User guide

UC864-E/G/WD/WDU Hardware User Guide

1vv0300766a Rev.4

- 03/02/09

11.8.3. 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

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 ↑

fo ↓ Vpp

fo ↑

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.

11.9. Using the Temperature Monitor Function

11.9.1. Short Description

The Temperature Monitor is a function of the module that permits to control its

internal temperature and if properly set (see the #TEMPMON command on AT

Interface guide) it raises to High Logic level a GPIO when the maximum temperature

is reached.

11.9.2. Allowed GPIO

The AT#TEMPMON set command could be used with one of the following GPIO:

Signal Function Type

Drive

strength

Note

TGPIO_ GPIO01 Configurable CMOS 2mA

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.