LM4781TA/NOPB National Semiconductor, LM4781TA/NOPB Datasheet

IC AMP AUDIO PWR 35W AB TO220-27

LM4781TA/NOPB

Manufacturer Part Number
LM4781TA/NOPB
Description
IC AMP AUDIO PWR 35W AB TO220-27
Manufacturer
National Semiconductor
Series
Overture™r
Type
Class ABr
Datasheet

Specifications of LM4781TA/NOPB

Output Type
3-Channel
Max Output Power X Channels @ Load
35W x 3 @ 8 Ohm
Voltage - Supply
20 V ~ 70 V, ±10 V ~ 35 V
Features
Depop, Mute, Short-Circuit and Thermal Protection
Mounting Type
Through Hole
Package / Case
TO-220-27 (Bent and Staggered Leads)
For Use With
LM4781TABD - BOARD EVALUATION LM4781TA
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Other names
*LM4781TA
*LM4781TA/NOPB
LM4781TA

Available stocks

Company
Part Number
Manufacturer
Quantity
Price
Part Number:
LM4781TA/NOPB
Manufacturer:
National Semiconductor
Quantity:
135
© 2003 National Semiconductor Corporation
LM4781 Overture
3 Channel 35W Audio Power Amplifier with Mute
General Description
The LM4781 is a three channel audio amplifier capable of
typically delivering 35W per channel of continuous average
output power into an 8Ω load with less than 0.5% THD+N
from 20Hz - 20kHz.
The LM4781 is fully protected utilizing National’s Self Peak
Instantaneous Temperature (˚Ke) (SPiKe
cuitry. SPiKe provides a dynamically optimized Safe Operat-
ing Area (SOA). SPiKe protection completely safeguards the
LM4781’s outputs against over-voltage, under-voltage, over-
loads, shorts to the supplies or GND, thermal runaway and
instantaneous temperature peaks. The advanced protection
features of the LM4781 places it in a class above discrete
and hybrid amplifiers.
Each amplifier of the LM4781 has an independent smooth
transition fade-in/out mute.
The LM4781 can easily be configured for bridge or parallel
operation for higher power and bi-amp solutions.
Typical Application
SPiKe
Protection and Overture
are trademarks of National Semiconductor Corporation.
FIGURE 1. Typical Audio Amplifier Application Circuit
DS200673
TM
Audio Power Amplifier Series
) protection cir-
Key Specifications
Features
n SPiKe Protection
n Low external component count
n Quiet fade-in/out mute mode
n Wide supply range: 20V - 70V
n Signal-to-Noise Ratio ≥ 93dB (ref. to P
Applications
n Audio amplifier for component stereo
n Audio amplifier for compact stereo
n Audio amplifier for self-powered speakers
n Audio amplifier for high-end and HD TVs
j
j
j
j
j
j
j
1kHz into 8Ω
Output Power/Channel with 0.5% THD+N,
THD+N at 3 x 20W into 8Ω (20Hz - 20kHz) 0.2% (typ)
THD+N at 3 x 20W into 6Ω (20Hz - 20kHz) 0.3% (typ)
THD+N at 3 x 20W into 4Ω (20Hz - 20kHz) 0.5% (typ)
Mute Attenuation
PSRR
Slew Rate
200673B5
O
= 1W)
www.national.com
August 2003
110dB (typ)
85dB (min)
9V/µs (typ)
35W (typ)

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LM4781TA/NOPB Summary of contents

Page 1

... Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit SPiKe ™ Protection and Overture ™ are trademarks of National Semiconductor Corporation. © 2003 National Semiconductor Corporation Audio Power Amplifier Series Key Specifications j Output Power/Channel with 0.5% THD+N, 1kHz into 8Ω ...

Page 2

Connection Diagrams www.national.com Plastic Package (Note 14) 200673B2 Top View Order Number LM4781TA See NS Package Number TA27A TO-220 Top Marking 200673A6 Top View U - Wafer Fab Code Z - Assembly Plant Code XY - Date Code TT - ...

Page 3

... Absolute Maximum Ratings 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications Supply Voltage | (No Signal Supply Voltage | (Input Signal) Common Mode Input Voltage Differential Input Voltage (Note 13) Output Current Power Dissipation (Note 3) ...

Page 4

Electrical Characteristics The following specifications apply for V Limits apply for T = 25˚C. A Symbol Parameter CMRR Common Mode Rejection Ratio (Note 15) A Open Loop Voltage Gain VOL GBWP Gain Bandwidth Product e Input Noise IN SNR Signal-to-Noise ...

Page 5

Bridged Amplifier Application Circuit FIGURE 2. Bridged Amplifier Application Circuit 5 200673B4 www.national.com ...

Page 6

Parallel Amplifier Application Circuit www.national.com FIGURE 3. Parallel Amplifier Application Circuit 6 200673B3 ...

Page 7

Single Supply Application Circuit FIGURE 4. Single Supply Amplifier Application Circuit Note: * Optional components dependent upon specific design requirements. Auxiliary Amplifier Application Circuit FIGURE 5. Special Audio Amplifier Application Circuit 20067306 200673B6 7 www.national.com ...

Page 8

External Components Description (Figures 1-5) Components 1 R Prevents current from entering the amplifier’s non-inverting input. This current may pass through to the load B during system power down, because of the amplifier’s low input impedance when the undervoltage circuitry ...

Page 9

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. Inter- action may occur for ...

Page 10

Typical Performance Characteristics THD+N vs Output Power/Channel ± 24V 6Ω, 80kHz BW L Output Power/Channel vs Supply Voltage f = 1kHz 4Ω, 80kHz BW L Output Power/Channel vs Supply Voltage f = 1kHz 8Ω, ...

Page 11

Typical Performance Characteristics Total Power Dissipation vs Output Power/Channel 1% THD (max 6Ω, 80kHz BW L Crosstalk vs Frequency ± 20V 10W, OUT R = 4Ω, 80kHz BW L Two Channels On Crosstalk vs Frequency ± ...

Page 12

Typical Performance Characteristics Mute Attenuation vs Mute Pin Current P = 10W/Channel OUT Large Signal Response Common-Mode Rejection Ratio www.national.com (Continued) Supply Current vs 20067321 200673C1 Frequency Response 200673C3 12 Supply Voltage 20067333 Power Supply Rejection Ratio 200673C2 Open Loop ...

Page 13

Typical Performance Characteristics Clipping Voltage vs Supply Voltage THD+N vs Frequency ± 28V & 35W, OUT Chs 1&3 in Parallel Mode (Note18 4Ω, 80kHz BW L THD+N vs Output Power ± 20V, Chs 1&3 in ...

Page 14

Typical Performance Characteristics THD+N vs Output Power ± 24V, All Chs in Parallel Mode (Note18 2Ω, 80kHz BW L Output Power vs Supply Voltage Chs 1&3 in Parallel Mode (Note18 1kHz 4Ω, 80kHz BW ...

Page 15

Typical Performance Characteristics Note 17: Bridge mode graphs were taken using the demo board and inverting the signal to the channel B input. Note 18: Parallel mode graphs were taken using the demo board connecting each output through a 0.1Ω/3W ...

Page 16

Application Information tics section shows the area of device operation where SPiKe Protection Circuitry is not enabled. The SPiKe Pro- tection Response waveform graph shows the waveform dis- tortion when SPiKe is enabled. Please refer to AN-898 for more detailed ...

Page 17

Application Information sible as compared to a single-ended amplifier under the same conditions. This increase in attainable output power assumes that the amplifier is not current limited or clipped. A direct consequence of the increased power delivered to the load ...

Page 18

Application Information the device employs Under-Voltage Protection, which elimi- nates unwanted power-up and power-down transients. The basis for these functions are a stable and constant half- supply potential split-supply application, ground is the stable half-supply potential. But in ...

Page 19

Application Information Note 19: CCIR/ARM: A Practical Noise Measurement Method; by Ray Dolby, David Robinson and Kenneth Gundry, AES Preprint No. 1353 (F-3). In addition to noise filtering, differing meter types give differ- ent noise readings. Meter responses include: 1. ...

Page 20

Application Information LAYOUT, GROUND LOOPS AND STABILITY The LM4781 is designed to be stable when operated at a closed-loop gain greater, but as with any other high-current amplifier, the LM4781 can be made to oscillate under certain ...

Page 21

Application Information If the DC blocking input capacitor ( used as shown, the IN lower -3dB point is found using Equation (8) as discussed in the Proper Selection of External Components section. FIGURE 6. Inverting Amplifier Application Circuit ...

Page 22

Application Information www.national.com (Continued) FIGURE 7. Reference PCB Schematic 22 200673C8 ...

Page 23

Application Information LM4781 REFERENCE BOARD ARTWORK Composite Layer Top Layer (Continued) 200673A9 200673A8 23 200673B0 Silk Layer 200673B1 Bottom Layer www.national.com ...

Page 24

Application Information Bill Of Materials for Reference PCB Symbol Value 33kΩ IN1 IN2 IN3 1kΩ 20kΩ ...

Page 25

... 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 AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant ...

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