Specifications

2–27

Selecting Your Hardware Components

Publication

1747-6.2

Transistor Output Transient Pulses

This section applies to the following SLC 500 fixed I/O processors

and SLC 500 I/O modules that have transistor outputs.

Fixed I/O Processors I/O Modules

1747- 2

1746-OB8

1747-

1746-OBP8

1747-L20G 1746-OV8

1747-L20L 1746-OB16

1747-L20N 1746-OBP16

1747-L30L 1746-OV16

1747-L40E 1746-OVP16

1747- 4

1746-OB32

1747-

1746-OV32

For the SLC 500 products listed above, the maximum duration of the

transient pulse occurs when minimum load is connected to the

output. However, for most applications the energy of the transient

pulse is not sufficient to energize the load.

ATTENTION: A transient pulse occurs in transistor

outputs when the external DC supply voltage is applied

to the common output terminals (e.g., via the master

control relay). The sudden application of voltage

creates this transient pulse. (See the following graph.)

This condition is inherent in transistor outputs and is

common to solid state devices. A transient pulse can

occur regardless of the processor having power or not.

Duration of Transient (T)

Transient (I)

(On-State Load Current)

Current

Time