BG95-M3 - Voltage drop with 2G network

Technical Subjects
1

Hello,

We use the BG95-M3 module to send data. The system is recorder has a 3.6V battery that can deliver peak of 2A.

After the input of the battery, we use a TPS61023DRLT module (BOOST Convertor) to raise the voltage to 3.7V.

We have an identical schematic on the detailed one in the datasheet.

As shown in the picture below, the capacitor are close to the BG95 module

image
image826×550 9.22 KB

When using the 2G network, we have a problem of voltage drop.
The voltage drops below the recommended 3.3V and it turns off.

We have tried adding extra capacity on the power supply, but we get the same result

**Why do we have such steep declines? **
How to fix it?

Best regards,

2

The peak current in 2G mode is as high as 2A. Even the battery itself cannot sustain its voltage at this discharge current.

We have added capacitance as high as 220uF to 470uF.

3

Hello,

I added a 680uF capacitor and still have voltage drops.

4

We added both capacitors before and after the boost converter.

The capacitance also depends on the number of Tx slots of your 2G connection.
In our case only one Tx slot is used or the burst width is limited to 577us.

You need to monitor the current on some equipment and make adjustments.

By the way please note that some Lithium batteries e.g. Li/SOCl₂ cannot support high drain current and it will not work no matter how much capacitance you have added.

In our case we use Lithium Sulphide as well as Lithium Polymer batteries without issues.

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