ULN2003A: Maximum and Minimum Channel 1 to 7 base Input Voltage of ULN2003A

Hello,

Unfortunately the complete text of my query was not uploaded in my previous post of same subject. so I am re-posting my question.

My application requires to drive 3 inductive load of 40 mA and I have chosen the part ULN2003A to drive the load."COM" is  connected to +12V DC. And Channel 1 to 7 base input to ULN would be between 12 to 14 V DC.I following the datasheet at "http://www.ti.com/lit/ds/symlink/uln2003a.pdf ". Under section  "6.1 Absolute Maximum Ratings " , Vin max  is 30 V DC. and "6.6 Electrical Characteristics: ULN2003A and ULN2004A " says On state input voltage Vi(on) is 3V. and page 9 shows graph of Maximum and Typical Input Current vs Input Voltage for Input voltage upto 5V only.

My doubt is whether ULN2003A can be used in continuous operation  for 12 V input to channel 1 to 7 ?

Thanks & Best Regards

Ars

Hello Ars,

Thank you for clarifying. I think there are three main questions here:

1. Yes, The device is rated for up to 30Vin.
2. the 3V spec is the voltage required to get 300mA on the ouput
a. the device can be run above 3V
3. The plot is there to cover voltage in the GPIO voltage range but the device can handle the higher voltage

Overall, using a 12-14V input with the ULN2003A device should be fine.

Let me know if you have any other questions.
Best,
Nick

Hello Nick,

Thanks for your reply.

And I have noted your input ,that Vi   to ULN2003A can be 12V as per my application requirement. However it would have been better if TI mention it clearly in the data sheet about the operating range of Vin.

The above section of the data sheet shows Vin ( Max ) as 3V. But what i understood from your reply and several other post about uln2003a , that  min 3V Vi(on)is required to get Ic = 300mA. I feel the "3 V " data should come under "MIN" value instead of "MAX"....then it would be more clear to user.

I was referring to the Figure 8. Minimum Output Current vs Input Current on page 9 for min input current require for Output current of 17mA.But o/p current starts only from 100mA

As my application requirement is Vi(On) : 12 to 14 V DC , could you please tell what is the min Iin require at Vi=12V  to get output current of 17 mA  to drive inductive load?

Any equation for the above ? I think Vi(on) , Vi(OFF) & Ii(on) are the important data for designer to  make the device ON / OFF.

Any suggestion for cost-effective protection circuit on the output side? What could be possible causes that can lead to failure of  the ic while switching inductive load and how to prevent it. In two cases i found field failure of  ULN2003V12 part.In that It was driving relay coil of only 11mA.

Best Regards,

Ars

Hey Ars,

Thank you for your feedback on the Min vs Max classification.

There was a similar E2E post about currents less than 100mA: http://e2e.ti.com/support/interface/industrial_interface/f/142/p/581092/2134013?tisearch=e2e-quicksearch&keymatch=uln2003A%20beta#2134013

• At 17mA, the beta (gain) of the device is ~180. Iin = Iout/B = 17mA/180 = ~94uA

The internal diode is there for protection from transients caused by inductive loads, what other kind of protection are you looking for?

Best,

Nick