test procedure

hi all, i have a bunch of ULN2001 IC'S. SOME GOOD SOME BAD. i would like to test these. can anyone supply a circuit for a quick go-no go test for these ic's ?

Possibly clock a chip like a CD4017 decade counter divider using a 555 timer running astable at about a 1 second clock rate. Configure the 4017 to count to N and recycle. Use outputs 0 through 6 of the 4017 to drive the ULN2001 chips and place a resistor as a load and an LED at each output. N would be 7 on the 4017. That would make for a quick and dirty test jig for the ULN2001 chips. Hell, if you have a function generator on the bench drop the 555 and use a function generator to clock the 4017.

Ron

hi, thanks for your quick reply. is there any chance your could post a circuit diagram?

I'll get one up this evening when I get off work.

Ron

Attached is a rough schematic of what I would use. Please keep in mind that this approach will only tell you if the chip works. It is not designed to test the chip to specifications. The outputs show some LEDs and load resistors. The ULN series should be able to drive 500 mA. If the voltage were for example 12 volts and you wanted a 400 mA load resistor they would be 30 Ohms and 5 Watt resistors. If you just want to see if the darlingtons work, then the loads are not needed, just use 7 LEDs with series resistors choosing the series resistors based on the voltage.

The ULN is being driven by a CD4017 decade counter divider. If you run a 1 Hz. clock pulse in the 4017's outputs Q0 through Q6 will sequentially go High turning on the ULN series chip's darlingtons. The LEDs on the outputs will sequentially light one by one. The base resistors for the ULN series will be a function of the voltage you decide to use with the 4017. The entire thing can be run on 12 volts. Just a matter of what you want to run things at.

Again, this is just one basic way to go about seeing if the chip works or not. It does not actually test the chip to specifications. Methods for doing that are covered in the ULN2000 series data sheet.

Ron

hi ron, thats just super. thanks so much for your help. i will construct the circuit and test away. again, thanks. pete. s. florida

hi ron, little confusion about resistor values. i'll be using 12 volts. which are the 30 ohm? what would be the value of resistors between the 4017 and the uln chips?

The base resistors (The ULN2001 does not have a base resistor in the package) would be about 5.4KΩ. The 30 Ohm I mentioned would be at the outputs and only needed if you want to really load the ULN2001 so at 12 volts it is pushing about 400 mA of current. However, figure that 400 mA at 12 volts you will need 5 watt resistors as loads. Rather large. If you just want to see if the outputs work then just use the LED portion.

Ron

ron, does pin 9 of the uln get connected to 12 volts?

No, pin 9 is left open.

Since you just mentioned testing what I assumed to be a small lot of ULN2001s I just gave a basic circuit I felt should work. Again, this is not testing or checking all the parameters to specifications, it's just basic. They work or they don't.

Ron