Electronics > Projects, Designs, and Technical Stuff
Does this Digital output design correct?
Danesh_SA:
Dear Yansi,
Thank you for your reply,
my application need 200mA per channel ,total is 4*200=800mA .with this situation,do you think to add external free wheel diode on each output?
Yansi:
I am not sure, but 800mA total current seems a bit too much for the IC.
What is the maximum specified current total per whole IC?
If you need just 4 outputs, at least think about paralleling 2 channels per output to help it a bit with heat dissipation.
Danesh_SA:
ULN2803 Continuous collector current is 500mA .
I want to use 100mA Continuous current per each channel,and 200mA peak current .I use fast fuses on each of the output.
But i really think about add discrete free wheel diodes on outputs.I see it many times.
Yansi:
Fuses won't help anything. Absolutely anything.
Reason for fuses is fire prevention, not silicon protection. Transistors always burn faster, than fuses.
If you need robust industrial outputs, use apropriate circuitry. ULN2803 is outta question.
For example, ROHM BD8LB600FS or similar. Is quite on the cheap side and a robust solution for this. Or the good old fashioned 4 channel VN340 switch.
There are a lot of industrial grade both low- and high- side switches (typically for PLC or sensor output applications). Just google for them.
TrickyNekro:
--- Quote from: MarkF on January 02, 2020, 04:17:41 am ---The ULN2803 inputs can NOT exceed +5V. So, you need to limit the current to about 1mA.
--- End quote ---
Maybe not all created equal then? Look page 4: http://www.ti.com/lit/ds/symlink/uln2803a.pdf
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