User's Guide

UC864-E-AUTO / AWS-AUTO Hardware User Guide
1vv0300795 Rev.11 – 2010/11/18
Reproduction forbidden without Telit Communications S.p.A’s. written authorization - All Rights Reserved. Page 59 of 78
12.8.2. Frequency Behavior
The frequency behavior 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.
12.8.3. Power Supply Influence
After applying a signal with a different amplitude from suggested by the
manufacturer, a performance change will follow, according to the rule “ if resonance
frequency f
ff
f
o
oo
o increases, amplitude decreases ”.
Because resonance frequency depends on acoustic design and lowering the
amplitude of the driving signal, the response bandwidth tends to become narrow, and
vice versa.
Summarizing: Vpp ↑  f
ff
f o
o o
o ↓ Vpp  f
ff
f o
o o
o ↑
The risk is that the f
ff
f o
o o
o could easily fall outside of new bandwidth; consequently the
SPL could be much lower than the expected.
12.8.4. 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
WARNINGWARNING
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.
This damages the device permanently.