The ACPL-K370 and ACPL-K376 are voltage/current threshold detection optocouplers. The ACPL-K376 is a lowcurrent version of the ACPL-K370. To obtain lower current operation, the ACPL-K376 uses a high-efficiency AlGaAs LED which has higher light output at lower drive currents. Both devices have a threshold sensing input buffer IC that allows threshold levels to be set by a single external resistor over a wide range of input voltages.The input buffer has several performance enhancing features: hysteresis for extra noise immunity and switching immunity, a diode bridge for easy use with AC input signals, and internal clamping diodes to protect the buffer and LED from over-voltage and over-current transients. Because threshold sensing is done prior to driving the LED, variations in optical coupling from the LED to the detector will not effect the threshold levels.The ACPL-K370 input buffer IC has a nominal turn-on threshold of 3.8 V(VTH+) and 2.77 mA (ITH+). The buffer IC for the ACPL-K376 is designed for lower input current. The nominal turn-on threshold for the ACPL-K376 is 3.8 V (VTH+) and 1.32 mA (ITH+), which reduces power dissipation by 52%.The high-gain output stage features an open-collector output for both TTL compatible saturation voltages and CMOS compatible breakdown voltages.By combining many unique functions in a single package, the ACPL-K370 and ACPL-K376 are ideal components for industrial control computer input boards and other applications where a predetermined input threshold level is needed