Mini PCIe EC25-A vs EC21-A vs EG25-G power draw

IoT Modules LTE Standard Module
1

Hello,

I am having issue with a mini PC keeps rebooting when Quectel mini PCIe module is installed:

  1. Mini PC keeps rebooting about every 2 minutes with EC25-A.
  2. Mini PC keeps rebooting about twice a day with EG25-G.
  3. I am wondering if I can use EC21-A to stop rebooting from happening.

Questions:

  1. What is the maximum power draw comparison among EC25-A, EC21-A, EG25-G? I am hoping that I can stop my mini PC from rebooting if it turns out that EC21-A has the lowest power draw?
  2. Is there a way to adjust power usage like reducing TRX power over AT+Command?

Thank you.

2

Dear Ekawahyu,

Thank you for reaching out,

The reboots are very likely caused by the mini PC’s 3.3 V supply to the mini PCIe slot not being able to handle the peak current of the LTE module, rather than a firmware issue.

  1. Power draw (EC25-A vs EC21-A vs EG25-G)
    All three mini PCIe LTE modules can draw similar peak current (around a few amps on 3.3 V during TX bursts). EC21-A may have slightly lower average power, but it will not remove those peak bursts, so it is unlikely to stop the reboot by itself.

  2. Reducing power via AT commands
    LTE TX power is controlled by the network, and there is no standard AT command to cap maximum TX power for power-supply reasons. Power-saving features (e.g. PSM/eDRX) only reduce average power, not the instant peak that is resetting your mini PC.

I would recommend checking the mini PC’s 3.3 V rail rating for the mini PCIe slot (it should safely support ~2–3 A peak) and measuring the 3.3 V line during uplink traffic to see if it dips when the module transmits.

Best Regards,
Aghelan

3

Hi Aghelan,

Thank you for your response.

I understand that this issue is related to the mini PC not able to handle the peak current draw and I am replacing those PC as we speak. But this cannot be done with all mini PCs I have in the field, for a short period of time. So the temporary/quick/economic mitigation for now, is replacing EC25-A with EG25-G because we have them in stock. This seems to help a lot in reducing the watchdog reboot from hundreds of times daily down to twice a day.

Since we don’t have that many fund to purchase mini PCs at the moment, the plan is to try to replace the EG25-G with EC25-A, with the hope that it would lessen the watchdog reboot from twice daily to (maybe) twice a week. That sounds a lot better, and we also plan to put EC21-A anyway in our next mini PCs build, so why not spend the fund now to help fixing the existing one.

So, the question remains, what are those numbers of EC25-A vs EG25-G vs EC21-A current/power draws, so that I can make better decision from my end. Please point me to links containing those information for me. Thank you.

Regards,
Eka

4

Dear Ekawahyu,

Thank you for the detailed explanation. I have shared the power consumption figures and the relevant hardware design documents with you via email.

Kindly check your inbox for the detailed answer to your questions.

Best Regards,
Aghelan