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ETN051701-D02
BPA100 Benchtop Piezo Amplifier
4) 150 V peak to peak, 7 kHz sine wave into 1.1 µF capacitive load
4.3 Fans
The fan speed is regulated by the controller depending on the load and temperature conditions. Under idle or very light load
conditions the fan speed is normally reduced to make operation quieter and reduce any potential accumulation of dust.
4.4 Powering Down The Unit
As the power supply voltages collapse, the output voltage will show some transients as the amplifier powers down. Likewise,
due to the large capacitance in the power supply lines, a small voltage can be present on the output for a while after the mains
power is switched off. The oscilloscope waveform capture (A) below shows the typical behavior with 10 µF load capacitance
connected and the output at 0 V. After the power is switched off, a small (approximately -0.5 V) spike is seen, the output voltage
rises to about +0.4 Volt and then gradually decays. In most applications this behaviour can be ignored as the small residual
voltages associated with it are negligible.
If the amplifier is switched off while outputting a high voltage, it will take a few seconds for the voltage to decay. The waveform
capture (B) below shows the output voltage when the amplifier is turned off when outputting a co150 V.
Fig. 4.1 Power Down Behavior
Warning
The amplifier may cause drive voltage spikes on power down. Ensure that the unit is powered down before making
connections or disconnections.
A - Typical Shutdown Behavior B - Shutdown with +150 V Output
