Integra M2106+
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This document is the sole and exclusive property of Wavecom. Not to be distributed or divulged without prior written
agreement.
WA_DE_PTS_003-001
April, 2007
3.9.2.1
Common Speaker Output Characteristics
The connection can be differential or single-ended but the use of a differential connection to reject common
mode noise and TDMA noise is strongly recommended. Moreover in single-ended mode, ½ of the power is
lost. When using a single-ended connection, ensure to have a good ground plane, good filtering as well as
shielding, in order to avoid any disturbance on the audio path.
Both SPK1 and SPK2 speaker outputs are push-pull amplifiers and can be loaded down to 32
Ω
and up to
1 nF. The impedance of the speaker amplifier output in differential mode is:
R
≤
1
Ω
±10 %.
These outputs are differential and the output power can be adjusted in steps of 2 dB (see details in Table 3:
Speaker gain vs Max output voltage). The output can be directly connected to a speaker.
SPKx P
SPKx N
Figure 14: Speaker differential connection
In case of a single-ended connection, only half of the output power is available when compared to a
differential connection.
SPKx P
C1
+
SPKx N
C2
+
Z
h p
Sp ea ker
C3
3 3 t o 1 0 0 p F
R1
Figure 15: Speaker single-ended connection
C1 = from 100 nF to 47 µF as per the speaker characteristics.
C2=C1
R1 = Speaker impedance
Nevertheless, in a 32
Ω
speaker case, it is possible to use a cheaper and smaller solution: R1=82
Ω
and
C2=4.7 µF ceramic.
The gain in the speaker outputs are internally adjusted and can be tuned by using an AT command (refer to
the AT commands documentation [7] for details).
