Sierra Wireless AIRPRIME WISMO218 - Manual (Page 60)

WA_DEV_W218_PTS_002 Rev 006 April 29, 2010 60
Product Technical Specification &
Customer Design Guidelines Interfaces
3.12. BUZZER Output
The signal BUZZER outputs a square wave at the desired tone frequency. The tone frequencies are
programmable and can be re-programmed on-the-fly to generate monophonic audio ringtones or alert
tones. The tone level can also be adjusted in 4dB steps, or it can be muted.
3.12.1. Features
The signal BUZZER can be used in conjunction with an external transistor/MOSFET for driving a
buzzer in order to give a maximum current of 100mA (PEAK) and an average of 40mA, depending on
application requirement.
Figure 27. BUZZER Output
Table 23: BUZZER Electrical Characteristics
Parameter Condition Minimum Typical Maximum Unit
V
OH
High impedance load 2.7 2.85 - V
Load with I
oH
= 4mA - 2.4 - V
I
PEAK
- - - 4 mA
V
OL
- - - 0.1 V
Frequency - 200 - 2500 Hz
Duty cycle - 0* - 100* %
Tone level 4 dB step -24 - 0 dB
* Be mindful of the maximum frequency and the minimum/maximum duty cycle. There is a limitation due to the
RC environment. The amplitude modulation becomes less fine when the set limits are reached.
3.12.2. Pin Description
Table 24: BUZZER Pin Descriptions
Signal Pin Number I/O I/O Type Description
BUZZER 34 O 2.8V Buzzer output
3.12.3. Application
The maximum peak current of the transistor/MOSFET is 100mA and the maximum average current is
40mA, while the peak current of the BUZZER pin should be less than 4mA. A diode against transient
peak voltage must be added as shown below.