Specifications

Product Technical Specification & Customer Design Guidelines
Interfaces
© Confidential
Page: 68 / 116
This document is the sole and exclusive property of WAVECOM. Not to be distributed or divulged without
prior written agreement.
WA_DEV_Q64_PTS_001-003 January 9, 2009
BUZZER
C1
D1
VCC
3.12.3 Application
The maximum peak current is 100 mA and the maximum average current is 40 mA.
A diode against transient peak voltage must be added as described below.
R1
Q64
Figure 24: Example of buzzer implementation
Where:
R1 must be chosen in order to limit the current at I
PEAK
max and must be adjusted in
function of the frequency and the duty cycle used.
C1 = 0 to 100 nF (depending on the buzzer type)
D1 = BAS16 (for example)
A low filter is recommended at low frequencies.
Calculation of the Low Filter:
Req is the total resistor in line.
C is the capacitive charge on BUZZER signal and the ground
The cut-off frequency (F
c
) must be higher than F
BUZZER
Due to the conception of the signal, the frequency modulation of the BUZZER signal is
64 * F
BUZZER
F
C
must be at least 64 * F
BUZZER
.
F
C
= 1 / (2.π.Req.C)