

Staggered Lead Isolated Package

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Absolute Maximum Ratings (Notes 6, 5)

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

Supply Voltage |V

|+|V−|

(No Signal) 94V

Supply Voltage |V

|+|V−|

(Input Signal) 84V

Common Mode Input Voltage (V+or V−) and

|+|V−| ≤ 80V

Differential Input Voltage (Note

16) 60V

Output Current Internally Limited

ESD Susceptibility (Note 8) 3000V

Junction Temperature (Note 9) 150˚C

Soldering Information

T Package (10 seconds) 260˚C

Storage Temperature −40˚C to +150˚C

Thermal Resistance

1˚C/W

43˚C/W

Power Dissipation (Note 7) 125W

Operating Ratings (Notes 5, 6)

Temperature Range

≤ TA≤ T

MIN

MAX

Supply Voltage |V

−20˚C ≤ TA≤ +85˚C

|+|V−| 20V to 84V

Electrical Characteristics (Notes 5, 6)

The following specifications apply for V+= +28V, V−= −28V, I apply for T

= 25˚C.

Symbol Parameter Conditions

|+|V−| Power Supply Voltage (Note 14) V

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

pin7

−V−≥ 9V

Current out of Pin 8 Mute: Off

(Note 4) Output Power (Continuous Average) THD+N=0.1% (max)

f=1kHz;f=20kHz

|=|V−| = 28V, RL=4Ω

|=|V−| = 28V, RL=8Ω

|=|V−| = 35V, RL=8Ω

Peak P

THD + N Total Harmonic Distortion Plus Noise 60W, R

Instantaneous Peak Output Power 135 W

30W, R

20 Hz ≤ f ≤ 20 kHz

=26dB

SR (Note 4) Slew Rate (Note 13) V

(Note 4) Total Quiescent Power Supply Current VCM= 0V, Vo= 0V, Io= 0A 50 85 mA (max)

Input Offset Voltage V

= 2.0Vp-p, t

= 0V, Io=0mA

(Note 3)

PSRR (Note 3)

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−| = 20V, t

Output Dropout Voltage (Note 15) |V

Power Supply Rejection Ratio V

–VO|, V+= 28V, Io= +100 mA

–V−|, V−= −28V, Io= −100 mA

= 40V to 20V, V−= −40V,

= 0V, Io=0mA

CM +

= 40V, V−= −40V to −20V,

= 0V, Io=0mA

= −0.5 mA with RL=4Ω unless otherwise specified. Limits

MUTE

LM3886

Typical

(Note 10)

(Note 11)

0.5 mA,

115 80 dB (min)

68 38 50

=4Ω, =8Ω,

0.03

= 2 ns 19 8 V/µs (min)

RISE

1 10 mV (max)

= 10 ms, VO= 0V 11.5 7 A (min)

1.6

2.5

120

105

Limit

20 84

60 30

2.0

3.0

Units

(Limits)

V (min)

V (max)

W (min) W (min)

V (max) V (max)

dB (min)

LM3886

% %

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Electrical Characteristics (Notes 5, 6) (Continued)

The following specifications apply for V+= +28V, V−= −28V, I

LM3886

apply for T

= 25˚C.

Symbol Parameter Conditions

CMRR (Note 3)

VOL

Common Mode Rejection Ratio V

Open Loop Voltage Gain |V

= 60V to 20V, V−= −20V to −60V,

= 20V to −20V, Io=0mA

|=|V−| = 28V, RL=2kΩ, ∆VO= 40V

(Note 3)

GBWP Gain-Bandwidth Product |V

(Note 4) Input Noise IHF — A Weighting Filter

SNR Signal-to-Noise Ratio P

|=|V−| = 30V

= 100 kHz, VIN= 50 mVrms

= 600Ω (Input Referred)

= 1W, A-Weighted,

Measured at 1 kHz, R

= 60W, A-Weighted,

Measured at 1 kHz, R

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

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

Note 2: Operation is guaranteed up to 84V, however, distortion may be introduced from SPIKe Protection Circuitry if proper thermal considerations are not taken into account. Refer to the Thermal Considerations section for more information. (See SPIKe Protection Response)

Note 3: DC Electrical Test; refer to Test Circuit #1.

Note 4: AC Electrical Test; refer to Test Circuit #2.

Note 5: All voltages are measured with respect to the GND pin (pin 7), unless otherwise specified.

Note 6: 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 7: 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.

Note 8: Human body model, 100 pF discharged through a 1.5 kΩ resistor.

Note 9: The operating junction temperature maximum is 150˚C, however, the instantaneous Safe Operating Area temperature is 250˚C.

Note 10: Typicals are measured at 25˚C and represent the parametric norm.

Note 11: Limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 12: The LM3886T 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 13: 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 larger.

Note 14: V

Note 15: 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.

Note 16: The Differential Input Voltage Absolute Maximum Rating is based on supply voltages of V

−

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=4Ω unless otherwise specified. Limits

MUTE

LM3886

Typical

(Note 10)

Limit

(Note 11)

110 85 dB (min)

115 90 dB (min)

8 2 MHz (min)

2.0 10 µV (max)

=25Ω

92.5 dB

110 dB

0.004

0.009

−

potential when the LM3886 is directly

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

= +40V and V−= −40V.

Units

(Limits)

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Test Circuit #1 (DC Electrical Test Circuit)

Test Circuit #2 (AC Electrical Test Circuit)

LM3886

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Single Supply Application Circuit

LM3886

*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

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Equivalent Schematic (excluding active protection circuitry)

LM3886

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External Components Description

(Figure 1 and Figure 2)

LM3886

Components Functional Description

1. R

2. R

3. C

4. C Provides AC coupling at the input and output of the amplifier for single supply operation.

5. R

6. C

(Note 17)

7. Ri Inverting input resistance to provide AC Gain in conjunction with Rf1.

8. Ci (Note 17)

9. R

10. R

(Note 17)

11. C

(Note 17)

12. R

13. C

14. R

(Note 17)

15. C

(Note 17)

16. L (Note 17)

17. R (Note 17)

18. C

19. S1 Mute switch that mutes the music going into the amplifier when opened.

Note 17: Optional components dependent upon specific design requirements. Refer to the Application Information section for more information.

Acts as a volume control by setting the voltage level allowed to the amplifier’s input terminals.

Provides DC voltage biasing for the single supply operation and bias current for the positive input terminal.

Provides bias filtering.

Prevents currents from entering the amplifier’s non-inverting input which may be passed through to the load upon power-down of the system due to the low input impedance of the circuitry when the under-voltage circuitry is off. This phenomenon occurs when the supply voltages are below 1.5V.

Reduces the gain (bandwidth of the amplifier) at high frequencies to avoid quasi-saturation oscillations of the output transistor. The capacitor also suppresses external electromagnetic switching noise created from fluorescent lamps.

Feedback capacitor. Ensures unity gain at DC. Also a low frequency pole (highpass roll-off) at:

= 1/(2πRi Ci)

Feedback resistance to provide AC Gain in conjunction with Ri.

At higher frequencies feedback resistance works with C

to provide lower AC Gain in conjunction with Rf1and

Ri. A high frequency pole (lowpass roll-off) exists at:

=[Rf1Rf2(s + 1/Rf2Cf)]/[(Rf1+Rf2)(s + 1/Cf(Rf1+Rf2))]

Compensation capacitor that works with R

and Rf2to reduce the AC Gain at higher frequencies.

Mute resistance set up to allow 0.5 mA to be drawn from pin 8 to turn the muting function off.

→

is calculated using: RM≤ (|VEE| − 2.6V)/I8 where I8 ≥ 0.5 mA. Refer to the Mute Attenuation vs.

Mute Current curves in the Typical Performance Characteristics section.

Mute capacitance set up to create a large time constant for turn-on and turn-off muting.

Works with C

Works with R

= 1/(2πRSNCSN)

to stabilize the output stage by creating a pole that eliminates high frequency oscillations.

Provides high impedance at high frequencies so that R may decouple a highly capacitive load and reduce the Q of the series resonant circuit due to capacitive load. Also provides a low impedance at low frequencies to short out R and pass audio signals to the load.

Provides power supply filtering and bypassing.

OPTIONAL EXTERNAL COMPONENT INTERACTION

Although the optional external components have specific desired functions that are designed to reduce the bandwidth and eliminate unwanted high frequency oscillations they may cause certain undesirable effects when they interact. Interaction may occur for components whose reactances are in close proximity to one another. One example would be the coupling capacitor, C

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, and the compensation capacitor, Cf.

These two components act as low impedances to certain frequencies which will couple signals from the input to the output. Please take careful note of basic amplifier component functionality when designing in these components.

The optional external components shown in Figure 2 and described above are applicable in both single and split voltage supply configurations.

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