Darlington Arrays

First hit on google..............

The ULN even has the diodes.

John

Thanks, but what's the thing that looks like a NOT gate symbol? The the symbol for a darlington pair?

Read further down the data sheet - it shows the internal diagrams for each darlington stage for 01,02 & 03 versions.

From a logic designer's viewpoint, these parts are groups of inverters, as shown in the logic diagram on page 2 of that data sheet. Page 3 shows the actual circuit of one inverter, for each of the varieties of the part.

The 2003 input circuit makes it TTL-compatible. The 2002 and 2004 are designed to be driven from other sources. An old Motorola datasheet (perhaps Freescale now) listed the intended driving sources for each variety.

By the way, there's an 8-channel version: ULN2803.

These parts include diodes, so you don't need an external one.

Yup. There's a diode for every output on the ULN2003. Remember -- to take advantage, though, you have to connect pin 16 to Vcc (or the power source for the relay coils).

Good luck Chris

All the outputs are open collector and pull to the (E) pin when on. the (E) pin needs to be connected to your supply's common/(-)

They all have an internal diode for each already, also, it has a diode array tied to a "COM" common pin. With that control, you can connect the "COM" to the (-) rail and all of the outputs will turn on or, connect "COM" to the (+) rail and they'll aid in protection.

One leg of each relay are joined all together to the (+) of your supply. Each remaining leg of the relays will connect to a single output.

Hope that was clear enough.

Pin 9, not 16.

Oops, right. Thanks -- hope the OP took a look at the .pdf above and got it right.

Cheers Chris