Digital isolators optimised for SPI communications

Supporting up to 40-MHz SPI clock speeds, the new digital isolators are over six times faster, over 80 percent smaller and cost as much as 85 percent less than competing optocoupler- or digital isolator-based solutions. Faster SPI clock speeds enable higher throughout in data acquisition systems, allowing for higher performance and more rapid system response times. A high level of functional integration provides system designers with a simple solution for isolating high-speed SPI signals along with commonly required low-speed status and control signals in a single package.

The ADuM315x family supports a range of high-data-rate, SPI communications applications including distributed control systems, programmable logic controllers, and sensor monitors used in industrial automation, instrumentation equipment and motor controls.

The highly integrated ADuM315x SPI digital isolator family simplifies the design of a complete SPI digital isolation solution by using just three components, compared to the 18 to 32 components required by alternative digital isolator- or optocoupler-based solutions. The ADuM315x family features low propagation delay and jitter in the CLK, MO-SI, MI-SO and SS channels to support SPI clock rates of up to 40 MHz. The new digital isolators also support the maximum sample rate for select ADI 12-, 16- and 18-bit precision A/D converters. The family has a 3.75 kVrms isolation rating and will be followed later in 2014 by SPIsolator devices rated to 5 kVrms.

• The ADuM3150 supports a delayed clock output on the master side of the part that can be used with an additional general-purpose port on the master to support up to 40-MHz clock speeds.
• The ADuM3151, ADuM3152 and ADuM3153 provide four high-speed channels and three additional independent, low-data-rate channels in different configurations.
• The ADuM3154 digital isolator provides a slave-select multiplexing system that allows up to four slave devices to be serviced from one isolator.