Out in Front: February 1, 1996
Isolated interfaces eliminate ground loops and provide equipment protection where there is a difference of potential between chassis. The MAX1480 and MAX1490 family of high- and low-speed, full- and half-duplex data transceivers in 0.6-in.-wide plastic DIPs provides optically isolated interfaces for RS-485 and RS-422 standards. Typical isolation is 1600 Vrms for 1 minute and 2000 Vrms for 1 sec; common-mode input voltage ranges from -7 to +12V with respect to isolated ground.
The full-duplex MAX1490A and half-duplex MAX1480A support data rates as high as 2.5 Mbps. In contrast, the 250-kbps full-duplex MAX1490B and half-duplex MAX1480B incorporate reduced-slew-rate drivers that minimize EMI and reduce reflections from improperly terminated lines. All driver outputs are short-circuit-protected, and all receiver outputs provide a predetermined logic state if their input is open. A single 5V supply on the nonisolated logic side of the barrier powers the entire device. The full-duplex MAX1490A/B devices and half-duplex MAX1480A/B devices come in 24- and 28-pin DIPs, respectively. Prices begin at $9.66 (1000).
-- by Bill Schweber
Maxim Integrated Products, Sunnyvale, CA. (408) 737-7600, ext 6087