2 × 2 W, Filterless, Stereo, Class-D
Audio Amplifier with ALC and I2C
SSM2380
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781.329.4700 www.analog.com
Fax: 781.461.3113 ©2010–2011 Analog Devices, Inc. All rights reserved.
FEATURES
Filterless, stereo, Class-D amplifier with Σ-Δ modulation
2 W into 4 Ω load and 1.4 W into 8 Ω load at 5.0 V supply
with <1% total harmonic distortion plus noise (THD + N)
Highly configurable I2C interface for gain adjust, automatic
level control (ALC), and ultralow EMI emissions mode
MODE pin can disable I2C interface for more traditional
stereo amplifier configuration
Stereo-to-mono mixer option via I2C control
93% efficiency at 5.0 V, 1.4 W into 8 Ω speaker
Signal-to-noise ratio (SNR): >100 dB
Single-supply operation from 2.5 V to 5.5 V
Ultralow shutdown current: 20 nA
Short-circuit and thermal protection
Pop-and-click suppression
Available in 16-ball, 2.0 mm × 2.0 mm WLCSP
APPLICATIONS
Mobile phones
MP3 players
Portable electronics
GENERAL DESCRIPTION
The SSM2380 is a fully integrated, high efficiency, stereo, Class-D
audio amplifier. It is designed to maximize performance for mobile
phone applications. The application circuit requires a minimum
of external components and operates from a single 2.5 V to 5.5 V
supply. It is capable of delivering 2 W of continuous output power
with <1% THD + N driving a 4 Ω load from a 5.0 V supply.
The SSM2380 features a highly flexible I2C interface with many
useful settings. Using the I2C control interface, the gain of the
SSM2380 can be selected from 1 dB to 24 dB (plus mute) in
47 steps with no external components. Other features accessed
from the I2C interface include independent left/right channel
shutdown, variable ultralow EMI emission control mode, auto-
matic level control (ALC) for high quality speaker protection,
and stereo-to-mono mixing operation.
The SSM2380 features a high efficiency, low noise modulation
scheme that requires no external LC output filters. The modulation
continues to provide high efficiency even at low output power.
The SSM2380 operates with 93% efficiency at 1.4 W into 8 Ω
or with 85% efficiency at 2 W into 4 Ω from a 5.0 V supply and
has an SNR of >100 dB.
Spread-spectrum pulse density modulation is used to provide
lower EMI-radiated emissions compared with other Class-D
architectures. An added benefit of spread-spectrum Σ- modu-
lation is that no synchronization (SYNC) is needed when using
multiple Class-D amplifiers. For applications that require long
speaker cables (>10 cm), the SSM2380 includes a user-selectable
ultralow EMI emissions mode that eliminates the need for EMI
filters at the Class-D outputs.
The SSM2380 has a micropower shutdown mode with a typical
shutdown current of 20 nA. Shutdown is enabled by applying
a logic low to the SD pin or through an optional independent
channel soft shutdown via I2C.
The device also includes pop-and-click suppression circuitry.
This suppression circuitry minimizes voltage glitches at the
output during turn-on and turn-off, reducing audible noise
on activation and deactivation.
The fully differential inputs of the SSM2380 provide excellent
rejection of common-mode noise on the input. Input coupling
capacitors can be omitted if the dc input common-mode voltage
is approximately VDD/2.
The SSM2380 is specified over the commercial temperature
range of −40°C to +85°C. It has built-in thermal shutdown
and output short-circuit protection. It is available in a 16-ball,
2 mm × 2 mm wafer level chip scale package (WLCSP).
SSM2380
Rev. A | Page 2 of 32
TABLE OF CONTENTS
Features .............................................................................................. 1
Applications....................................................................................... 1
General Description......................................................................... 1
Revision History ............................................................................... 2
Functional Block Diagram .............................................................. 3
Specifications..................................................................................... 4
I2C Timing Characteristics.......................................................... 5
Absolute Maximum Ratings............................................................ 6
Thermal Resistance ...................................................................... 6
ESD Caution.................................................................................. 6
Pin Configuration and Function Descriptions............................. 7
Typical Performance Characteristics ............................................. 8
Theory of Operation ...................................................................... 14
Overview...................................................................................... 14
Pop-and-Click Suppression....................................................... 14
Output Modulation Description .............................................. 14
Operating Modes........................................................................ 15
ALC Mode Operation ................................................................ 15
Gain Select Mode Operation .................................................... 16
I2C Control Mode Operation.................................................... 16
Automatic Level Control (ALC)............................................... 16
Mixer Mode................................................................................. 18
Applications Information.............................................................. 19
Layout .......................................................................................... 19
Input Capacitor Selection.......................................................... 19
Power Supply Decoupling ......................................................... 20
Typical Application Circuits ......................................................... 21
I2C Interface .................................................................................... 24
Register Map ................................................................................... 25
Register Map Details ...................................................................... 26
Register R0: Left Channel Gain Control, Address 0x00........ 26
Register R1: Right Channel Gain Control, Address 0x01..... 26
Register R2: Mode Control, Address 0x02.............................. 27
Register R3: ALC Control 1, Address 0x03............................. 27
Register R4: ALC Control 2, Address 0x04............................. 28
Register R5: Shutdown, Address 0x05..................................... 29
Register R6: Error, Address 0x06.............................................. 29
Register R7: Error Clear, Address 0x07................................... 29
Register R8: Reset, Address 0x08 ............................................. 29
Outline Dimensions ....................................................................... 30
Ordering Guide .......................................................................... 30
REVISION HISTORY
2/11—Rev. 0 to Rev. A
Changes to Setting the ALC Threshold Voltage Section........... 15
10/10—Revision 0: Initial Version
SSM2380
Rev. A | Page 3 of 32
FUNCTIONAL BLOCK DIAGRAM
0.1µF
VDDVDD
INTERNAL
OSCILLATOR
OUTR+
OUTR–
EDGE
OUTL+
OUTL–
I
2
C
INR+
VDD 2.5V TO 5.5V
INR–
INL+
INL–
GNDGND
10µF
22nF
22nF
22nF
22nF
SHUTDOWN
EMISSION CONTROL
SD
LEFT IN+
LEFT IN–
GAIN1
GAIN = 6dB, 12dB, 18dB, OR 24dB
GAIN0
RIGHT IN–
RIGHT IN+
SCK
SDA
MODE
SSM2380
08752-001
ALCTH
BIAS
GAIN
CONTROL
(+ALC)
Σ-∆
MODULATOR
Σ-∆
MODULATOR
Σ-∆
MODULATOR
FET
DRIVER
FET
DRIVER
EMI
CONTROL
Figure 1.
SSM2380
Rev. A | Page 4 of 32
SPECIFICATIONS
VDD = 5.0 V, TA = 25°C, RL = 8 Ω +33 µH, gain = 6 dB, I2C control mode, unless otherwise noted.
Table 1.
Parameter Symbol Test Conditions/Comments1 Min Typ Max Unit
DEVICE CHARACTERISTICS f = 1 kHz, 20 kHz bandwidth
Output Power PO R
L = 8 Ω, THD = 1%, VDD = 5.0 V 1.43 W
R
L = 8 Ω, THD = 1%, VDD = 3.6 V 0.73 W
R
L = 8 Ω, THD = 10%, VDD = 5.0 V 1.8 W
R
L = 8 Ω, THD = 10%, VDD = 3.6 V 0.92 W
R
L = 4 Ω, THD = 1%, VDD = 5.0 V 2.581 W
R
L = 4 Ω, THD = 1%, VDD = 3.6 V 1.3 W
R
L = 4 Ω, THD = 10%, VDD = 5.0 V 3.21 W
R
L = 4 Ω, THD = 10%, VDD = 3.6 V 1.62 W
Efficiency η PO = 1.4 W into 8 Ω, VDD = 5.0 V
Normal, low EMI mode 93 %
Ultralow EMI mode 91 %
Total Harmonic Distortion Plus
Noise
THD + N PO = 1 W into 8 Ω, f = 1 kHz, VDD = 5.0 V 0.005 %
P
O = 0.5 W into 8 Ω, f = 1 kHz, VDD = 3.6 V 0.005 %
Input Common-Mode Voltage
Range
VCM 1.0 VDD − 1.0 V
Common-Mode Rejection Ratio CMRRGSM V
CM = 2.5 V ± 100 mV at 217 Hz, output referred 55 dB
Channel Separation XTALK P
O = 100 mW, f = 1 kHz 78 dB
Average Switching Frequency fSW 325 kHz
Differential Output Offset
Voltage
VOOS Gain = 6 dB 2.0 mV
POWER SUPPLY
Supply Voltage Range VDD Guaranteed from PSRR test 2.5 5.5 V
Power Supply Rejection Ratio PSRR VDD = 2.5 V to 5.0 V, dc input floating 70 85 dB
PSRRGSM VRIPPLE = 100 mV at 217 Hz, inputs ac-grounded,
CIN = 0.1 µF
60 dB
Supply Current, Stereo ISY V
IN = 0 V, no load, VDD = 5.0 V 6.8 mA
V
IN = 0 V, no load, VDD = 3.6 V 6.0 mA
V
IN = 0 V, no load, VDD = 2.5 V 5.8 mA
V
IN = 0 V, RL = 8 Ω + 33 µH, VDD = 5.0 V 7.0 mA
V
IN = 0 V, RL = 8 Ω + 33 µH, VDD = 3.6 V 6.1 mA
V
IN = 0 V, RL = 8 Ω + 33 µH, VDD = 2.5 V 5.5 mA
Shutdown Current ISD SD = GND 20 nA
GAIN CONTROL
Closed-Loop Gain Gain GAINx = I2C control mode 1 24 dB
SHUTDOWN CONTROL
Input Voltage High VIH 1.35 V
Input Voltage Low VIL 0.35 V
Turn-On Time tWU SD rising edge from GND to VDD 7 ms
Turn-Off Time tSD SD falling edge from VDD to GND 5 µs
Output Impedance ZOUT SD = GND >100 kΩ
NOISE PERFORMANCE
Output Voltage Noise en VDD = 3.6 V, f = 20 Hz to 20 kHz, inputs are
ac-grounded, gain = 6 dB, A-weighted
30 µV rms
Signal-to-Noise Ratio SNR PO = 1.4 W, RL = 8 Ω, gain = 6 dB 100 dB
P
O = 1.4 W, RL = 8 Ω, gain = 24 dB 90 dB
1 Although the SSM2380 has good quality above 2 W, continuous output power beyond 2 W must be avoided due to device packaging limitations.
SSM2380
Rev. A | Page 5 of 32
I2C TIMING CHARACTERISTICS
Table 2.
Limit
Parameter tMIN t
MAX Unit Description
tSCS 600 ns Start condition setup time
tSCH 600 ns Start condition hold time
tPH 600 ns SCK pulse width high
tPL 1.3 s SCK pulse width low
fSCK 0 526 kHz SCK frequency
tDS 100 ns Data setup time
tDH 900 ns Data hold time
tRT 300 ns SDA and SCK rise time
tFT 300 ns SDA and SCK fall time
tHCS 600 ns Stop condition setup time
Timing Diagram
08752-002
SCK
SDA
t
RT
t
SCH
t
PL
t
DS
t
PH
t
DH
t
FT
t
SCS
t
HCS
Figure 2. I2C Timing
SSM2380
Rev. A | Page 6 of 32
ABSOLUTE MAXIMUM RATINGS
Absolute maximum ratings apply at 25°C, unless otherwise noted. THERMAL RESISTANCE
θJA is specified for the worst-case conditions, that is, a device
soldered in a circuit board for surface-mount packages.
Table 3.
Parameter Rating
Supply Voltage 6 V
Input Voltage VDD
Common-Mode Input Voltage VDD
ESD Susceptibility 4 kV
Storage Temperature Range −65°C to +150°C
Operating Temperature Range −40°C to +85°C
Junction Temperature Range −65°C to +165°C
Lead Temperature
(Soldering, 60 sec)
300°C
Table 4. Thermal Resistance
Package Type PCB θJA θ
JB Unit
16-Lead, 2.0 mm × 2.0 mm WLCSP 2S2P 57 14 °C/W
ESD CAUTION
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
SSM2380
Rev. A | Page 7 of 32
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
TOP VIEW
(BALL SIDE DOWN)
Not to Scale
08752-003
1
A
B
C
D
234
BALL
A
1
INDICATOR
OUTL+ VDDVDD
GAIN0 GAIN1
D
OUTR+
OUTL– GND OUTR–GND
SCK
EDGE
SDA
ALCTH
MOE
INL+ INR– INR+INL–
SD
Figure 3. Pin Configuration (Bottom View)
Table 5. Pin Function Descriptions
Pin No. Mnemonic Description
A1 OUTL+ Noninverting Output for Left Channel.
A2, A3 VDD Power Supply for Output Amplifiers.
A4 OUTR+ Noninverting Output for Right Channel.
B1 OUTL− Inverting Output for Left Channel.
B2, B3 GND Ground for Output Amplifiers.
B4 OUTR− Inverting Output for Right Channel.
C1 SD Shutdown Input. Active low digital input.
C2 MODE Three-Mode Interface Control Pin.
C3 SCK/EDGE/GAIN0 2-Wire I2C Control Interface Clock Input (SCK). MODE is connected to GND.
Low Emissions Mode Enable Pin (EDGE). MODE is floating.
Gain Select Pin, LSB (GAIN0). MODE is connected to VDD.
C4 SDA/ALCTH/GAIN1 2-Wire I2C Control Interface Data Input/Output (SDA). MODE is connected to GND.
Variable Threshold Voltage for ALC (ALCTH). MODE is floating.
Gain Select Pin, MSB (GAIN1). MODE is connected to VDD.
D1 INL+ Noninverting Input for Left Channel.
D2 INL− Inverting Input for Left Channel.
D3 INR− Inverting Input for Right Channel.
D4 INR+ Noninverting Input for Right Channel.
SSM2380
Rev. A | Page 8 of 32
TYPICAL PERFORMANCE CHARACTERISTICS
EDGE pin = GND, unless otherwise noted.
100
10
1
0.1
0.01
0.001
0.0001 0.001 0.01
OUTPUT POWER (W)
0.1 1 10
THD + N (%)
08752-020
R
L
= 8Ω + 33µH
GAIN = 6dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
100
10
1
0.1
0.01
0.001
0.0001 0.001 0.01
OUTPUT POWER (W)
0.1 1 10
THD + N (%)
08752-021
R
L
= 8Ω + 33µH
GAIN = 24dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
Figure 4. THD + N vs. Output Power into 8 Ω, Gain = 6 dB Figure 7. THD + N vs. Output Power into 8 Ω, Gain = 24 dB
100
10
1
0.1
0.01
0.001
0.0001 0.001 0.01
OUTPUT POWER (W)
0.1 1 10
THD + N (%)
08752-022
R
L
= 4Ω + 15µH
GAIN = 6dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
100
10
1
0.1
0.01
0.001
0.0001 0.001 0.01
OUTPUT POWER (W)
0.1 1 10
THD + N (%)
08752-023
R
L
= 4Ω + 15µH
GAIN = 24dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
Figure 5. THD + N vs. Output Power into 4 Ω, Gain = 6 dB Figure 8. THD + N vs. Output Power into 4 Ω, Gain = 24 dB
100
10
1
0.1
0.01
0.001
0.0001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-024
V
DD
= 5V
R
L
= 8Ω + 33µH
GAIN = 6dB
1W
0.5W
0.25W
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-025
VDD = 5V
RL = 8Ω + 33µH
GAIN = 24dB
1W
0.5W
0.25W
Figure 6. THD + N vs. Frequency, VDD = 5 V, RL = 8 Ω, Gain = 6 dB Figure 9. THD + N vs. Frequency, VDD = 5 V, RL = 8 Ω, Gain = 24 dB
SSM2380
Rev. A | Page 9 of 32
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-026
VDD = 5V
RL = 4Ω + 15µH
GAIN = 6dB
2W
1W
0.5W
Figure 10. THD + N vs. Frequency, VDD = 5 V, RL = 4 Ω, Gain = 6 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-028
VDD = 3.6V
RL = 8Ω + 33µH
GAIN = 6dB
0.5W
0.25W
0.125W
Figure 11. THD + N vs. Frequency, VDD = 3.6 V, RL = 8 Ω, Gain = 6 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-030
VDD = 3.6V
RL = 4Ω + 15µH
GAIN = 6dB
1W
0.5W
0.25W
Figure 12. THD + N vs. Frequency, VDD = 3.6 V, RL = 4 Ω, Gain = 6 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-027
VDD = 5V
RL = 4Ω + 15µH
GAIN = 24dB
2W
1W
0.5W
Figure 13. THD + N vs. Frequency, VDD = 5 V, RL = 4 Ω, Gain = 24 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-029
VDD = 3.6V
RL = 8Ω + 33µH
GAIN = 24dB
0.5W
0.25W
0.125W
Figure 14. THD + N vs. Frequency, VDD = 3.6 V, RL = 8 Ω, Gain = 24 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-031
VDD = 3.6V
RL = 4Ω + 15µH
GAIN = 24dB
1W
0.5W
0.25W
Figure 15. THD + N vs. Frequency, VDD = 3.6 V, RL = 4 Ω, Gain = 24 dB
SSM2380
Rev. A | Page 10 of 32
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-032
VDD = 2.5V
RL = 8Ω + 33µH
GAIN = 6dB
0.25W
0.125W
0.0625W
Figure 16. THD + N vs. Frequency, VDD = 2.5 V, RL = 8 Ω, Gain = 6 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-034
VDD = 2.5V
RL = 4Ω + 15µH
GAIN = 6dB
0.5W
0.25W
0.125W
Figure 17. THD + N vs. Frequency, VDD = 2.5 V, RL = 4 Ω, Gain = 6 dB
7.5
7.0
6.5
6.0
5.5
5.0
4.5
4.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
08752-036
BOTH CHANNELS
GAIN = 6dB
R
L
= 4Ω + 15µH
R
L
= 8Ω + 33µH
NO LOAD
Figure 18. Supply Current vs. Supply Voltage, Gain = 6 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-033
VDD = 2.5V
RL = 8Ω + 33µH
GAIN = 24dB
0.25W
0.125W
0.0625W
Figure 19. THD + N vs. Frequency, VDD = 2.5 V, RL = 8 Ω, Gain = 24 dB
100
10
1
0.1
0.01
0.001
10 100 1k
FREQUENCY (Hz)
10k 100k
THD + N (%)
08752-035
VDD = 2.5V
RL = 4Ω + 15µH
GAIN = 24dB
0.5W
0.25W
0.125W
Figure 20. THD + N vs. Frequency, VDD = 2.5 V, RL = 4 Ω, Gain = 24 dB
7.0
6.5
6.0
5.5
5.0
4.5
4.0
2.5 3.0 3.5 4.0 4.5 5.0 5.5
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (mA)
08752-037
BOTH CHANNELS
GAIN = 24dB
R
L
= 4Ω + 15µH
R
L
= 8Ω + 33µH
NO LOAD
Figure 21. Supply Current vs. Supply Voltage, Gain = 24 dB
SSM2380
Rev. A | Page 11 of 32
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
08752-038
f = 1kHz
R
L
= 8Ω + 33µH
GAIN = 6dB
THD + N = 10%
THD + N = 1%
Figure 22. Maximum Output Power vs. Supply Voltage, RL = 8 Ω, Gain = 6 dB
0
3.5
3.0
2.5
2.0
1.5
0.5
1.0
2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
08752-040
f = 1kHz
R
L
= 4Ω + 15µH
GAIN = 6dB
THD + N = 10%
THD + N = 1%
Figure 23. Maximum Output Power vs. Supply Voltage, RL = 4 Ω, Gain = 6 dB
100
90
80
70
60
50
40
30
20
10
0
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8
OUTPUT POWER (W)
EFFICIENCY (%)
08752-042
R
L
= 8Ω + 33µH
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
Figure 24. Efficiency vs. Output Power into 8 Ω
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
08752-039
f = 1kHz
R
L
= 8Ω + 33µH
GAIN = 24dB
THD + N = 10%
THD + N = 1%
Figure 25. Maximum Output Power vs. Supply Voltage, RL = 8 Ω, Gain = 24 dB
0
3.5
3.0
2.5
2.0
1.5
0.5
1.0
2.5 3.0 3.5 4.0 4.5 5.0
SUPPLY VOLTAGE (V)
OUTPUT POWER (W)
08752-041
f = 1kHz
R
L
= 4Ω + 15µH
GAIN = 24dB
THD + N = 10%
THD + N = 1%
Figure 26. Maximum Output Power vs. Supply Voltage, RL = 4 Ω, Gain = 24 dB
100
90
80
70
60
50
40
30
20
10
0
0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0
OUTPUT POWER (W)
EFFICIENCY (%)
08752-043
R
L
= 4Ω + 15µH
V
DD
= 2.5V
V
DD
= 3.6V V
DD
= 5V
Figure 27. Efficiency vs. Output Power into 4 Ω
SSM2380
Rev. A | Page 12 of 32
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5
OUTPUT POWER (W)
SUPPLY CURRENT (A)
08752-044
BOTH CHANNELS
R
L
= 8Ω + 33µH
GAIN = 6dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
Figure 28. Supply Current vs. Output Power into 8 Ω
0
–20
–30
–40
–50
–60
–70
–80
–90
–100
–10
10 100 1k
FREQUENCY (Hz)
10k 100k
CMRR (dB)
08752-047
Figure 29. Common-Mode Rejection Ratio (CMRR) vs. Frequency
0
–20
–40
–60
–80
–100
–120
–14010 100 1k
FREQUENCY (Hz)
10k 100k
CROSSTALK (dB)
08752-046
V
DD
= 5V
V
RIPPLE
= 500mV rms
R
L
= 8Ω + 33µH
LEFT TO RIGHT
RIGHT TO LEFT
Figure 30. Crosstalk vs. Frequency
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
0123 45
OUTPUT POWER (W)
SUPPLY CURRENT (A)
08752-045
6
BOTH CHANNELS
R
L
= 4Ω + 15µH
GAIN = 6dB
V
DD
= 2.5V
V
DD
= 3.6V
V
DD
= 5V
Figure 31. Supply Current vs. Output Power into 4 Ω
0
–20
–30
–40
–50
–60
–70
–80
–90
–100
–10
10 100 1k
FREQUENCY (Hz)
10k 100k
PSRR (dB)
08752-048
Figure 32. Power Supply Rejection Ratio (PSRR) vs. Frequency
SSM2380
Rev. A | Page 13 of 32
6
4
3
2
1
0
–1
–2
5
–2 0 2
TIME (ms)
4 6 8 101214161820
VOLTAGE (V)
08752-049
SD INPUT
OUTPUT
6
4
3
2
1
0
–1
–2
5
–160 –120 –80
TIME (µs)
–40 0 40 80 120 160 200 240
VOLTAGE (V)
08752-050
OUTPUT
SD INPUT
Figure 33. Turn-On Response Figure 34. Turn-Off Response
SSM2380
Rev. A | Page 14 of 32
THEORY OF OPERATION
OVERVIEW
The SSM2380 stereo, Class-D audio amplifier features a filterless
modulation scheme that greatly reduces the external component
count, conserving board space and, thus, reducing system cost.
The SSM2380 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.
Most Class-D amplifiers use some variation of pulse-width
modulation (PWM), but the SSM2380 uses Σ- modulation to
determine the switching pattern of the output devices, resulting
in a number of important benefits.
• Σ- modulators do not produce a sharp peak with many
harmonics in the AM frequency band, as pulse-width
modulators often do.
• Σ- modulation provides the benefits of reducing the
amplitude of spectral components at high frequencies,
that is, reducing EMI emissions that might otherwise
be radiated by speakers and long cable traces.
• The SSM2380 does not require external EMI filtering for
twisted speaker cable lengths shorter than 10 cm. If longer
speaker cables are used, the SSM2380 has an emission sup-
pression mode that allows significantly longer speaker cable.
• Due to the inherent spread-spectrum nature of Σ- modu-
lation, the need for modulator synchronization is eliminated
for designs that incorporate multiple SSM2380 amplifiers.
Using the I2C control interface, the gain of the SSM2380 can
be selected from 1 dB to 24 dB (plus mute) in 47 steps with no
external components and fixed input impedance. Other features
accessed from the I2C interface include the following:
• Independent left/right channel shutdown
• Variable ultralow EMI emission control mode
• Automatic level control (ALC) for high quality speaker
protection
• Stereo-to-mono mixing operation
The SSM2380 also offers protection circuits for overcurrent and
overtemperature protection.
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 and, therefore, as
not coming from the system input signal. Such transients may
be generated when the amplifier system changes its operating
mode. For example, the following may be sources of audible
transients: system power-up and power-down, mute and
unmute, input source change, and sample rate change.
The SSM2380 has a pop-and-click suppression architecture that
reduces these output transients, resulting in noiseless activation
and deactivation.
OUTPUT MODULATION DESCRIPTION
The SSM2380 uses three-level, Σ- output modulation. Each
output can swing from GND to VDD and vice versa. Ideally, when
no input signal is present, the output differential voltage is 0 V
because there is no need to generate a pulse. In a real-world
situation, noise sources are always present.
Due to the constant presence of noise, a differential pulse is
generated, when required, in response to this stimulus. A small
amount of current flows into the inductive load when the differ-
ential pulse is generated.
Most of the time, however, the output differential voltage is 0 V,
due to the Analog Devices, Inc., three-level, Σ- output modu-
lation. This feature ensures that the current flowing through the
inductive load is small.
When the user wants to send an input signal, an output pulse
(OUTx+ and OUTx−) is generated to follow the input voltage.
The differential pulse density (VOUT) is increased by raising the
input signal level. Figure 35 depicts three-level, Σ- output
modulation with and without input stimulus.
OUTPUT > 0V
+5V
0V
OUT+
+5V
0V
OUT–
+5V
0V
V
OUT
OUTPUT < 0V
+5V
0V
OUT+
+5V
0V
OUT–
0V
–5V
V
OUT
OUTPUT = 0V
OUT+
+5V
0V
+5V
0V
OUT–
+5V
–5V
0V
V
OUT
08752-004
Figure 35. Three-Level, Σ-Δ Output Modulation
With and Without Input Stimulus
SSM2380
Rev. A | Page 15 of 32
OPERATING MODES
The SSM2380 has three unique operating modes, controlled by
the MODE pin. When MODE (Ball C2) is connected to GND,
the SSM2380 operates in I2C control mode; Ball C3 and Ball C4
function as SCK and SDA for the I2C input. In I2C control mode,
the user has full control of all internal registers of the SSM2380
(see Table 1 1).
When MODE (Ball C2) is connected to VDD, the SSM2380
operates in gain select mode; Ball C3 and Ball C4 function as
the gain select pins, GAIN0 and GAIN1. All ALC and emission
control features are disabled in gain select mode, and the user
can set the gain to 6 dB, 12 dB, 18 dB, or 24 dB only.
When MODE (Ball C2) is not connected (floating), the SSM2380
operates in ALC mode; Ball C3 and Ball C4 function as EDGE and
ALCTH. In ALC mode, the default gain is 18 dB. The user can
enable or disable the emission control (EMI) feature by connect-
ing EDGE (Ball C3) to VDD or GND. In addition to emission
control, the ALC is activated. The user must connect a resistor
from ALCTH (Ball C4) to GND. This resistor allows the user to
limit the output level to any setting from 45% to 90% of VDD.
Table 6. MODE Pin Selection Guide
SSM2380 Ball
Ball C2 (MODE) Ball C3 Ball C4 Operating Mode
High (connected to VDD) GAIN0 GAIN1 Gain select mode
Low (connected to GND) SCK SDA I2C control mode
Open (floating) EDGE ALCTH ALC mode
ALC MODE OPERATION
When MODE is not connected (floating), the SSM2380 is in ALC
mode, disabling the I2C interface. In ALC mode, the user has
control of only two functions: setting the ALC threshold voltage
and activating or deactivating the emission limiting circuitry.
Setting the ALC Threshold Voltage
To set the ALC threshold voltage, connect ALCTH (Ball C4)
to GND with a series resistor. Figure 36 shows the relationship
between the RTH resistor setting and the output voltage limit as
a percentage of the supply rail.
To calculate the resistor value, use the following equations:
Limit (%) = 100 × (REXT + 53)/(2.2 × REXT + 58) k
REXT = (53 − 58 × Limit/100)/(2.2 × (Limit/100 – 1))%
For example, to set an 80% limit,
REXT = (53 − 58 × 80/100)/(2.2 × (80/100 − 1) k
Therefore, 8.7 kΩ is required.
Maximum output power is derived from VTH using the
following equation:
SP
DD
OUT R
VLimit
P
2
2
100/)( ⎟
⎟
⎠
⎞
⎜
⎜
⎝
⎛×
=
where RSP is the speaker impedance.
95
90
85
80
75
70
65
60
55
50
45
100 1k 10k 100k 1M
RESISTOR (Ω)
OUTPUT VOLTAGE LIMIT (%)
08752-005
TYPICAL CONDITION
INTERNAL RESISTOR – 20%
INTERNAL RESISTOR + 20%
Figure 36. Output Voltage Limit (VTH) vs. RTH
In ALC mode, the attack, hold, and release times associated
with ALC operation are at fixed levels, as indicated in Table 7.
Table 7. Attack, Hold, and Release Times for ALC Mode
Time Duration
Attack Time 256 s (per 0.5 dB step)
Hold Time 90 ms to 120 ms (nonadjustable)
Release Time 128 ms (per 0.5 dB step)
Activating or Deactivating the Emission Limiting Circuitry
To activate or deactivate the emission limiting circuitry, connect
EDGE (Ball C3) to GND or to VDD. When EDGE is connected
to GND, the SSM2380 is in normal operating mode, deactivating
the emission limiting function. The device operates with maximum
efficiency and noise level performance in this setting. The user
can also pass FCC Class B emission testing with 10 cm twisted
pair speaker wire for loudspeaker connection.
If longer speaker wire is desired, connect the EDGE pin to VDD
to activate the emission limiting circuitry. The trade-off is slightly
lower efficiency and noise performance. The penalty for using the
emission control circuitry is far less than the decreased perfor-
mance observed when using a ferrite bead based EMI filter for
emission limiting purposes.
SSM2380
Rev. A | Page 16 of 32
GAIN SELECT MODE OPERATION
When MODE is connected to VDD, the SSM2380 is in gain
select mode, disabling the I2C interface. The ALC and emission
limiting functions are also disabled. Ball C3 and Ball C4 function
as the gain select pins, GAIN0 and GAIN1. Tabl e 8 shows the
user-selectable gain settings for the SSM2380.
Table 8. Gain Settings in Gain Select Mode
GAIN0 (Ball C3) GAIN1 (Ball C4) Gain Setting (dB)
GND GND 6
VDD GND 12
GND VDD 18
VDD VDD 24
I2C CONTROL MODE OPERATION
When MODE is connected to GND, the SSM2380 operates in
I2C control mode, enabling Ball C3 and Ball C4 to act as SCK
and SDA for the I2C input. In I2C control mode, the user has
full control of all features of the SSM2380 (see Table 11).
• Gain control: 48-step, left/right independent control
(ALC is off)
• ALC control (limiter/compressor): configurable attack
and release times; configurable threshold voltage (16 level
settings, 64% to 96% of VDD); optional fixed-power mode
(does not track rail)
• Output stage: active emissions edge rate control
(four settings)
• Mixer: option to send left channel input to both left and
right channel outputs or to send right channel input to
both outputs
AUTOMATIC LEVEL CONTROL (ALC)
Automatic level control (ALC) is a function that automatically
adjusts amplifier gain to generate the desired output amplitude
with reference to a particular input stimulus. The primary use for
the ALC is to protect an audio power amplifier or speaker load
from the damaging effects of clipping or current overloading.
This is accomplished by limiting the output amplitude of the
amplifier upon reaching a preset threshold voltage. Another
benefit of the ALC is that it makes sound sources with a wide
dynamic range more intelligible by boosting low level signals,
while in turn limiting very high level signals.
Before activating the ALC by setting the ALC_EN bit (Bit 7 in
Register R4), the user has full control of the left and right channel
PGA gain (programmable in Register R0 and Register R1). After
the ALC is activated (ALC_EN = 1), the user has no control over
the gain settings in Register R0 and Register R1; the left channel
PGA gain is locked into the device and controls the gain for both
the left and right channels. To change the gain, the user must
reset the ALC_EN bit to 0 and then load the new gain settings.
Figure 37 shows the input vs. output and gain characteristics
of the ALC that is implemented in the SSM2380.
5.6
5.2
4.8
4.4
4.0
3.6
3.2
2.8
2.4
1.6
1.2
2.0
0.8
0.4
0
0 20 40 60 80 100 120 140 160 180 200
TIME (ms)
OUTPUT VOLTAGE LEVEL (V)
08752-006
INPUT
GAIN = 6dB
GAIN = 12dB
GAIN = 18dB
GAIN = 24dB
Figure 37. Input vs. Output and Gain Characteristics
When the input level is small and below the ALC threshold value,
the gain of the amplifier stays at the preset gain setting. When
the input exceeds the ALC threshold value, the ALC gradually
reduces the gain from the preset gain setting down to 1 dB.
ALC Compression and Limiting Modes
The ALC implemented on the SSM2380 has two operation
modes: compression and limiting. When the ALC is triggered
for medium-level input signals, the ALC is in compression mode.
In this mode, an increase of the output signal is one-third the
increase of the input signal. For example, if the input signal
increases by 3 dB, the ALC reduces the amplifier gain by 2 dB
and thus the output signal increases by only 1 dB.
As the input signal becomes very large, the ALC transitions to
limiting mode. In this mode, the output stays at a given threshold
level, VTH, even if the input signal grows larger. As an example of
limiting mode operation, when a large input signal increases by
3 dB, the ALC reduces the amplifier gain by 3 dB and thus the
output increases by 0 dB. When the amplifier gain is reduced to
1 dB, the ALC cannot reduce the gain further, and the output
increases again. This is because the total range of the ALC opera-
tion has bottomed out due to extreme input voltage at high gain. To
avoid potential speaker damage, the maximum input amplitude
should not be large enough to exceed the maximum attenuation
(to a level of 1 dB) of the limiting mode.
SSM2380
Rev. A | Page 17 of 32
Attack Time, Hold Time, and Release Time
When the amplifier input signal exceeds a preset threshold,
the ALC reduces amplifier gain rapidly until the output voltage
settles to a target level. This target level is maintained for a certain
period. If the input voltage does not exceed the threshold again,
the ALC increases the gain gradually.
The attack time is the time taken to reduce the gain from maxi-
mum to minimum. The hold time is the time that the reduced
gain is maintained. The release time is the time taken to increase
the gain from minimum to maximum. These times are shown
in Table 9.
Table 9. Attack, Hold, and Release Times for I2C Control Mode
Time1 Duration
Attack Time 32 s to 4 ms (per 0.5 dB step)
Hold Time 90 ms to 120 ms
Release Time 4 ms to 512 ms (per 0.5 dB step)
1 The attack time and release time can be adjusted using the I2C interface.
The hold time cannot be adjusted.
Soft-Knee Compression
Often performed using sophisticated DSP algorithms, soft-knee
compression provides maximum sound quality with effective
speaker protection. Instead of using a fixed compression setting
prior to limiting, the SSM2380 allows for a much more subtle
transition into limiting mode, preserving the original sound
quality of the source audio. Figure 38 to Figure 40 show the
various soft-knee compression settings. If desired, compression
can be disabled. When compression is disabled, the part operates
in limiter-only mode.
0
0.5
1.0
1.5
2.0
2.5
0 0.05 0.10 0.15 0.20 0.30 0.35 0.40 0.450.25 0.50
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
08752-007
00 (LIMITER MODE)
01 (COMPRESSION MODE 1)
10 (COMPRESSION MODE 2)
11 (COMPRESSION MODE 3)
2.5V × 0.77 = 1.925V
Figure 38. Adjustable Compression Settings, VDD = 2.5 V,
ALC Threshold Level = 77%
0
0.5
1.5
2.0
2.5
1.0
3.0
3.5
0 0.1 0.2 0.3 0.4 0.6 0.7 0.8 0.90.5 1.0
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
08752-018
00 (LIMITER MODE)
01 (COMPRESSION MODE 1)
10 (COMPRESSION MODE 2)
11 (COMPRESSION MODE 3)
3.6V × 0.77 = 2.772V
Figure 39. Adjustable Compression Settings, VDD = 3.6 V,
ALC Threshold Level = 77%
0
0.5
1.5
2.0
2.5
1.0
3.0
4.0
3.5
4.5
0 0.2 0.4 0.6 0.8 1.2 1.4 1.6 1.81.0 2.0
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
08752-019
00 (LIMITER MODE)
01 (COMPRESSION MODE 1)
10 (COMPRESSION MODE 2)
11 (COMPRESSION MODE 3)
5.0V × 0.77 = 3.85V
Figure 40. Adjustable Compression Setting, VDD = 5.0 V,
ALC Threshold Level = 77%
ALC Soft Transition
The ALC operation of the SSM2380 incorporates techniques to
reduce the audible artifacts associated with gain change transi-
tions. First, the gain is changed in small increments of 0.5 dB.
In addition to this small step size, the rate of gain change is
reduced, proportional to the attack time setting. This feature
drastically reduces and virtually eliminates the presence of zipper
noise and other artifacts associated with gain transitions during
ALC operation. Figure 41 shows the soft transition operation.
08752-008
SOFT TRANSITION (32µs TO 256µs)
NORM
A
L TRANSITION
0.5dB
0.5dB
Figure 41. Soft Transition
SSM2380
Rev. A | Page 18 of 32
MIXER MODE
When I2C control mode is activated, the user can send left
channel input to both left and right channel outputs or send
right channel input to both outputs. This is achieved by
selecting Register R2, Bit 0 or Bit 1.
Using Mixer Mode with the ALC
If the ALC is enabled and the user also wishes to use the mixer
operation, follow the guidelines in this section. Left channel
gain controls the ALC; therefore, sending left channel input
to the left and right channel outputs poses no problem for the
ALC. However, to source the right channel input to the left and
right channel outputs when using the ALC, the user must first
load the left channel gain (Register R0, Bit 7).
With the ALC disabled, the user can also use the full mixer
capability; that is, if the user wishes to mix the right and left
inputs for both the right and left outputs, the ALC must be
disabled. If the user needs both the mixing and ALC functions,
the left or right channel must be muted to avoid problems.
When the ALC is active, the following options are acceptable:
• Left output = left input; right output = right input
• Left output = left input; right output = left input
• Left output = right input; right output = right input
To use the following options, the ALC must be disabled:
• Left output = left input + right input; right output = right
input
• Left output = left input; right output = left input + right
input
• Left output = left input + right input; right output = left
input + right input
SSM2380
Rev. A | Page 19 of 32
APPLICATIONS INFORMATION
LAYOUT
As output power increases, care must be taken to lay out printed
circuit board (PCB) traces and wires properly among the amplifier,
load, and power supply. A good practice is to use short, wide
PCB tracks to decrease voltage drops and minimize inductance.
Ensure that track widths are at least 200 mil for every inch of
track length for lowest DCR, and use 1 oz or 2 oz copper PCB
traces to further reduce IR drops and inductance. A poor layout
increases voltage drops, consequently affecting efficiency. Use
large traces for the power supply inputs and amplifier outputs
to minimize losses due to parasitic trace resistance.
Proper grounding guidelines help to improve audio performance,
minimize crosstalk between channels, and prevent switching
noise from coupling into the audio signal. To maintain high
output swing and high peak output power, the PCB traces that
connect the output pins to the load, as well as the PCB traces to
the supply pins, should be as wide as possible to maintain the
minimum trace resistances. It is also recommended that a large
ground plane be used for minimum impedances.
In addition, good PCB layout isolates critical analog paths from
sources of high interference. High frequency circuits (analog and
digital) should be separated from low frequency circuits. Properly
designed multilayer PCBs can reduce EMI emissions and increase
immunity to the RF field by a factor of 10 or more compared with
double-sided boards. A multilayer board allows a complete layer
to be used for the ground plane, whereas the ground plane side
of a double-sided board is often disrupted by signal crossover.
If the system has separate analog and digital ground and power
planes, the analog ground plane should be directly beneath the
analog power plane, and, similarly, the digital ground plane should
be directly beneath the digital power plane. There should be no
overlap between analog and digital ground planes or between
analog and digital power planes.
INPUT CAPACITOR SELECTION
The SSM2380 does not require input coupling capacitors if the
input signal is biased from 1.0 V to VDD − 1.0 V. Input capacitors
are required if the input signal is not biased within this recom-
mended input dc common-mode voltage range, if high-pass
filtering is needed, or if a single-ended source is used. If high-
pass filtering is needed at the input, the input capacitor and the
input resistor of the SSM2380 form a high-pass filter whose
corner frequency is determined by the following equation:
fC = 1/(2π × RIN × CIN)
The input capacitor can significantly affect the performance of
the circuit. Not using input capacitors degrades both the output
offset of the amplifier and the dc PSRR performance.
In I2C control mode, the input impedance changes depending on
the gain setting from Register R0 and Register R1 (LGAIN[5:0]
and RGAIN[5:0] bits). Table 10 shows the RIN value for each
PGA gain setting.
Table 10. Input Impedance for I2C Control Mode
LGAIN[5:0],
RGAIN[5:0] Gain (dB) RIN (kΩ)
101110 24.0 7.3
101101 23.5 7.7
101100 23.0 8.1
101011 22.5 8.5
101010 22.0 9.0
101001 21.5 9.5
101000 21.0 10.0
100111 20.5 10.5
100110 20.0 11.1
100101 19.5 11.7
100100 19.0 12.3
100011 18.5 12.9
100010 18.0 13.6
100001 17.5 14.3
100000 17.0 15.0
011111 16.5 15.8
011110 16.0 16.6
011101 15.5 17.4
011100 15.0 18.3
011011 14.5 19.2
011010 14.0 20.1
011001 13.5 21.1
011000 13.0 22.1
010111 12.5 23.1
010110 12.0 24.2
010101 11.5 25.3
010100 11.0 26.4
010011 10.5 27.6
010010 10.0 28.8
010001 9.5 30.0
010000 9.0 31.3
001111 8.5 32.6
001110 8.0 34.0
001101 7.5 35.3
001100 7.0 36.7
001011 6.5 38.1
001010 6.0 39.6
001001 5.5 41.1
001000 5.0 42.6
000111 4.5 44.1
000110 4.0 45.6
000101 3.5 47.1
000100 3.0 48.7
000011 2.5 50.3
000010 2.0 51.8
000001 1.5 53.4
000000 1.0 55.0
SSM2380
Rev. A | Page 20 of 32
POWER SUPPLY DECOUPLING
To ensure high efficiency, low total harmonic distortion (THD),
and high PSRR, proper power supply decoupling is necessary.
Noise transients on the power supply lines are short-duration
voltage spikes. Although the actual switching frequency is typi-
cally 325 kHz, these spikes can contain frequency components
that extend into the hundreds of megahertz.
The power supply inputs must be decoupled with a good
quality, low ESL, low ESR capacitor, usually of approximately
4.7 µF. This capacitor bypasses low frequency noises to the
ground plane.
For high frequency transient noises, use a 0.1 µF capacitor
as close as possible to the VDD pins of the device. Placing the
decoupling capacitors as close as possible to the SSM2380 helps
to maintain efficient performance.
SSM2380
Rev. A | Page 21 of 32
TYPICAL APPLICATION CIRCUITS
OUTL
INL MODULATORGAIN
OUTR
INR MODULATORGAIN
ALC
08752-011
Figure 42. SSM2380 Mixer Operation Block Diagram
08752-012
STDN
B4
GND
GND
OUT_R–
OUT_R+
OUT_L–
OUT_L+
H6
HDR1X2C34
510pF
H7
HDR1X2
C36
510pF
C35
510pF
C33
510pF
VDD
C27
0.1µF
C26
10µF
L INPUT +
L INPUT–
R INPUT +
R INPUT–
GND
GND
GND
U8
SSM2380
A1
A3
B3
C2
D1
B1D2
B2
D4
D3
A4
A2
C4C1
C3
OUTL+
VDD
GND
MODE
INL+
OUTL–INL–
GND
INR+
INR–
OUTR+
VDD
OUTR–
SDA
SCK
R14 0Ω
R16 0Ω
C22
0.22µF
C25
0.22µF
R17 0Ω
C24
0.22µF
R15 0Ω
C23
0.22µF
SCK
SDA
I2CVDD
I2C[0..1]
SD
R20
2.5kΩ
R21
2.5kΩ
B1
MPZ1608S121A
B2
MPZ1608S121A
B3
MPZ1608S121A
B4
MPZ1608S121A
Figure 43. SSM2380 Typical Schematic, I2C Control Mode
0.1µF
VDDVDD
INTERNAL
OSCILLATOR
OUTR+
OUTR–
OUTL+
OUTL–
I2C
INR+
VDD 2.5V TO 5.5V
INR–
INL+
INL–
GNDGND
10µF
22nF
22nF
22nF
22nF
SHUTDOWN
SD
LEFT IN+
LEFT IN–
RIGHT IN–
RIGHT IN+
SCK
SDA
MODE =
SSM2380
GND
Σ-∆
MODULATOR
FET
DRIVER
I2C OPERATION (MODE PIN = GND)
08752-013
BIAS
GAIN
CONTROL
(+ALC)
Σ-∆
MODULATOR
EMI
CONTROL
Σ-∆
MODULATOR
FET
DRIVER
Figure 44. SSM2380 I2C Control Mode Configuration (MODE Pin = GND)
SSM2380
Rev. A | Page 22 of 32
08752-014
H7
HDR1X2
H6
HDR1X2
VDD
C35
510pF
C36
510pF
C33
510pF
C34
510pF
OUT_R–
OUT_L–
OUT_L+
OUT_R+
C23
0.22µF
C22
0.22µF
C24
0.22µF
C25
0.22µF
C26
10µF
C27
0.1µF
EMI CTRL
ALC THRESHOLD RESISTOR
L INPUT +
R INPUT –
R INPUT +
L INPUT–
STDN
GND
GND
GND
GND
GND
A1
A3
B3
C2
D1
B1D2
B2
D4
D3
A4
A2
B4
C3C1
C4
FLOAT
OUTL+
VDD
GND
MODE
INL+
OUTL–INL–
GND
INR+
INR–
OUTR+
VDD
OUTR–
EDGE
ALCTH
U8
SSM2380
SD
R20
12kΩ
B1
MPZ1608S121A
B2
MPZ1608S121A
B3
MPZ1608S121A
B4
MPZ1608S121A
Figure 45. SSM2380 Typical Schematic, ALC Mode
0.1µF
VDDVDD
INTERNAL
OSCILLATOR
OUTR+
OUTR–
EDGE
OUTL+
OUTL–
I2C
DISABLED
INR+
VDD 2.5V TO 5.5V
INR–
INL+
INL–
GNDGND
10µF
22nF
22nF
22nF
22nF
SHUTDOWN
EMISSION CONTROL
SD
LEFT IN+
LEFT IN–
RIGHT IN–
RIGHT IN+
SSM2380
MODE = OPEN
08752-015
ALCTH
RTH
Σ-∆
MODULATOR
FET
DRIVER
BIAS
18dB
GAIN
(+ALC)
Σ-∆
MODULATOR
EMI
CONTROL
Σ-∆
MODULATOR
FET
DRIVER
A
LC OPERATION (MODE PIN = OPEN)
Figure 46. SSM2380 ALC Mode Configuration (MODE Pin = Open (Floating))
SSM2380
Rev. A | Page 23 of 32
0
8752-016
GAIN SELECT G1
GAIN SELECT G0
H7
HDR1X2
H6
HDR1X2
OUT_L+
OUT_R+
OUT_L–
OUT_R–
C34
510pF
C36
510pF
C33
510pF
C35
510pF
R INPUT +
L INPUT–
L INPUT +
R INPUT –
C23
0.22µF
C22
0.22µF
C25
0.22µF
C24
0.22µF
C26
10µF
C27
0.1µF
0Ω
0Ω
0Ω
0Ω
STDN
R17
R15
R14
R16
VDD
GND
INL+
INL–
GND
INR+
INR–
VDD
U8
SSM2380
OUTL+
MODE
OUTL–
OUTR+
OUTR–
GAIN1
GAIN0
GND
GND
GND
GND
B3
B2
A1
A3
C2
D1
B1D2
D4
D3
A4
A2
B4
C4C1
C3
VDD
I2CVDD
SD
B1
MPZ1608S121A
B2
MPZ1608S121A
B3
MPZ1608S121A
B4
MPZ1608S121A
Figure 47. SSM2380 Typical Schematic, Gain Select Mode
0.1µF
VDDVDD
INTERNAL
OSCILLATOR
OUTR+
OUTR–
OUTL+
OUTL–
INR+
VDD 2.5V TO 5.5V
INR–
INL+
INL–
GNDGND
10µF
22nF
22nF
22nF
22nF
GAIN = 6dB, 12dB,
18dB, OR 24dB
SHUTDOWN
SD
LEFT IN+
LEFT IN–
GAIN1
GAIN0
RIGHT IN–
RIGHT IN+
MODE =
SSM2380
VDD
VDD)GAIN OPERATION (MODE PIN =
Σ-∆
MODULATOR
FET
DRIVER
08752-017
BIAS
GAIN
CONTROL
Σ-∆
MODULATOR
Σ-∆
MODULATOR
FET
DRIVER
I C
DISABLED
2
EMI
CONTROL
Figure 48. SSM2380 Gain Select Mode Configuration (MODE Pin = VDD)
SSM2380
Rev. A | Page 24 of 32
I2C INTERFACE
SDA generates the serial control data-word, and SCK clocks the
serial data. The I2C bus address (Bits[A7:A1]) is 0x31 (01100010
for write and 01100011 for read). Bit A0 is the designated
read/write bit.
The I2C interface provides access to the user-selectable control
registers and operates with a 2-wire interface.
Each control register consists of 16 bits, MSB first. Bits[B15:B9]
are the register map address, and Bits[B8:B0] are the register data
for the associated register map.
08752-009
P
98
1TO 7
98
1TO 7
98
1TO 7
S
SDA
SC
K
START ADDR R/W ACK ACKSUBADDRESS ACK STOPDATA
Figure 49. SSM2380 2-Wire I2C Generalized Clocking Diagram
08752-010
WRITE
SEQUENCE
READ
SEQUENCE SA1A7 A0 A(S) A(S) SB15 B9 0
01
0P
0... A1A7 A0 A(S)... B0 B8B7 A(M) A(M)...
B0B7 P...
......
DEVICE
ADDRESS
DEVICE
ADDRESS
REGISTER
ADDRESS
SA1A7 A0 A(S) A(S) A(S)B15 B9 B8
0
... ...
DEVICE
ADDRESS
REGISTER
ADDRESS
REGISTER
DATA
(SLAVE DRIVE)
REGISTER
DATA
S =
P =
A0 =
A(S) =
A(M) =
A(M) =
START BIT.
STOP BIT.
I
2
C R/W BIT.
ACKNOWLEDGE BY SLAVE.
ACKNOWLEDGE BY MASTER.
ACKNOWLEDGE BY MASTER (INVERSION).
Figure 50. I2C Write and Read Sequences
SSM2380
Rev. A | Page 25 of 32
REGISTER MAP
Table 11. Register Map
Reg Address Name Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 Default
R0 0x00 Left channel
gain control
LTOR LMUTE LGAIN[5:0] 00100010
R1 0x01 Right channel
gain control
RTOL RMUTE RGAIN[5:0] 00100010
R2 0x02 Mode control 0 0 EDGE[1:0] OCREC OTREC R2L L2R 00001100
R3 0x03 ALC Control 1 0 0 RTIME[2:0] LTIME[2:0] 00101011
R4 0x04 ALC Control 2 ALC_EN COMP[1:0] ALC_VFIX ALCLV[3:0] 01001011
R5 0x05 Shutdown 0 0 0 0 0 0 STDNR STDNL 00000011
R6 0x06 Error 0 0 0 0 OCR OCL OTW OTP 00000000
R7 0x07 Error clear 0 0 0 0 0 0 0 0 00000000
R8 0x08 Reset 0 0 0 0 0 0 0 0 00000000
SSM2380
Rev. A | Page 26 of 32
REGISTER MAP DETAILS
REGISTER R0: LEFT CHANNEL GAIN CONTROL, ADDRESS 0x00
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
LTOR LMUTE LGAIN[5:0]
Table 12. Left Channel Gain Control Register Bit Descriptions
Bits Bit Name Description
7 LTOR Left-to-right channel gain data load control.
0 = disable simultaneous loading of left channel gain data to left and right channel registers (default).
1 = enable simultaneous loading of left channel gain data to left and right channel registers.
6 LMUTE Left channel input mute.
0 = disable mute (default).
1 = enable mute on left channel amplifier.
[5:0] LGAIN[5:0] Left channel gain control. Each step represents a 0.5 dB increase in gain. For ALC operation, these bits control
the gain setting for both the left and right channels. If the ALC_EN bit in Register R4 is set to 1, these bits cannot
be changed.
Setting Gain
000000 1 dB
… …
100010 18 dB (default)
… …
101101 23.5 dB
101110 to 111111 24 dB
REGISTER R1: RIGHT CHANNEL GAIN CONTROL, ADDRESS 0x01
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
RTOL RMUTE RGAIN[5:0]
Table 13. Right Channel Gain Control Register Bit Descriptions
Bits Bit Name Description
7 RTOL Right-to-left channel gain data load control.
0 = disable simultaneous loading of right channel gain data to left and right channel registers (default).
1 = enable simultaneous loading of right channel gain data to left and right channel registers.
6 RMUTE Right channel input mute.
0 = disable mute (default).
1 = enable mute on right channel amplifier.
[5:0] RGAIN[5:0]
Right channel gain control. Each step represents a 0.5 dB increase in gain. If the ALC_EN bit in Register R4 is set
to 1, these bits cannot be changed.
Setting Gain
000000 1 dB
… …
100010 18 dB (default)
… …
101101 23.5 dB
101110 to 111111 24 dB
SSM2380
Rev. A | Page 27 of 32
REGISTER R2: MODE CONTROL, ADDRESS 0x02
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 EDGE[1:0] OCREC OTREC R2L L2R
Table 14. Mode Control Register Bit Descriptions
Bits Bit Name Description
[5:4] EDGE[1:0] Edge rate control.
Setting Rate Control
00 Normal mode (default)
01 Slow edge
10 Slow edge (VDD > 3.0 V recommended)
11 Slow edge (VDD > 4.0 V recommended)
3 OCREC Overcurrent autorecovery enable.
0 = disabled.
1 = enabled (default).
2 OTREC Overtemperature autorecovery enable.
0 = disabled.
1 = enabled (default).
1 R2L Right channel signal mix enable (send right channel input to left and right channel outputs).
0 = mix disabled (default).
1 = mix enabled.
0 L2R Left channel signal mix enable (send left channel input to left and right channel outputs).
0 = mix disabled (default).
1 = mix enabled.
REGISTER R3: ALC CONTROL 1, ADDRESS 0x03
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 RTIME[2:0] LTIME[2:0]
Table 15. ALC Control 1 Register Bit Descriptions
Bits Bit Name Description
[5:3] RTIME[2:0] Release time setting (0.5 dB step).
Setting Release Time
000 4 ms/step (6 dB/48 ms)
001 8 ms/step
010 16 ms/step
011 32 ms/step
100 64 ms/step
101 128 ms/step (default)
110 256 ms/step
111 512 ms/step
[2:0] LTIME[2:0] Attack time setting (0.5 dB step).
Setting Attack Time
000 32 s/step (6 dB/384 s)
001 64 s/step
010 128 s/step
011 256 s/step (default)
100 512 s/step
101 1 ms/step
110 2 ms/step
111 4 ms/step
SSM2380
Rev. A | Page 28 of 32
REGISTER R4: ALC CONTROL 2, ADDRESS 0x04
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
ALC_EN COMP[1:0] ALC_VFIX ALCLV[3:0]
Table 16. ALC Control 2 Register Bit Descriptions
Bits Bit Name Description
7 ALC_EN ALC enable (gain setting loaded to ALC control).
0 = disabled (default).
1 = enabled.
[6:5] COMP[1:0] Compressor setting.
Setting Compression
00 Limiter mode (1:∞)
01 Compression Mode 1 (1:4 to 1:∞)
10 Compression Mode 2 (1:1.7 to 1:4 to 1:∞) (default)
11 Compression Mode 3 (1:2 to 1:2.5 to 1:∞)
4 ALC_VFIX ALC threshold mode setting.
0 = supply tracking (default).
1 = fixed power.
[3:0] ALCLV[3:0] ALC threshold level setting. See Table 17 for a complete list of the settings (default value is 1011).
Table 17. ALC Threshold Level Settings
ALCLV[3:0]
Supply Tracking Mode
(ALC_VFIX = 0) Fixed Power Mode (ALC_VFIX = 1)
Value % of VDD Voltage Limit (V) Power, 8 Ω Load (W) Power, 4 Ω Load (W)
1111 96 4.36 1.19 2.38
1110 93 4.25 1.13 2.25
1101 90 4.13 1.06 2.13
1100 88 4.01 1.0 2.01
1011 85 3.89 0.95 1.89
1010 83 3.77 0.89 1.78
1001 80 3.65 0.83 1.67
1000 78 3.54 0.78 1.56
0111 76 3.42 0.73 1.46
0110 74 3.30 0.68 1.36
0101 72 3.18 0.63 1.27
0100 70 3.06 0.59 1.17
0011 69 2.95 0.54 1.09
0010 67 2.83 0.50 1.00
0001 66 2.71 0.46 0.92
0000 64 2.59 0.42 0.84
SSM2380
Rev. A | Page 29 of 32
REGISTER R5: SHUTDOWN, ADDRESS 0x05
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 0 STDNR STDNL
Table 18. Shutdown Register Bit Descriptions
Bits Bit Name Description
1 STDNR Right channel shutdown control.
0 = power up right channel.
1 = power down right channel (default).
0 STDNL Left channel shutdown control.
0 = power up left channel.
1 = power down left channel (default).
REGISTER R6: ERROR, ADDRESS 0x06
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 OCR OCL OTW OTP
Table 19. Error Register Bit Descriptions (Read-Only Register)
Bits Bit Name Description
3 OCR Overcurrent error bit, right channel.
0 = no error detected (default).
1 = error state flagged (if OCREC bit in the mode control register is set to 1).
2 OCL Overcurrent error bit, left channel.
0 = no error detected (default).
1 = error state flagged (if OCREC bit in the mode control register is set to 1).
1 OTW Overtemperature warning bit.
0 = no error detected (default).
1 = warning state flagged (if OTREC bit in the mode control register is set to 1).
0 OTP Overtemperature error bit.
0 = no error detected (default).
1 = error state flagged (if OTREC bit in the mode control register is set to 1).
REGISTER R7: ERROR CLEAR, ADDRESS 0x07
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 0 0 0
Table 20. Error Clear Register Bit Descriptions
Bits Bit Name Description
[7:0] Error clear Recovery from error condition. Used when autorecovery is disabled.
REGISTER R8: RESET, ADDRESS 0x08
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
0 0 0 0 0 0 0 0
Table 21. Reset Register Bit Descriptions
Bits Bit Name Description
[7:0] Reset Clear all registers to their default values. Used when autorecovery is disabled.
SSM2380
Rev. A | Page 30 of 32
OUTLINE DIMENSIONS
102609-B
A
B
C
D
0.640
0.595
0.550
2.000
1.960 SQ
1.920
0.345
0.330
0.315
1
2
3
4
BOTTOM VIEW
(BALL SIDE UP)
TOP VIEW
(BALL SIDE DOWN)
0.270
0.240
0.210
0.340
0.320
0.300
BALL 1
IDENTIFIER
SEATING
PLANE
0.05 MAX
COPLANARITY
0.50
REF
Figure 51. 16-Ball Wafer Level Chip Scale Package [WLCSP]
(CB-16-3)
Dimensions shown in millimeters
ORDERING GUIDE
Model1 Temperature Range Package Description Package Option
SSM2380CBZ-REEL −40°C to +85°C 16-Ball Wafer Level Chip Scale Package [WLCSP] CB-16-3
SSM2380CBZ-REEL7 −40°C to +85°C 16-Ball Wafer Level Chip Scale Package [WLCSP] CB-16-3
EVAL-SSM2380Z Evaluation Board
1 Z = RoHS Compliant Part.
SSM2380
Rev. A | Page 31 of 32
NOTES
SSM2380
Rev. A | Page 32 of 32
NOTES
I2C refers to a communications protocol originally developed by Philips Semiconductors (now NXP Semiconductors).
©2010–2011 Analog Devices, Inc. All rights reserved. Trademarks and
registered trademarks are the property of their respective owners.
D08752-0-2/11(A)
