Integrated Electronics Piezo-Electric

IEPE is a set of initials for “Integrated Electronic Piezo Electric”. It is a standard for electronics in transducers (like accelerometers and microphones) that have built-in amplifiers.

ICP is short for “Integrated Circuit-Piezoelectric”. ICP is a trademark name of PCB Corporation for their proprietary implementation of IEPE.

Other trademark names of IEPE from different companies include CCLD, IsoTron or DeltaTron.

Most IEPE sensors work at a constant current between 2 and 20 mA. A common value is 4 mA.

Supplying the IEPE sensor with constant current, results in a positive bias voltage, typically between 8 and 12 Volts, at the output.

The supply or compliance voltage of the constant current source should be 24 to 30 V which is about two times the bias voltage.

Compliance Voltage example calculation

Example sensor specifications:

Excitation - Compliance Voltage minimum required = 500 g * 10 mV / g +12 V = 17 V

This (17 V) is within the compliance voltage of the SIRIUS ACC amplifier specifications. See table below.

DEWESoft SIRIUS ACC amplifiers, IEPE mode specifications

ACC amplifier is constantly monitoring bias voltage of the sensor. 

• If <4 Volts DEWESoft will detect input short and inicate with RED light ring indicator on the BNC input.
• Within limits >4 V and < 19 V DEWESoft will detect as normal sensor connection with GREEN light ring.
• When bias voltage is >19 V DEWESoft will not detect as sensor connected, NO light ring indication.

Green light ring indication, sensor is connected.

Sensor simulation

A simple resistor or potentiometer termination on the ACC input does the trick. 50R terminator is fine for input short. For normal sensor detection calculate resistance R = U / I = Normal Bias Voltage / Excitation current = 12 V / 2 .. 20 mA 

Jernej Kovačič, 13.05.2020, updated 27.10.2021