LH1526AAC View Datasheet(PDF) - Infineon Technologies

Part Name

Description

Manufacturer

LH1526AAC

Dual 1 Form A Solid-State Relays

Infineon Technologies 

Applications

Input Control

The LH1526 low turn-on current SSR has highly sensitive photo-

detection circuits that will detect even the most minute currents

flowing through the LED. Leakage current must be considered

when designing a circuit to turn on and off these relays.

Figure 19 shows a typical logic circuit for providing LED drive

current. R1 is the input resistor that limits the amount of cur-

rent flowing through the LED. For 5.0 V operation, a 2700 Ω

resistor will limit the drive current to about 1.4 mA. Where

high-speed actuation is desirable, use a lower value resistor

for R1. An additional RC peaking circuit is not required with

the LH1526 relay.

R2 is an optional pull-up resistor which pulls the logic level

high ouput (VOH) up toward the VS potential. The pull-up resis-

tance is set at a high value to minimize the overall current

drawn from the VS. The primary purpose of this resistor is to

keep the differential voltage across the LED below its turn-on

threshold. LED dropout voltage is graphed vs. temperature in

the Typical Performance Characteristics section. When the

logic gate is high, leakage current will flow through R2. R2 will

draw up to 8 mA before developing a voltage potential which

might possibly turn on the LED.

Many applications will operate satisfactorily without a pull-up

resistor. In the logic circuit in Figure 1 the only path for current

to flow is back into the logic gate. Logic leakage is usually neg-

ligible. Each application should be evaluated, however, over

the full operating temperature range to make sure that leakage

current through the input control LED is kept to a value less

than the minimum LED forward current for switch turn-off

specification.

Figure 19. Input Control Circuit

VS

R2

100 kΩ

ANY TTL OR

BUFFERED CMOS

LOGIC

R1

2700 Ω

SSR

 2001 Infineon Technologies Corp. • Optoelectronics Division • San Jose, CA

www.infineon.com/opto • 1-888-Infineon (1-888-463-4636)

3–119

LH1526AB/AAC/AACTR

March 26, 2000-17

Share Link: