lm4891mm

Manufacturer Part Numberlm4891mm
Description1 Watt Audio Power Amplifier
ManufacturerNational Semiconductor Corporation
lm4891mm datasheet
 


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LM4891
1 Watt Audio Power Amplifier
General Description
The LM4891 is an audio power amplifier primarily designed
for demanding applications in mobile phones and other por-
table communication device applications. It is capable of
delivering 1 watt of continuous average power to an 8Ω BTL
load with less than 1% distortion (THD+N) from a 5V
power supply.
Boomer audio power amplifiers were designed specifically to
provide high quality output power with a minimal amount of
external components. The LM4891 does not require output
coupling capacitors or bootstrap capacitors, and therefore is
ideally suited for mobile phone and other low voltage appli-
cations where minimal power consumption is a primary re-
quirement.
The LM4891 features a low-power consumption shutdown
mode, which is achieved by driving the shutdown pin with
logic high. Additionally, the LM4891 features an internal ther-
mal shutdown protection mechanism.
The LM4891 contains advanced pop & click circuitry which
eliminates noises which would otherwise occur during
turn-on and turn-off transitions.
The LM4891 is unity-gain stable and can be configured by
external gain-setting resistors.
Typical Application
FIGURE 1. Typical Audio Amplifier Application Circuit
Boomer
®
is a registered trademark of National Semiconductor Corporation.
© 2002 National Semiconductor Corporation
Key Specifications
PSRR at 217Hz, V
j
Power Output at 5.0V & 1% THD
j
Power Output at 3.3V & 1% THD
j
Shutdown Current
j
DC
Features
n Available in space-saving packages: micro SMD, MSOP,
SOIC, and LLP
n Ultra low current shutdown mode
n BTL output can drive capacitive loads
n Improved pop & click circuitry eliminates noises during
turn-on and turn-off transitions
n 2.2 to 5.5V operation
n No output coupling capacitors, snubber networks or
bootstrap capacitors required
n Thermal shutdown protection
n Unity-gain stable
n External gain configuration capability
Applications
n Mobile Phones
n PDAs
n Portable electronic devices
DS200074
October 2002
= 5V, 8Ω Load
62dB (typ)
DD
1.0W (typ)
400mW (typ)
0.1µA (typ)
20007401
www.national.com

lm4891mm Summary of contents

  • Page 1

    ... The LM4891 is unity-gain stable and can be configured by external gain-setting resistors. Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit Boomer ® registered trademark of National Semiconductor Corporation. © 2002 National Semiconductor Corporation Key Specifications PSRR at 217Hz Power Output at 5.0V & 1% THD j Power Output at 3.3V & ...

  • Page 2

    ... Order Number LM4891M See NS Package Number M08A SO Marking 20007472 Top View XY - Date Code TT - Die Traceability Bottom 2 lines - Part Number MSOP Marking 20007471 Top View G - Boomer Family 91 - LM4891MM 10 Pin LLP Marking 20007479 Top View Digit Datecode Letter Code for Traceability L4891 - LM4891LD ...

  • 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 (Note 11) Storage Temperature Input Voltage Power Dissipation (Note 3) ESD Susceptibility (Note 4) ESD Susceptibility (Note ...

  • Page 4

    Electrical Characteristics V The following specifications apply for V 25˚C. (Continued) Symbol Parameter P Output Power ( 8Ω Output Power ( 4Ω ) THD+N Total Harmonic Distortion+Noise PSRR Power Supply Rejection Ratio Note 1: All voltages are measured ...

  • Page 5

    Typical Performance Characteristics THD+N vs Frequency 5V, 8Ω and PWR = 250mW DD L THD+N vs Frequency 2.6V, 8Ω and PWR = 100mW DD L THD+N vs Power Out @ ...

  • Page 6

    Typical Performance Characteristics THD+N vs Power Out @ V = 2.6V, 8Ω Power Supply Rejection Ratio (PSRR) Input terminated with 10Ω R Power Supply Rejection Ratio (PSRR) Input terminated with 10Ω R www.national.com (Continued) , 1kHz L 20007443 ...

  • Page 7

    Typical Performance Characteristics Power Dissipation vs Output Power V = 3.3V DD Output Power vs Load Resistance Supply Current vs Shutdown Voltage (Continued 20007449 20007451 Clipping (Dropout) Voltage vs 20007474 7 Power Dissipation vs Output Power = ...

  • Page 8

    Typical Performance Characteristics Open Loop Frequency Response Load DD Power Derating Curves (P = 670mW) DMAX Power Derating - 10 Pin LD Pkg P = 670mW, 5V, 8Ω DMAX www.national.com (Continued) Open Loop Frequency Response 20007475 ...

  • Page 9

    Typical Performance Characteristics (Continued) Noise Floor Application Information BRIDGE CONFIGURATION EXPLANATION As shown in Figure 1, the LM4891 has two operational amplifiers internally, allowing for a few different amplifier configurations. The first amplifier’s gain is externally config- urable, while the ...

  • Page 10

    Application Information SHUTDOWN FUNCTION In order to reduce power consumption while not in use, the LM4891 contains a shutdown pin to externally turn off the amplifier’s bias circuitry. This shutdown feature turns the amplifier off when a logic high is ...

  • Page 11

    Application Information As stated in the External Components section, R junction with C create a highpass filter ≥ 1/(2π*20 kΩ*20 Hz) = 0.397 µF; use 0.39 µF i The high frequency pole is determined by the product of ...

  • Page 12

    Application Information FIGURE 3. Differential Amplifier Configuration for LM4891 FIGURE 4. Reference Design Board and Layout - micro SMD www.national.com (Continued) 12 20007429 20007425 ...

  • Page 13

    Application Information LM4891 micro SMD BOARD ARTWORK Silk Screen Bottom Layer Inner Layer V DD (Continued) 20007457 20007459 20007461 13 Top Layer 20007458 Inner Layer Ground 20007460 www.national.com ...

  • Page 14

    Application Information FIGURE 5. Reference Design Board and PCB Layout Guidelines - MSOP & SO Boards www.national.com (Continued) 14 20007468 ...

  • Page 15

    Application Information LM4891 SO DEMO BOARD ARTWORK Silk Screen Top Layer Bottom Layer LM4891 MSOP DEMO BOARD ARTWORK (Continued) 20007462 20007463 20007464 15 Silk Screen 20007465 Top Layer 20007466 Bottom Layer 20007467 www.national.com ...

  • Page 16

    Application Information Item Part Number 1 551011208-001 LM4891 Mono Reference Design Board 10 482911183-001 LM4891 Audio AMP 20 151911207-001 Tant Cap 1uF 16V 10 21 151911207-002 Cer Cap 0.39uF 50V Z5U 20% 1210 25 152911207-001 Tant Cap 1uF 16V 10 ...

  • Page 17

    Physical Dimensions inches (millimeters) unless otherwise noted Note: Unless otherwise specified. 1. Epoxy coating. 2. 63Sn/37Pb eutectic bump. 3. Recommend non-solder mask defined landing pad. 4. Pin 1 is established by lower left corner with respect to text orientation pins ...

  • Page 18

    ... Physical Dimensions www.national.com inches (millimeters) unless otherwise noted (Continued) MSOP Order Number LM4891MM NS Package Number MUA08A 18 ...

  • Page 19

    Physical Dimensions inches (millimeters) unless otherwise noted (Continued) SO Order Number LM4891M NS Package Number M08A 19 www.national.com ...

  • Page 20

    ... 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 ...