GL865-DUAL V3 Hardware User Guide
1vv0301018 Rev.5 – 2013-08-05
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 55 of 76
Mod. 0805 2011-07 Rev.2
11.8.2.
Frequency Behavior
The frequency behavior represents the effectiveness of the reproduction of the applied signals.
Because performance is related to a square driving waveform (whose amplitude varies from
0V to V
pp
), if you modify the waveform (
e.g. from square to sinus
) the frequency response will
change.
11.8.3.
Power Supply Influence
Applying a signal whose amplitude is different from that suggested by the manufacturer, the
performance change following the rule “if resonance frequency f
o
increases, amplitude
decreases”.
Because resonance frequency depends on acoustic design, by lowering the amplitude of the
driving signal the response bandwidth tends to become narrow, and vice versa.
Summarizing:
V
pp
↑
f
o
↓
V
pp
↓
f
o
↑
The risk is that the f
o
could easily fall outside of new bandwidth; consequently the SPL could
be much lower than the expected.
11.8.4.
Working Current Influence
In the component data sheet you will find the value of MAX CURRENT: this represents the
maximum average current that can flow at nominal voltage without current limitation. In
other words it is not the peak current, which could be twice or three times higher. If driving
circuitry does not support these peak values, the SPL will never reach the declared level or the
oscillations will stop.
WARNING:
It is very important to respect the sense of the applied voltage: never apply to the
"-" pin
a
voltage more positive than the
"+" pin
: if this happens, the diaphragm vibrates in the opposite
direction with a high probability to be expelled from its physical position. This damages the
device permanently.