LM4851LQ National Semiconductor, LM4851LQ Datasheet

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LM4851LQ

Manufacturer Part Number
LM4851LQ
Description
Integrated Audio Amplifier System
Manufacturer
National Semiconductor
Datasheet
© 2002 National Semiconductor Corporation
LM4851
Integrated Audio Amplifier System
General Description
The LM4851 is an audio power amplifier system capable of
delivering 1.1W (typ) of continuous average power into a
mono 8Ω bridged-tied load (BTL) with 1% THD+N and
115mW (typ) per channel of continuous average power into
stereo 32Ω BTL loads with 0.5% THD+N, using a 5V power
supply.
The LM4851 features a 32 step digital volume control and
eight distinct output modes. The digital volume control and
output modes are programmed through a three-wire SPI
serial control interface, that allows flexibility in routing and
mixing audio channels. The LM4851 has 3 inputs: one pair
for a two-channel stereo signal and the third for a single-
channel mono input.
The LM4851 is designed for cellular phone, PDA, and other
portable handheld applications. It delivers high quality output
power from a surface-mount package and requires only five
external components.
The industry leading micro SMD package utilizes only 2mm
x 2.3mm of PCB space, making the LM4851 the most space
efficient audio sub system available today.
Typical Application
Boomer
®
is a registered trademark of National Semiconductor Corporation.
FIGURE 1. Typical Audio Amplifier Application Circuit
DS200408
Key Specifications
n THD+N at 1kHz, 1.5W into 4Ω BTL (LQ)
n THD+N at 1kHz, 1.1W into 8Ω BTL
n THD+N at 1kHz, 115mW into 32Ω BTL
n Single Supply Operation
Features
n Mono 1.1W (typ) and stereo 115mW (typ) output
n SPI programmable 32 step digital volume control
n Eight distinct SPI programmable output modes
n micro-SMD and LLP surface mount packaging
n “Click and pop” suppression circuitry
n Thermal shutdown protection
n Low shutdown current (0.1µA, typ)
Applications
n Mobile phones
n PDAs
(-40.5dB to +6dB)
20040831
December 2002
www.national.com
2.6 to 5.0V
0.5% (typ)
1% (typ)
1% (typ)

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LM4851LQ Summary of contents

Page 1

... Typical Application FIGURE 1. Typical Audio Amplifier Application Circuit Boomer ® registered trademark of National Semiconductor Corporation. © 2002 National Semiconductor Corporation Key Specifications n THD+N at 1kHz, 1.5W into 4Ω BTL (LQ) n THD+N at 1kHz, 1.1W into 8Ω BTL n THD+N at 1kHz, 115mW into 32Ω BTL ...

Page 2

... Order Number LM4851ITL, LM4851IBL See NS Package Number TLA18AAA, BLA18AAB www.national.com 18-Bump micro SMD Marking (ITL) 200408A5 20040829 See NS Package Number LQA24A for Exposed-DAP LLP 2 200408B3 Top View XY- Date Code TT - Die Traceability G - Boomer Family B1 - LM4851ITL 200408A7 Top View Order Number LM4851LQ ...

Page 3

... L R and 20Hz to 20kHz OUT OUT P = 100mW 32Ω OUT L SPKR ; f = 20Hz to 20kHz OUT 4Ω OUT L LM4851LQ SPKR ; f = 20Hz to 20kHz OUT P = 800mW 8Ω OUT L A-weighted (Note 10 200mV ; f = 217Hz RIPPLE PP Input floating; Input referred V = 200mV ; f = 217Hz RIPPLE PP Input terminated into 50Ω ...

Page 4

... Output modes 0V Output mode SPKR ; R = 4Ω OUT L THD 1kHz LM4851LQ SPKR ; R = 8Ω OUT L THD 1kHz R and 32Ω OUT OUT L THD+N = 0.5 1kHz 4 LM4851 Units (Limits) Typical ...

Page 5

... L R and 20Hz to 20kHz OUT OUT P = 20mW 32Ω OUT L SPKR ; f = 20Hz to 20kHz OUT P = 300mW 4Ω OUT L LM4851LQ SPKR ; f = 20Hz to 20kHz OUT P = 250mW 8Ω OUT L A-weighted (Note 10 200mV ; f = 217Hz RIPPLE PP Input floating; Input referred V = 200mV ; f = 217Hz RIPPLE PP Input terminated into 50Ω ...

Page 6

... This is the BYPASS pin capacitor. It provides half-supply filtering. B Typical Performance Characteristics THD+N vs Frequency (LM4851LQ) THD+N vs Frequency www.national.com 2 area of 1oz printed circuit board copper ground plane. Functional Description , also creates a highpass filter with the internal resistor R i THD+N vs Frequency (LM4851LQ) 200408B4 THD+N vs Frequency 20040863 1/(2π ...

Page 7

... Typical Performance Characteristics THD+N vs Frequency THD+N vs Frequency THD+N vs Output Power (LM4851LQ) (Continued) THD+N vs Frequency 20040865 THD+N vs Frequency 20040867 THD+N vs Output Power (LM4851LQ) 200408B6 7 20040866 20040868 200408B7 www.national.com ...

Page 8

Typical Performance Characteristics THD+N vs Output Power THD+N vs Output Power THD+N vs Output Power www.national.com (Continued) THD+N vs Output Power 20040839 THD+N vs Output Power 20040841 THD+N vs Output Power 20040843 8 20040840 20040842 20040844 ...

Page 9

Typical Performance Characteristics Power Supply Rejection Ratio Power Supply Rejection Ratio Power Supply Rejection Ratio (Continued) Power Supply Rejection Ratio 20040845 Power Supply Rejection Ratio 20040860 Power Supply Rejection Ratio 20040862 9 20040874 20040861 20040859 www.national.com ...

Page 10

Typical Performance Characteristics Output Power vs Supply Voltage Output Power vs Supply Voltage Output Power vs Load Resistance www.national.com (Continued) Output Power vs Supply Voltage 20040846 vs Load Resistance 20040848 Power Dissipation vs Output Power 20040869 10 20040847 Output Power ...

Page 11

Typical Performance Characteristics Power Dissipation vs Output Power Channel Separation vs Frequency Frequency Response (Continued) vs Supply Voltage 20040872 Frequency Response 200408A6 Frequency Response 200408A9 11 Supply Current 20040855 200408A8 200408B0 www.national.com ...

Page 12

Typical Performance Characteristics Output Noise vs Output Mode ( volume control gain X = Not applicable www.national.com (Continued) Frequency Response = 3V, 5V; A-weighted) DD Output Mode SPKROUT LOUT/ROUT Output Noise Output Noise (µ ...

Page 13

Application Information SPI PIN DESCRIPTION DATA: This is the serial data input pin. CLK: This is the clock input pin. ENB: This is the SPI enable pin and is active-high. SPI OPERATION DESCRIPTION The serial data bits are organized into ...

Page 14

Application Information Gain (dB) Data 7 -40.5 0 -39.0 0 -37.5 0 -36.0 0 -34.5 0 -33.0 0 -31.5 0 -30.0 0 -28.5 0 -27.0 0 -25.5 0 -24.0 0 -22.5 0 -21.0 0 -19.5 0 -18.0 0 -16.5 1 ...

Page 15

... LM4851’s thermal shutdown protection. Further detailed and specific information con- cerning PCB layout and fabrication and mounting an LQ (LLP) is found in National Semiconductor’s AN1187. PCB LAYOUT AND SUPPLY REGULATION CONSIDERATIONS FOR DRIVING 3Ω AND 4Ω LOADS Power dissipated by a load is a function of the voltage swing across the load and the load’ ...

Page 16

Application Information as load impedance decreases. Therefore, to maintain the highest load dissipation and widest output voltage swing, PCB traces that connect the output pins to a load must be as wide as possible. Poor power supply regulation adversely affects ...

Page 17

Application Information power, higher ambient temperatures are allowed as output power or duty cycle decreases. If the result of Equation (5) is greater than that of Equation (6), then decrease the supply voltage, increase the load impedance, or reduce the ...

Page 18

Demonstration Board Layout FIGURE 3. Recommended IBL, ITL PC Board Layout: Top Silkscreen FIGURE 4. Recommended IBL, ITL PC Board Layout: Inner Layer www.national.com 200408A1 FIGURE 5. Recommended IBL, ITL PC Board Layout: 200408A2 FIGURE 6. Recommended IBL, ITL PC ...

Page 19

Demonstration Board Layout (Continued) FIGURE 7. Recommended LQ PC Board Layout: Top Silkscreen Layer FIGURE 8. Recommended LQ PC Board Layout: Top Layer FIGURE 9. Recommended LQ PC Board Layout: 200408B8 FIGURE 10. Recommended LQ PC Board Layout: 200408B9 FIGURE ...

Page 20

Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 18-Bump micro SMD Order Number LM4851IBL NS Package Number BLA18AAB X = 1.996 X = 2.225 X = 0.945 ...

Page 21

Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 18-Bump micro SMD Order Number LM4851ITL NS Package Number TLA18AAA X = 1.996 X = 2.225 X = 0.600 www.national.com ...

Page 22

... 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 (Continued) Order Number LM4851LQ NS Package Number LQA24A 2 ...

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