Piezo Linear Amplifier
Piezo Linear Amplifier
The EPA-104 is a high voltage (±200 Vp), high current (±200 mA), and high frequency (DC to 250 KHz) amplifier designed to drive higher capacitive (low impedance) loads, such as low voltage stacks, at moderate frequencies; or lower capacitive loads, such as ultrasonic devices, at high frequencies.
The ability of an amplifier to drive a piezoelectric device statically is determined by its voltage capability and stability. Its ability to drive a piezo device dynamically is determined by the capacitance of the actuator, the voltage to which it must be driven, and the number of times it must be charged and discharged per second. These establish the current, voltage, and frequency requirements of the amplifier.
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Low electrical noise, low distortion: The EPA-104 is made with a high quality Apex ® High Voltage Hybrid Operational Amplifier, and utilizes high regulation linear power supplies. It is housed in a heavy high conductivity aluminum case which provides an excellent shield from external electromagnetic interference.
Input and Output Protection: Piezo loads present special problems to electronic drivers. Piezo Systems amplifiers provide heavy input and output protection to take care of all shorting, turn-on, turn-off, and load generated voltage occurrences which can damage either the amplifier or your actuator.
Manual Bias Controls (voltage polarity and DC offset): Useful for making manual adjustments of drive voltage to verify piezoelectric actuator static motion, for static settings, or for applying DC bias to dynamically driven piezo actuators such as piezoelectric stacks.
Input Control (via analog signal to the BNC input connector): Accepts up to ± 10 V signal waveforms from external signal generators, computer controllers, or feedback networks from DC to rated frequency. The combined AC plus DC offset voltage is adjustable from zero to the rated voltage.
Estimating the Current Requirement of a Piezoelectric Actuator
To estimate the peak current requirement of a piezoelectric actuator, solve the appropriate equation:
Ipeak (in Amperes) = 2 π f C Vpeak- (driven with a sine wave)
Ipeak (in Amperes) = 4 f C Vpeak - (driven with a triangle wave)
Ipeak (in Amperes) = C dV / dt - (driven with a square wave)
Where f is the maximum operating frequency in Hertz, C is the capacitance of the piezoelectric device in Farads, dt is the square wave rise time, and Vp is maximum peak drive voltage. The amplifier must be able to supply Vp, lp and f.
|Maximum Voltage||± 200 volts peak|
|Maximum Current||± 200 mA peak|
|Output Power||40 watts peak|
|Frequency Range||DC to 250 KHz|
|| Into 1 K ohm resistive load: Flat, DC to 300 KHz; 3db roll-off, 400 KHz;
Into capacative load: see chart below.
|Voltage Gain||Variable gain, adjustable from 0 to 20X|
|Phase Shift||-.083° per KHz, typical|
|Slew Rate (no load)||380 volts / µsecond|
|Maximum Input Voltage||± 10 volts peak|
|Maximum DC Component||± 10 volts DC|
|Input Coupling||Direct DC coupling only|
|Input Impedance||10K ohm|
|Output Coupling||DC coupling|
|Variable DC Offset||Normally zero volts. Adjustable to ± 200 volts peak|
|Load Impedance||Capable of driving any load within the voltage and current limitations of the amplifier|
|Output Noise (300 KHz bandwidth)||2 mvrms with input shorted|
|AC Power Source||User settable: 100-130 VAC, 50/60 Hz; or 200-250 VAC, 50/60 Hz|
|Circuit Protection||Overload, short circuit and thermal protection.|
|Front Panel Controls||Gain adjust; DC Polarity selector (+, 0, -); DC offset adjust|
|Rear Panel Controls||On/off switch; Line voltage selector|
|| BNC for Input (ground referenced); safety shrouded banana jacks for high voltage output
terminals (ground referenced)
|Weight||6.4 kg (14 lbs)|
||12" (305mm) long x 12" (305mm) deep x 5" (127mm) high|
Peak Voltage Delivered To Capacative Load At Peak Current Rating Versus Operating Frequency
|Steady state sinusoidal waveforms,
Temperature = 25 ° C