Class D Audio Amp - CS&S electronic

Class D Audio Amp LGMM2104M Data Sheet (V0.2) Last updated 2008/3/12

CONFIDENTIAL Copyright © 2002 LG Electronics Inc. All rights reserved

LGMM2104M Class D Mono Audio Amp

The information contained herein is subject to change without notice. The information contained herein is presented only as a guide for the applications of our products.

No

responsibility is assumed by LG for any infringements of patents or other rights of the third parties that may result from its use. No license is granted by implication or otherwise under any patent or patent rights of LG or others. These LG products are intended for usage in general electronic equipment (office equipment, communication equipment, measuring equipment, domestic electrification, etc.). Please make sure that you consult with us before you use these LG products in equipment that require high quality and / or reliability, and in equipment that could have major impact to the welfare of human life (atomic energy control, airplane, spaceship, traffic signal, combustion control, all types of safety devices, etc.). LG cannot accept liability to any damage which may occur in case these LG products were used in the mentioned equipment without prior consultation with LG.

ⓒ 2004 LG Electronics Inc.

All Rights Reserved

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LGMM2104M Class D Mono Audio Amp REVISION HISTORY REVISION #

DATE

CHANGE DESCRIPTION

Preliminary

2007. 7

The first preliminary datasheet issued

Rev0.1

2007.12.26

Application note attached

Rev0.2

2008.3.12

Evauation Board Information attached

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Table of Contents 1

General Description .................................................................. 6

2

Electrical Characteristics .......................................................... 7

3

Block Diagram .......................................................................... 9

4

Pin Description ......................................................................... 9

5

Typical Performance Characteristics ...................................... 10

6

Applications Information ....................................................... 13 6.1 General Amplifier Function ............................................. 13 6.2 Spread Spectrum and Self-Oscillation Modulation ...........13 6.3 Input Circuit Configuration ............................................. 14 6.4 Output Circuit Configuration ........................................... 16 6.5 Another Implementation Consideration .......................... 18 6.6 Output Measurement Environment ................................. 18 6.7 Reference Evaluation board Layout and Schematic ........ 19 6.8 Package Outline Drawing................................................. 20

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1. General Description

Features

Descriptions

- Supply Voltage Range: 2.5~5.5V

The LGMM2104M is a high efficiency filter-free class-D audio power amplifier of delivering 2.6W of continuous average power to a 4 Ω from a 5.5V supply in a Bridge Tied Load (BTL) configuration. Under same conditions, the amplifier can provide 1.4W to an 8 BTL load with less than 1% THD+N. For portable applications it offers space and cost savings because no output filter is required when using inductive speakers. With more than 90% efficiency and very low shutdown current, it increases the life time of your battery. The LGMM2104M processes analog inputs with the unique pulse-width modulation method that lowers output noise and EMI. The gain can be reduced by external input resistors. The LGMM2104M provides thermal and short circuit protection.

- High Efficiency up to 90% - Low Power consumption - Shutdown Current: < 1uA - Quiescent Current: ~2mA

- High Audio Performance - THD+N: < 0.01% - Maximum Output Power: 2.65W

- Low-EMI: Unique PWM Control Method - Default Gain 24dB - Short & Thermal Protection - “Pop and Click” Noise Suppression - Pb-Free Packages are Available

Applications Package Info.

- Cellular Phones - MP3 Players

- 8Pin DFN 2x2 mm (available)

- PDAs and Smart Phones

- 9Pin WCSP 1.45x1.45mm (Under Development)

- Portable Audio

Application Circuit Pin Configuration

LGMM2104M

LGMM2104M

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2. Electrical Characteristcs Absolute Maximum Ratings Over operating free-air temperature range unless otherwise noted

Symbol VDD IP/IM TA TJ Tstg

Rating Supply Voltage Input Voltage Operating free-air temperature range Operating junction temperature range Storage temperature range ESD Protection Human Body Model (HBM) (Note 1) Machine Model (MM) (Note2)

Max 6 -0.3 to VDD+0.3 -40 to 85 -40 to 150 -65 to 85

Unit V V °C °C c

>2000 >200

V

Stresses exceeding those listed under absolute maximum ratings may cause permanent damage to device. 1. Human Body Model: 100pF discharged through a 1.5k resistor following specification JESD22/A114. 2. Machine Model: 200pF discharged through all pins following specification JESD22/A115.

Recommended Operating Conditions Symbol VDD VIH VIL VIC TA

Rating Supply Voltage Low-level input Voltage ( SD ) Low-level input Voltage ( SD ) Common mode input voltage Operating free-air temperature range

MIN 2.5 1.3

MAX 5.5 VDD

Unit V V

0

0.3

V

0.5 -40

VDD-0.8 85

V °C

Electrical Characteristics Parameter Operating Supply Voltage Supply Quiescent Current

Symbol VDD IQ

Shutdown Current Switching Frequency

ISD FSW

Output offset Voltage

|VOC|

Power Supply Rejection Ratio

PSRR

Common-mode Rejection Ratio

CMRR

Conditions TA=-40 °C to +85 °C VDD=5.5V, No load VDD=3.6V,No load VDD=2.5V,No load VDD=2.5V to 5.5V

MIN 2.5

MAX 5.5 3 2 1.8 1

Unit V mA

25

mV

-60

dB

-60

dB

380±30% Inputs ac grounded, AV=6dB VDD=2.5 to 5.5V Inputs shorted together VDD=2.5 to 5.5V

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µA kHz


Operating Characteristics Parameter Output power

Symbol POUT

Conditions Load=4Ω, Fin=1kHz, THD+N=1%

Load=8Ω, Fin=1kHz, THD+N=1%

Total harmonic distortion plus noise

THD+N

Signal-to-noise ratio Output voltage noise

SNR

Efficiency

η

Thermal Shutdown Temperature

VN

TSD

TYP VDD=2.5

MAX 0.5

VDD=3.6

1.1

VDD=5.5 VDD=2.5

2.6 0.31

VDD=3.6

0.7

VDD=5.5 VDD=5.5V, Fin=1kHz, Load=8Ω, POUT=1W VDD=3.6V, Fin=1kHz, Load=8Ω, POUT=0.5W VDD=2.5V, Fin=1kHz, Load=8Ω, POUT=0.2W VDD=5V, POUT=1W, Load=8Ω, A weighted noise VDD=3.6V, Fin=20Hz to 20kHz, No weighting Inputs AC grounded with A weighting CIN=1uF VDD=5.5V VDD=3.6V Load=8Ω VDD=2.5V VDD=5.5V Load=4Ω VDD=3.6V VDD=2.5V Inputs ac grounded, AV=6dB

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Unit

W

1.6 0.01 0.01 0.01

% 100

dB

50 40 91 90 89 86 84 81 150

µVRMS

%

°C


3. Block Diagram VDD IP

Pre-Amplifier & Gain Adjust

SD

Output Driver

Gate Driver

Output Driver

PWM Modulator

IM

Click & Pop Suppression

Gate Driver

Bias/Reference

SD

I/O I I I I O O I

PIN 1,5 7 2 3 8 6 4

(Thermal/ Overcurrent/ LVP)

Description Power Supply Voltages Power Ground Voltages Positive Audio Signal Negative Audio Signal Positive Output Negative Output Shutdown Control Signal(Active low)

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OM

Protection Circuit

4. Pin Description Name VDD VSS IP IM OP OM

OP

VSS


5. Typical Performance Characteristics 1. Frequency Response

Frequency Response +25

Gain [dB]

+20 +15 +10 +5 +0

20

50

100

200

500

1k

Frequency[Hz]

2. THD+N vs. Output Power

RL=8Ω VDD=5.5V VDD=3.6V VDD=2.5V

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2k

5k

10k

20k

LGMM2104M Class D Mono Audio Amp 3. THD+N vs. Frequency THD+N vs. Frequency, RL = 8 ohm 10 5 2

: VDD=5.6V, Output Power = 500mW : VDD=3.6V, Output Power = 400mW : VDD=2.5V, Output Power = 200mW

1

THD+N [%]

0.5 0.2 0.1 0.05 0.02 0.01 0.005 0.002 0.001 20

50

100

200

500

1k

Frequency [Hz]

[dBV]

4. Output Noise Spectrum [55uVrms]

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2k

5k

10k

20k

LGMM2104M Class D Mono Audio Amp 5. Output power vs. Efficiency

VDD=2.5V

VDD=3.6V

VDD=5.0V

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6. APPICATION INFORMATION 6.1 General Amplifier Function

[Fig1. LGMM2104M Class-D Audio Amplifier basic block diagram] The LGMM2104M is a fully differential input/output amplifier and features a filter-less self oscillation (not using internal oscillator) and spread spectrum modulation scheme. The LGMM2104M requires input resistors for gain selections. The differential outputs (OP and ON) switch at about 380KHz from VDD to GND. When there is no input signal, the duty cycle of two outputs (OP and ON) is 50% in phase. Two signals cancel each other because of differential output. When there is input signal, the each pulse width of output signals (OP and ON) is changing depending on input signal amplitude. The difference of two output signals yields the differential output voltage.

6.2 Spread Spectrum and Self-Oscillation Modulation The LGMM2104M features a filter-less spread spectrum and self-oscillation modulation scheme that eliminates the need for output filter. The switching frequency varies by -40% below 400KHz frequency depending on input signal amplitude, improving EMI emissions radiated by the speaker, associated cables and traces. The spread spectrum architecture of LGMM2104M spreads the energy across larger bandwidth. So switching carrier frequency does not affect the audio reproduction. And self-oscillation scheme does not require internal oscillation, so LGMM2104M is effectively circuit designed.

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LGMM2104M Class D Mono Audio Amp 6.3 Input Circuit Configuration Differential Input Configuration VDD C1 R1 IP IM

Figure2 shows the normal LGMM2104M differential

OP

input configuration. But if the design uses a

VSS

LGMM2104M CPA011M

C1 R1 SD

differential source that is biased with common- mode

OM VDD

Audio Output

input voltage range, input coupling capacitors are not

C3

required.

[Fig2. LGMM2104M Differential Input Config.] The external resistors must be placed close to IP and IM for gain setting. Default gain Av (R1 =0 Ω) is 24dB ( x16 ).

AV =

2 × 80 K Ω ( R1 + 10 K Ω )

Single Ended Input Configuration

Audio Input

VDD C1 R1 IP IM C1 R1 SD

The LGMM2104M can be configured as a

OP

LGMM2104M CPA011M

single-ended amplifier but input capacitors are

VSS

needed to block any DC at input terminal. The

OM VDD C3

Audio Output

value of input capacitor is important to consider as it directly affects the low frequency performance.

[Fig3. LGMM2104M Single-Ended Input Config.#1]

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LGMM2104M Class D Mono Audio Amp To improve audio sound quality at VDD C1 R1 IP

Input Mono Ground

IM

IM(Negative input pin) had better

VSS

LGMM2104M CPA011M

connect with ground of CODEC chip.

OM

C1 R1

VDD

SD

CODEC Chip

single-ended input configuration,

OP

Audio Output

That is, noise signal of CODEC chip

C3

flows to audio amplifier, then the noise signal at LGMM2104M can be

[Fig4. LGMM2104M Single-Ended Input Config.#2]

crossly cancelled. If IM is

separately grounded with CODEC chip, the noise signal of CODEC chip to IP(Positive input pin) can be amplified.

Input Filter Design

R1

C1

Input Signal

VDD

C2

R2

IP

Ri

IM

R1

C1

C2

Input filter can be sometimes be

VSS

designed

OM

Ri

R2

OP

SD

VDD

consumption

Audio Output

for and

reducing improving

current sound

quality because there are generally the

C3

constraints of overall system and the actual frequency band of interest.

[Fig5. LGMM2104M Filter Design Config.] Althougn high-fidelity audio reproduction needs a flat gain response between 20Hz and 20KHz, portable devices such as cellular phone need only limited frequency audio band reproduction because of poor frequency response of speaker unit below 150Hz.

f LF ≈

1 2π R1C1

f HF ≈

1 2π ( Ri + R 2)C 2

The value of Ri is 10KΩ

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LGMM2104M Class D Mono Audio Amp 6.4 Output Circuit Configuration Output Line Placement The LGMM2104M does not require an output filter (filter-less scheme) and has the high EMI immunity characteristics.

P C B R o u tin g

S p e a k e r W ire

N o t G o o d R o u tin g

N o rm a l R o u tin g

B e s t R o u tin g

[Fig6. Output Line Description to reduce EMI] To reduce the EMI, it is important that speaker line is twisted, shielded or closely paralleled.

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LGMM2104M Class D Mono Audio Amp Output Filter But if failing radiated emission testing without LC filter, a ferrite bead can be often used in the design. The traces from amplifier to speaker must be usually shorter because the line is functioning like RF antenna. If choosing a ferrite bead, choose one

Ferrite Bead

OP

with high impedance at high frequency, but

C

very

frequencies. OM

Ferrite Bead

[Fig7. Typical Ferrite Bead Filter]

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low

impedance

at

low

LGMM2104M Class D Mono Audio Amp 6.5 Another Implementation Consideration The external components like resistor and capacitor must be closely placed to audio amplifier. The traces between amplifier and external components distort the audio input signal and affect the power drop or fluctuation. The use of power and ground planes will give the best THD+N performance. While reducing trace resistance, the parasitic capacitors between power and ground help to filter power supply line. The output signal line must be considered to be safely separated from another signal line. Sometimes the output line affects badly another chip’s signal lines.

6.6 Output Measurement Environment

Power Supply or Battery

Oscilloscope

Current Mesurement

Hearing Test

Audio Precision

Audio Precision

R1

Audio Source

IP

1k

OP

Audio AMP IM

C5 4.7nF C4

OM Audio Output

R2 4.7nF

Oscilloscope

1k

Media Chipset Measurement Filter

Evaluation Board

[Fig8. Test Setup Environment]

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Mutimeter

LGMM2104M Class D Mono Audio Amp 6.7 REFERENCE EVALUATION BOARD LAYOUT and SCHEMATIC EVM Board component placement and Board Layer

< Top Placement >

Parts Descriptions Parts C1/C2

Parameter

Descriptions

Ceramic 1uF 0603 X7R Top place

Input DC coupling

CLPF1/CLPF2

Ceramic 4.7nF 0603 X7R Top place

Measurement filter

C3

Ceramic 0.1uF 0603 X7R Top place

Power noise reduction

C4

Tantal 10uF 0603 X7R Top place

Power noise reduction

Chip 1KΩ 0603 5% Top Place

Measurement filter

100Ω 0603 5% Top Place

Gain Control Resistor

RLPF1/RLPF2 R1/R2

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LGMM2104M Class D Mono Audio Amp 6.8 Package Outline Drawing - 8Pin DFN 2x2 mm (Lead Pitch 0.50mm)

[ Side View ]

[ Bottom View ]

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Class D Audio Amp - CS&S electronic

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