SSM2302CPZ-REEL Analog Devices Inc, SSM2302CPZ-REEL Datasheet - Page 12

• Manufacturer Part Number: SSM2302CPZ-REEL
• Description: IC,Audio Amplifier,DUAL,LLCC,16PIN,PLASTIC
• Manufacturer: Analog Devices Inc
• Type: Class Dr

Specifications of SSM2302CPZ-REEL

• Output Type: 2-Channel (Stereo)
• Max Output Power X Channels @ Load: 1.4W x 2 @ 8 Ohm
• Voltage - Supply: 2.5 V ~ 5 V
• Features: Depop, Differential Inputs, Short-Circuit and Thermal Protection, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 16-LFCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: SSM2302Z-EVAL - BOARD EVAL FOR SSM2302
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

SSM2302
APPLICATION NOTES
OVERVIEW
The SSM2302 stereo Class-D audio amplifier features a filterless
modulation scheme that greatly reduces the external components
count, conserving board space and thus reducing systems cost.
The SSM2302 does not require an output filter, but instead relies
on the inherent inductance of the speaker coil and the natural
filtering of the speaker and human ear to fully recover the audio
component of the square-wave output. While most Class-D ampli-
fiers use some variation of pulse-width modulation (PWM), the
SSM2302 uses a Σ-Δ modulation to determine the switching
pattern of the output devices. This provides a number of important
benefits. Σ-Δ modulators do not produces a sharp peak with
many harmonics in the AM frequency band, as pulse-width
modulators often do. Σ-Δ modulation provides the benefits of
reducing the amplitude of spectral components at high frequencies;
that is, reducing EMI emission that might otherwise be radiated
by speakers and long cable traces. The SSM2302 also offers
protection circuits for overcurrent and temperature protection.
GAIN SELECTION
Pulling the GAIN pin high of the SSM2302 sets the gain of the
speaker amplifier to 12 dB; pulling it low sets the gain of the
speaker amplifier to 6 dB.
It is possible to adjust the SSM2302 gain by using external resistors
at the input. To set a gain lower than 12 dB refer to Figure 22 for
differential input configuration and Figure 23 for single-ended
configuration. For external gain configuration from a fixed 12 dB
gain, please use the following formula:
To set a gain lower than 6 dB refer to Figure 24 for differential
input configuration and Figure 25 for single-ended configuration.
For external gain configuration from a fixed 6 dB gain, use the
following formula:
POP-AND-CLICK SUPPRESSION
Voltage transients at the output of audio amplifiers can occur when
shutdown is activated or deactivated. Voltage transients as low
as 10 mV can be heard as an audio pop in the speaker. Clicks
and pops can also be classified as undesirable audible transients
generated by the amplifier system, therefore as not coming from
the system input signal. Such transients can be generated when
the amplifier system changes its operating mode. For example, the
following can be sources of audible transients: system power-up/
power-down, mute/unmute, input source change, and sample rate
change. The SSM2302 has a pop-and-click suppression architecture
that reduces this output transients, resulting in noiseless activation
and deactivation.
External Gain Settings = 20 log[4/(1 + R/150 kΩ)]
External Gain Settings = 20 log[2/(1 + R/150 kΩ)]
Rev. 0 | Page 12 of 20
EMI NOISE
The SSM2302 uses a proprietary modulation and spread-
spectrum technology to minimize EMI emissions from the
device. Figure 26 shows SSM2302 EMI emission starting from
100 kHz to 30 MHz. Figure 27 shows SSM2302 EMI emission
from 30 kHz to 2 GHz. These figures clearly describe the SSM2302
EMI behavior as being well below the FCC regulation values,
starting from 100 kHz and passing beyond 1 GHz of frequency.
Although the overall EMI noise floor is slightly higher, frequency
spurs from the SSM2302 are greatly reduced.
The measurements for Figure 26 and Figure 27 were taken with
a 1 kHz input signal, producing 0.5 W output power into an 8 Ω
load from a 3.6 V supply. Cable length was approximately 5 cm.
The EMI was detected using a magnetic probe touching the 2”
output trace to the load.
70
60
50
40
30
20
10
70
60
50
40
30
20
10
0
0
0.1
10
= HORIZONTAL
= VERTICAL
= REGULATION VALUE
= HORIZONTAL
= VERTICAL
= REGULATION VALUE
Figure 26. EMI Emissions from SSM2302
Figure 27. EMI Emissions from SSM2302
100
1
FREQUENCY (MHz)
FREQUENCY (MHz)
10
1k
100
10k