A-6-2 Load Short-Circuit Protection For Cj1W-Od204/Od212/Od232/Md232 - Omron CJ2 User Manual

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A-6-2
Load Short-circuit Protection for CJ1W-
OD204/OD212/OD232/MD232
As shown below, normally when the output bit turns ON (OUT), the transistor will turn ON and then out-
put current (Iout) will flow. If the output (Iout) is overloaded or short-circuited exceeding the detection
current (Ilim), the output current (Iout) will be limited as shown in second figure below. When the junc-
tion temperature (Tj) of the output transistor reaches the thermal shutdown temperature (Tstd), the out-
put will turn OFF to protect the transistor from being damaged, and the alarm output bit will turn ON to
light the ERR indicator. When the junction temperature (Tj) of the transistor drops down to the reset
temperature (Tr), the ERR indicator will be automatically reset and the output current will start flowing.
Normal Operation
ON
OUT
OFF
ON
I
OUT
OFF
ON
ERR
OFF
Operation for Overload or Short Circuit
ON
OUT
OFF
I
lim
ON
I
OUT
OFF
ON
ERR
OFF
Operating Restrictions for the CJ1W-OD204/OD212/OD232/MD232
These Units are provided with short-circuit protection, these are for protecting internal circuits against
momentary short-circuiting in the load. As shown in Figure 2, the short-circuit protection is automati-
cally released when the Tj equals to Tr. Therefore, unless the cause of short-circuit is removed,
ON/OFF operations will be repeated in the output. Leaving short-circuits for any length of time will
cause internal temperature rise, deterioration of elements, discoloration of the case or PCBs, etc.
Therefore, observe the following restrictions.
CJ2 CPU Unit Hardware User's Manual
OUT: OUTPUT instruction
I
OUT
ERR: Alarm output, ERR indicator
I
lim
Tj:
Tstd: Thermal shutdown temperature
Tr:
Tj =Tstd Tj =Tr
: Output current
:
Detection current
Junction temperature of transistor
Reset temperature
Appendices
A-117

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