Hint/Voltage Amplifier for Operating Electrostatic Microactuators (2) PA-85 or equivalent

2008-05-09 (金) 23:13:25 (4478d)

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.


  • 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


  1. Use 0.1 A fuse. The PCB (below) says 0.5 A but it is WRONG. (Feb. 6, 2000)
  2. You may copy the following layout to make your printed circuit board. E-mail to me for a MacDrawPro data file of this.