PALO ALTO, CALIF. - Agilent Technologies Inc.'s Semiconductor Products Group last week launched a line of optocouplers that are directly compatible with 3.3-V low-power microcontrollers and low-voltage TTL circuits. The parts thus eliminate the need for a 5-V power supply in many applications.
The family, supporting voltage levels from 2.7 to 3.3 V, comprises single- and dual-channel optocouplers in dual-in-line and miniature SO-8 surface-mount packages. Performance characteristics include speeds from 100 kbaud to 15 Mbaud and isolation of up to 25 kV/microsecond.
Optocouplers provide electrical isolation between parts of a system that run at different voltages. "There is a clear market demand for 3.3-V optocouplers, brought on by the shift of virtually all classes of semiconductors to the 3.3-V level," said Rainer Ihra, worldwide marketing manager for optocouplers at Agilent's Electronics Components Division.
Agilent's optocouplers are aimed at telecom, computing and industrial applications, particularly battery-operated portables and handhelds.
The devices meet Jedec specifications for 3.3-V LV TTL and LV CMOS logic, simplifying the implementation of isolation in systems implementing 3.3-V circuits. The optocouplers are also said to enable higher data rates.
Examples of the devices in the family include the HCPL-270L, 273L, 070L and 073L, which are specified for 100-kbaud performance, 10-kV/microseconds common-mode rejection (and an input "on" current of 0.5 milliamps; the HCPL-250L and 253L, specified for 1 Mbaud, 1-kV/microseconds CMR and an on current of 16 mA; and the HCPL-260L, 263L, 060L and 063L, which offer 15-Mbaud speeds, 25-kV/microseconds CMR and an input on current of 5 mA.
The application shown on page 163 is for data transmission in parallel mode. Dual-channel 3.3-V optocouplers such as the HCPL-263L isolate the analog sensor and its analog-to-digital converter circuitry from the rest of the system. Each optocoupler has two channels (HCPL-263L) for the parallel data word. A single-channel 3.3-V optocoupler (HCPL-260L) is used for the clock signal. The clock, control and data signals must keep pace with each other as they pass through the optocoupler to minimize data transfer errors and achieve maximum circuit speed. The high CMR and the switching characteristics of the new optocouplers suit them for data communications.
The devices are available in production quantities today. Unit pricing ranges from 80 cents to $1.40 for the single-channel optocouplers and $1.60 to $2.80 for dual-channel versions depending on the packaging, capabilities and performance selected.
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EETInfo No. 610