PWM outputs

[William Steed]

Just working with one of your 888 plc's and I would like some clarification, what is the maximum continuous output current from outputs #7 and 8 when in PWM mode.  I know the max intermittant is 10Adc @24 Vdc, but I think I read in two different manuals that it is either 1A or 2A.

Thanks

Will

[support]

Maximum current for for output #7 and #8 for T100MD888 and T100MD2424 are:

1) Peak at 10A
2) Continuous at 2A for 100% duty cycle without heat sink.

The MOSFET actually can take higher current but you will then need to attach heat sink to the MOSFET's metal tab and also provide forced air cooling to the heat sink.

For T100MD1616+, the peak current is 1A and continuos current is 250mA.

[William Steed]

Thanks for the quick response, that leads me to several more questions.

I am going to need around 3.5 amps continuous from the PWM outputs, I was already planning to use a fan to cool my enclosure, if I attach the heat sink to the mosfet will I be safe.

And secondly, what is the maximum duty cycle allowed at the peak 10A, I am guessing possibly around 1%.

Thanks very much, and I have to say what a great product you have there, the adaptability has helped my project immensly.

Will Steed

[support]

If you attach a heat sink properly to the metal tab on the MOSFET (IRL530 for MD888+) and have constant air flow pass the heat sink to bring out the generated heat then you should be pretty safe.

Maximum duty cycle allowable is 100% as long as the heat issue is taken care of. At 50% duty, the heat will be reduced by half. Hence you could have a 20% duty cycle for 10A current output which is equivalent to 2A at 100% duty cycle.

Thank you for your nice comments. The M-series PLC's unique Ladder+BASIC langugage is different from the pure ladder logic based PLCs offered by other vendors and we are glad to learn that you do enjoy programming our PLCs.