NSC LM49270SQX, LM49270 Datasheet

December 2006

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

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 I2C 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 I2C 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.

Key Specifications

■ Stereo Class D Amplifier Efficiency:

= 3.3V, 450mW/Ch into 8Ω

84%

= 5V, 1W/Ch into 8Ω

84%

■ Quiescent Power Supply Current, V

= 3.3V

Speaker Mode 5.5mA

Headphone Mode (OCL) 4mA

■ Power Output/Channel, V

= 5V

Class D Speaker amplifier:

RL = 4Ω, THD+N = ≤ 10%

2.2W

RL = 8Ω, THD+N = ≤ 1%

1.06W

Headphone amplifier:

RL = 16Ω, THD+N = ≤ 1%

155mW

RL = 32Ω, THD+N = ≤ 1%

90mW

■ Shutdown current

0.02μA

Features

■

Stereo filterless Class D amplifier

■

Selectable OCL/CC headphone amplifier

■

Headphone sense ability

■

National’s 3D Enhancement

■

RF suppression

■

I2C 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

Applications

■

Portable DVD players

■

Smart phones

■

PDAs

■

Laptops

Boomer® is a registered trademark of National Semiconductor Corporation.

LM49270 Filterless 2.2W Stereo Class D Audio Subsystem with OCL Headphone Amplifier, 3D

Enhancement, and Headphone Sense

Typical Application

20212994

FIGURE 1. Typical Audio Amplifier Application Circuit

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LM49270

Connection Diagrams

SQ Package

5mm x 5mm x 0.8mm

20212990

Top View

Order Number LM49270SQ

See NS Package Number NSQAQ028

SQ Markings

20212901

Top View

NS = National Logo

U = Fab Code

Z = Assembly Plant

XY = 2 Digit date code

TT = Die Traceability

49270SQ = LM49270SQ

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LM49270

TABLE 1. Pin Descriptions

PIN NAME DESCRIPTION

1 RHP Right channel headphone output

2 VOC VDD/2 buffer output

3 LHP Left channel headphone output

4 HPV

Headphone supply input

5 R3DIN Right channel 3D input

6 L3DIN Left channel 3D input

7 BYPASS Bias bypass

8 LIN Left channel input

9 RIN Right channel input

10 GND Analog ground

11 NC No connect

12 LSV

Speaker supply voltage input

13 RLS+ Right channel non-inverting speaker output

14 RLS- Right channel inverting speaker output

15 NC No connect

16 NC No connect

17 I2CV

I2C supply voltage input

18 LSGND Speaker ground

19 V

Power supply

20 ADR Address

21 NC No connect

22 LLS- Left channel inverting speaker output

23 LLS+ Left channel non-inverting speaker output

24 LSV

Speaker supply voltage input

25 SDA Serial data input

26 SCL Serial clock input

27 HPS Headphone sense input

28 GND Headphone ground

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LM49270

Absolute Maximum Ratings (Notes 1, 2)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Supply Voltage (Note 1) 6.0V Storage Temperature −65°C to +150°C Input Voltage –0.3V to VDD +0.3V

Power Dissipation (Note 3) Internally Limited ESD Susceptibility(Note 4) 2000V ESD Susceptibility (Note 5) 200V Junction Temperature (T

JMAX

)

150°C

Thermal Resistance

35.1°C/W

Operating Ratings (Notes 1, 2)

Temperature Range

MIN

≤ TA ≤ T

MAX

−40°C ≤ TA ≤ 85°C

Supply Voltage (VDD, LSVDD, HPVDD)

2.4V ≤ VDD ≤ 5.5V

I2C Voltage (I2CVDD)

2.4V ≤ I2CVDD ≤ 5.5V

Electrical Characteristics VDD = 3.3V (Notes 1, 2) The following specifications apply for Headphone:

AV = 0dB, R

L(HP)

= 32Ω; for Loudspeakers: AV = 6dB, R

L(SP)

= 15μH + 8Ω + 15μH , f = 1kHz, unless otherwise specified. Limits

apply for TA = 25°C.

Symbol Parameter Conditions

LM49270

Units

(Limits)

Typical Limit

(Note 6) (Notes 7, 8)

Supply Current

VIN = 0, RL = No Load, Both channels active Speaker ON, HP OFF Speaker OFF, CC HP ON Speaker OFF, OCL HP ON

5.5 3 4

7.6

4.7

5.75

mA (max) mA (max) mA (max)

Shutdown Supply Current 0.02 2

μA (max)

Output Offset Voltage

Headphone Speaker

10 10

25 60

mV (max) mV (max)

OUT

Output Power

Speaker Mode, f = 1kHz

THD+N = 1%

RL = 4Ω

RL = 8Ω

700 450 400

mW (min)

THD+N = 10%

RL = 4Ω

RL = 8Ω

870 560

mW mW

CC Headphone Mode, f = 1kHz

THD+N = 1%

RL = 16Ω

RL = 32Ω

60 36 30

mW (min)

THD+N = 10%

RL = 16Ω

RL = 32Ω

74 55

mW mW

OCL Headphone Mode, f = 1kHz

THD+N = 1%

RL = 16Ω

RL = 32Ω

60 36 30

mW (min)

THD+N = 10%

RL = 16Ω

RL = 32Ω

73 55

mW mW

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LM49270

Symbol Parameter Conditions

LM49270

Units

(Limits)

Typical Limit

(Note 6) (Notes 7, 8)

THD+N Total Harmonic Distortion + Noise

Speaker Mode, f = 1kHz

OUT

= 100mW, RL = 8Ω

0.02

CC Headphone Mode, f = 1kHz

OUT

= 12mW, RL = 32Ω

0.015

OCL Headphone Mode, f = 1kHz

OUT

= 12mW, RL = 32Ω

0.02

Noise

Speaker Mode, A-Wtg, Input Referred

μV

CC Headphone Mode, A-Wtg, Input Referred

μV

OCL Headphone Mode, A-Wtg, Input Referred

μV

Efficiency

Speaker Mode

RL = 8Ω

84 %

Xtalk Crosstalk

Speaker Mode, f = 1kHz, VIN = 1Vp-p

71 dB

CC Headphone Mode, f = 1kHz, VIN = 1Vp-p

70 dB

OCL Headphone Mode, f = 1kHz, VIN = 1Vp-p

55 dB

Turn-on Time

30 ms

OFF

Turn-off Time

64 ms

Input Impedance

Maximum Gain

23.5

kΩ

Minimum Gain

210

kΩ

Gain

Maximum Gain, Speaker Mode 30 dB

Minimum Gain, Speaker Mode –47 dB

Maximum Gain, Headphone Mode 18 dB

Minimum Gain, Headphone Mode –59 dB

PSRR Power Supply Rejection Ratio

Speaker Mode, V

RIPPLE

= 200mVp-p Sine f = 217Hz f = 1kHz

68 68

dB dB

Headphone Mode, V

RIPPLE

= 200mVp-p Sine, CC Mode f = 217Hz f = 1kHz

73 73

dB dB

Headphone Mode, V

RIPPLE

= 200mVp-p Sine, OCL Mode f = 217Hz f = 1kHz

75 79

dB dB

HPS

(Th)

Headphone Sense Threshold

Detect Headphone 2.9 V (min)

Detect no Headphone 1.8 V (max)

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LM49270

Electrical Characteristics VDD = 5.0V (Notes 2, 1) The following specifications apply for Headphone”

AV = 0dB, R

L(HP)

= 32Ω,: for Loudspeakers: AV = 6dB, R

L(SP

) = 15μH + 8Ω + 15μH, f = 1kHz unless otherwise specified. Limits

apply for TA = 25°C.

Symbol Parameter Conditions

LM49270

Units

(Limits)

Typical Limit

(Note 6) (Notes 7, 8)

Supply Current

VIN = 0, RL = No Load, Both channels active Speaker ON, HP OFF Speaker OFF, CC HP ON Speaker OFF, OCL HP ON

8.5

3.6

4.7

12.4

5.5

6.5

mA (max) mA (max) mA (max)

Shutdown Supply Current 0.15 2

μA (max)

Output Offset Voltage

Headphone Speaker

10 10

25 60

mV (max) mV (max)

OUT

Output Power

Speaker Mode, f = 1kHz,

THD+N = 1%

RL = 4Ω

RL = 8Ω

1.75

1.06

W W

THD+N = 10 %

RL = 4Ω

RL = 8Ω

2.2

1.35

W W

CC Headphone Mode, f = 1kHz,

THD+N = 1%

RL = 16Ω

RL = 32Ω

155

mW mW

THD+N = 10%

RL = 16Ω

RL = 32Ω

177 140

mW mW

OCL Headphone Mode, f = 1kHz,

THD+N = 1%

RL = 16Ω

RL = 32Ω

155

mW mW

THD+N = 10%

RL = 16Ω

RL = 32Ω

175 140

mW mW

THD+N

Total Harmonic Distortion + Noise

Speaker Mode, f = 1kHz

OUT

= 100mW, RL = 8Ω

0.03

CC Headphone Mode, f = 1kHz

OUT

= 12mW, RL = 32Ω

0.02

OCL Headphone Mode, f = 1kHz

OUT

= 12mW, RL = 32Ω

0.03

Noise

Speaker Mode, A-Wtg, Input Referred

μV

CC Headphone Mode, A-Wtg, Input Referred

μV

OCL Headphone Mode, A-Wtg, Input Referred

μV

Efficiency

Speaker Mode

RL = 8Ω

84 %

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LM49270

Symbol Parameter Conditions

LM49270

Units

(Limits)

Typical Limit

(Note 6) (Notes 7, 8)

Xtalk Crosstalk

Speaker Mode, f = 1kHz, VIN = 1Vp-p

–85 dB

CC Headphone Mode, f = 1kHz, VIN = 1Vp-p

–70 dB

OCL Headphone Mode, f = 1kHz, VIN = 1Vp-p

–58 dB

Turn-on Time

43 ms

OFF

Turn-off Time

100 ms

Input Impedance

Maximum Gain

23.5

kΩ

Minimum Gain

210

kΩ

Gain

Maximum Gain, Speaker Mode 30 dB

Minimum Gain, Speaker Mode –47 dB

Maximum Gain, Headphone Mode 18 dB

Minimum Gain, Headphone Mode –59 dB

PSRR Power Supply Rejection Ratio

Speaker Mode, V

RIPPLE

= 200mVp-p Sine f = 217Hz f = 1kHz

61 61

dB dB

Headphone Mode, V

RIPPLE

= 200mVp-p Sine, CC Mode f = 217Hz f = 1kHz

75 74

min

Headphone Mode, V

RIPPLE

= 200mVp-p Sine, OCL Mode f = 217Hz f = 1kHz

78 75

dB dB

HPS

(Th)

Headphone Sense Threshold

Detect Headphone 4.4 V (min)

Detect no Headphone 3 V (max)

Note 1: All voltages are measured with respect to the ground pin, unless otherwise specified.

Note 2: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

functional, but do not guarantee specific performance limits. Electrical Characteristics state DC and AC electrical specifications under particular test conditions which guarantee specific performance limits. This assumes that the device is within the Operating Ratings. Specifications are not guaranteed for parameters where no limit is given, however, the typical value is a good indication of device performance.

Note 3: The maximum power dissipation must be derated at elevated temperatures and is dictated by T

JMAX

, θJA, and the ambient temperature, TA. The maximum

allowable power dissipation is P

DMAX

= (T

JMAX

– TA)/ θJA or the number given in Absolute Maximum Ratings, whichever is lower. For the LM49270 see power

derating currents for more information.

Note 4: Human body model, 100pF discharged through a 1.5kΩ resistor.

Note 5: Machine Model, 220pF–240pF discharged through all pins.

Note 6: Typicals are measured at 25°C and represent the parametric norm.

Note 7: Limits are guaranteed to National's AOQL (Average Outgoing Quality Level).

Note 8: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

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LM49270

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