Specifications

WM_PRJ_Q2501_PTS_002 - 001
March 2004
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3.3.7 Buzzer interface
The buzzer output (BUZ) is a digital one. A buzzer can be directly connected
between this output and VBATT.
Pin description
Signal Pin # I/O I/O type Description
BUZ 69 O Open
collector
Buzzer output
The maximum peak current is 80 mA and the maximum average current is
40 mA. A diode against transient peak voltage must be added as described
below.
BUZ
C1
D1
VBATT
R1
WISMO
Q2501
Figure 25: Example of buzzer implementation
R1 must be chosen in order to limit the current at I
PEAK
max.
C1 = 0 to 100 nF (depending on the buzzer type).
Recommended characteristics for the buzzer:
 Type: electro-magnetic.
 Impedance: 7 to 30 Ω.
 Sensitivity: 90 dB SPL min @ 10 cm.
 Current: 60 to 90 mA.
The BUZ output can also be used to drive a LED as shown in the Figure Below:
BUZ
VBATT
« BUZZER »
D701
1
2
R701
470
Ω
C700
100 nF
Figure 26: LED driven by the BUZ output