ULN2003AI: About Maximum Collector Current

Hi M. Tachibana, 

Thanks for reaching out on E2E!

Please find the answers for your questions below:

1. Absolute maximum ratings of peak collector current is specified as 500 mA at Ta = 25 °C.
How much is the peak collector current at Ta = -25 °C?
Is it 500 mA, the same as at 25 °C?

[AH]: Ultimately, the limiting factor for the maximum rating of the current will be due to thermal limitations. As more current passes through the device, the thermal junction temperature will increase. The maximum ratings are dependent on the device not exceeding the maximum junction temps. At higher temperatures, this is a concern and we spec the device as such, as shown in Figure 4. At lower temperatures, it should be fine. Therefore, 500mA maximum current at -25C is acceptable. 

2. On page 9 of the data sheet, Figure 5 shows the characteristics of "Maximum Collector Current vs Duty Cycle" for the N package.
Do you have the same characteristic data for NS package?

[AH]: We don't have the same characteristic data for the NS package. However, we do have the RθJA value (64 C/W), and you can use this value to calculate the maximum collector current for the NS package. Depending on the number of channels, you can multiply the power dissipation * RθJA to find the junction temperature rise. As long as the junction temperature does not exceed 125C, you should be fine.

3. Do you have data of Maximum Collector Current vs Duty Cycle for NS package at -25 °C?
Or, because Tjmax doesn't rise over 150 °C, does the Maximum Collector Current stay 500 mA even if N = 7 and Duty-Cycle = 100 %?

[AH]: Your statement is correct, you can assume the maximum collector current at 500mA or you can calculate the thermal junction temperature rise as shown in Step 2.

Thanks,

Arthur Huang

To find the latest information on Power Switches, visit www.ti.com/powerswitch

Please click "This resolved my issue" button if this post answers your question.