I am wanting to use teh TLP521-4 to control variosu solenoid valves. I will be controlling the TLP521 either directly from the arduino via resistor or through a PCF8574.
However I am wanting to control a 24V solenoid. It takes 2W so about 85mA. Can I run this directly from the TLP521 (with protection diode)or do I need to add an additional transistor for higher power? These valves etc could be on for may hours at a time.
If it is possible to run these directly (or not), what is the MAXIMUM current I can control directly at 24V as this will be in a 24V switch panel, as these are only one of the control valves I will be using, all spec'd slightly differently.
According to the datasheet, the TLP521-4 requires a recommended 16mA for the led. The Arduino and the PCF8574 can do that.
The output of the TLP521-4 is recommended 1mA and maximum 10mA. The absolute maximum is 50mA. The maximum voltage is 55V, and the maximum power dissapation is 100mW.
The solenoid is 24V, 83mA. So the TLP521-4 is by far not enough to control the solenoid.
I was confused as it says Collector - Emitter 55v (min) on page 1.
So for me to be able to read other datasheets properly, the If (forward current) is teh current required to drive the LED and the Ic (collector current) is teh maximum current the output transistor can cope with.
Do you know of others which are VERY common? In Bangladesh I have to literally ask for each possible component in turn as tehre are no lists of what the shops stock, so having a list of possible COMMON equivalents is much easier.
In general for an industrial use solution would you suggest using an opto-coupler or just direct conection to the solenoid through a mosfet as we are only talking about 24V?
The datasheet has a table which is split for the led and for the optotransistor. I have to look twice myself to see which side of the optocoupler is mentioned.
The MC1415 is a good choice. The current is low, so those drivers are simple and good.
The most common driver like that is the ULN2803.
An optocoupler takes away many troubles with grounding, currents, spikes, and so on.
But even with an optocoupler, the design can be wrong.
Read my post here, Arduino autoreset ?! - #15 by system - Programming Questions - Arduino Forum
It is about a relay board with optocouplers, but still causes troubles.
If you make a device that is small, and everything is close to each other, you can do without the optocoupler. But with high currents you must be very careful how the ground wires are connected.
I'm working on chinese industrial belly washing machines, so probably better to use optocouplers as who knows what probelsm I will encounter. At the end of the day, I reckon I will have to find ways of reducing teh EMI from the large 3 phase motors etc...
Hmmm Not certain how yet, but have to finish the design and programming before I can actually adapt a machine to test.