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In general, the device which is electrically separated and isolated between the input
side and the output side, and whose output signal is controlled by input signal, is called
Relay.
Relays are classified in two types. One type is with the contacts and the other is without
the contacts (Non-contact). The main products of the contact type relays are
Mechanical Relays, Reed Relays and Mercury Relays. PhotoDMOS-FET Relays are the
Non-contact type.
PhotoDMOS-FET Relay consists of LED (Light Emitting Diode), Photodiode Array
and one MOSFET or two MOS FETs. Input side consists of LED and output side
consists of Photodiode Array and two MOS FETs.
Input side and output side, optically coupled, are electrically separated and isolated.
The one MOSFET or two MOS FETs of output side are driven by the photo-voltaic force
generated by Photodiode Array when LED emits light. Regarding the PhotoMOS Relay
with one MOSFET, it can control DC signal only. However the PhoroMOS Relay with
two MOS FETs, since these two MOS FETs are connected with source common, it can
control AC signal or DC signal.
Since PhotoDMOS-FET Relay is using semiconductor technology, its life span is very
long, high reliability and high availability comparing with mechanical relays. As
PhotoDMOS-FET Relay is Non-contact type relay, operation sound recognized in
mechanical relays is not heard from PhotoDMOS-FET Relay. PhotoDMOS-FET Relay is
driven by LED, therefore it can operate accurately without being affected by inductive
noise generated by the drive coil as in the case of mechanical relay.
PhotoDMOS-FET Relay
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OMRON/歐姆龍