LM4819MX/NOPB - National Semiconductor

LM4819

LM4819 350mW Audio Power Amplifier with Shutdown Mode

Literature Number: SNAS133C

LM4819

350mW Audio Power Amplifier with Shutdown Mode

General Description

The LM4819 is a mono bridged power amplifier that is ca-

pable of delivering 350mW

RMS

output power into a 16Ωload

or 300mW

RMS

output power into an 8Ωload with 10%

THD+N from a 5V power supply.

The LM4819 Boomer audio power amplifier is designed

specifically to provide high quality output power and mini-

mize PCB area with surface mount packaging and a minimal

amount of external components. Since the LM4819 does not

require output coupling capacitors, bootstrap capacitors or

snubber networks, it is optimally suited for low-power por-

table applications.

The closed loop response of the unity-gain stable LM4819

can be configured using external gain-setting resistors. The

device is available in LLP, MSOP, and SO package types to

suit various applications.

Key Specifications

nTHD+N at 1kHz, 350mW continuous average output

power into 16Ω10% (max)

nTHD+N at 1kHz, 300mW continuous average output

power into 8Ω10% (max)

nShutdown Current 0.7µA (typ)

Features

nLLP, SOP, and MSOP surface mount packaging.

nSwitch on/off click suppression.

nUnity-gain stable.

nMinimum external components.

Applications

nGeneral purpose audio

nPortable electronic devices

nInformation Appliances (IA)

Typical Application

Boomer®is a registered trademark of National Semiconductor Corporation.

20013601

FIGURE 1. Typical Audio Amplifier Application Circuit

April 2002

LM4819 350mW Audio Power Amplifier with Shutdown Mode

Connection Diagrams

Small Outline (SO) Package Mini Small Outline (MSOP) Package

20013635

Top View

Order Number LM4819M

See NS Package Number M08A

20013636

Top View

Order Number LM4819MM

See NS Package Number MUA08A

LLP Package SO Marking

20013674

Top View

Order Number LM4819LD

See NS Package Number LDA08B

20013672

Top View

XY - Date Code

TT - Die Traceability

Bottom 2 lines - Part Number

MSOP Marking

20013671

Top View

G - Boomer Family

19 - LM4819MM

LM4819

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Absolute Maximum Ratings (Notes 2, 3)

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 (P

) (Note 4) Internally Limited

ESD Susceptibility (Note 5) 3.5kV

ESD Susceptibility (Note 6) 250V

Junction Temperature (T

) 150˚C

Soldering Information (Note 1)

Small Outline Package

Vapor Phase (60 seconds) 215˚C

Infrared (15 seconds) 220˚C

Thermal Resistance

(MSOP) 56˚C/W

(MSOP) 210˚C/W

(SOP) 35˚C/W

(SOP) 170˚C/W

(LLP) 117˚C/W (Note 10)

(LLP) 150˚C/W (Note 11)

Operating Ratings (Notes 2, 3)

Temperature Range

MIN

≤T

MAX

−40˚C ≤T

≤85˚C

Supply Voltage 2.0V ≤V

≤5.5V

Electrical Characteristics V

=5V (Notes 2, 3)

The following specifications apply for V

= 5V, R

=16Ωunless otherwise stated. Limits apply for T

= 25˚C.

Symbol Parameter Conditions

LM4819 Units

(Limits)

Typical Limit

(Note 7) (Notes 8, 9)

Quiescent Power Supply Current V

= 0V, I

= 0A 1.5 3.0 mA (max)

Shutdown Current V

PIN1

(Note 12) 1.0 5.0 µA (max)

SDIH

Shutdown Voltage Input High 4.0 V (min)

SDIL

Shutdown Voltage Input Low 1.0 V (max)

Output Offset Voltage V

= 0V 5 50 mV (max)

Output Power THD = 10%, f

= 1kHz 350 mW

THD = 10%, f

= 1kHz, R

=8Ω300 mW

THD+N Total Harmonic Distortion + Noise P

= 270mW

RMS

=2,f

1kHz

Electrical Characteristics V

=3V (Notes 2, 3)

The following specifications apply for V

= 3V and R

=16Ωload unless otherwise stated. Limits apply to T

= 25˚C.

Symbol Parameter Conditions

LM4819 Units

(Limits)

Typical Limit

(Note 7) (Notes 8, 9)

Quiescent Power Supply Current V

= 0V, I

= 0A 1.0 3.0 mA (max)

Shutdown Current V

PIN1

(Note 12) 0.7 5.0 µA (max)

SDIH

Shutdown Voltage Input High 2.4 V (min)

SDIL

Shutdown Voltage Input Low 0.6 V (max)

Output Offset Voltage V

= 0V 5 50 mV

Output Power THD = 10%, f

= 1kHz 110 mW

THD = 10%, f

= 1kHz, R

=8Ω90 mW

THD+N Total Harmonic Distortion + Noise P

= 80mW

RMS

=2,f

1kHz

Note 1: See AN-450 "Surface Mounting and their Effects on Product Reliability" for other methods of soldering surface mount devices.

Note 2: All voltages are measured with respect to the ground pin, unless otherwise specified.

Note 3: 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’s performance.

Note 4: The maximum power dissipation must be derated at elevated temperatures and is dictated by TJMAX,θJA, and the ambient temperature TA. The maximum

allowable power dissipation is PDMAX =(T

JMAX–TA)/θJA. For the LM4819, TJMAX = 150˚C and the typical junction-to-ambient thermal resistance (θJA) when board

mounted is 210˚C/W for the MSOP package and 170˚C/W for the SOP package.

Note 5: Human body model, 100pF discharged through a 1.5 kΩresistor.

LM4819

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Electrical Characteristics V

=3V(Notes 2, 3)

The following specifications apply for V

= 3V and R

=16Ωload unless otherwise stated. Limits apply to T

25˚C. (Continued)

Note 6: Machine Model, 220pF–240pF capacitor is discharged through all pins.

Note 7: Typical specifications are specified at 25˚C and represent the parametric norm.

Note 8: Tested limits are guaranteed to National’s AOQL (Average Outgoing Quality Level).

Note 9: Datasheet min/max specification limits are guaranteed by designs, test, or statistical analysis.

Note 10: The given θJA is for an LM4819 package in an LDA08B with the Exposed-DAP soldered to a printed circuit board copper pad with an area equivalent to

that of the Exposed-DAP itself. The Exposed-DAP of the LDA08B package should be electrically connected to GND or an electrically isolated copper area.

Note 11: The given θJA is for an LM4819 package in an LDA08B with the Exposed-DAP not soldered to any printed circuit board copper.

Note 12: The shutdown pin (pin1) should be driven as close as possible to VDD for minimum current in Shutdown Mode.

External Components Description (Figure 1)

Components Functional Description

1. R

Combined with R

, this inverting input resistor sets the closed-loop gain. R

also forms a high pass filter with

at f

= 1/(2πR

2. C

This input coupling capacitor blocks DC voltage at the amplifier’s terminals. Combined with R

, it creates a

high pass filter with R

at f

= 1/(2πR

). Refer to the section, Proper Selection of External Components for

an explanation of how to determine the value of C

3. R

Combined with R

, this is the feedback resistor that sets the closed-loop gain: A

= 2(R

4. C

This is the power supply bypass capacitor that filters the voltage applied to the power supply pin. Refer to the

Application Information section for proper placement and selection of C

5. C

This is the bypass pin capacitor that filters the voltage at the BYPASS pin. Refer to the section, Proper

Selection of External Components, for information concerning proper placement and selection of C

LM4819

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Typical Performance Characteristics

THD+N vs Frequency THD+N vs Frequency

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THD+N vs Frequency THD+N vs Frequency

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THD+N vs Frequency THD+N vs Frequency

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LM4819

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Typical Performance Characteristics (Continued)

THD+N vs Output Power THD+N vs Output Power

20013643 20013644

THD+N vs Output Power THD+N vs Output Power

20013645 20013673

THD+N vs Output Power THD+N vs Output Power

20013647 20013646

LM4819

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Typical Performance Characteristics (Continued)

Output Power vs Supply Voltage

=8Ω

Output Power vs Supply Voltage

=16Ω

20013649 20013648

Output Power vs Supply Voltage

=32Ω

Output Power vs Load Resistance

20013651 20013650

Power Dissipation vs

Output Power

=5V

Power Dissipation vs

Output Power

=3V

20013653 20013652

LM4819

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Typical Performance Characteristics (Continued)

Power Derating Curves Frequency Response vs

Input Capacitor Size

20013655 20013654

Supply Current vs

Supply Voltage

20013669

LM4819

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Application Information

BRIDGE CONFIGURATION EXPLANATION

As shown in Figure 1, the LM4819 consist of two operational

amplifiers. External resistors, R

and R

set the closed-loop

gain of the first amplifier (and the amplifier overall), whereas

two internal 20kΩresistors set the second amplifier’s gain at

-1. The LM4819 is typically used to drive a speaker con-

nected between the two amplifier outputs.

Figure 1 shows that the output of Amp1 servers as the input

to Amp2, which results in both amplifiers producing signals

identical in magnitude but 180˚ out of phase. Taking advan-

tage of this phase difference, a load is placed between V

and V

and driven differentially (commonly referred to as

"bridge mode"). This results in a differential gain of

= 2 *(R

) (1)

Bridge mode is different from single-ended amplifiers that

drive loads connected between a single amplifier’s output

and ground. For a given supply voltage, bridge mode has a

distinct advantage over the single-ended configuration: its

differential output doubles the voltage swing across the load.

This results in four times the output power when compared

to a single-ended amplifier under the same conditions. This

increase in attainable output assumes that the amplifier is

not current limited or the output signal is not clipped. To

ensure minimum output signal clipping when choosing an

amplifier’s closed-loop gain, refer to the Audio Power Am-

plifier Design Example section.

Another advantage of the differential bridge output is no net

DC voltage across the load. This results from biasing V

and V

at half-supply. This eliminates the coupling capacitor

that single supply, single-ended amplifiers require. Eliminat-

ing an output coupling capacitor in a single-ended configu-

ration forces a single supply amplifier’s half-supply bias volt-

age across the load. The current flow created by the half-

supply bias voltage increases internal IC power dissipation

and may permanently damage loads such as speakers.

POWER DISSIPATION

Power dissipation is a major concern when designing a

successful bridged or single-ended amplifier. Equation (2)

states the maximum power dissipation point for a single-

ended amplifier operating at a given supply voltage and

driving a specified load.

DMAX

=(V

)

/(2π

) (W) Single-ended (2)

However, a direct consequence of the increased power de-

livered to the load by a bridged amplifier is an increase in the

internal power dissipation point for a bridge amplifier oper-

ating at the same given conditions. Equation (3) states the

maximum power dissipation point for a bridged amplifier

operating at a given supply voltage and driving a specified

load.

DMAX

= 4(V

)

/(2π

) (W) Bridge Mode (3)

The LM4819 has two operational amplifiers in one package

and the maximum internal power dissipation is four times

that of a single-ended amplifier. However, even with this

substantial increase in power dissipation, the Lm4819 does

not require heatsinking. From Equation (3), assuming a 5V

power supply and an 8Ωload, the maximum power dissipa-

tion point is 633mW. The maximum power dissipation point

obtained from Equation (3) must not exceed the power dis-

sipation predicted by Equation (4):

DMAX

=(T

JMAX

-T

)/θ

(W) (4)

For the micro MUA08A package, θ

= 210˚C/W, for the

M08A package, θ

= 170˚C/W , and T

JMAX

= 150˚C for the

LM4819. For a given ambient temperature, T

, Equation (4)

can be used to find the maximum internal power dissipation

supported by the IC packaging. If the result of Equation (3) is

greater than the result of Equation (4), then decrease the

supply voltage, increase the load impedance, or reduce the

ambient temperature. For a typical application using the

M08A packaged LM4819 with a 5V power supply and an 8Ω

load, the maximum ambient temperature that does not vio-

late the maximum junction temperature is approximately

42˚C. If a MUA08A packaged part is used instead with the

same supply voltage and load, the maximum ambient tem-

perature is 17˚C. In both cases, it is assumed that a device

is a surface mount part operating around the maximum

power dissipation point. The assumption that the device is

operating around the maximum power dissipation point is

incorrect for an 8Ωload. The maximum power dissipation

point occurs when the output power is equal to the maximum

power dissipation or 50% efficiency. The LM4819 is not

capable of the output power level (633mW) required to op-

erate at the maximum power dissipation point for an 8Ωload.

To find the maximum power dissipation, the graph Power

Dissipation vs. Output Power must be used. From the

graph, the maximum power dissipation for an 8Ωload and a

5V supply is approximately 575mW. Substituting this value

back into equation (4) for P

DMAX

and using θ

= 210˚C/W

for the MUA08A package, the maximum ambient tempera-

ture is calculated to be 29˚C. Using θ

= 170˚C/W for the

M08A package, the maximum ambient temperature is 52˚C.

Refer to the Typical Performance Characteristics curves

for power dissipation information for lower output powers

and maximum power dissipation for each package at a given

ambient temperature.

POWER SUPPLY BYPASSING

As with any power amplifier, proper supply bypassing is

critical for low noise performance and high power supply

rejection. The capacitors connected to the bypass and power

supply pins should be placed as close to the LM4819 as

possible. The capacitor connected between the bypass pin

and ground improves the internal bias voltage’s stability,

producing improved PSRR. The improvements to PSRR

increase as the bypass pin capacitor value increases. Typi-

cal applications employ a 5V regulator with 10µF and 0.1µF

filter capacitors that aid in supply stability. Their presence,

however, does not eliminate the need for bypassing the

supply nodes of the LM4819. The selection of bypass ca-

pacitor values, especially C

, depends on desired PSRR

requirements, click and pop performance as explained in the

section, Proper Selection of External Components, as

well as system cost and size constraints.

SHUTDOWN FUNCTION

The voltage applied to the LM4819’s SHUTDOWN pin con-

trols the shutdown function. Activate micro-power shutdown

by applying V

to the SHUTDOWN pin. When active, the

LM4819’s micro-power shutdown feature turns off the ampli-

fier’s bias circuitry, reducing the supply current. The logic

threshold is typically 1/2V

. The low 0.7µA typical shut-

down current is achieved by applying a voltage that is as

near as V

as possible to the SHUTDOWN pin. A voltage

that is less than V

may increase the shutdown current.

Avoid intermittent or unexpected micro-power shutdown by

ensuring that the SHUTDOWN pin is not left floating but

connected to either V

or GND.

LM4819

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Application Information (Continued)

There are a few ways to activate micro-power shutdown.

These included using a single-pole, single-throw switch, a

microcontroller, or a microprocessor. When using a switch,

connect an external 10kΩto 100kΩpull-up resistor between

the SHUTDOWN pin and V

. Connect the switch between

the SHUTDOWN pin and ground. Select normal amplifier

operation by closing the switch. Opening the switch con-

nects the shutdown pin to V

through the pull-up resistor,

activating micro-power shutdown. The switch and resistor

guarantee that the SHUTDOWN pin will not float. This pre-

vents unwanted state changes. In a system with a micropro-

cessor or a microcontroller, use a digital output to apply the

control voltage to the SHUTDOWN pin. Driving the SHUT-

DOWN pin with active circuitry eliminates the pull-up resistor

PROPER SELECTION OF EXTERNAL COMPONENTS

Optimizing the LM4819’s performance requires properly se-

lecting external components. Though the LM4819 operates

well when using external components with wide tolerances,

best performance is achieved by optimizing component val-

ues.

The LM4819 is unity gain stable, giving the designer maxi-

mum design flexibility. The gain should be set to no more

than a given application requires. This allows the amplifier to

achieve minimum THD+N and maximum signal-to-noise ra-

tio. These parameters are compromised as the closed-loop

gain increases. However, low gain demands input signals

with greater voltage swings to achieve maximum output

power. Fortunately, many signal sources such as audio CO-

DECs have outputs of 1V

RMS

(2.83V

P-P

). Please refer to the

Audio Power Amplifier Design section for more informa-

tion on selecting the proper gain.

Another important consideration is the amplifier’s close-loop

bandwidth. To a large extent, the bandwidth is dictated by

the choice of external components shown in Figure 1. The

input coupling capacitor, C

, forms a first order high pass filter

that limits low frequency response. This value should be

chosen based on needed frequency response for a few

distinct reasons discussed below

Input Capacitor Value Selection

Amplifying the lowest audio frequencies requires a high

value input coupling capacitor (C

in Figure 1). A high value

capacitor can be expensive and may compromise space

efficiency in portable designs. In many cases the speakers

used in portable systems, whether internal or external, have

little ability to reproduce signals below 150Hz. Applications

using speakers with limited frequency response reap little

improvement by using a large input capacitor.

Besides affecting system cost and size, C

has an effect on

the LM4819’s click and pop performance. When the supply

voltage is first applied, a transient (pop) is created as the

charge on the input capacitor changes from zero to a quies-

cent state. The magnitude of the pop is directly proportional

to the input capacitor’s value. Higher value capacitors need

more time to reach a quiescent DC voltage (usually 1/2 V

)

when charged with a fixed current. The amplifier’s output

charges the input capacitor through the feedback resistor,

. Thus, selecting an input capacitor value that is no higher

than necessary to meet the desired -3dB frequency can

minimize pops.

As shown in Figure 1, the input resistor (R

) and the input

capacitor, C

produce a -3dB high pass filter cutoff frequency

that is found using Equation (5).

-3dB

= 1/(2 πR

) (Hz) (5)

As an example when using a speaker with a low frequency

limit of 150Hz, C

, using Equation (5) is 0.063µF. The 0.39µF

shown in Figure 1 allows the LM4819 to drive a high

efficiency, full range speaker whose response extends down

to 20Hz.

Besides optimizing the input capacitor value, the bypass

capacitor value, C

requires careful consideration. The by-

pass capacitor’s value is the most critical to minimizing

turn-on pops because it determines how fast the LM4819

turns on. The slower the LM4819’s outputs ramp to their

quiescent DC voltage (nominally 1/2V

), the smaller the

turn-on pop. While the device will function properly (no os-

cillations or motorboating), with C

less than 1.0µF, the

device will be much more susceptible to turn-on clicks and

pops. Thus, a value of C

equal to or greater than 1.0µF is

recommended in all but the most cost sensitive designs.

Bypass Capacitor Value Selection

Besides minimizing the input capacitor size, careful consid-

eration should be paid to the value of C

, the capacitor

connected to the BYPASS pin. Since C

determines how

fast the LM4819 settles to quiescent operation, its value is

critical when minimizing turn-on pops. The slower the

LM4819’s outputs ramp to their quiescent DC voltage (nomi-

nally 1/2V

), the smaller the turn-on pop. Choosing C

equal to 1.0µF along with a small value of C

(in the range of

0.1µF to 0.39µF) produces a click-less and pop-less shut-

down function. As discussed above, choosing C

no larger

than necessary for the desired bandwidth helps minimize

clicks and pops.

Optimizing Click and Pop Reduction Performance

The LM4819 contains circuitry that minimizes turn-on and

shutdown transients or "clicks and pops". For this discus-

sion, turn on refers to either applying the power or supply

voltage or when the shutdown mode is deactivated. While

the power supply is ramping to it’s final value, the LM4819’s

internal amplifiers are configured as unity gain buffers. An

internal current source charges the voltage of the bypass

capacitor, C

, connected to the BYPASS pin in a controlled,

linear manner. Ideally, the input and outputs track the voltage

charging on the bypass capacitor. The gain of the internal

amplifiers remains unity until the bypass capacitor is fully

charged to 1/2V

. As soon as the voltage on the bypass

capacitor is stable, the device becomes fully operational.

Although the BYPASS pin current cannot be modified,

changing the size of the bypass capacitor, C

, alters the

device’s turn-on time and magnitude of "clicks and pops".

Increasing the value of C

reduces the magnitude of turn-on

pops. However, this presents a tradeoff: as the size of C

increases, the turn-on time (Ton) increases. There is a linear

relationship between the size of C

and the turn on time.

Below are some typical turn-on times for various values of

0.01µF 20ms

0.1µF 200ms

0.22µF 440ms

0.47µF 940ms

1.0µF 2S

LM4819

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Application Information (Continued)

In order to eliminate "clicks and pops", all capacitors must be

discharged before turn-on. Rapidly switching V

may not

allow the capacitors to fully discharge, which may cause

"clicks and pops".

AUDIO POWER AMPLIFIER DESIGN EXAMPLE

The following are the desired operational

parameters:

Given:

Power Output 100mW

Load Impedance 16Ω

Input Level 1Vrms (max)

Input Impedance 20kΩ

Bandwidth 100Hz–20kHz ±0.25dB

The design begins by specifying the minimum supply voltage

necessary to obtain the specified output power. To find this

minimum supply voltage, use the Output Power vs. Supply

Voltage graph in the Typical Performance Characteristics

section. From the graph for a 16Ωload, (graphs are for 8Ω,

16Ω, and 32Ωloads) the supply voltage for 100mW of output

power with 1% THD+N is approximately 3.15 volts.

Additional supply voltage creates the benefit of increased

headroom that allows the LM4819 to reproduce peaks in

excess of 100mW without output signal clipping or audible

distortion. The choice of supply voltage must also not create

a situation that violates maximum dissipation as explained

above in the Power Dissipation section. For example, if a

3.3V supply is chosen for extra headroom then according to

Equation (3) the maximum power dissipation point with a

16Ωload is 138mW. Using Equation (4) the maximum am-

bient temperature is 121˚C for the MUA08A package and

126˚C for the M08A package.

After satisfying the LM4819’s power dissipation require-

ments, the minimum differential gain is found using Equation

(6).

(6)

Thus a minimum gain of 1.27 V/V allows the LM4819 to

reach full output swing and maintain low noise and THD+N

performance. For this example, let A

= 1.27. The amplifi-

er’s overall gain is set using the input (R

) and feedback (R

)

resistors. With the desired input impedance set to 20kΩ, the

feedback resistor is found using Equation (7).

/2 (V/V) (7)

The value of R

is 13kΩ.

The last step in this design example is setting the amplifier’s

-3dB frequency bandwidth. To achieve the desired ±0.25dB

pass band magnitude variation limit, the low frequency re-

sponse must extend to at least one-fifth the lower bandwidth

limit and the high frequency response must extend to at least

five times the upper bandwidth limit. The gain variation for

both response limits is 0.17dB, well with in the ±0.25dB

desired limit.

The results are:

= 100Hz/5 = 20Hz

= 20 kHz*5 = 100kHz

As mentioned in the External Components section, R

and

create a high pass filter that sets the amplifier’s lower

band pass frequency limit. Find the coupling capacitor’s

value using Equation (8).

≥1/(2πR

) (F) (8)

≥0.398µF, a standard value of 0.39µF will be used. The

product of the desired high frequency cutoff (100kHz in this

example) and the differential gain, A

, determines the up-

per pass band response limit. With A

= 1.27 and f

100kHz, the closed-loop gain bandwidth product (GBWP) is

127kHz. This is less than the LM4819’s 900kHz GBWP. With

this margin the amplifier can be used in designs that require

more differential gain while avoiding performance restricting

bandwidth limitations.

LM4819

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Application Information (Continued)

The LM4819 is unity-gain stable and requires no external

components besides gain-setting resistors, an input coupling

capacitor, and proper supply bypassing in the typical appli-

cation. However, if a closed-loop differential gain of greater

than 10 is required, a feedback capacitor (C

) may be

needed as shown in Figure 2 to bandwidth limit the amplifier.

This feedback capacitor creates a low pass filter that elimi-

nates possible high frequency oscillations. Care should be

taken when calculating the -3dB frequency in that an incor-

rect combination of R

and C

will cause rolloff before

20kHz. A typical combination of feedback resistor and ca-

pacitor that will not produce audio band high frequency rolloff

is R

= 20kΩand C

= 25pF. These components result in a

-3dB point of approximately 320 kHz. It is not recommended

that the feedback resistor and capacitor be used to imple-

ment a band limiting filter below 100kHz.

20013624

FIGURE 2. HIGHER GAIN AUDIO AMPLIFIER

LM4819

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Application Information (Continued)

20013629

FIGURE 3. DIFFERENTIAL AMPLIFIER CONFIGURATION FOR LM4819

20013668

FIGURE 4. REFERENCE DESIGN BOARD and PCB LAYOUT GUIDELINES

LM4819

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Application Information (Continued)

LM4819 SO DEMO BOARD ARTWORK

Silk Screen

20013662

Top Layer

20013663

Bottom Layer

20013664

LM4819

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Application Information (Continued)

LM4819 MSOP DEMO BOARD ARTWORK

Silk Screen

20013665

Top Layer

20013666

Bottom Layer

20013667

LM4819

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Application Information (Continued)

LM4819 LD DEMO BOARD ARTWORK

Composite View

20013631

Silk Screen

20013632

Top Layer

20013633

Bottom Layer

20013630

Mono LM4819 Reference Design Boards

Bill of Material for all Demo Boards

Item Part Number Part Description Qty Ref Designator

1 551011208-001 LM4819 Mono Reference Design Board 1

10 482911183-001 LM4819 Audio AMP 1 U1

20 151911207-001 Tant Cap 1uF 16V 10 1 C1

21 151911207-002 Cer Cap 0.39uF 50V Z5U 20% 1210 1 C2

25 152911207-001 Tant Cap 1uF 16V 10 1 C3

30 472911207-001 Res 20K Ohm 1/10W 5 3 R1, R2, R3

35 210007039-002 Jumper Header Vertical Mount 2X1 0.100 2 J1, J2

LM4819

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Application Information (Continued)

PCB LAYOUT GUIDELINES

This section provides practical guidelines for mixed signal

PCB layout that involves various digital/analog power and

ground traces. Designers should note that these are only

"rule-of-thumb" recommendations and the actual results will

depend heavily on the final layout.

General Mixed Signal Layout Recommendation

Power and Ground Circuits

For two layer mixed signal design, it is important to isolate

the digital power and ground trace paths from the analog

power and ground trace paths. Star trace routing techniques

(bringing individual traces back to a central point rather than

daisy chaining traces together in a serial manner) can have

a major impact on low level signal performance. Star trace

routing refers to using individual traces to feed power and

ground to each circuit or even device. This technique will

take require a greater amount of design time but will not

increase the final price of the board. The only extra parts

required will be some jumpers.

Single-Point Power / Ground Connections

The analog power traces should be connected to the digital

traces through a single point (link). A "Pi-filter" can be helpful

in minimizing high frequency noise coupling between the

analog and digital sections. It is further recommended to put

digital and analog power traces over the corresponding digi-

tal and analog ground traces to minimize noise coupling.

Placement of Digital and Analog Components

All digital components and high-speed digital signals traces

should be located as far away as possible from analog

components and circuit traces.

Avoiding Typical Design / Layout Problems

Avoid ground loops or running digital and analog traces

parallel to each other (side-by-side) on the same PCB layer.

When traces must cross over each other do it at 90 degrees.

Running digital and analog traces at 90 degrees to each

other from the top to the bottom side as much as possible will

minimize capacitive noise coupling and cross talk.

LM4819

www.national.com17

Physical Dimensions inches (millimeters) unless otherwise noted

MSOP

Order Number LM4819MM

NS Package Number MUA08A

Order Number LM4819M

NS Package Number M08A

LM4819

www.national.com 18

Physical Dimensions inches (millimeters) unless otherwise noted (Continued)

LLP

Order Number LM4819LD

NS Package Number LDA08B

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.

For the most current product information visit us at www.national.com.

LIFE SUPPORT POLICY

NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS

WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR

CORPORATION. As used herein:

1. Life support devices or systems are devices or systems

which, (a) are intended for surgical implant into the body, or

(b) support or sustain life, and whose failure to perform when

properly used in accordance with instructions for use

provided in the labeling, can be reasonably expected to result

in a significant injury to the user.

2. A critical component is any component of a life support

device or system whose failure to perform can be reasonably

expected to cause the failure of the life support device or

system, or to affect its safety or effectiveness.

BANNED SUBSTANCE COMPLIANCE

National Semiconductor certifies that the products and packing materials meet the provisions of the Customer Products Stewardship

Specification (CSP-9-111C2) and the Banned Substances and Materials of Interest Specification (CSP-9-111S2) and contain no ‘‘Banned

Substances’’ as defined in CSP-9-111S2.

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Support Center

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Tel: 1-800-272-9959

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Email: europe.support@nsc.com

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www.national.com

LM4819 350mW Audio Power Amplifier with Shutdown Mode

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