Voltage Amplifier for Electrostatic Microactuators †
Most electrostatic micro actuators need driving voltage over 100 V at DC to 100 kHz range. Apex microtechnolgy offers operation amplifiers for high-voltage applications. Their Op-Amp PA85A is one of the best amplifiers for most MEMS capacitive actuators. The maximum output voltage is 450 V (+/- 225 V) at 200 mA. Its slew rate is as large as 1000 V/microsecond. PA85A package is a 8-pin metal can. They also offer the same chip in a single-inline mold package (PA98 data sheet). The package becomes hot during operation. Do not forget to put a heat sink of over 4.2 degreeC/Watt. Please read the data sheet carefully before building this amp. In particular, choose appropriate values for the phase compensation and current limiter.
The above circuits diagram is for a voltage amplifier of a gain of 50x. Use a potentiometer for the 1 kOhm resister at the inverting input. Diodes between the inverting and non-inverting inputs are for overload protection. Diodes between the power lines and op-amp are fool-proof for the wrong polarity of the power supply.
Reference †
- See also an equivalent IC from Burr-Brown 3583.
- If you are just interested in making a high DC voltage, see Cockcroft-Walton Charge Pump or use a DC-DC Converter.
- Original design is by courtesy of Prof. Dai Kobayashi, Tokyo Denki University.
- For other high voltage applications, see my corresponding link page.
- Last update Jan. 21, 2000
Errata †
- Use 0.1 A fuse. The PCB (below) says 0.5 A but it is WRONG. (Feb. 6, 2000)
- You may copy the following layout to make your printed circuit board. E-mail to me for a MacDrawPro data file of this.
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