Digital Output DC Current Sensor Avoids Sampling and A/D Converter Circuitry

Typical current sensing techniques that use a Hall Effect sensor or a resistive shunt deliver an analog output that requires additional circuitry for use in digital control circuits. Micro Oscillator Inc. has introduced an isolated high-side DC current sensor that provides a uni-directional current sensing system with a frequency output.  The pulsed output of the ICS I-A1 current sensor eliminates the need for electronic sampling and A/D converter circuitry.  The current measurement is performed by a current frequency converter that utilizes an integrator. The ratio of gain resistor to sensor resistor resistance values determines the ratio of sense current to integrator input current level. The internal sense resistor has a maximum 10A rating.

Specified for a -40°C to 85°C operating temperature range, the unit’s accuracy over temperature is 0.5% (from -40°C to 85°C), accuracy over voltage is 0.5% (from V_S=10 to 16V) and total accuracy is 2.5%. An optocoupler provides 2 KV_RMS isolation voltage between the current sensor and the output.

For more information on Micro Oscillator, Inc.’s ICS I-A1, click here

Split-Core Coils Sensor Suitable For Use In Class 1 Power Devices

LEM has introduced the first of its AC current sensor families based on Perfect Loop Technology. After calibration, the new RT series achieves absolute accuracy of better than 0,65% – including position error – making them the first split-core Rogowski coils to be suitable for use in Class 1 power devices.

An imperfect coil structure induces an unbalanced geometry and increases sensitivity to the position of the measured conductor within the sensor, or to the proximity of external electric cables. The RT series of sensors overcomes the problem of asymmetry resulting from the discontinuity at the sensor opening, which is inherent in conventional split-core Rogowski coils. LEM engineers have invented a unique magnetic coupling technology that allows a perfect extension of the magnetic flux at the loop opening, which compensates for coil asymmetry.

The thin, light and flexible format of the RT sensors allows them to fit into applications in which traditional current transformers are typically too heavy and bulky, especially when measuring high currents. Their split-core construction allows them to be easily wrapped around the conductor without dismantling cables or shutting down operation. The benchmark accuracy of RT series sensors provides enhanced performance in current and power monitors as well as energy meters.

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Mini Voltage/Current Detection Optocouplers

Avago Technologies announced two new miniature voltage/current threshold detection optocouplers for use in a wide range of industrial control applications.  The ACPL-K370/K376 optocouplers are designed to detect AC/DC sources and convert the voltage to a logic interface across an optical coupling barrier to provide safe isolation in electronically noisy environments found in industrial applications.  These voltage/current sensing optocouplers are ideal for use in applications such as limit switch sensors, low voltage detectors, relay contact monitors, relay coil voltage monitors, and current sensors.

The new ACPL-K370/K376 series, which are an upgrade from Avago’s HCPL-0370/3700/3760 optocoupler family, utilizes threshold sensing input buffer ICs which permit control of threshold levels over a wide range of input voltages up to 1140 Vpeak, with a single external resistor.  Some of the key benefits provided by this new optocoupler series include a smaller stretched SO-8 (SSO-8) package which meets 8mm clearance and creepage requirements, and requires 30 percent less printed circuit board space compared to dual-inline packages (DIP-8). Additionally, the input buffer of these optocouplers offer several key features to enhance threshold sensing such as hysteresis for extra noise and switching immunity, a diode bridge for easy use with AC input signals, and internal clamping diodes to protect the buffer and light emitting diode (LED) from a wide range of over-voltage and over-current transients.

With the addition of the ACPL-K370/K376 series, Avago can offer another SSO-8 package option in addition to existing DIP packages to provide customers with more optocoupler options for higher voltage industrial applications.  The ACPL-K376 is a low-current version of the ACPL-K370.  To obtain lower current operation, the ACPL-K376 uses a high-efficiency aluminum gallium arsenide (AIGaAs) LED which provides higher light output at lower drive currents.