GE866-QUAD Hardware User Guide
Reproduction forbidden without written authorization from Telit Communications S.p.A. - All Rights Reserved.
Page 61 of 82
Mod. 0805 2011-07 Rev.2
11.7.2.
Frequency Behaviour
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 Vpp), if you modify the waveform (e.g. from
square to sinus) the frequency response will change.
11.7.3.
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 fo
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 fo could easily fall outside of new bandwidth; consequently the
SPL could be much lower than the expected.
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.
11.7.4.
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.
