The LT218D is a miniature 1-Form A solid state relay in a 4 pin SOP package that employs optically coupled MOSFET technology to provide 1500V of input to output isolation. The optically coupled input is controlled by a highly efficient GaAlAs infrared LED and MOS FETs on the output side.



SOP package 4 Pin type in miniature design (4.4×4.3×2.0mm / .173×.169×.083inch)

Low driver power requirements (TTL/CMOS Compatible)

No moving parts

High reliability

Arc-Free with no snubbing circuits

1500Vrms Input/Output isolation

Tape & Reel version available


Telecommunications (PC, Electronic notepad)

Measuring and Testing equipment

Industrial control

Security equipments

High speed inspection machine


Photo DMOS-FET Relay Specifications


Part Name: LT218D

(Load voltage: 40V / Load current: 4.0A/DC)


Absolute Maximum Ratings(Ambient Temperature: 25℃)


Item Symbol Value Units Note
Input Continuous LED Current IF 50 mA  
Peak LED Current IFP 1000 mA f=100Hz, duty=1%
LED Reverse Voltage VR 5 V  
Input Power Dissipation PIn 75 mW  
Output Load Voltage VL 40 V(DC)  
Load Current IL 4.0 A  
Peak Load Current IPeak 35 A 300μs(1 pulse)
Output Power Dissipation Pout 250 mW  
Total Power Dissipation PT 2 W  
I/O Breakdown Voltage VI/O 1500 Vrm RH=60%, 1min
Operating Temperature Topr -40 to +85  
Storage Temperature Tstg -40 to +100  
Pin Soldering Temperature Tsol 260 10 sec max.


Electrical Specifications(Ambient Temperature: 25℃)


Item Symbol MIN. TYP. MAX. Units Conditions
Input LED Forward Voltage VF   1.2 1.4 V IF=10mA
Operation LED Current IF on   0.5 5.0 mA  
Recovery LED Voltage VF off 0.7     V  
Output On-Resistance Ron   0.2 0.6 Ω IF=5mA,IL=100mA, Time to flow is within 1 sec.
Off-State Leakage Current ILeak     0.1 uA VL=Rating
Output Capacitance Cout   240   pF VL=0, f=1MHz
Transmission Turn-On Time Ton   1.0 3.0 ms IF=5mA, IL=100mA,
Turn-Off Time Toff   0.03 0.5 Ms
Coupled I/O Isolation Resistance RI/O 1010     Ω DC500V
I/O Capacitance CI/O   0.8 1.5 pF f=1MHz