User`s manual

RabbitFLEX User’s Manual www.rabbit.com 51
4.3.12.3 Speaker
DAC channel #0 can be configured as an input to a speaker. A pulse width modulated (PWM) signal goes
through a low-pass filter, changing the high speed digital signal from the Rabbit processor into a smoothly
varying analog signal. This signal is not strong enough to drive the speaker, so it goes through a low volt-
age audio power amplifier before connecting to the speaker line. Figure 4-23 is a circuit schematic of the
filter/amplifier. The output to the speaker is on J6.
Figure 4-23 Loudspeaker Circuit Schematic
Figure 4-24 Speaker Characteristics
NOTE: The operating temperature range for the speaker differs from the operating tempera-
ture range (–40°C to +70°C) of the rest of the RabbitFLEX BL300F components.
A sample WAV files is provided in /Samples/RabbitFlex_BL300F/audio/ or in
/Samples/RabbitFlex_SBC40/audio/ depending on your version of Dynamic C.
Speaker
VERSION 5.03
Speaker
100 kW
R14
4.7 kW
R13
100 nF
C7
DAC 0-3 V
Analog Output
+5 V
U6
LM386
R15
10 W
C8
100 nF
C9
330 µF