Opto Coupled SSRs Increase Performance And Reliability

Assembled using a coplanar structure, the HSRxxx solid-state relays (SSRs) are said to provide a wider input-to-output isolation gap and to offer an additional margin for passing UL1459 line-cross testing. The new SSRs also combine a higher maximum operating voltage with lower on-state resistance than typical over-under structured relays. Four models, the HSR312, HSR412, HSR312L, and HSR412L, employ an AlGaAs infrared LED optically coupled to a photovoltaic generator that drives a power MOSFET detector and provides 4 kVRMS of isolation. The HSR312 and HSR312L switch loads up to 250V and the HSR412 and HSR412L can switch up to 400V. The HSR312L and HSR412L employ active current limit circuitry that allows them to withstand current transients. Other features of the four SSRs include a dual MOSFET output configuration that allows for series or parallel connection. Parallel connection of the FETs lowers maximum on-state resistance and allows higher maximum load current for all models. Series connection provides lower active current limit for the HSR312L and HSR412L. Available in six-pin through-hole or six-pin SMT dual-in-line packages, the HSR312, HSR412, HSR312L and HSR412L are priced at $0.85, $0.90, $089 and $0.93, respectively, each/1,000. FAIRCHILD SEMICONDUCTOR, San Jose, CA. (888) 522-5372.