lm4940tsx National Semiconductor Corporation, lm4940tsx Datasheet

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lm4940tsx

Manufacturer Part Number
lm4940tsx
Description
6w Streo Audio Power Amplifier
Manufacturer
National Semiconductor Corporation
Datasheet
© 2005 National Semiconductor Corporation
LM4940
6W Stereo Audio Power Amplifier
General Description
The LM4940 is a dual audio power amplifier primarily de-
signed for demanding applications in flat panel monitors and
TV’s. It is capable of delivering 6 watts per channel to a 4Ω
load with less than 10% THD+N while operating on a
14.4V
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4940 does not require boot-
strap capacitors or snubber circuits. Therefore, it is ideally
suited for display applications requiring high power and mini-
mal size.
The LM4940 features a low-power consumption active-low
shutdown mode. Additionally, the LM4940 features an inter-
nal thermal shutdown protection mechanism along with short
circuit protection.
The LM4940 contains advanced pop & click circuitry that
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
The LM4940 is a unity-gain stable and can be configured by
external gain-setting resistors.
Typical Application
Boomer
DC
®
is a registered trademark of National Semiconductor Corporation.
power supply.
FIGURE 1. Typical Stereo Audio Amplifier Application Circuit
DS200756
Key Specifications
Features
n Pop & click circuitry eliminates noise during turn-on and
n Low current, active-low shutdown mode
n Low quiescent current
n Stereo 6W output, R
n Short circuit protection
n Unity-gain stable
n External gain configuration capability
Applications
n Flat Panel Monitors
n Flat Panel TV’s
n Computer Sound Cards
j
j
j
turn-off transitions
Quiscent Power Supply Current
P
Shutdown current
OUT
V
DD
(SE)
= 14.4V, R
L
= 4Ω, 10% THD+N
L
= 4Ω
20075672
www.national.com
40mA (max)
40µA (typ)
April 2005
6W (typ)

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lm4940tsx Summary of contents

Page 1

... The LM4940 is a unity-gain stable and can be configured by external gain-setting resistors. Typical Application FIGURE 1. Typical Stereo Audio Amplifier Application Circuit Boomer ® registered trademark of National Semiconductor Corporation. © 2005 National Semiconductor Corporation Key Specifications j Quiscent Power Supply Current j P ...

Page 2

Connection Diagram www.national.com Plastic Package, TO-263 200756E7 Top View U = Wafer Fab Code Z = Assembly Plant Code XY = Date Code TT = Die Traceability Order Number LM4940TS See NS Package Number TS9A 2 ...

Page 3

Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Supply Voltage (pin 6, referenced to GND, pins 4 and 5) Storage Temperature Input Voltage pins 3 and 7 ...

Page 4

Typical Application FIGURE 2. Typical Stereo Audio Amplifier Application Circuit External Components Description Components This is the inverting input resistance that, along with resistance 1/(2π This is the input coupling capacitor. It ...

Page 5

Typical Performance Characteristics THD+N vs Frequency V = 12V 4Ω, SE operation both channels driven and loaded (average shown 1W OUT V THD+N vs Frequency V = 12V 8Ω, ...

Page 6

Typical Performance Characteristics THD+N vs Output Power V = 12V 16Ω, SE operation single channel driven/single channel measured 1kHz IN THD+N vs Output Power V = 12V 8Ω, SE operation, A ...

Page 7

Typical Performance Characteristics Output Power vs Power Supply Voltage R = 16Ω, SE operation both channels driven and loaded (average shown), at (from top to bottom at 12V): THD+N = 10%, THD Power Supply Rejection vs ...

Page 8

Typical Performance Characteristics Channel-to-Channel Crosstalk vs Frequency V = 12V 8Ω 1W, SE operation OUT at (from top to bottom at 1kHz measured; V driven, V OUTA INA Clipping Voltage vs Power ...

Page 9

Application Information FIGURE 3. Typical LM4940 Stereo Amplifier Application Circuit HIGH VOLTAGE BOOMER WITH INCREASED OUTPUT POWER Unlike previous 5V Boomer ® amplifiers, the LM4940 is de- signed to operate over a power supply voltages range of 10V to 15V. ...

Page 10

Application Information If the result of Equation (3) is greater than that of Equation (4), then decrease the supply voltage, increase the load impedance, or reduce the ambient temperature. Further, ensure that speakers rated at a nominal 4Ω do not ...

Page 11

Application Information C (µF) B 1.0 2.2 4 order eliminate "clicks and pops", all capacitors must be discharged before turn-on. Rapidly switching V allow the capacitors to fully discharge, which may cause "clicks and pops". There is a ...

Page 12

Application Information RECOMMENDED PRINTED CIRCUIT BOARD LAYOUT Figure 5 through Figure 7 show the recommended two-layer PC board layout that is optimized for the TO263-packaged LM4940 and associated external components. This circuit board is designed for use with an external ...

Page 13

Demonstration Board Layout (Continued) FIGURE 6. Recommended TS PCB Layout: Bottom Layer 13 20075665 www.national.com ...

Page 14

Physical Dimensions inches (millimeters) unless otherwise noted National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and ...

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