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Data subject to change. Copyright © 2005-2012 Avago Technologies. All rights reserved. Obsoletes 5989-1944EN

AV02-3835EN - October 2, 2012

Design Considerations for Replacement of Electro-

Mechanical Relays

The HSSR-7110 family can replace electro-mechanical re-

lays with comparable output voltage and current ratings.

The following design issues need to be considered in the

replacement circuit.

Input Circuit: The drive circuit of the electro-mechanical

relay coil needs to be modified so that the average for-

ward current driving the LED of the HSSR- 7110 does not

exceed 20 mA. A nominal forward drive current of 10 mA

is recommended. A recommended drive circuit with 5 volt

VCC and CMOS logic gates is shown in Figure 1. If higher

VCC voltages are used, adjust the current limiting resistor

to a nominal LED forward current of 10 mA. One impor-

tant consideration to note is that when the LED is turned

off, no more than 0.6 volt forward bias should be applied

across the LED. Even a few microamps of current may be

sufficient to turn on the HSSR- 7110, although it may take

a considerable time. The drive circuit should maintain at

least 5 mA of LED current during the ON condition. If the

LED forward current is less than the 5 mA level, it will cause

the HSSR-7110 to turn on with a longer delay. In addition,

the power dissipation in the output power MOSFETs in-

creases, which, in turn, may violate the power dissipation

guidelines and affect the reliability of the device.

Output Circuit: Unlike electromechanical relays, the de-

signer should pay careful attention to the output on-resis-

tance of solid state relays. The previous section, “On- Re-

sistance and Rating Curves” describes the issues that need

to be considered. In addition, for strictly dc applications

the designer has an advantage using Connection B which

has twice the output current rating as Connection A. Fur-

thermore, for dc-only applications, with Connection B the

on-resistance is considerably less when compared to Con-

nection A.

Output over-voltage protection is yet another important

design consideration when replacing electro-mechanical

relays with the HSSR-7110. The output power MOSFETs

can be protected using Metal oxide varistors (MOVs) or

TransZorbs against voltage surges that exceed the 90 volt

output withstand voltage rating. Examples of sources of

voltage surges are inductive load kickbacks, lightning

strikes, and electro-static voltages that exceed the speci-

fications on this data sheet. For more information on out-

put load and protection refer to Application Note 1047.

References:

1. Application Note 1047, “Low On-Resistance Solid State

Relays for High Reliability Applications.”

2. Reliability Data for HSSR-7111, HSSR-7112, and

HSSR-711E.

MOV is a registered trademark of GE/RCA Solid State.

TransZorb is a registered trademark of General Semicon-

ductor.

MIL-PRF-38534 Class H, Class E and DLA SMD Test Pro-

gram

Class H:

Avago Technologies’ s Hi-Rel Optocouplers are in compli-

ance with MIL-PRF-38534 Class H. Class H devices are also

in compliance with DLA drawing 5962-93140.

Testing consists of 100% screening and quality confor-

mance inspection to MIL-PRF-38534.

Class E:

Class E devices are in compliance with DLA drawing 5962-

9314001Exx. Avago Technologies has defined the Class E

device on this drawing to be based on the Class K require-

ments of MIL-PRF-38534 with exceptions. The exceptions

are as follows:

1. Nondestructive Bond Pull, Test method 2023 of MIL-

STD-883 in device screening is not required.

2. Particle Impact Noise Detection (PIND), Test method

2020 of MIL-STD-883 in device screening and group C

testing is not required.

3. Die Shear Strength, Test method 2019 of MIL-STD-883

in group B testing is not required.

4. Internal Water Vapor Content, Test method 1018 of MIL-

STD-883 in group C testing is not required.

5. Scanning Electron Microscope (SEM) inspections, Test

method 2018 of MIL-STD-883 in element evaluation is

not required.