SSM2211

Rev. D | Page 20 of 24

The polarity of the speakers is important, as each output is 180

degrees out of phase with the other. By connecting the minus

terminal of Speaker 1 to Pin 5, and the plus terminal of

Speaker 2 to Pin 8, proper speaker phase can be established.

8 V p­p. If the available input signal is 1.4 V rms or more, use

When you have determined the closed-loop gain required by

your source level, and can develop 1 W across the 8 Ω load

resistor with the normal input signal level, replace the resistor

with your speaker. Your speaker can be connected across the

be connected to the (+) terminal of the speaker.

The maximum power dissipation of the device, assuming both

loads are equal, can be found by doubling Equation 11. If the

loads are different, use Equation 11 to find the power dissipa-

tion caused by each load, then take the sum to find the total

power dissipated by the SSM2211.

EVALUATION BOARD

An evaluation board for the SSM2211 is available. For more

information, call 1-800-ANALOGD.

8

SSM2211

5

GND

CH A

CH B

PROBES

CH B

INV. ON

DISPLAY

A+B

OSCILLOSCOPE

2.5V

COMMON

MODE

8

Ω

1W

V+

8

4

SSM2211

5

3

2

1

6

J1

J2

C1

0.1µF

7

1µF

CW

ON

SHUTDOWN

R1

51kΩ

+

+

20kΩ

20kΩ

1W 8Ω

VOLUME

20kΩ POT.

AUDIO

INPUT

C1

0.1µF

C2

10µF

Figure 51. Using an Oscilloscope to Display the Bridged-Output Voltage

Figure 50. Evaluation Board Schematic

The voltage gain of the SSM2211 is given by Equation 20.

I

F

V

R

R

A

×

= 2

(20)

To use the SSM2211 in a single-ended-output configuration,

replace J1 and J2 jumpers with electrolytic capacitors of a

suitable value, with the negative terminals to the output

returned to ground. Note that the maximum output power is

reduced to 250 mW (one-quarter of the rated maximum), due

to the maximum swing in the nonbridged mode being one-half

and power being proportional to the square of the voltage. For

frequency response down 3 dB at 100 Hz, a 200 μF capacitor is

required with 8 Ω speakers.

The SSM2211 evaluation board also comes with a shutdown

switch, which allows the user to switch between on (normal

operation) and the power-conserving shutdown mode.

If desired, the input signal may be attenuated by turning the

and Pin 3. With V+ = 5 V, there is 2.5 V common-mode voltage

LFCSP PRINTED CIRCUIT BOARD LAYOUT

CONSIDERATIONS

The LFCSP is a plastic encapsulated package with a copper lead

frame substrate. This is a leadless package with solder lands on

the bottom surface of the package, instead of conventional

formed perimeter leads. A key feature that allows the user to

paddle (DAP) on the bottom surface of the package. When

soldered to the PCB, the DAP can provide efficient conduction

of heat from the die to the PCB. In order to achieve optimum

package performance, consideration should be given to the PCB

pad design for both the solder lands and the DAP. For further

information the user is directed to the Amkor Technology

document, “Application Notes for Surface Mount Assembly of

Amkor’s MicroLead Frame (MLF) Packages.” This can be

downloaded from the Amkor Technology website,

www.amkor.com, as a product application note.

CAUTION: The ground lead of the oscilloscope probe, or any

other instrument used to measure the output signal, must not

be connected to either output, as this shorts out one of the

amplifier outputs and can possibly damage the device.

A safe method of displaying the differential output signal using a

grounded scope is shown in Figure 51. Connect Channel A probe

post. Invert Channel B, and add the two channels together. Most

multichannel oscilloscopes have this feature built in. If you must

connect the ground lead of the test instrument to either output

signal pins, a power-line isolation transformer must be used to

isolate the instrument ground from the power supply ground.

Recall that

R

P

V

×

=