There is a saying, ‘You can never have too much of a good thing’. That certainly seems to be the principle that Panasonic Industry Europe has followed in its development of PhotoMOS® MOSFET relays: the family stretches to more than 400 products, a broad portfolio which enables the design engineer to find a specialized relay for an impressive range of applications, from RF devices to battery-powered systems, from automotive circuits to industrial battery management systems.
And if an application is constrained in its choice of package, the PhotoMOS family has an answer here too, since the relays are available in many different package styles and sizes.
So why has the PhotoMOS MOSFET relay concept turned out to be such a good thing?
It is best explained by comparison to traditional relays. A PhotoMOS relay is optically coupled, providing the galvanic isolation between the control (input) side and the load circuit (output side) that a magnetically coupled electromechanical relay offers. But in a PhotoMOS relay, the output from the control circuit’s photodetector drives the gates of two bidirectionally connected MOSFETs at the output, rather than a coil actuating an armature and contacts.
Unlike an electromechanical relay, this electronic circuit contains no moving parts, and so suffers from no wear and tear, and there is no contact bounce or switching noise.
The use of MOSFETs as the switching element brings special advantages to the PhotoMOS products:
- Silent switching
- Linear output
- Low operating current
- Low off-state leakage current
- No threshold voltage
- Stable on-resistance for life
- High reliability with long service life
- Small size
- Fast switching speed
- High resistance to vibration and shock
These characteristics apply to every one of the 400+ parts in the PhotoMOS family. Many applications will use the GU (‘General Use’) series of PhotoMOS products, but there are in addition many special series, including the HF products, which feature very low on-resistance for high power efficiency, the HS series for battery-powered applications, and the PD series in a flat Power DIP package.
There are various ways to find the right PhotoMOS part number. The Panasonic PhotoMOS app for iOS is a good place to start. And your local Future Electronics branch always has FAEs on hand to help with product selection and application design, helping you to get the best value out of these outstanding products.
