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ULN2003A: Application questions with VS=5V for Bata value

Brian Wang0928
Genius 14150 points
Part Number: ULN2003A

Customer is using the ULN2003A for the isolation design for motor driver. From datasheet Fig3(Collector Current vs. Input Current), it only addresses the VS=8V and VS=10V. However, in my custmer application, the VS is 5V. we would like to know if you can offer the curve with VS=5V and does device work well with below conditions?


 

Conditions:

VS=5V for ULN2003

Input pin Current  of ULN2003 is about 0.1mA (There is an input resistor =24Kohm connected to the input pin against voltage spike)

Output pin is connected to the Diode of opto coupler, and the output current of ULN2003 is about 2mA for MCU isolation application. Thanks.  

  • 0
    TI__Genius 15780 points

    Hi Brian,

    The ULN2003A is capable of driving 5V loads with no issues. If you are looking for a specific input/output current ratio, please refer to the graph below.

    Based on your requirements, a beta value of 20 is needed at a load of 2mA. It looks like the device is not able to support such a low ratio at that low of an output current.

    Thanks,

    Alek Kaknevicius

  • 0 in reply to Aleksandras_Kaknevicius
    TI__Genius 14150 points

    Hi Alek,

    Thanks. There are few questions for DELTA engineers.

    1. With test conditions of Iin=100uA and Iout=2mA on ULN2003, does it work well with Ta = 25 degree to 50 degree?

    2. As plot diagram you sent, it looks that the hFE is variable with output current, is it correct? From datasheet Fig3, it looks the hFE has no big change. What's the different?

    Very thanks.

    Brian Wang 

  • 0 in reply to Brian Wang0928
    TI__Genius 15780 points

    Hi Brian,

    1. According to the hFE vs. IOUT graph, the hFE value at 25°C and greater is above 20. This means that the conditions of Iin = 100uA and IOUT = 2mA would work here.

    2. That is correct, hFE is variable with output current. Figure 3 is a bit confusing, since it is showing the performance of the device with a 10Ω load. For VS=10V, this would be a 1A load, and for 8V, this would be an 800mA load, so the hFE for each of these would vary. If the VS=8V curve had an 8Ω load (1A), then it would look the same as the VS=10V curve. Both figures are dependent on output current, but they show it differently. I would refer to the hFE graph since it is clearer.

    Please let me know if you need more clarification.

    Thanks,

    Alek Kaknevicius