[BC660K] Minimum VBAT when operating with network

IoT Modules LPWA Module
1

I am doing some tests with BC660K regarding the minimum VBAT voltage.

According to the datasheet BC66&BC660K-GL Compatible Design Version 1.0 Date: 2023-02-18, it states on Table 6 at page 16 that for BC660K-GL the VBAT minimum is 2.2V, typical is 3.3V, maximum is 4.3V.

By checking with a variable power supply, I can verify that it is true, but only when I have NO SIM CARD inserted. That is, the module keeps on when VBAT >= 2.2V.

But, when the SIM Card is inserted (and attached to network, and connected to MQTT), and I am fading down the VBAT from 3.3V to minimum possible value, I noticed that the module dies after around 2.8V, and if the module is sending data, then the module dies at around 2.9V.

I wonder if this is expected, or what should be the numbers.

Obs.: The current never goes more than 100mA in my observations (at peak of TX).

2

What is your purpose in doing this?

3

To ensure a safe threshold where I can detect (via FW) and take some action before the module dies.

4

VBAT minimum value is 2.2V, typical value is 3.3V, maximum value is 4.3V, is VBAT pin voltage domain, under what circumstances the module can not work, to test the current at that time, excessive current fluctuation will cause the module to die.

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5

I was able to run BC660K-GL with SIM card using 2.2V, around this value it starts to die off. Maybe the capacitors are not sufficient and the voltage drops below 2.2V during transmission burst?

6

What is the current value？ it may be that the current value is too small