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ULN2003A: I want to use 2003A instant of ULN2803

Rajapatel
Intellectual 380 points
Part Number: ULN2003A

Hi All

Currently, I am using ULN2803 for controlling my relay (24V-80mA)  but ULN2803 is costly compared to ULN2003A, so can I use the 2003A instant of 2803, 

only 1 difference I found in between ULN2803 & ULN2003 number of channel. and I want 8 channels also ... so for 1 channel I am planning to use Mosfet ... SO it is the right design ???

My Controller operates @ 3.3V

  • 0
    TI__Mastermind 31165 points

    Zafar,

    In addition to the ULN2003A having seven channels versus the ULN2803A's eight channels, the ULN2003A also comes in SOP, DIP, and SOIC packages compared to ULN2308A which just comes in an SOIC package. The thermal parameters such as RθJA will also be slightly different between the two devices so make sure that this is acceptable for your application. 

    Judging by the schematic you attached it appears everything is setup in order with the ULN2003A.

  • 0 in reply to Timothy Logan
    Intellectual 380 points

    Yes, I also saw only channel different  in both IC

    - Actually, In my case I want to drive 24VDC Relay (HFD23-024-1ZS) with 32VDC with ULN2003A - so it it possible ????.

    I saw some solution available in google - "ADD one resistance series with Relay coil to limit current " but i am NOT getting Resistance value and watt calculation - Could you please gild me 

    https://www.futureelectronics.com/p/8546624

    and with Same 32VDV I also want to control OMRON 24V Sold state Relay ( G7L-2A-BUBJ-CB ) 

    https://www.amazon.com/dp/B005T74294/ref=cm_sw_em_r_mt_dp_U_M5zmEbV1N6F6W

  • 0 in reply to Rajapatel
    TI__Mastermind 31165 points

    Zafar,

    It all depends about what currents you are trying to drive and whether or not the ULN2003A is going to be able to support it from a thermal point-of-view. Specifically for this use case you need to take the load current of the relay you provided and run it through the 9.2.2.3 Power Dissipation and Temperature section of the datasheet to make sure that the ULN2003A does not get so hot that it gets damaged.

  • 0 in reply to Timothy Logan
    Intellectual 380 points

    Hi All

    Thanks for your response...

     Now, Still, I have some confusion could you please help me on this 

    I am trying to control 24VDC Relay with 34VDC available input (because We don't want to add again one regulator 7824 for that)  with adding one series Resistance R??? so Is it Possible ???

    Could you please help me with calculating Resistance value and watt ??

    as per datasheet Relay taking 70mA @VDC

    Sold state Relay ( G7L-2A-BUBJ-CB )  -  https://omronfs.omron.com/en_US/ecb/products/pdf/en-g7l.pdf

     

  • 0 in reply to Rajapatel
    TI__Genius 13690 points

    Hi,

    With respect to the ULN2003 device, you would have to know the current that you are trying to drive in order to know if the thermal specifications of the device will allow you to drive the relay in your design.

    With respect to the relay you would have to contact a subject matter expert of the devices you are trying to use. After doing some research I found out that with relays it gets a little tricky if you substitute power dissipation with the maximum voltage a current ratings of the device. If you try to limit your current in order to make up for the higher voltage you could end up degrading the lifetime of the relay. In order to find out what would be the proper way to drive your relays, if recommended, you would have to get in contact with their respective manufacturers to ensure proper system functionality.

    Best regards,

    Andy Robles