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ULN2803C: ULN2803C

M SANDEEP
Prodigy 160 points
Part Number: ULN2803C
Other Parts Discussed in Thread: ULN2003A, ULN2003AI, TPL7407L, TPL7407LA, ULQ2003A-Q1

Tool/software:

HI Team,

We have a requirement to control the 5V based relays using Relay driver...

Can we use ULN2803C Relay driver for controlling the 5V based Relays ( G5Q-14-DC5) ? Or Can you please suggest us to use proper device for Controlling the 5V relays..
Please find the below image for proper understanding...

  • 0
    Prodigy 160 points

    Hi team,

    Can you please give me a response on this asap...

  • 0 in reply to M SANDEEP
    TI__Mastermind 29230 points

    Hi M,

    Yes, this is ok. Please make sure the current through each channel will be less than what is shown in Figure 5-4 of the ULN2003A data sheet.

    Thanks,

    Patrick

  • 0 in reply to Patrick Shalton
    Prodigy 160 points

    Hi Patrick,

    Thanks for your response...
    Can you please give some clear data on the below attached part numbers...
    ULN2803C,
    ULN2003A,
    ULN2003AI,
    TPL7407L...

    Queries:
    1. Are all capable for 5V, 12V & 24V based relay driving? 
    2. What are the newest components & best for future project use & long life stock availability?
    3. Cost effective & Proper functioning while driving AC & DC loads ?
    4. Industrial temperature range- -40°C to +85°C min?

    Based on the attached part numbers & Queries please suggest us correct device to use for multiple projects to maintain standard functioning & long life stock availability....

    Thanks, best regards

    M Sandeep

  • 0 in reply to M SANDEEP
    TI__Mastermind 29230 points

    Hi M,

    1. Yes.

    2. All components are mature in the industry and will have a very long lifetime - no issues there.

    3. Most cost effective will be ULN2003A, with TPL7407LA, ULQ2003A-Q1, and ULN2003AI following close behind. Please refer to the 1ku pricing on the product folders.

    4. All devices except the ULN2003A can support that temperature range.

    ULQ2003A-Q1 sounds like the best device for your needs, but please review the pricing of each of the devices vs your requirements, and consider the lower output low voltage/higher current capability of the TPL7407 to determine if it better suits your needs.

    Thanks,

    Patrick

  • 0 in reply to Patrick Shalton
    Prodigy 160 points

    Hi Patrick,

    Can you please find the below circuit for driving the 5V based relays using the TPL7407LAPWR driver,


    1. Can you please verify this design is correct or not?
    2. And also as per the datasheet we have given 12V supply to COM pin and 5V relay is used based on our requirement 
    3. And in future if we want to use the ULN2003A/AI in place of TPL7407LA can we these supply ratings or not?

  • 0 in reply to M SANDEEP
    Prodigy 160 points

    And also If we want to use the ULN2003A/AI, 
    Can we use single 5V supply to both COM & Relay supply?
    Can you please give us clear cut details on this supply ratings for both ULN2003A & TPL7407LA if we use the 5V relays...

  • 0 in reply to M SANDEEP
    TI__Mastermind 29230 points

    Hi M,

    That design looks good.

    Yes, you can directly drop the ULN device into the TPL footprint with this circuit.

    With TPL, you can use 5V as a COM supply but the gate drive strength will be reduced and thus the Rdson will be reduced from what is specified in the data sheet.

    With ULN, there will be no change in specs, using 5V is within intended data sheet operating conditions - with ULN the COM pin is just for dissipating inductive energy.

    Thanks,

    Patrick

  • 0 in reply to Patrick Shalton
    Prodigy 160 points

    Hi

    Thanks for your response,

    We have simulated the TPL7407lA Relay driver with 4 inductive loads for verifying the load conditions,
    Here, we attached the Tina simulation file & simulated waveforms for your understanding,

    Here, we observed the current spike at Relay OFF state in ICOM wave form shown in below figure, So can you please clarify this and also how much current drawn on the COM pin when at full load..

    TPL7407LA_Relay Driver.TSC

  • +1 in reply to M SANDEEP
    TI__Mastermind 29230 points

    Hi M,

    Yes, this current spike is expected. Each inductive load draws a little less than 80mA, so when all 4 channels are turned off at once, the integrated flyback diode on the COM pin dissipates the current back to the COM source, so your COM current is a bit less than 80*4 = 320mA.

    Thanks,

    Patrick