LX1711CDB_技术文档

LXE1710 EVALUATION BOARD

USER GUIDE

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A

M I C R O S E M I

C O M P A N Y

Rev. 1.1, 2000-12-01

Page 1

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

NTRODUCING

UDIO

LX1710/1711 A

I

MAX

Thank you for your interest in the latest generation of AudioMAX products. The enclosed LXE1710 evaluation

board is a fully functional mono amplifier designed to demonstrate the “new and improved” Switching Class-D

Power Amplifier IC from Linfinity Microsemi. The LX1710/1711 is a completely new controller design with

superior performance over the LX1720 stereo controller IC. Key improvements include better SNR, lower noise

floor, and reduced THD therefore resulting in a much “quieter” and “cleaner” sounding amplifier.

The evaluation board has been configured with easy-to-use terminal block connections for power supply/battery hook

up and speaker connections. An RCA jack or separate audio +/- pins allow a quick interface to your audio source.

Jumpers are also provided to enable/disable the amplifier (Sleep control) and to turn off the audio input (Mute

control). With minimal setup, the user can be listening to the amplifier in a matter of a few minutes.

Both the LX1710 and LX1711 operate from a single supply voltage. The LXE1710 evaluation board can

e

LX1711 can handle a higher supply voltage (7V to 25V) and provides greater than 50W continuous output power

change frequency response for other load optimization.

Thank you again for your interest in the new “quieter”, high efficiency Class-D Audio Amplifier from Linfinity

Microsemi. Please let us know what you think and stay tuned for future product releases to our AudioMAX family

of products.

Regards,

Linfinity Microsemi

http://www.linfinity.com

(714) 898-8121

Rev. 1.1, 2000-12-01

Page 2

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

ABLE OF ONTENTS

T

C

LX1710 / 1710 AudioMAX Evaluation Board Features and Circuit Description .............................4

Input Compensation

Output Stage

Filter Stage

Quick Start Guide............................................................................................................................................5

Application Schematic...................................................................................................................................6

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

Performance Graphs......................................................................................................................................8

Application Information

Filter Design Tradeoffs (1-Stage vs. 2-Stage).............................................................................................9

LC Filter Design...........................................................................................................................................9

MOSFET Selection....................................................................................................................................10

Inductor Selection......................................................................................................................................12

Capacitor Selection ...................................................................................................................................13

Gate Resistor ............................................................................................................................................14

Oscillator Configuration.............................................................................................................................14

Multi Channel Requirements and Frequency Synchronization..................................................................14

PCB Layout ...............................................................................................................................................15

Board Layout..................................................................................................................................................16

Printed Circuit Board ...................................................................................................................................17

Bill of Materials..............................................................................................................................................18

Rev. 1.1, 2000-12-01

Page 3

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

Part Number

Product

Description

AudioMAX High

Fidelity Controller IC

V_DD= 7V to 15V, Switching Class-D Mono

Power Amplifier IC, 28-Pin SSOP Package.

LX1710CDB

LX1711CDB

LXE1710

AudioMAX High

Power Controller IC

V_DD= 7V to 25V, Switching Class-D Mono

Power Amplifier IC, 28-Pin SSOP Package.

LX1710 AudioMAX

Evaluation Board

Fully Operational Mono Audio Amplifier.

UDIO

LX1710/1711 A

VALUATION OARD EATURES AND IRCUIT ESCRIPTION

MAX E

B

F

C

D

•

Fully Assembled Mono Evaluation Board with

LX1710 Class-D Controller IC

Improved SNR and Noise Floor Performance

•

Supports Full Audio Bandwidth

•

Terminal Block Connectors for Supply

Voltage and Speaker Connection

RCA Plug for Audio Input Signal

Output Power of 25W typical (LX1710, 15V_DD

,

•

Output Power of 54W typical (LX1711, 25V_DD

The AudioMAX Evaluation Amplifier Board allows the

user to quickly connect and evaluate the LX1710

Switching Class-D Mono Controller IC. Easy-to-

connect terminal blocks and an RCA plug are

provided for interfacing to Power, Speaker, and Audio

Input connections. The single stage output filter has

been configured to drive a 4

audio bandwidth amplification (See Application

section LC filter design for component selection,

calculations, and suggested inductor and capacitor

values for other loads). The LXE1710 Evaluation

Board operates from a single supply voltage.

capacitors set up the controller operating frequency,

response characteristics, and comparator ramp

fundamental to Class-D operation.

OUTPUT STAGE

The next section is the output stage. The controller

IC generates a PWM output by controlling external

FETs connected in a full bridge configuration. The full

bridge configuration is connected between the single

supply voltage (PVDD) and ground (PGND) with the

output of the bridge driving the LC filter stage.

Because the FETs are either fully “on” or fully “off”,

Class-D topology is extremely efficient (up to 85%

typical), circuit power dissipation is minimal, and

maximum power is delivered to the speaker. The

bridge output also drives the RC low pass filter, which

provides the feedback for the control loop through the

FBK+ and FBK- inputs.

The Class-D Amplifier Controller IC requires a

minimal number of external components to create a

complete amplifier solution. See LXE1710 Evaluation

Board Schematic and Bill of Materials for circuit

specifics.

A Class-D Amplifier is a “switching”

amplifier that converts a low-level, analog audio input

signal into a high power, pulse-width modulated

(PWM) output. The switching frequency (500kHz

typical but can be adjusted) is much higher than the

audio bandwidth (20Hz to 20kHz), and is easily

filtered out with a simple LC filter. The support

circuitry can be generally grouped into three areas

(input circuit, output power stage, and output filter).

FILTER STAGE

The single stage, second order LC filter is used to

remove the switching frequency. The frequency

response and corner frequency can be easily

adjusted for optimization of various loads. The LC

evaluation board component values have been

chosen for a 4

INPUT COMPENSATION

for component selection.

The first group is the compensation network and

control setting components. These resistors and

Rev. 1.1, 2000-12-01

Page 4

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

UICK TART UIDE

Q

S

G

The LXE1710 Evaluation Board is a fully functional,

Class-D Amplifier. Connection to a single supply

voltage (VDD from either a battery or power supply),

speakers, and your audio source is all that is required

to begin evaluating the amplifier and listening to music.

The following outlines the necessary connections and

control jumpers.

can be used to drive other speaker loads but

frequency response may not be optimal. See

LC filter design section for recommended

inductor and capacitor modifications.

4) Audio Input Connection: Connect your audio

source to the RCA Jack CN1, Audio In. For

other type interfaces, the audio input signal can

also be connected to the amplifier board using

the J3 (In- and In+) location. Strip Line Plugs

can be inserted into J3 for connectivity.

1) Verify contents of Evaluation Kit: The easy-to-

use amplifier is all contained on a single board.

Visually inspect to see if the board or any

components were damaged during shipping.

All components are located on the top side of

the PCB except for the decoupling capacitor,

C17. A copy of the LX1710/1711 Datasheet

should also be enclosed or a PDF version can

be downloaded from the Microsemi.com

website

5) Jumper Selection Controls: The “on/off” or

enable to the module is controlled with the

SLEEP/ signal.

Jumper J1 connects the

SLEEP/ to “on” or “ off”. SLEEP/ is an active

Low control. Jumper J2 connects the MUTE

control which enables/disables the audio input

to the amplifier. MUTE is an active High signal.

See table below.

(http://www.microsemi.com/datasheets/MSC1580.PDF).

2) Power and Ground Connections: The voltage

supply and ground connections are made

through terminal block TB1. Connect your “+”

(+7V to +15V) power supply or battery to the

+V input of TB1. Connect your supply or

battery ground to the GND input of TB1.

Please ensure the correct positive and ground

connections are made before turning on the

power supply.

6) Power Source: If a power supply is being used,

make sure it is set to the correct voltage level

and turn the power supply on.

7) Audio Source: Make sure the audio source

signal is set to a minimum level. Start or “play”

audio source and adjust source volume to

desired level.

8) Listen to AudioMAX: If the amplifier is not

operating properly, verify preceding steps or

contact Linfinity for technical assistance (714)

898-8121.

3) Speaker Connection: The amplifier is designed

“+” and “-“ to the +OUT and –OUT input of

terminal block TB2 respectively. The amplifier

To Speaker +

To Speaker -

To Power Supply +V

7V-15V for LX1710

7V-25V for LX1711

Jumper

toward

OFF

Amplifier

enabled

(SLEEP/ is

OFF)

Jumper

toward

ON

Amplifier

disabled

(SLEEP/ is

ON)

Jumper

floating

To Power Supply

Ground

Amplifier

disabled

(SLEEP/ is

ON)

J1 Jumper:

SLEEP/

Optional

Audio In -

Audio Input

enabled

(MUTE is

OFF)

Audio Input

enabled

(MUTE is

OFF)

Audio Input

disabled

(MUTE is ON)

J2 Jumper:

MUTE

Optional

Audio In +

Jumper Settings

To Audio

Source

Rev. 1.1, 2000-12-01

Page 5

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

CHEMATIC

S

V_IN7V to 15V

C9

0.1µF

35V

+

25

28_NC

CLOCK

C22

.1µF

RS1

.0347

VDD

C17

220µF

25V

24

PVDD

+

C13

+

2.2µF

27

23

C11

4.7µF

IS-

P+

C12

.1µF

26

5

CP

Q1

R12

RPW M

L1 15µH

10 ohm

R5 34.8K

6

CPW M

C1

1µF

C16

100pF

R3

24.3K

1

4

R13

15 ohm

1W

VREF

V25

C20

.68µF

Q2

22

20

C8

.1µF

50V

N+

P-

R11

10 ohm

C7

220pF

C2

1µF

C18

.47µF

2

10

11

9

GND

LX1710

C21

SLEEP

MUTE

C19

.47µF

.68µF

Q3

R6

10 ohm

SLEEP

MUTE

AUDIO

INPUT

NC

INAMPOUT

INPUT+

L2 15µH

R8 10K

Q4

21

19

7

N-

R10

10 ohm

C3

470nF

R4

24.3K

C26

330pF

PGND

C6

220pF

8

3

INPUT-

NC

C10

R9 10K

C14

4.7µF

+

470nF

18

16

CN

C5

18pF

14

13

15

EAOUT

EAIN

FBK+

FBK-

C4

150pF

R1 56.2K

17

12

NC

FAOUT

STATUS

R2 10K

– Evaluation Board Schematic

Rev. 1.1, 2000-12-01

Page 6

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

LECTRICAL HARACTERISTICS

E

C

Unless otherwise specified, the following specifications apply over the operating ambient temperature 0°C<TA<70°C.

For test circuit, see LXE1710 Evaluation Board Schematic diagram.

PARAMETER

SYMBOL

TEST CONDITIONS

MIN.

TYP.

MAX

UNITS

Supply Voltage LX1710

VDD

7

15

V

V_IN=15V, P_O=38W, R_L

THD+N=1%

Supply Current

IDD

IQ

3

A

mA

W

Quiescent Current

V_IN=15V, No Input

43

14

25

38

V_IN=15V, R_L

10Hz to 22kHz

V_IN=15V, R_L

10Hz to 22kHz

V_IN=15V, R_L

Output Power

PO

W

10Hz to 22kHz

V_IN=15V, f_IN=1kHz, P_O=10W

V_IN=15V, f_IN=1kHz, P_O=20W

f_IN=1kHz, P_O=1W

82

85

%

Efficiency

0.05

%

Total Harmonic Distortion Plus

Noise

THD+N

f_IN=20Hz to 20kHz, PO=1W

0.3

%

Signal-To-Noise Ratio

SNR

81

dBV

V_IN=15V, V_RIPPLE=1V_RMS

10Hz to 10kHz

,

Power Supply Rejection Ratio

PSRR

-70

dB

Rev. 1.1, 2000-12-01

Page 7

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

ERFORMANCE RAPHS

P

G

90%

85%

80%

75%

70%

65%

60%

55%

50%

45%

60

50

40

30

20

10

0

5

10

15

20

25

30

6

11

16

21

26

Output Power (W)

Supply Voltage (V_IN

)

f_IN=1kHz

V_IN= 15V

R_L

THD+N=1%

+20

100

50

+15

+10

+5

20

10

5

2

1

-0.08

-0.59

0.5

0.26

0.1

-5

0.04

-10

0.02

0.01

-15

-20

0.005

0.002

0.001

17.88k

18.2

10

50

100 200

500

1k 2k

5k

10k

50k

80k

24.56

30

1.13 2

50m

100m 200m 500m

5

10 20

Frequency (Hz)

Output Power (W)

V_IN=15V

R_L

R_O=1W_RMS

V_IN=15V

f_IN=1kHz

R_L

Rev. 1.1, 2000-12-01

Page 8

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

PPLICATION NFORMATION

A

I

LX1710 Filter Implementation, 1-stage vs. 2- stage

100

50

20

10

5

2

1

0.5

0.55626

2-Stage

1-Stage

0.2

0.12572

0.1

0.05

0.02

0.01

0.005

0.002

0.001

1.15

1

25.04

20 30

50m

100m

200m

500m

2

5

10

Watts(W)

FILTER DESIGN TRADEOFFS (1-STAGE VS. 2-STAGE)

impedance changes could result in a +/- 6dB

change.

A 1-stage or 2-stage filter may be used depending on

your application and performance targets. The main

tradeoff in this selection is price (number of

components, component costs, PCB area) vs.

performance. The primary advantage of the single

stage filter is lower cost whereas the main benefit to a

2-stage filter is that it will provide steeper attenuation.

This allows the corner frequency to be selected further

outside of the audio band (to minimize the effects of

impedance variations in the passband) and still

provide adequate RF attenuation.

•

THD: There are minimal differences between

the 1-stage and 2-stage implementations with

other parameters such as THD+N as seen in

the above graph.

Single Stage Filter Disadvantages

•

EMI and Switching Frequency: For the 1-

stage, the switching frequency must be higher

than 400kHz to ensure the corner frequency

will provide adequate amplifier performance in

the high end of the audio frequency range. If

f_S< 400kHz, then f_C< f_S/10 = 40kHz which is

too close to the desired audio band. A higher

oscillation frequency could translate into

greater MOSFET switching losses, slightly

lower efficiency, and increased EMI effects.

With a 2-stage 4th order filter, the switching

frequency f_Scan be reduced to 120kHz. If f_S=

120kHz, then f_C= f_S/3 = 40kHz. The lower

oscillation frequency could help minimize EMI

issues.

Single Stage Filter Advantages

•

Low Cost: The 1-stage LC filter uses one half

the number of inductors/capacitors resulting in

a substantial cost savings over a 2-stage

design. Key parameters such as THD+N,

frequency response, and nose performance

do not change significantly.

•

Power Loss: Since current will flow in two

inductors and not four, the inductor power loss

will be less in the single stage design. The

overall amplifier will have a wider dynamic

range and improved efficiency.

LC FILTER DESIGN

Filter Design: This easy-to-design filter can

limit audio signal changes within +/- 3dB

across the audio band with impedance

vari

The output filter helps to reconstruct the amplified

audio signal and filter out the switching frequency.

The design of the filter depends on the type of

attenuation and frequency response desired at the

output. The output filter designed into the LXE1710

a

steeper rolloff with the 2-stage filter,

Rev. 1.1, 2000-12-01

Page 9

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

evaluation board is a second order, LC type filter as

shown below. Tradeoffs between performance and

component cost must be considered when determining

the complexity or type of filter selected.

the required audio response and is used in the

calculation below.

Q

0.707

C =

=

= 0.56µF

Rω R(2πf^C) 4(2π )(50000)

OUT+

L

15µH

C = 0.68µF is usedin theEvaluationBoard

C

0.68µF

To Compute the Inductor Value:

1

R

L =

=

=14.9µH

ω²C (2πf^C)²C [(2π )(50000)]²(.68µ)

L =15µH is usedin theEvaluationBoard

C

0.68µF

L

15µH

OUT-

LXE1710 Evaluation Board

Frequency Response

Its Laplace Transform function is:

+15

+12.5

+10

+7.5

+5

S

C

+2.5

+0

H(S) =

=

1

ω

S²

S

S²

S ω ²

-2.5

-5

+

RC

LC

Q

-7.5

-10

-12.5

-15

10

20

50

10

20

50

1k

2k

5k

10

20

50 80

1

Frequency (Hz)

Where

ω =

LC

Frequency response of the audio amplifier was

Q = RCω

The Class-D amplifier evaluation board design has a

pass-band of 20Hz to 20kHz to support the audio

frequency range and is configured to utilize a switching

or oscillator frequency f_s= 500kHz. Depending on the

application, this oscillator frequency may be adjusted

(see section on Oscillator Configuration) to optimize

amplifier performance or modified for other

–4dB

Therefore, to improve

attenuation respectively.

frequency response performance for other loads, the

value of Q must be increased/decreased by changing

the capacitor. Since a different value C will affect the

corner frequency, values for L and C must be

recalculated. Below are recommended inductor and

capacitor values for 2

considerations such as EMI effects.

Further

requirements of the filter are that the pass band

attenuation of switching frequency f_sshould be lower

than 40dB and the corner frequency of the LC filter

should be set higher than 20kHz to avoid attenuating

audio signals in the desired audio band by more than

single stage LC filter design.

Capacitor C (µF)

Inductor L (µH)

1.0

0.68

0.47

10

15

22

1dB. A speaker DC impedance o

=

C

50kHz corner frequency are defined for the evaluation

board.

Filter Component Values

The Q (selectivity factor or ratio of the center

frequency divided by the bandwidth) of the filter must

also be considered when designing a filter. Too high a

Q will result in a boost of the audio signal across the

audio band whereas a low Q will cause too much

attenuation of the signal. A Q value of 0.707 provides

Please note: These recommended values are guidelines

for speaker loads. Actual speakers have varying

impedances, which may require revised filter calculations

and optimization. Furthermore, your application may have

different design goals than those chosen for the LX1710

evaluation board.

Rev. 1.1, 2000-12-01

Page 10

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

MOSFET SELECTION

R

^NDS= 0.03Ω, R^PDS= 0.095Ω

^DS= (2.5)²[2(0.03+ 0.095)] =1.56W

P

As seen in previous sections, the user can design the

output filter of the amplifier to meet performance or

costs targets. In addition, the amplifier’s power stage

(selection of MOSFETs) can be selected depending on

these tradeoffs. The efficiency of the amplifier circuit

can be approximated by the following equation.

MOSFET power loss is proportional to on-resistance.

I ²R

I ²[2(R^NDS+ R^PDS+ R^IND) + R

]+ P^CROSS

L

2

P

OUT

S

MOSFETSwitchingLoss= P^CROSS=CV f n

ꢀ =

=

P

IN

L

Where

C

V

= Input Capacitance

= Supply Voltage

Where

R_L

R_NDS

=

DC Resistance of Speaker

f_S= Switching Frequency

n

n-channel MOSFET on-resistance

p-channel MOSFET on-resistance

DC Resistance of Inductor

= Number of MOSFETS

R_PDS

=

Assume

C

V

= 1000pF

= 15VDC

R_IND

P_CROSS

MOSFET Switching Loss

f_S= 500kHz

P

^CROSS= (1×10⁻⁹)(15²)(500×10³)(4) = 0.45W

The overall efficiency is a function of primarily the

MOSFETs and output filter inductors. The “Inductor”

section’s contribution will be considered later. The

MOSFET Power loss is a function of the on-resistance

and gate charge.

MOSFET switching loss is proportional to total gate

charge, supply voltage, and switching frequency.

There are a few other important parameters to

consider when selecting the output power components

besides the on-resistance and gate charge of the

MOSFETs. The drain-source voltage must provide

ample margin for circuit noise and high speed

switching transients. Since the amplifier configuration

requires output bridge operation at the supply voltage,

the MOSFETs should have a drain-source voltage of

at least 50% greater than the supply voltage. The

power dissipation of the MOSFETs should also be

able to dissipate the heat generated by the internal

MOSFET Power Loss = P^DS= I ²[2(R^NDS+ R^PDS)]

If

P

O

= 25W at 4Ω

P

25

4

Then I =

=

= 2.5A

R

losses and be greater than the sum of P_DSand P_CROSS

Linfinity recommends that in selecting MOSFETs, R_DS

.

The LX1710 Evaluation Board is designed using

FDS4953 p-channel and FDS6612A n-channel

MOSFETS.

<10nC. The table below provides

g

several MOSFET options.

FDS6612A FDS4953

Si4532ADY

IRF7105

n-channel p-channel n-channel p-channel n-channel p-channel

RDS(ON)@VGS = +/-10V

0.022

0.053

0.08

0.10

0.25

Drain-Source On-Resistance

VDSS (V)

30

8.4

9

-30

-5

8

30

4.9

8

-30

-3.9

10

25

3.5

9.4

-25

-2.3

10

Drain-Source Voltage

Drain Current (continuous)

Total Gate Charge

ID(continuous) (A)

Q_g(typical) (nC)

Vishay

Siliconix

Vishay

Siliconix

International International

Fairchild

Manufacturer

Rectifier

MOSFET Component Options

Rev. 1.1, 2000-12-01

Page 11

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

INDUCTOR SELECTION

Inductor Power Loss = P^IND= (I ²)(2)(R^IND

)

The output filter inductors are key elements in the

performance of the Class-D audio power amplifier.

The LX1710 Evaluation board utilizes two 15µH radial

leaded R.F. inductors from Inductor Supply, Inc. (ISI).

When evaluating component options, inductors such

as from Coilcraft can be used for other performance /

price tradeoffs. See inductor table below.

Inductor selection criteria also involves tradeoffs

between performance (efficiency) and component

costs. The critical specifications for the inductor are

the DC resistance, DC current, and peak current

ratings. The inductors should be able to handle the

amplifier’s power as well as operate within its linear

P

_IND= (2.5²)(2)(.056) = 0.7W

region.

Saturating the inductors could decrease

performance (increase THD) and even produce a

short, which may damage either the circuit or the

speaker.

The efficiency approximation can now be completed.

P^OUT

P^IN

I ²R^L

Other variables when selecting an inductor depend on

the switching frequency of the designed amplifier. A

higher switching frequency implies that the corner

frequency of the LC filter is higher. With a higher f_C,

the inductor value is smaller.

ꢀ =

=

I ²[2(R^NDS+ R^PDS+ R^IND) + R^L]+ P^CROSS

I ²R^L

ꢀ =

P^DS+ P^IND+ P^CROSS+ I ²R^L

The amplifier’s application and design constraints will

help determine whether the inductors are selected for

size, power, or performance. Various inductors such

as those that are shielded may also have different EMI

effects and distortion performance.

25

= 90.2%

1.56 +.7 +.45+ 25

The overall efficiency ( ) of the amplifier circuit is given

in the previous MOSFET section. The inductor’s

power loss contribution is a function of the inductor’s

The efficiency is a function of the power and switching

loss in the MOSFETs and inductors.

DC resistance, R_IND

.

Self Resonant

Frequency min

(MHz)

Inductance

Test

Frequency

DC Resistance DC Current

Manufacturer

Part Number

Q min

max (A_RMS

)

RL622-150K

15.0

50

2.520MHz

100kHz

56

32

2.50

12.0

ISI

DO5022P-153HC

4.4

20

Coilcraft

Inductor Component Options

Rev. 1.1, 2000-12-01

Page 12

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

CAPACITOR SELECTION

The LC filter design section discusses filter options

and the calculation of component values. However,

the specification of capacitor type depends on the

application in the circuit.

The table provides

descriptions and guidelines for capacitors in the

AudioMAX amplifier board.

Reference

Capacitor

Designator

Comments

C10, C11

FET gate drive

Audio input path

Output filter

These

These decoupling capacitors are used for the audio input +/- signals.

C3 C14

C18, C19,

C20, C21

The output filter metal film capacitors (low ESR, 5% tolerance) work well to set an accurate

corner frequency at a low cost.

These metal film capacitors are used for the power supply bypass for the FETs. Place

adjacent to the FETs or consider lower value ESR solutions depending on the PCB

component placement.

C8, C12

FET bypass

C22

C9, C13

C17

LX1710 bypass

The metal film capacitor is a high frequency bypass for the LX1710 IC.

VDD,

PVDD bypass

These tantalum capacitors provide the bypass for the IC supply voltage and output driver

supply voltage utilizing a minimal footprint area.

The electrolytic filter capacitor smoothes out ripple current and should be placed close to the

output FETs.

Output power stage

C16

Oscillator frequency

Feedback filter

The timing capacitor (5% tolerance) sets the oscillator frequency.

C6, C7

C4, C5

C1, C2

C26

These (5%) capacitors are used in the RC filter to provide feedback for the control loop.

These (5%) capacitors create the compensation network. Make sure the appropriate

“temperature grade” is used to ensure stability.

Error amplifier

Voltage references

The filter capacitors provide the bypass for the 5V and 2.5V references.

The RC filter minimizes high frequency noise to the amplifier.

Audio input filter

Capacitor Description

Rev. 1.1, 2000-12-01

Page 13

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LXE1710 EVALUATION BOARD

USER GUIDE

Gate Resistor Impact On THD+N

100

50

20

10

2

1

0.26978

0.1

No Gate Resistor

W ith 10Ω Gate Resistor

0.04675

0.01

0.005

0.001

50m

100m

200m

500m

11.131

2

5

10

20 24.56 30

Output Power (W )

V_IN= 15V

f_IN= 1kHz

R_L

GATE RESISTOR

and valley voltages, and the charge and discharge

currents are proportional to the supply voltage. This

keeps the frequency relatively constant while keeping

the slope of the PWM ramp proportional to the voltage

on the VDD pin. For operating frequencies other than

333kHz, the frequency can be approximated by the

following equation:

Series resistors (R6, R10, R11, R12) can be added to

the gate of MOSFETs (Q1 to Q4) to control the

switching transition times.

distortion as seen in the THD+N vs. Output Power

graph below. The slower switching speeds will

This reduces signal

however, increase power dissipation and therefore

slightly decrease the overall efficiency of the amplifier.

1

Frequency =

V_IN

(0.577)(R^PWM)(C^PWM) + 320ns

R12

P+

Q1

10

Ω

OUT+

R11

N+

Q2

MULTI CHANNEL REQUIREMENTS AND FREQUENCY

SYNCHRONIZATION

10

Ω

For applications that require more than a single

channel, the oscillators of multiple LX1710/1711

controllers can be configured for synchronous

operation. One unit, the master, is programmed for

the desired frequency with the RPWM and CPWM as

usual. Additional units will be slave units, and their

oscillators will be disabled by leaving the RPWM pin

disconnected. The CLOCK pin and the CPWM pin of

the slave units should be tied to the CLOCK pin and

the CPWM pin of the master unit respectively. In this

configuration, the CLOCK pins of the slave units begin

receiving instead of transmitting clock pulses. Also,

the CPWM pins quit driving the PWM capacitor in the

slave units. Note that for optimum performance, all

slave units should be located within a few inches of the

master unit.

resistors, which improves (decreases) the THD+N

from 0.1% to 0.05% with a slight impact on efficiency

of approximately 2%. The recommended gate resistor

OSCILLATOR CONFIGURATION

The oscillator is programmed by the external timing

components RPWM and CPWM. For a nominal

frequency of 333kHz, RPWM and CPWM should be

set to 49.9kOhms and 100pF respectively. Note that

in order to keep the slope of the PWM ramp voltage

proportional to the supply voltage, both the ramp peak

Rev. 1.1, 2000-12-01

Page 14

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Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

PCB LAYOUT RECOMMENDATIONS

from the switching circuit. In general, minimizing the

high frequency, high power currents from flowing

through the same copper as the audio signal

references are recommended. Signal traces that

could be sensitive to noise should be node to node

connections (no “shared” traces). Stray capacitance at

the controller pins RPWM, EAOUT, EAIN, and FAOUT

can affect the circuit performance and components

associated with these pins should be placed as close

to the controller IC as possible.

Like most analog circuits, component placement,

signal routing, and power/ground isolation can affect

the overall performance of the design. The layout

should utilize individual ground traces/planes for the

audio amplifier whenever possible. The audio input

and controller ground, FET ground, and output filter

ground are routed using a “star” connection in the

LXE1710 evaluation board. See PCB layer views.

The power to the controller IC should be routed using

separate traces that do not carry high current pulses

Rev. 1.1, 2000-12-01

Page 15

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

RINTED IRCUIT OARD AYOUT

P

C

B

L

TB1: Power Supply Terminal Block

J3: Optional Connections

Audio In +, Audio In -

CN1: RCA Jack

+V, GND

Audio In

Silkscreen Layer

TB2: Audio Output Terminal Block

J1: Sleep Jumper

J2: Mute Jumper

+ OUT, - OUT

Rev. 1.1, 2000-12-01

Page 16

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

RINTED IRCUIT OARD

P

C

B

Bottom Layer

Top Layer

Rev. 1.1, 2000-12-01

Page 17

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11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

LXE1710 EVALUATION BOARD

USER GUIDE

ILL OF ATERIALS

B

M

Line

Reference

Designators

U1

Part Description

Item

Manufacturer & Part #

Case

Qty

LX1710

FDS6612A

FDS4953

1

2

3

4

5

6

7

8

9

Controller

SSOP 28

SO-8

1

2

1

2

1

2

1

2

N-Channel MOSFET

Q2, Q4

Q1, Q3

REV.X

L1, L2

P-Channel MOSFET

SO-8

SGE2758

Printed Circuit Board

RL622-150K

161-4214

Inductor, 15uH

TH

Phono Jacks, 90° Nickel Plated, Wht

Strip Line Plugs, Straight, Single Row .100"

Shorting Jumpers, Open Top, Black

Terminal Block 2 pos 5mm

CN1

CA-S36-24B-44

151-8030

J1, J2

J1

301-021-1000

TB1, TB2

Line

Item

Reference

Designators

Part Description

Capacitor, COG, 18pF, 50V, 5%

Capacitor, COG, 150pF, 50V, 5%

Part Description

Case

1206

Qty

1206N180J500NT

12065C180JAT2A

1206N151J500NT

12065C151JAT2A

12065C221JAT2A

ECU-V1H331KBM

1206B474M160NT

1206YC474MAT2A

1206B105K500NT

12065C105KAT2A

0805N101J500NT

08055C101JAT2A

TAJA104M035R

1

C5

1

2

1206

C4

3

4

Capacitor, COG, 220pF, 50V, 5%

Capacitor, X7R, 330pF, 50V, 10%

1206

C6, C7

C26

2

1

5

6

7

Capacitor, X7R, .47uF, 16V, 20%

Capacitor, X7R, 1uF, 50V, 10%

Capacitor, COG, 100pF, 50V, 5%

1206

0805

C3, C14

C1, C2

C16

2

1

8

9

Capacitor Tant 0.1uF 35V 20%

Capacitor Tant 2.2uF 25V 20%

3216

C9

1

T491A225M025AS

T491A475M016AS

TAJA475M016R

C13

10

Capacitor, Tant, 4.7uF, 16V, 20%

3216

C10, C11

2

ECQ-V1H104JL

11

12

13

14

Capacitor Stacked MF 0.1uF 50V 5%

Capacitor Stacked MF 0.47uF 50V 5%

Capacitor Stacked MF 0.68uF 50V 5%

Capacitor, Elect 220uF, 25V, 20%

TH

NT

C8, C12, C22

C18, C19

C20, C21

C17

3

2

1

ECQ-V1H474JL

ECQ-V1H684JL

RV-25V221MH10-R

Line

Item

Reference

Designators

Part Description

Case

Qty

CR32J103T

CR32F2432T

CR J100T

1

2

3

4

5

6

7

Resistor, 10K, 5%, 1/4W

Resistor, 24.3K, 1%, 1/4W

Resistor, 10 Ohm, 5%, 1/8W

Resistor, 10K, 5%, 1/8W

Resistor, 34.8K, 1%, 1/8W

Resistor,20K, 5%, 1/8W

Resistor, 56.2K, 1%, 1/8W

1206

0805

R2

1

2

4

2

1

R3, R4

R6, R10, R11, R12

CR21J103T

R8, R9

R5

CR21F3482T

CR J203T

R7

CR21F5622T

RM73B3A150J

MCR100JZHJ150

LR2010-01-R0374-F

R1

8

9

Resistor, 15 Ohm 5% 1W

2512

R13

RS1

1

Resistor, Low Value Flat .0374

Rev. 1.1, 2000-12-01

Page 18

Microsemi

Linfinity Microelectronics Division

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570


型号：	LX1711CDB
厂家：	Microsemi
描述：	EVALUATION KIT 评估套件
文件：	总18页 (文件大小：336K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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