LM4918LQ National Semiconductor, LM4918LQ Datasheet

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LM4918LQ

Manufacturer Part Number
LM4918LQ
Description
Stereo Audio Amp with AGC Control
Manufacturer
National Semiconductor
Datasheet

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LM4918LQ
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© 2004 National Semiconductor Corporation
LM4918
Stereo Audio Amp with AGC Control
General Description
The LM4918 is a monolithic integrated circuit that provides a
automatic gain control (AGC), and stereo bridged audio
power amplifiers capable of producing 1W into 8Ω with less
than 1.0% THD.
Boomer
to provide high quality audio while requiring a minimum
amount of external components. The LM4918 incorporates a
AGC and stereo bridged audio power amplifiers making it
optimally suited for multimedia monitors, portable radios,
desktop and portable computer applications.
The LM4918 features an externally controlled, low-power
consumption shutdown mode, and a power amplifier mute
for maximum system flexibility and performance.
Typical Application
Boomer
®
is a registered trademark of National Semiconductor Corporation.
®
audio integrated circuits were designed specifically
FIGURE 1. Typical Audio Amplifier Application Circuit
DS200913
Key Specifications
Features
n 0.75dB per step/32step AGC Control Interface
n Automatic Gain Control Circuitry
n Stereo Bridged power amplifiers
n “Click and pop” suppression circuitry
n Thermal shutdown protection circuitry
n Selectable Auto Detect Std-by mode and Logic control
Applications
n Portable Computers
n Desktop Computers
n Multimedia monitors
j
j
j
THD+N at 1kHz, 1W, 8Ω
Total quiescent power supply current
Total shutdown power supply current
20091301
February 2004
www.national.com
18mA (typ)
0.3% (typ)
1µA (typ)

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LM4918LQ Summary of contents

Page 1

... Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit Boomer ® registered trademark of National Semiconductor Corporation. © 2004 National Semiconductor Corporation Key Specifications j THD+N at 1kHz, 1W, 8Ω j Total quiescent power supply current ...

Page 2

... Connection Diagrams www.national.com LQ Package Top View Order Number LM4918LQ See NS Package Number LQA32B LQ Marking 200913H7 Top View NS - Std NS Logo U - Wafer Fab Code Z - Assembly Plant Code Digit Date Code TT - Die Run Traceability L4918LQ - LM4918LQ 2 20091302 ...

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 Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note 5) Junction Temperature Electrical Characteristics Symbol Parameter ...

Page 4

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified. Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is functional, ...

Page 5

Typical Performance Characteristics THD+N vs Frequency 4Ω, BTL THD+N vs Frequency 8Ω, BTL THD+N vs Frequency 32Ω, SE, P ...

Page 6

Typical Performance Characteristics THD+N vs Output Power 8Ω, BTL DD L THD+N vs Output Power 32Ω Output Power vs Load Resistance BTL www.national.com (Note 12) (Continued) THD+N ...

Page 7

Typical Performance Characteristics Power Dissipation vs Output Power V = 3V, BTL DD Power Dissipation vs Output Power and 3V 32Ω (Note 12) (Continued) Power Dissipation vs Output Power V DD 200913G6 ...

Page 8

Typical Performance Characteristics PSRR vs Frequency 8Ω, BTL, Full System DD L Inputs 10Ω Terminated to GND PSRR vs Frequency 32Ω, SE, Full System DD L Inputs 10Ω Terminated to ...

Page 9

Typical Performance Characteristics Supply Voltage vs Output Power R = 8Ω, BTL,10% and 1% THD+N L Channel Separation and 3V 8Ω, BTL DD L (Note 12) (Continued) Supply Voltage vs Output Power R = 32Ω, ...

Page 10

Application Information BRIDGE CONFIGURATION EXPLANATION As shown in Figure 1, the LM4918 consists of two pairs of operational amplifiers, forming a two-channel (channel L and channel R) stereo amplifier. (Though the following discusses channel L, it applies equally to channel ...

Page 11

Application Information mize thermal design may compromise the LM4918’s perfor- mance and activate unwanted, though necessary, thermal shutdown protection. The LM4918LD must have its DAP soldered to a copper pad on the PCB. The DAP’s PCB copper pad is then, ...

Page 12

Application Information FIGURE 3. Block Diagram with external component for AGC closed loop AUTOMATIC GAIN CONTROL (AGC) The AGC represents a closed loop gain control network in conjunction with the peak detect monitoring the outputs of the power amplifier section. ...

Page 13

Application Information STEP (Continued) TABLE 1. Typical VAGCREF ...

Page 14

Application Information SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4918 contains a shutdown pin to externally turn off the amplifier’s bias circuitry. This shutdown feature turns the amplifier off when a logic high (0.8 ...

Page 15

Application Information negative peak circuit is described by jumpers in place on S2 and S4, while removed from S1 and S3. Operating in the negative manner places the Vpk_Bfr directly to VagcRef, and makes Vpk_in the effective AGC gain reference ...

Page 16

Application Information LM4918 LLP BOARD ARTWORK Top Overlay Top Layer www.national.com (Continued) 200913I6 200913I5 16 Top Solder 200913I7 Bottom Layer 200913I4 ...

Page 17

... 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 specifications. inches (millimeters) unless otherwise noted LQ Package Order Number LM4918LQ NS Package Number LQA32B 2. A critical component is any component of a life ...

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