Sierra Wireless AirPrime SL808 Series Product Technical Specification & Customer Design Manuallines page 59

Table 4-27: Speaker interface parameters
Parameter / Description
Output DC offset voltage between
MIC1_P and MIC1_N, SPK_P and
SPK_N
Output common mode voltage,
SPK_P and SPK_N
Z Differential output impedance
OUT1
a. Preliminary values
Rev 1 Dec.10 Proprietary and Confidential - Specifications subject to change
If a single-ended connection is used, only one of either SPK outputs have to be
chosen. The result is a maximal output power divided by 4.
4.10.3.3 Differential connection example
Figure 4-9: Example - SPK differential connection
The impedance of the speaker amplifier output in differential mode is
R1  10%.
Note that the connection between the speaker and the AirPrime SL808X
Embedded Module pins must be designed to keep the serial impedance lower
than 3  when it is connected in differential mode.
4.10.3.4 Single-ended connection example
33 pF
Zhp to
100 pF
Figure 4-10: Example - SPK single-ended connection
Take note of the following when connecting the speaker in single-ended mode:
• 6.8µF < C1 < 47 µF (depending on the characteristics of the speaker and the
output power)
• C1 = C2
• R1 = Zhp
Test
Fully differential
Measured at each
output pin with respect
to AVSS:
V = 2.5 V to 2.7 V
DD
At 1.02 kHz, for outputs
SPK_P and SPK_N
SPK_P
SPK_N
C1
+
C3
C2
R1
+
a a a
Min Typ Max
-20 20
1.13 1.25 1.38
1
SPK_P
SPK_N
Units
mV
V

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