lm4834

Manufacturer Part Numberlm4834
Description1.75w Audio Power Amplifier With Dc Volume Control And Microphone Preamp
ManufacturerNational Semiconductor Corporation
lm4834 datasheet
 


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LM4834
1.75W Audio Power Amplifier with DC Volume Control
and Microphone Preamp
General Description
The LM4834 is a monolithic integrated circuit that provides
DC volume control, and a bridged audio power amplifier
capable of producing 1.75W into 4Ω with less than 1.0%
(THD). In addition, the headphone/lineout amplifier is ca-
pable of driving 70 mW into 32Ω with less than 0.1%(THD).
The LM4834 incorporates a volume control and an input
microphone preamp stage capable of driving a 1 kΩ load
impedance.
Boomer
®
audio integrated circuits were designed specifically
to provide high quality audio while requiring a minimum
amount of external components in surface mount packaging.
The LM4834 incorporates a DC volume control, a bridged
audio power amplifier and a microphone preamp stage,
making it optimally suited for multimedia monitors and desk-
top computer applications.
The LM4834 features an externally controlled, low-power
consumption shutdown mode, and both a power amplifier
and headphone mute for maximum system flexibility and
performance.
Block Diagram
FIGURE 1. LM4834 Block Diagram
Boomer
®
is a registered trademark of NationalSemiconductor Corporation.
© 2004 National Semiconductor Corporation
Key Specifications
n THD at 1.1W continuous average output power into 8Ω
at 1kHz
n Output Power into 4Ω at 1.0% THD+N
n THD at 70mW continuous average output power into
32Ω at 1kHz
n Shutdown Current
n Supply Current
Features
n PC98 Compliant
n “Click and Pop” suppression circuitry
n Stereo line level outputs with mono input capability for
system beeps
n Microphone preamp with buffered power supply
n DC Volume Control Interface
n Thermal shutdown protection circuitry
Applications
n Multimedia Monitors
n Desktop and Portable Computers
Connection Diagram
See NS Package Number MSA028CB for SSOP
10001501
DS100015
August 2000
0.5% (max)
1.75W (typ)
0.1% (typ)
1.0µA (max)
17.5mA (typ)
SSOP Package
10001502
Top View
Order Number LM4834MS
www.national.com

lm4834 Summary of contents

  • Page 1

    ... DC volume control, and a bridged audio power amplifier capable of producing 1.75W into 4Ω with less than 1.0% (THD). In addition, the headphone/lineout amplifier is ca- pable of driving 70 mW into 32Ω with less than 0.1%(THD). The LM4834 incorporates a volume control and an input microphone preamp stage capable of driving a 1 kΩ load impedance. Boomer ® ...

  • Page 2

    ... LM4834 Typical Limit (Note 6) (Note 7) 4.5 5.5 17.5 26 0.6 2.0 LM4834 Typical Limit (Note 6) (Note 7) 2.6 3.65 -75 -88 -92 -105 -92 -105 = 25˚C. A LM4834 Typical Limit (Note 6) (Note 7) 0.9 = 123 OUT = 1 kΩ 4.72 1.2 28 220˚C 29˚C/W 95˚C/W ≤ 5.5V Units (Limits) V (min) V (max) mA (max) µA (max) Units (Limits) dB (max) dB (min) ...

  • Page 3

    ... R = 32Ω 1.0 µ 120 Hz,V B RIPPLE 200 mVmrs 1.1W OUT A-Wtd Filter − T )/θ .For the LM4834MS 150˚C, and the typical junction-to-ambient thermal resistance, when board A JA JMAX 3 = 25˚C. A LM4834 Typical Limit (Note 6) (Note 7) 2.5 2.5 LM4834 Typical ...

  • Page 4

    Typical Application Truth Table for Logic Inputs Mode Mute www.national.com FIGURE 2. Typical Application Circuit HP Sense DC Vol. Control Line/HP Left 0 Adjustable Fixed Level 1 Adjustable ...

  • Page 5

    External Components Description Components Input coupling capacitor which blocks the DC voltage at the amplifier’s input terminals. Also creates a high i pass filter with explanation of how to determine the value ...

  • Page 6

    Typical Performance Characteristics THD+N vs Frequency Bridge Power Amp THD+N vs Frequency Line Out/HP Amplifiers THD+N vs Output Power Bridged Power Amp www.national.com (Continued) THD+N vs Frequency Line Out/HP Amplifiers 10001506 THD+N vs Frequency Line Out/HP Amplifiers 10001508 THD+N vs ...

  • Page 7

    Typical Performance Characteristics THD+N vs Output Power Bridged Power Amp THD+N vs Output Power Line Out/HP Amplifiers Output Power vs Load Resistance Bridged Power Amp (Continued) THD+N vs Output Power 10001512 THD+N vs Output Power 10001514 10001516 7 Line Out/HP ...

  • Page 8

    Typical Performance Characteristics Volume Control Characteristics Noise Floor Line Out/HP Amp Power Supply Rejection Ratio Bridged Power Amp www.national.com (Continued) 10001525 10001520 Line Out/HP Amplifiers 10001522 8 Noise Floor Bridged Power Amp 10001519 Noise Floor Mic Preamp 10001521 Power Supply ...

  • Page 9

    Typical Performance Characteristics Power Supply Rejection Ratio Mic Preamp Power Dissipation vs Output Power Line Out/HP Amplifiers Power Derating Curve (Continued) 10001524 Low Frequency Enhancement 10001526 10001528 9 Power Dissipation vs Output Power Bridged Power Amp 10001518 Characteristics Bridged Power ...

  • Page 10

    Typical Performance Characteristics Crosstalk Line Out/HP Amplifiers www.national.com (Continued) 10001530 10 ...

  • Page 11

    ... MUTE FUNCTION By placing a logic level high on the mute pin (pin 15), the Right and Left Sum Out pins will be muted. If the LM4834 is in the headphone mode, the HP/Line out pins as well as the Sum Out pins are muted. The mute pin must not be floated. ...

  • Page 12

    ... JA = 95˚C/W and T = The LM4834’s bridged amplifier should be used in low gain JMAX , of the configurations to minimize THD+N values, and maximize the A signal to noise ratio. Low gain configurations require large input signals to obtain a given output power. Input signals equal to or greater than 1Vrms are available from sources such as audio codecs ...

  • Page 13

    ... CLICK AND POP CIRCUITRY The LM4834 contains circuitry to minimize turn-on transients or “click and pops”. In this case, turn-on refers to either power supply turn-on or the device coming out of shutdown mode. When the device is turning on, the amplifiers are internally configured as unity gain buffers ...

  • Page 14

    ... English www.national.com Français Tel: +33 ( 8790 SSOP Package Order Number LM4834MS NS Package Number MSA028CB for SSOP 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system affect its safety or effectiveness ...