SSM2250RM-R2 Analog Devices Inc, SSM2250RM-R2 Datasheet - Page 9

• Manufacturer Part Number: SSM2250RM-R2
• Description: IC AMP AUDIO PWR 1.5W AB 10MSOP
• Manufacturer: Analog Devices Inc
• Series: SoundMAX®r
• Type: Class ABr

Specifications of SSM2250RM-R2

• Rohs Status: RoHS non-compliant
• Output Type: 1-Channel (Mono) with Stereo Headphones
• Max Output Power X Channels @ Load: 1.5W x 1 @ 8 Ohm; 90mW x 2 @ 32 Ohm
• Voltage - Supply: 2.7 V ~ 6 V
• Features: Depop, Shutdown
• Mounting Type: Surface Mount
• Package / Case: 10-MSOP, Micro10™, 10-uMAX, 10-uSOP

The maximum power dissipation for a single-ended output is
Because the SSM2250 is designed to drive two single-ended
loads simultaneously, the worst-case maximum power
dissipation in SE mode is twice the value of Equation 5.
A thorough mathematical explanation behind Equation 4 and
Equation 5 is provided in the
Example
Given worst-case stereo headphone loads of 32 Ω, the maxi-
mum power dissipation of the SSM2250 in SE mode with a 5 V
supply is
With an 8 Ω internal speaker attached, the maximum power
dissipation in BTL mode is (from Equation 4)
It can easily be seen that power dissipation from BTL mode
operation is of greater concern than SE mode.
Figure 16. Power Dissipation vs. Single-Ended Output Power (V
P
P
P
DISS
DISS
DISS
0.35
0.25
0.15
0.05
0.3
0.2
0.1
0
,
,
,
MAX
0
MAX
MAX
V
DD
=
=
=
= 5V
2
2π
2
V
π
( )
×
π
5
R
2
DD
2
2
V
L
32
( )
5
8
R
= 16Ω
0.1
2
V
L
2
Ω
Ω
2
=
OUTPUT POWER (W)
=
79
633
SSM2211
mW
R
L
mW
0.2
= 8Ω
data sheet.
R
L
0.3
= 4Ω
DD
= 5 V)
0.4
Rev. A | Page 9 of 12
(5)
(6)
(7)
Solving for Maximum Ambient Temperature
To protect the SSM2250 against thermal damage, the junction
temperature of the die should not exceed 150°C. The maximum
allowable ambient temperature of the application can be easily
found by solving for the expected maximum power dissipation
in Equation 4 and Equation 5, and using Equation 8.
Continuing from the previous example, the θ
14-lead TSSOP package on a 4-layer board is 140°C/W. To
ensure that the SSM2250 die junction temperature stays below
150°C, the maximum ambient temperature can be solved using
Equation 8.
The maximum ambient temperature must remain below 61°C
to protect the device against thermal damage.
Another method for finding the maximum allowable ambient
temperature is to use the power derating curve in Figure 17.
The y-axis corresponds to the expected maximum power
dissipation, and the x-axis is the corresponding maximum
ambient temperature. Either method returns the same answer.
Maximum Output Power
The maximum amount of power that can be delivered to a
speaker is a function of the supply voltage and the resistance of
the speaker. Figure 17 shows the maximum BTL output power
possible from the SSM2250. Maximum output power is defined
as the point at which the output has greater than 1% distortion.
Figure 17. Maximum Power Dissipation vs. Ambient Temperature
T
AMB
1.0
0.8
0.6
0.4
0.2
0
,
0
MAX
14-LEAD TSSOP
θ
10-LEAD MSOP
θ
JA
JA
=
=
=
= 140°C/W
= 180°C/W
+
+
+
150
150
61
o
25
C
o
o
C
C
AMBIENT TEMPERATURE (°C)
−
−
θ
(
140
JA
×
o
C
P
50
DISS
/
W
,
MAX
×
. 0
633
T
FREE AIR
NO HEAT SINK
JA
JMAX
7
W
5
of the SSM2250
SSM2250
)
= 150°C/W
100
(8)