Si826x: Optocoupler-compatible isolated gate driver.Si834x: Isolated smart switch for industrial IO.Si838x: Bi-directional input 8ch digital isolator to replace photocoupler for 24V PLC.S86xx: 1ch~6ch 150Mbps digital isolator.Here is a digital isolator product page with useful features. It offers improved performance, reliability and ease of use, making it ideal for system component installations and new designs. It is flat in the temperature range of -40 to +125☌.Ĭompared to photocouplers, digital isolators can achieve high-speed data rates and low delays, exhibit little characteristic change due to temperature changes, and offer high added value in terms of timing design. Propagation delays for CMOS digital isolators are shown at the bottom of the graph as Si86xx characteristic curves. Also, the rise/fall times (tPHL and tPLH) are not symmetrical and should be examined separately. Optocouplers behave differently with and without a "peaking" capacitor (Cp) that momentarily increases the LED current during turn-on and turn-off to improve response. Here is an example of timing variations due to temperature.įigure Photocoupler/CMOS isolator propagation delay vs. The delay time of the photocoupler is easily affected by temperature and other factors even if the input signal is the same. In this way, digital isolators are obviously easier to design than photocouplers. The photocoupler design margins, which have large variations in characteristics, are cut and the characteristics deteriorate. There are many considerations such as device variation, temperature, current, as well as device aging. It is possible to predict characteristics, including changes over time, to some extent, making it easy to design with high reliability.ĭriving high-speed power devices requires severe design, such as design with strict timing specifications. Photocouplers have large temperature characteristics and changes over time, so it is necessary to consider various characteristics when designing.ĭigital isolators, on the other hand, have defined specifications including temperature characteristics and changes over time. ・Definition of easy-to-design specifications The isolator has low EMI and high immunity to magnetic and electric fields. In order to maintain high performance, insulating devices with characteristics that can eliminate external electric and magnetic field interference are important. ・Low EMI, immunity to high electric and magnetic fieldsĮMI causes data errors, especially in medical applications with low amplitude signals such as electrocardiographs. There are many isolator products with high CMTI. Devices with high CMTI (Common-Mode Transient Immunity) characteristics for such environments are required. There are environments where common mode changes are severe, such as driving power devices that operate at high speed and environments with a lot of noise. Isolators are also rated for long-term reliability.
In such applications, the isolator must have a lifetime of 20 years or more in a high temperature environment exceeding 120☌. Below are some details.Īpplications such as HEV/EV and wind energy systems are used in harsh environments. Digital isolator and photocoupler technology Features of Digital IsolatorĬompared to optocouplers, digital isolators have advantages such as size, speed, stability, power consumption, easy-to-use specification definitions, and reliability, and can be used in a variety of applications.
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