Voltage Attenuator

The project shown here converts bipolar +/-10V (Dual 10V) signal and provides a single-ended 0 to 5V signal. The circuit attenuates a +/-10V, 10Khz bandwidth bipolar signal converts to a single-ended signal, and also filters it by a 3rd-order Butterworth filter to drive a single-ended analog-to-digital converter (ADC). The project was built using OPA2206 OPAMP which protects the input signal from overvoltage up to 40V beyond either supply. The board can be used for applications such as programable logic controllers (PLCs), low-power data acquisition systems (DAQs), and field instruments where high precision, low power, and signal fault protection are needed. OPA2206 is ideal for this application because of the high supply range, high DC precision (4-uV offset and 0.08-uV/C offset drift), and low power consumption (220uA quiescent current) that minimizes the thermal dissipation requirements. Because of the internal OVP topology, the device provides better DC and AC accuracy under normal operating conditions compared to passive external protection and results in a smaller system solution.

The first stage of the signal chain is an attenuator and level shifter. The input signal to this stage is bipolar ±10 V that is attenuated to ±2.5 V, then is level-shifted so that the output is a single-ended, 0V to 5V signal. The feedback and gain resistors were selected as 20 kΩ and 80 kΩ, respectively. Thus, the combined impedance is 100 kΩ, which lowers the input current to the signal chain and minimizes errors resulting from higher output impedance sensors. The second stage of the signal chain uses the second channel of the OPA2206 to create a 3rd-order Butterworth filter with a –3-dB response of 20 kHz. For more information on filter design, please refer to the datasheet.

Features

• Power Supply +/-12V DC (Dual 12V DC)
• Input signal range: ±10 V
• Input signal frequency: up to 10 kHz
• 3rd-order Butterworth filter -3-dB frequency: 20 kHz
• Output voltage: 0 V to 5 V
• Trimmer Potentiometer to Adjust the Offset Voltage
• Input protection: up to ±52 V
• PCB Dimensions 22.38 x 18.26 mm

Connections

• CN1: Pin 1= Signal Output 0 to 5V, Pin 2 = GND
• CN2: Pin 1 = VC +12V, Pin 2 = GND, Pin 3 = -VE -12V, Pin 4 = +/-10V Signal Input, Pin 5 = GND
• D1: Power LED

Schematic

Parts List

Connections

Input – Output Diagrams

Gerber View

Photos

Video

OPA2206 Datasheet

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