Isolated Undervoltage and Overvoltage Detection Module

This high-speed, isolated Undervoltage and Overvoltage detection project is implemented with a dual isolated window comparator with an adjustable threshold (AMC23C14). This circuit is designed for industrial field-supply applications where the controller side must detect whether the remote module supply voltage is in a valid range.

The AMC23C14 has open-drain outputs that are pulled up to VCC, and are driven low when the input voltage exceeds the threshold voltage of each comparator.  In these measurements, OUT1 (trace 3) transitions low if Vsupply exceeds 28.8V, and OUT2 transitions low if Vsupply exceeds 20.8V. Component variations and the comparator hysteresis can affect the trip thresholds, but in this case, the trip point is within less than 1% of the desired values. The voltage thresholds vary slightly if V_supply is rising or falling. The second waveform depicts this with OUT1 triggering at 28.6V instead of 28.8V.

U1 (CRE1S0505SC) is an isolated DC-DC converter that provides 5V to the input side circuitry. The module can be powered from input side power, using R1 1K SMD size 0805 and Zener diode 27V 1W SMD. Do not install U1 in this case, the output side requires separate 2.7V to 5.5V VCC.

Over Current and Short Circuit Application

The project is designed for Under/Over voltage detection. However, the project also has provisions to be used for over-current and short-circuit detection. Read the datasheet of the chip for more info. Do not install R3, R6, and R7, Install R10 = 10mOhms SMD size 2512, solder jumper J1 under the PCB. This configuration will help you to detect over current and short circuit across the shunt resistor R10.

Features

• Power Supply 5V DC
• Input Signal 24V
• Over Voltage Level 28.8V
• Under Voltage Level 20.4V
• Output 1 and Output 2 Normally High, Low when Over/Under Condition Occurs
• Transient Response Time 390ns
• Trip threshold error: ±1% (max) at 250 mV
• Open-drain outputs with Pull Resistors
• Dual window comparator: – Window comparator 1: ±20-mV to ±300-mV adjustable threshold
• Window comparator 2: ±300-mV fixed threshold
• 7000-VPK reinforced isolation per DIN EN IEC 60747-17 (VDE 0884-17)
• 5000-VRMS isolation for 1 minute per UL1577
• 5 mm Mounting Hole
• PCB Dimensions 42.23 x 19.05mm

The AMC23C14 is a dual, isolated window comparator with a short response time. The open-drain outputs are separated from the input circuitry by an isolation barrier that is highly resistant to magnetic interference. This barrier is certified to provide reinforced galvanic isolation of up to 5 kVRMS according to VDE 0884-17 and UL1577, and supports a working voltage of up to 1 kVPK.

Both comparators have windows that are centred around 0 V, meaning that the comparators trip if the input exceeds the thresholds in a positive or negative direction. One comparator has fixed thresholds of ±300 mV. The second comparator has adjustable thresholds from ±20 mV to ±300 mV through a single external resistor.

The AMC23C14 also supports a positive-comparator only mode. When the voltage on the REF pin is greater than 550 mV, the negative comparators are disabled and only the positive comparators are functional. The reference voltage in this mode can be as high as 2.7 V. This mode is particularly useful for monitoring positive voltage supplies.

Connection

• CN1: Pin 1 Input Detection Power 24V DC, Pin 2 = GND
• CN2: Pin 1 = VCC 5V DC, Pin 2 = Output 1, Pin 3 = Output 2, Pin 4 = GND
• D1: Power LED

Schematic

Parts List

Connections

Block Diagram

Typical Application

Switching Thresholds and Hysteresis

Spice Simulation

Gerber View

Photos

Video

AMC23C14DWVR Datasheet

Please follow and like us: