Solid State Relays Dr. Lynn Fuller Webpage:

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1 ROCHESTER INSTITUTE OF TECHNOLOGY MICROELECTRONIC ENGINEERING Dr. Lynn Fuller Webpage: 82 Lomb Memorial Drive Rochester, NY Program webpage: SS-Relays.pptx Page 1

2 SWITCH TERMINOLOGY SPST Single Pole Single Throw SPDT Single Pole Double Throw DPST - Double Pole Single Throw DPDT Double Pole Double Throw SPST SPDT DPST NO Normally Open NC Normally Closed Opto Optical Isolation NO NC Page 2

3 SOLID STATE DEVICES Devices inside the SS-Relay include: Diodes, LEDs, Power MOSFETS, Power BJTs, SCR s, and TRIACs. p n I p n Other electrical components include Resistors, Capacitors, Bridge Rectifiers, Darlington BJT s, Photodiodes, JFETs, Temperature Sensors, and more. Darlington (High current gain BJT) Page 3

4 SOLID STATE DEVICES SCR s and TRIAC s ANODE ANODE A1 GATE GATE CATHODE ANODE P N P N CATHODE SCR SCR GATE CATHODE A2 TRIAC GATE The SCR and TRIAC are both PNPN structures (Thyristors). The SCR is triggered by positive gate current (into the gate) and conducts current only in one direction. It is turned off when the load current goes to ~zero. The TRIAC conducts in both directions, it is triggered by either a positive or a negative gate current. It is turned off when the load current goes to ~zero. Page 4

The switch typically can control large currents of a few amps to hundreds of amps.

5 INTRODUCTION use transistors, SCRs, TRIACs, etc., to turn on/off circuits. The control voltages are typically low voltage DC signals. The switch typically can control large currents of a few amps to hundreds of amps. Various types of output include DC, AC, zero crossing AC, Single Throw, Double Throw, Opto-Isolation, etc. Digikey lists from 22 Manufacturers, with output current of 20mA to 160A. Unit Cost $0.42 to $ Page 5

6 SS RELAY MANUFACTURERS INCLUDE Amprobe Broadcom Limited CEL Coto Technology Crydom Co. E-T-A On Semiconductor (Fairchild) Infineon Technologies Isocom Components IXYS Integrated Circuits Division Omron Automation and Safety Omron Electronics Panasonic Electric Works Phoenix Contact Red Lion Controls Sharp Microelectronics TE Connectivity Aerospace TE Connectivity Potter & Brumfield Toshiba Semiconductor TT Electronics/Optek Technology Vishay Semiconductor Opto Division Weidmuller Page 6

7 SS RELAY MANUFACTURERS INCLUDE Page 7

8 SS RELAY MANUFACTURERS INCLUDE Page 8

9 DC SOLID STATE RELAY DARLINGTON BJT Page 9

10 MOSFET AC AND DC SOLID STATE RELAY Page 10

11 MOSFET AC AND DC SOLID STATE RELAY An SSR based on a single MOSFET, or multiple MOSFETs in a paralleled array, can work well for DC loads. MOSFETs have an inherent substrate diode that conducts in the reverse direction, so a single MOSFET cannot block current in both directions. For AC (bi-directional) operation two MOSFETs are arranged back-to-back with their source pins tied together. Their drain pins are connected to either side of the output. The substrate diodes are alternately reverse biased to block current when the relay is off. When the relay is on, the common source is always riding on the instantaneous signal level and both gates are biased positive relative to the source by the photo-diode. It is common to provide access to the common source so that multiple MOSFETs can be wired in parallel if switching a DC load. Usually a network is provided to speed the turn-off of the MOSFET when the control input is removed. Page 11

12 ZERO CROSSOVER SWITCHING In AC circuits, SCR or TRIAC relays inherently switch off at the points of zero load current. The circuit will never be interrupted in the middle of a sine wave peak, preventing the large transient voltages that would otherwise occur due to the sudden collapse of the magnetic field around the inductance. This feature is called zero-crossover switching Page 12

13 ZERO CROSSING DETECTOR Page 13

14 REFERENCES more Page 14

15 HOMEWORK SOLID STATE RELAYS Page 15

16 Devices inside the SS-Relay include, LEDs, Power MOSFETS, Power BJTs, SCR s, Thyristors, Page 16

ECE:3410 Electronic Circuits

ECE:3410 Electronic Circuits IR Link Labs Textbook Blackboard A. Kruger IR Link Labs, Version 2.3 1 Specifications Design a simple IR remote control Press a button on a transmitter Turn on a 5 V, 50 ma,