Sierra Wireless WISMO218 - Manual (Page 50)

WA_DEV_W218_PTS_002 Rev 005 Page 50 of 109
Product Technical Specification &
Customer Design Guidelines
Parameters Min Typ Max Unit
200 Hz<F<4 kHz Z2 MICN
(MICP=Open)
Z2 MICP
(MICN=GND)
2.2
Z2 MICN
(MICP=GND)
Impedance between
MICP and MICN
without 2.2K
 to
GND
4.5
Impedance between
MICP and MICN with
2.2K
 to GND
3.2
Maximum working voltage
( MICP-MICN)
(THD 10%)
AT+VGT*=1
- -
210
mVpp
Maximum rating voltage
(MICP or MICN)
-0.5
-
4.4
V
* The input voltage depends on the input micro gain set by the AT command. Please refer to the document [2],
WISMO218 AT Commands Manual.
** Because both MICP and MICN are internally biased, it is necessary to use a coupling capacitor to connect an
audio signal provided by an active generator. Only a passive microphone can be directly connected to the MICP input.
Speaker Features
The speaker, SPK, can either have a single-ended or a differential connection. However, it is strongly
recommended to use a differential connection in order to reject common mode noise and TDMA
noise. Moreover, in single-ended mode, half (½) of the power is lost.
When using a single-ended connection, be sure to have a very good ground plane, very good filtering
as well as shielding in order to avoid any disturbance on the audio path.
Table 17. Speaker Details
Parameter Typ Unit Connection
Z (SPKP, SPKN) 16 or 32  Differential mode
Z (SPKP, SPKN) 8  Single-ended mode
Speakers Outputs Power
The maximal specifications given below are available with the maximum power output configuration
values set by an AT command. The typical values are recommended.