LM49270 - Filterless 2.2W Class D Audio Subsystem with OCL Headphone Amplifier, 3D Enhancement, and Headphone Sense

Datasheet	Packaging	Samples & Pricing	Eval. Boards	Knowledge Base

Features

•	Stereo filterless Class D amplifier
•	Selectable OCL/CC headphone amplifier
•	Headphone sense ability
•	National’s 3D Enhancement
•	RF suppression
•	I 2C control interface
•	32-step digital volume control
•	6 Operating Modes
•	Output short circuit protection and thermal shutdown protection
•	Minimum external components
•	Click and Pop suppression
•	Micro-power shutdown
•	Independent speaker and headphone volume controls
•	Available in space-saving 28 pin LLP package

Key Specification

■ Stereo Class D Amplifier Efficiency:
V_DD = 3.3V, 450mW/Ch into 8Ω	84%
V_DD = 5V, 1W/Ch into 8Ω	84%
■ Quiescent Power Supply Current, V_DD = 3.3V
Speaker Mode	5.5mA
Headphone Mode (OCL)	4mA
■ Power Output/Channel, V_DD = 5V
Class D Speaker amplifier:
R_L = 4Ω, THD+N = ≤ 10%	2.2W
R_L = 8Ω, THD+N = ≤ 1%	1.06W
Headphone amplifier:
R_L = 16Ω, THD+N = ≤ 1%	155mW
R_L = 32Ω, THD+N = ≤ 1%	90mW
■ Shutdown current	0.02μA

General Description

The LM49270 is a fully integrated audio subsystem designed for stereo multimedia applications. More...

Applications

•	Portable DVD players
•	Smart phones
•	PDAs
•	Laptops

Typical Application

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Parameters Values

Power@ 4Ohms, 10% THD 0.87 Watt

Power@ 4Ohms, 1% THD 0.7 Watt

Power@ 8Ohms, 10% THD 0.56 Watt

Power@ 8Ohms, 1% THD 0.45 Watt

THD 0.02 %

PSRR 75 dB

SNR Undefined dB

Channels 4 Channels

THD Conditions Pout = 12mW, RL=32ohm, OCL mode

PSRR Conditions f=217Hz, Vripple = 200mVpp, HP OCL mode

SNR Conditions Undefined

User Supply 3.3 Volt

Audio Mux Yes

Capless Headphone Yes

ClassD Driver Yes

Interface I2C

Stereo Inputs 1

National 3D Yes

Digital Volume Control Max 18 dB

Digital Volume Control Min -59 dB

Output Modes 6

Supply Range +2.4 - +5.5 V

Mono Inputs 0

Temperature Min -40 deg C

Temperature Max 85 deg C

Loudspeaker Type Class D

Headphone Type Virtual Ground

Loudspeaker Outputs 2

Typical Performance

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Connection Diagram

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Datasheet

RoHS Compliance Information	Size in Kbytes	Date
LM49270 Filterless 2.2W Stereo Class D Audio Subsystem with OCL Headphone Amplifier, 3D Enhancement, and Headphone Sense	2575 Kbytes	17-Mar-07	Download

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Package Availability, Models, Samples & Pricing

Part Number

Package

Factory Lead Time

Models

Samples &
Electronic
Orders

Budgetary Pricing

Std
Pack
Size

Package
Marking
Format

Type

Pins

Spec.

MSL
Rating

Peak
Reflow

RoHS
Report

CAD
Symbols

Weeks

Qty

$US each

LM49270SQEVAL

LM49270SQEVAL Evaluation Board

Preliminary

N/A

CALL

N/A

LM49270SQE

LLP

NOPB

260

RoHS

N/A

Full production

N/A

1K+

$2.45

reel
of
250

NS
UZXYTT
49270SQ

6 weeks

N/A

LM49270SQ

LLP

NOPB

260

RoHS

N/A

Full production

N/A

1K+

$2.45

reel
of
1000

NS
UZXYTT
49270SQ

6 weeks

N/A

LM49270SQX

LLP

NOPB

260

RoHS

N/A

Full production

N/A

1K+

$2.45

reel
of
4500

NS
UZXYTT
49270SQ

6 weeks

N/A

General Description

The LM49270 is a fully integrated audio subsystem designed for stereo multimedia applications. The LM49270 combines a 2.2W stereo Class D amplifier with a 155mW stereo headphone amplifier, volume control, headphone sense, and National’s unique 3D sound enhancement into a single device. The LM49270 uses flexible I 2C control interface for multiple application requirements.

The filterless stereo class D amplifiers delivers 2.2W/channel into a 4Ω load with less than 10% THD+N with a 5V supply. The headphone amplifier features National’s Output Capacitor-less (OCL) architecture that eliminates the output coupling capacitors required by traditional headphone amplifiers.

The IC features a headphone sense input (HPS) that automatically detects the presence of a headphone and configures the device accordingly. The LM49270 can automatically switch from OCL headphone output to a line driver output. If the VOC pin is pulled to GND, the VOC amplifier is disabled and the VOC pin is internally set to GND. This feature allows the LM49270 to be used as a line driver in OCL mode without a GND conflict on the headphone jack sleeve. Additionally, the headphone amplifier can be configured as capacitively coupled (CC).

The LM49270 features a 32 step volume control for the headphone and stereo outputs. The device mode select and volume are controlled through an I 2C compatible interface.

Output short circuit and thermal shutdown protection prevent the device from being damaged during fault conditions. Superior click and pop suppression eliminates audible transients on power-up/down and during shutdown. The LM49270 is available in a space saving 28-pin, 5x5mm LLP package.

Application Notes

Title	Size in Kbytes	Date
AN-1638: Application Note 1638 LM49270 Demonstration Board	321 Kbytes	24-May-07	Download
AN-1638 (Chinese): Application Note 1638 LM49270 Demonstration Board	550 Kbytes

If you have trouble printing or viewing PDF file(s), see Printing Problems.

[Information as of 7-Nov-2009]