Shop OBEX P1 Docs P2 Docs Learn Events
Connecting DS2003 High Current Driver — Parallax Forums

Connecting DS2003 High Current Driver

Roger PiersonRoger Pierson Posts: 62
edited 2006-11-01 21:03 in BASIC Stamp
I'll admit I don't have much experiance dealing directly with transisters, but I thought I could handle this apparently simple device. Alas, with a fair amount of shame, I admit defeat.

I thought I could put a 5 volt signal on the input and variable voltage / current on the output based on load resistance. This does not seem to be the case. I'm sure this is really simple and I am just being a dolt.

For testing, I've connected input A to VDD on the development board, and I've connected the ground and common lines to VSS. When I switch the power on I get .6 volts on the output. I need 24 volts and about 450 mA to drive my DC Solinoid switch. Can I not get there with a 5v input?

Here is the connection diagram from the data sheet:

00964701.jpg

Here is a link to the data sheet:

www.national.com/pf/DS/DS2003.html#Datasheet

Thanks,

Roger

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Roger Pierson
Senior Electronics Technicain
DTI Assoicates

Comments

  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-10-31 16:55
    Roger,
    ·
    ·· On this kind of IC the Common actually goes to Vdd or the positive voltage of what you’re driving.· Typically this would not be Vdd but could be.· The Common line essentially only connects the internal clamping diodes so the outputs are protected from back EMF from inductive loads.· What are you driving with this IC?· If not a Solenoid, Relay or Motor you may not even need to connect that pin.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2006-10-31 16:58
    Roger,
    ·
    ·· After looking at the datasheet this IC is essentially the same as the ULN2003, which we have example schematics for at the following link.· I hope this helps.· Take care.

    http://www.parallax.com/dl/docs/prod/motors/Stepper_Motor_27964.pdf

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Chris Savage
    Parallax Tech Support
  • Roger PiersonRoger Pierson Posts: 62
    edited 2006-10-31 18:12
    Chris, thanks for the reply. You and the handful of regulars on here that consistently help out are true American heros [noparse]:)[/noparse]

    I am trying to drive a 24vdc solenoid, eventually I need the BS2 to control this, but for now I'd be happy just getting the proper voltage / signal out of the DS2003. So far I've had no luck, even following the schematic at the link you posted.

    Here is what I have right now:

    GND terminal of the Solenoid is tied to the 24vdc return.
    POS terminal of the Solenoid is tied to output A of the DS2003.
    GND pin of the DS2003 is tied to VSS (seems like a safe bet).
    Input A pin of DS2003 is tied to VDD (will eventually be tied to a BS2 pin for control)
    Common pin of DS2003 is tied to VDD.

    In this configuration, I get .6vdc output when the development board is turned on (VDD is powered).

    I also tried connecting the positive terminal of the external 24vdc power supply to the DS2003 common pin instead of VDD. In that configuration I get -3vdc on the ouput when VDD is switched on.

    I guess I'm not understanding how this thing is supposed to work. Is the common pin supposed to be the supply voltage for the output pin? Or, does the input pin serve as both an enable and supply voltage?


    Thanks for the help,

    Roger

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Roger Pierson
    Senior Electronics Technicain
    DTI Assoicates
  • Randy EvansRandy Evans Posts: 24
    edited 2006-10-31 20:07
    · Roger:

    The 2003 is just a·7 darlington transistor array·with some resistors and diodes thrown in. Attached (hopefully) is a schematic
    bmp
    bmp
    ULN2003.bmp
    866K
  • Mike GreenMike Green Posts: 23,101
    edited 2006-10-31 20:28
    The Common pin is the common pin for the protection diodes and should (must!) be connected to the positive supply for the load (+24V in your case). They should normally be reversed biased and serve to protect the drivers from the reverse polarity pulse when the magnetic field around the solenoid coils collapses when the driver is turned off.
  • Roger PiersonRoger Pierson Posts: 62
    edited 2006-10-31 21:51
    I really appreciate the help guys.

    I've tried every approach suggested here and then some, still the biggest (or smallest) output I could get was -3.6vdc.

    I'm tired and frustrated for today. Maybe tomorrow I'll full around with the L293D that is built into the Professional Development Board, I think it will achieve the same function as I had hoped the DS2003 would.

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Roger Pierson
    Senior Electronics Technicain
    DTI Assoicates
  • stamptrolstamptrol Posts: 1,731
    edited 2006-10-31 23:58
    Roger,
    With reference to your earlier post, only two connections are wrong: (also assuming your solenoid draws less than 250 mA or so)

    This circuit works as a current sink. A high on the input, takes the corresponding ouput to GND.

    GND terminal of the Solenoid is tied to the 24vdc return. ****Should be Pos term of solenoid is tied to +24v****
    POS terminal of the Solenoid is tied to output A of the DS2003. ***** Should be Gnd term of relay is tied to Output A *****
    GND pin of the DS2003 is tied to VSS (seems like a safe bet).
    Input A pin of DS2003 is tied to VDD (will eventually be tied to a BS2 pin for control) *****when input A is at +5 volts, relay will operate****
    Common pin of DS2003 is tied to VDD. ****that is, +24v****

    This will work as per the post by Randy.

    Cheers,

    Tom

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Tom Sisk

    http://www.siskconsult.com
    ·
  • Roger PiersonRoger Pierson Posts: 62
    edited 2006-11-01 21:03
    Once again, thanks to everybody for the help. You guys are great!

    The problem turned out to be two-fold. When I first started messing with this circuit, I was switching the wrong lead, once I understood that this device was supposed to sink not source I re-wired but still wasn't getting usable output.

    It turns out my +24vdc power supply is too much. Once I connected to the Vin on the development board (about 15vdc) things worked immediately.

    Thanks everyone for your patience and expertise. I need a beer now. [noparse]:)[/noparse]

    -Roger

    ▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
    Roger Pierson
    Senior Electronics Technicain
    DTI Assoicates
Sign In or Register to comment.