Specifications

WM_PRJ_Q2501_PTS_002 - 001
March 2004
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3.3.6.3 Speaker outputs
These outputs are differential and the output power can be adjusted by step of
2 dB. Speaker outputs can be directly connected to a speaker.
The gain of the speaker outputs is internally adjusted and can be tuned using
an AT command (refer to AT commands documentation).
Pin description
Signal Pin # I/O I/O type Description
SPK2P 65 O Analog Speaker 2 positive output
SPK2N 67 O Analog Speaker 2 negative output
Pin description
Signal Pin # I/O I/O type Description
SPK1P 61 O Analog Speaker 1 positive output
SPK1N 63 O Analog Speaker 1 negative output
3.3.6.3.1 Common speaker output characteristics
The connection can be either differential or single-ended but using a differential
connection to reject common mode noise and TDMA noise is strongly
recommended
. When using a single-ended connection, be sure to have a very
good ground plane, a very good filtering as well as shielding in order to avoid
any disturbance on the audio path.
3.3.6.3.2 Differential connection
SPKxP
SPKxN
Figure 23: Speaker differential connection
Impedance of the speaker amplifier output in differential mode:
R ≤ 1Ω +/-10 %.
The connection between the module pins and the speaker must be designed to
keep the serial impedance lower than 3 Ω in differential mode.