Optocouplers Are High in Isolation, Low in Profile
Aug. 27, 2008
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A series of phototransistor optocouplers from Everlight Electronics provide a combination of performance benefits and low-profile packaging that can be exploited in a variety of isolated power supply designs. The EL3H7-G optocouplers, which come in 2.0-mm high 4-pin SSOPs, feature 3750-Vrms isolation, 5-mm minimum creepage distance, -55°C to +110°C operating temperature range, 80-V breakdown rating, and multiple current-transfer-ratio (CTR) bins.
The dc-input, phototransistor output optocouplers target applications such as dc-dc converters, battery chargers, general-purpose switching circuits and programmable controllers. According to the company, the EL3H7-G series devices either match or outperform other similarly packaged optouplers on a number of specifications (see the figure).
For example, the 3750-Vrms isolation voltage rating is said to match industry-best performance for a 4-pin SSOP device. According to Everlight, only one other vendor offers an optocoupler with this rating in the 4-pin SSOP and that device is 0.1 mm taller (2.1 mm). Meanwhile other competing devices in this package are said to carry isolation ratings of 3000 Vrms or less. In addition to the small package size, the EL3H7-G optocouplers offer a fine lead pitch of 1.27 mm.
Similarly, with regard to operating temperature range, Everlight claims that only one other competitor matches its upper tempertaure limit of 110°C, while most of the competiting devices specify a maximum operating temperature of 100°C.
“Because these 4-pin SSOP optocouplers are capable of reaching higher operating temperatures, they enable dc-dc converters to achieve higher efficiencies and power ratings, as well as improved thermal performance," says Krish Ramdass, Optoelectronics Marketing, Everlight Americas.
Pricing for the EL3H7-G optocouplers ranges from $0.10 to $0.20 per unit in production quantities. Available now, these devices are halogen-free, lead (Pb) free and RoHS-compliant to meet green environmental initiatives.