NSC LM4895MWC, LM4895MM, LM4895MDC, LM4895LDX, LM4895LD Datasheet

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LM4895

1 Watt Fully Differential Audio Power Amplifier With Shutdown Select and Fixed 6dB Gain

General Description

The LM4895 is a fully differential audio power amplifier primarily designed for demanding applications in mobile phones and other portable communication device applications. It is capable of delivering 1 watt of continuous average power to an 8Ω 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 LM4895 does not require output coupling capacitors or bootstrap capacitors, and therefore is ideally suited for mobile phone and other low voltage applications where minimal power consumption is a primary requirement.

The LM4895 features a low-power consumption shutdown mode. To facilitate this, Shutdown may be enabled by either logic high or low depending on mode selection. Driving the shutdown mode pin either high or low enables the shutdown select pin to be driven in a likewise manner to enable Shutdown. Additionally, the LM4895 features an internal thermal shutdown protection mechanism.

The LM4895 contains advanced pop & click circuitry which eliminates noises which would otherwise occur during turn-on and turn-off transitions.

The LM4895 has an internally fixed gain of 6dB.

Key Specifications

Improved PSRR at 217Hz 80dB

Power Output at 5.0V & 1% THD 1.0W(typ.)

Power Output at 3.3V & 1% THD 400mW(typ.)

Shutdown Current 0.1µA(typ.)

Features

n Fully differential amplification n Internal-gain-setting resistors n Available in space-saving packages micro SMD, MSOP

and LLP

n Ultra low current shutdown mode n Can drive capacitive loads up to 500 pF n Improved pop & click circuitry eliminates noises during

turn-on and turn-off transitions

n 2.2 - 5.5V operation n No output coupling capacitors, snubber networks or

bootstrap capacitors required

n Shutdown high or low selectivity

Applications

n Mobile phones n PDAs n Portable electronic devices

Typical Application

Boomer®is a registered trademark of National Semiconductor Corporation.

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FIGURE 1. Typical Audio Amplifier Application Circuit

October 2002

LM4895 1 Watt Fully Differential Audio Power Amplifier With Shutdown Select and Fixed 6dB

Gain

Connection Diagrams

9 Bump micro SMD Package

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Top View

Order Number LM4895IBP

See NS Package Number BPA09CDB

LLP Package

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Top View

Order Number LM4895LD

See NS Package Number LDA10B

Mini Small Outline (MSOP) Package

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Top View

Order Number LM4895MM

See NS Package Number MUB10A

LM4895

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Absolute Maximum Ratings (Note 2)

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

Supply Voltage 6.0V

Storage Temperature −65˚C to +150˚C

Input Voltage −0.3V to V

+0.3V

Power Dissipation (Note 3) Internally Limited

ESD Susceptibility (Note 4) 2000V

ESD Susceptibility (Note 5) 200V

Junction Temperature 150˚C

Thermal Resistance

(LD) 12˚C/W

(LD) 63˚C/W

(micro SMD) 220˚C/W

(MSOP) 56˚C/W

(MSOP) 190˚C/W

Soldering Information

See AN-1112 ’microSMD Wafers Level Chip Scale Package’.

See AN-1187 ’Leadless Leadframe Package (LLP)’.

Operating Ratings

Temperature Range

MIN

≤ TA≤ T

MAX

−40˚C ≤ TA≤ 85˚C

Supply Voltage 2.2V ≤ V

≤ 5.5V

Electrical Characteristics VDD=5V (Notes 1, 2, 8)

The following specifications apply for V

= 5V and 8Ω load unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4895

Units

(Limits)

Typical Limit

(Note 6) (Note 7)

Quiescent Power Supply Current VIN= 0V, Io= 0A 4 8 mA (max)

Shutdown Current V

shutdown

= GND 0.1 1 µA (max)

Output Power

THD = 1% (max);f=1kHz

LM4895LD, RL=4Ω (Note 11) 1.4 W (min)

LM4895, R

=8Ω 1 0.850

THD+N Total Harmonic Distortion+Noise P

= 0.4 Wrms; f = 1kHz 0.1 %

PSRR Power Supply Rejection Ratio

ripple

= 200mV sine p-p

f = 217Hz (Note 9) 84

dB (min)

f =1kHz (Note 9) 80

f = 217Hz (Note 10) 80 60

f =1kHz (Note 10) 77

CMRR Common-Mode Rejection Ratio f =217Hz 50 dB

Electrical Characteristics VDD=3V (Notes 1, 2, 8)

The following specifications apply for V

= 3V and 8Ω load unless otherwise specified. Limits apply for TA= 25˚C.

Symbol Parameter Conditions

LM4895

Units

(Limits)

Typical Limit

(Note 6) (Note 7)

Quiescent Power Supply Current VIN= 0V, Io= 0A 3.5 6 mA (max)

Shutdown Current V

shutdown

= GND 0.1 1 µA (max)

Output Power THD = 1% (max); f = 1kHz 0.35 W

THD+N Total Harmonic Distortion+Noise P

= 0.25Wrms; f = 1kHz 0.325 %

PSRR Power Supply Rejection Ratio

ripple

= 200mV sine p-p

f = 217Hz (Note 9) 84

f = 1kHz (Note 9) 80

f = 217Hz (Note 10) 77

f = 1kHz (Note 10) 75

CMRR Common-Mode Rejection Ratio f = 217Hz 49 dB

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

LM4895

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Electrical Characteristics VDD=3V(Notes 1, 2, 8)

The following specifications apply for V

= 3V and 8Ω load unless otherwise specified. Limits apply for TA=

25˚C. (Continued)

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 andAC 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

)/θJAor the number given inAbsolute Maximum Ratings, whichever is lower. For the LM4895, see power derating

currents for additional 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: Datasheet min/max specification limits are guaranteed by design, test, or statistical analysis.

Note 8: For micro SMD only, shutdown current is measured in a Normal Room Environment. Exposure to direct sunlight will increase I

by a maximum of 2µA.

Note 9: Unterminated input.

Note 10: 10Ω terminated input.

Note 11: When driving 4Ω loads from a 5V supply, the LM4895LD must be mounted to a circuit board.

External Components Description (Figure 1)

Components Functional Description

1. C

Supply bypass capacitor which provides power supply filtering. Refer to the Power Supply Bypassing section for information concerning proper placement and selection of the supply bypass capacitor.

2. C

Bypass pin capacitor which provides half-supply filtering. Refer to the section, Proper Selection of External Components, for information concerning proper placement and selection of C

Typical Performance Characteristics LD Specific Characteristics

LM4895LD

THD+N vs Output Power

= 5V, 4Ω R

LM4895LD

THD+N vs Frequency

= 5V, 4Ω RL, and Power = 1W

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LM4895

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Typical Performance Characteristics LD Specific Characteristics

(Continued)

LM4895LD

Power Dissipation vs Output Power

LM4895LD

Power Derating Curve

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Typical Performance Characteristics Non-LD Specific Characteristics

THD+N vs Frequency

at V

= 5V, 8Ω RL, and PWR = 400mW

THD+N vs Frequency

VDD= 3V, 8Ω RL, and PWR = 250mW

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THD+N vs Frequency

at V

= 3V, 4Ω RL, and PWR = 225mW

THD+N vs Frequency

VDD= 2.6V, 8Ω RL, and PWR = 150mW

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