drive relay?

[serdar_ozcan]

Hi,

Is it possible to drive 2 or 3 5V. relays with 16f628 or 16f628A (portA or portB) directly at same time?

Thanx.

SERDAR

[Melanie]

Reed Relays (500R coil) are no problem... you can have one on each pin of a Port and not overload the PIC. However each PIC pin can only source or sink around 25mA and most relays require more than that. In the Datasheet of your PIC you will also see the MAXIMUM ratings your PIC can handle in the Electrical Specifications section. You can strap several pins together (preferably via Diodes) but it's not a nice arrangement and easier to have an external Transistor. There are also consequences of switching Relays (or any large inductive loads) on the same Power Rail as the PIC... be aware of this as it starts to introduce transients onto the PICs supply line.