Isolated digital input chips offer flexible configuration in industrial applications

NOVOSENSE Microelectronics, a semiconductor company specialising in high-performance analog and mixed-signal ICs, has introduced two new isolated DI chips suitable for 24V digital signal input in industrial control applications such as PLCs, servos and inverters.

The four-channel NSI8604 and the four-channel NSI8608 provide input/output isolation when converting voltages from -60V to 60V to logic signals. These devices support bi-directional digital input functionality, enabling flexible system I/O configuration. Unlike digital isolators, the input stage of the chips integrates current-mode input with a function that limits currents to 2.1mA (typical), lowering power consumption and temperature rises in the target system.

Based on the company's innovative capacitive isolation technology, the ICs use OOK modulation technology to modulate input signals and transmit them via the SiO2 barrier to the secondary side, where they are demodulated and output through a buffer stage. While fully compatible with the current input form of optocouplers, the chips provide for simplified system design due to a higher degree of system integration and the eradication of a need for a field-side power supply.

Key features of these latest chips include an isolation withstand voltage of 3kVrms, CMTI of 35kV/μs, a data transmission rate of DC to 2Mbps and a data transmission delay figure of 380ns. The devices operate from a power supply voltage of 2.5V to 5.5V and are stable over a wide temperature range from -40C to 125C. Each IC meets the performance criteria for switch types 1, 2 and 3 in IEC 61131-2 and is compatible with the I/O level of most microcontrollers.

Available in industry-standard SSOP16 and SSOP20 packages, the NSI8604 and NSI8608 are pin-compatible with alternative technologies, permitting users to replace existing parts without modifying the system design.