ssm2135p Analog Devices, Inc., ssm2135p Datasheet - Page 8

• Manufacturer Part Number: ssm2135p
• Description: Dual Single-supply Audio Operational Amplifier
• Manufacturer: Analog Devices, Inc.

SSM2135
APPLICATION INFORMATION
The SSM2135 is a low voltage audio amplifier that has excep-
tionally low noise and excellent sonic quality even when driving
loads as small as 25 W. Designed for single supply use, the
SSM2135’s inputs common-mode and output swing to 0 V.
Thus with a supply voltage at 5 V, both the input and output
will swing from 0 V to 4 V. Because of this, signal dynamic
range can be optimized if the amplifier is biased to a 2 V reference
rather than at half the supply voltage.
The SSM2135 is unity-gain stable, even when driving into a fair
amount of capacitive load. Driving up to 500 pF does not cause
any instability in the amplifier. However, overshoot in the fre-
quency response increases slightly.
The SSM2135 makes an excellent output amplifier for 5 V only
audio systems such as a multimedia workstation, a CD output
amplifier, or an audio mixing system. The amplifier has large
output swing even at this supply voltage because it is designed
to swing to the negative rail. In addition, it easily drives load
impedances as low as 25 W with low distortion.
TPC 25. Gain Bandwidth Product and Phase Margin
vs. Temperature
50
70
65
60
55
20
18
16
14
12
10
–75
TPC 24. Open-Loop Gain vs. Temperature
8
6
4
2
0
–75
V
S
= 5V
–50
–50
–25
–25
TEMPERATURE – C
R
R
L
0
L
= 600
TEMPERATURE – C
= 2k
0
GBW
m
25
25
50
50
75
75
V
T
100
O
S
100
= 5.0V
= 3.9V
125
125
5
4
3
2
1
–8–
The SSM2135 is fully protected from phase reversal for inputs
going to the negative supply rail. However, internal ESD protec-
tion diodes will turn on when either input is forced more than
0.5 V below the negative rail. Under this condition, input cur-
rent in excess of 2 mA may cause erratic output behavior, in
which case a current limiting resistor should be included in the
offending input if phase integrity is required with excessive input
voltages. A 500 W or higher series input resistor will prevent
phase inversion even with the input pulled 1 V below the nega-
tive supply.
“Hot” plugging the input to a signal generally does not present a
problem for the SSM2135, assuming the signal does not have
any voltage exceeding the device’s supply voltage. If so, it is
advisable to add a series input resistor to limit the current, as
well as a Zener diode to clamp the input to a voltage no higher
than the supply.
500
400
300
200
100
TPC 27. Input Bias Current vs. Temperature
5
4
3
2
1
0
–75
0
TPC 26. Supply Current vs. Temperature
–75
–50
–50
V
S
=
–25
–25
18V
V
S
V
TEMPERATURE – C
= +5.0V
S
TEMPERATURE – C
=
0
0
15V
25
25
V
V
S
S
50
= +5.0V
50
=
15V
75
75
100
100
125
125
REV. E