Rainbow Electronics GE863-PY - Manual (Page 59)

GE863 Hardware User Guide
1vv0300783 Rev.0 - 10/06/08
Reproduction forbidden without Telit Communications S.p.A. written authorization - All Rights Reserved page 59 of 80
8.8.2 Frequency Behaviour
The frequency behaviour represents the effectiveness of the reproduction of the applied
signals.
Because its performance is related to a square driving waveform (whose amplitude varies from
0V to Vpp), if you modify the waveform (e.g. from square to sinus) the frequency response will
change.
8.8.3 Power Supply Influence
Applying a signal whose amplitude is different from that suggested by manufacturer, the
performance change following the rule “if resonance frequency f
o
increases, amplitude
decreases”.
Because of resonance frequency depends from acoustic design, lowering the amplitude of the
driving signal the response bandwidth tends to become narrow, and vice versa.
Summarizing: Vpp ↑ Æ f
o
↓ Vpp ↓ Æ 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.
8.8.4 Warning
It is very important to respect the sense of the applied voltage: never apply to the "-" pin a
voltage more positive than "+" pin : if this happens, the diaphragm vibrates in the opposite
sense with a high probability to be expelled from its physical position , damaging the device
forever .
8.8.5 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.