Analog Angle Article

Digital isolator IC megafamily offers multichannel, uni- and bi-directional high-speed, low-skew performance

Austin, Texas—A comprehensive family of CMOS-based digital isolator ICs once again demonstrates that for some design problems, electrical (galvanic) isolation of signal paths is often the best and, in some cases, the only way to go. Silicon Laboratories Inc. has introduced its Si84xx ISOpro digital isolators, comprising over 70 distinct devices with various combinations of channel count and directionality, up to six channels. The digital isolators are targeted at I2 C, SMBus, PMBus applications, as well as motor drive, medical instrumentation, hybrid electric vehicle, battery stack monitoring, industrial networking, and power supplies.

The vendor claims that these parts, in addition to being the first in these numerous BOM-reducing configurations, are the fastest parts available, and with one-half or less jitter than competitive parts, and far lower power consumption as well, among other features.

Block diagram of Si84xx digital isolator channel

(Click on image to enlarge)

Isolation is achieved using a miniature RF link approach, which SiLabs maintains is better and ore reliable than isolation based on optocoupler, giant magnetoresistive, pulse transformer, or other galvanic techniques. Dynamic performance is specified with channel-to-channel skew less than 2 nsec, and propagation delay less than10 nsec, both critical specs for high-speed, multichannel performance.

The devices feature data rates up to 150 Msps, a choice of isolation ratings up to 2.5 kVrms ; low jitter of under 250 psec (peak) (critical for minimizing data transmission errors and BER); ESD ratings of 4 kV HBM (human body model, 2 kV CDM (charged device model), and 400 V MM (machine model), as well as 25 kV/μsec CMTI (common mode transient immunity) and up to 50 V/m of electric field immunity. Overall power consumption is under 1.4 mA/channel at 1 Mbps.

Packaging, price, and availability : Samples of the ISOpro Si84xx one- and two-channel devices are available in narrow-body SOIC-8 packages; the 3, 4, 5, and 6-channel devices are in narrow-body SOIC-16 and wide-body SOIC-16 packages. Pricing starts at $0.59 in high volumes.

For more information , contact Silicon Laboratories,—Bill Schweber

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