SSM2019BRNZ Analog Devices Inc, SSM2019BRNZ Datasheet - Page 7

• Manufacturer Part Number: SSM2019BRNZ
• Description: Audio Amp Microphone 1-CH Mono Class-AB 8-Pin SOIC N
• Manufacturer: Analog Devices Inc
• Type: Class ABr

Specifications of SSM2019BRNZ

• Package: 8SOIC N
• Function: Microphone
• Amplifier Type: Class-AB
• Input Signal Type: Differential
• Typical Voltage Gain: 70 dB
• Total Harmonic Distortion Noise: 0.0035@2000Ohm %
• Typical Psrr: 124 dB
• Output Signal Type: Single
• Maximum Input Bias Current: 3(Typ)@±15V uA
• Maximum Input Offset Voltage: 0.05(Typ)@±15V mV
• Maximum Load Resistance: 2000 Ohm
• Output Type: 1-Channel Mono
• Voltage - Supply: 10 V ~ 36 V, ±5 V ~ 18 V
• Features: Differential Inputs
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Amplifier Class: AB
• No. Of Channels: 1
• Supply Voltage Range: ± 5V To ± 18V
• Load Impedance: 2kohm
• Operating Temperature Range: -40°C To +85°C
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Max Output Power X Channels @ Load: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

INPUTS
The SSM2019 has protection diodes across the base emitter
junctions of the input transistors. These prevent accidental
avalanche breakdown, which could seriously degrade noise
performance. Additional clamp diodes are also provided to prevent
the inputs from being forced too far beyond the supplies.
REV. 0
Figure 3. Three Ways of Interfacing Transducers for
High Noise Immunity
TRANSDUCER
TRANSDUCER
TRANSDUCER
b. Pseudo-Differential
(NONINVERTING)
c. True Differential
a. Single-Ended
(INVERTING)
R
R
Figure 4. SSM2019 in Phantom Powered Microphone Circuit
+48V
R5
100
C3
47 F
+IN
–IN
SSM2019
SSM2019
SSM2019
C1, C2: 22 F TO 47 F, 63V, TANTALUM OR ELECTROLYTIC
Z1–Z4: 12V, 1/2W
R3
6.8k
1%
R4
6.8k
1%
C1
C2
R1
10k
R2
10k
Z1
Z2
Z3
Z4
200pF
–7–
C4
Although the SSM2019 inputs are fully floating, care must be
exercised to ensure that both inputs have a dc bias connection
capable of maintaining them within the input common-mode
range. The usual method of achieving this is to ground one side
of the transducer as in Figure 3a. An alternative way is to float
the transducer and use two resistors to set the bias point as in
Figure 3b. The value of these resistors can be up to 10 kW, but
they should be kept as small as possible to limit common-mode
pickup. Noise contribution by resistors is negligible since it is
attenuated by the transducer’s impedance. Balanced transducers
give the best noise immunity and interface directly as in Figure 3c.
For stability, it is required to put an RF bypass capacitor directly
across the inputs, as shown in Figures 3 and 4. This capacitor
should be placed as close as possible to the input terminals. Good
RF practice should also be followed in layout and power supply
bypassing, since the SSM2019 uses very high bandwidth devices.
REFERENCE TERMINAL
The output signal is specified with respect to the reference terminal,
which is normally connected to analog ground. The reference
may also be used for offset correction or level shifting. A refer-
ence source resistance will reduce the common-mode rejection
by the ratio of 5 kW/R
1 W, then the CMR will be reduced to 74 dB (5 kW/1 W = 74 dB).
COMMON-MODE REJECTION
Ideally, a microphone preamplifier responds to only the difference
between the two input signals and rejects common-mode voltages
and noise. In practice, there is a small change in output voltage
when both inputs experience the same common-mode voltage
change; the ratio of these voltages is called the common-mode
gain. Common-mode rejection (CMR) is the logarithm of the ratio
of differential-mode gain to common-mode gain, expressed in dB.
PHANTOM POWERING
A typical phantom microphone powering circuit is shown in
Figure 4. Z1 to Z4 provide transient overvoltage protection for
the SSM2019 whenever microphones are plugged in or unplugged.
R
G
SSM2019
+18V
–18V
R
R
G1
G2
REF
. If the reference source resistance is
V
OUT
SSM2019