question regarding a decoder ic (RF600 D)

[danrogers]

im looking at the datasheet.. **broken link removed**

and noticed it states the low battery out put and also the data outputs low low wen operated. Does that mean that I would connect a led to the vcc (5v) and the gnd to the pin on the ic, same with the outputs, would i connect a relay to the vcc and its ground to the relevent pin on the ic?

thanks!

 

[Nigel Goodwin]

The device is a pre-programmed PIC, and the ports are subject to the same restrictions, about 20mA sink or source.

But as far as I'm aware it's a Manchester encoder/decoder, and outputs serial data to a processor, not individual remote control outputs.

 

[danrogers]

Hi Nigel. It as has serial data o/p along with four standard output pins?

I'm just not sure what it means when the say when the output is active it will be asserted low.

Also for the low battery o/p, it says that goes low when a low battery condition is activated, so how would I connect an led to that?

thanks

 

[Nigel Goodwin]

Sorry, I was thinking of a different chip set, it looks like the outputs are 'active low' so when an output is set, the pin goes low - so they sink current rather than source it.

 

[danrogers]

Thanks Nigel

So in basic terms for a noob such as myself, I would connect the v-in side of a relay to vcc, the gnd to the pin on the decoder, and wen active the IC would connect the gnd side to gnd?

Thanks for your help

 

[Nigel Goodwin]

You need to feed the relay with a transistor, the IC won't feed a relay directly. I would suggest getting the IC's and measuring what the acrual outputs do.

 

[danrogers]

Ok i will try and hook it up over the weekend thanks alot.

As for the LED for the low battery o/p, it says states the pin o/p goes low when the condition is detected, so I guess the same applies, connect the gnd of the led to the pin pn the ic?

 

[Nigel Goodwin]

Ok i will try and hook it up over the weekend thanks alot.

As for the LED for the low battery o/p, it says states the pin o/p goes low when the condition is detected, so I guess the same applies, connect the gnd of the led to the pin pn the ic?

Yes, connect the LED from the +ve supply (Vdd) to the pin.

 

[danrogers]

Thank you Nigel.

One other thing, how do I know how much current the o/p pins can sink? I can't seem to see it on the data sheet?

 

[Nigel Goodwin]

Thank you Nigel.

One other thing, how do I know how much current the o/p pins can sink? I can't seem to see it on the data sheet?

I had a read, it seems pretty vague - at one point it says 25mA, and at another only 1mA - yet it shows an LED connected with no series resistor?. Assuming it is a PIC (which as far as I'm aware RF Solutions use) then it's 20-25mA per pin.

 

[danrogers]

Quite poorly documented really I think. I noticed that the led with no current limiting! I should hope it has internal.

Thanks very much for taking a look at that my friend 20mA should drive a transistor i would imagine.

 

[audioguru]

The max allowed output current from a PIC is 25mA but they can supply 60mA for a moment then burn out if the supply is 5.0V.
When the supply voltage drops then the max output current from a PIC also drops.

Of course an LED needs a current-limiting resistor or circuit. It is not a resistor like an incandescent light bulb heater, it is a diode with a certain spec'd forward voltage. An LED is fed with current, not voltage. So a current-limiting resistor or circuit must feed an LED.