SM5100B-D Module No Logical Reason of Malfunction

Hi FOlks,

I have this >> http://www.sparkfun.com/products/9607 , i had to power it externally from a 4.8v source from four AA batteries each with a 1000mAh , so that i can support its 2 to 2.2 Amp boost to start it, was successful initially as i was able to make the calls but after making some ring's on the other phones i slept and when i woke up and tried again in the same setup with same power and refurbished cells but there is nothing coming out of this SIM, nothing working now.

what could be the possible case?

4.8V ? On that page there is a run of unhappy users blowing their regulators for having used > 4.2V. And some confusion, I guess, as to the propriety of using Arduino logic (0/5V) directly with the SM5100's 3V pins (probably not good.)

Some of the conversation: UART 5V tolerant? Driving from Arduino is 5V signalling, however this SM5100B is only operating at 3.8V… unless this module is specifically 5V tolerant on the UART pins(and I can’t see this in the data sheet…) then its a time bomb… Anyone damaged UART on this module?

Interesting question, the datasheet says 3.2v is max. “then its a time bomb" I hate it if SparkFun sell such expensive things with errors on them

That’s the 2nd time I have fatal problems with this module. The first time the GSM module was burned. I got in contact with Nate and he asked me to measure the voltage output of the SPX29302. I did and it gave 3.98V. So Nate said the regulator was damaged and overheated the GSM module. Today I soldered the second shield and I removed the GSM chip. I attached the shield to arduino duemilanove and start measuring the output voltage of SPX29302. Now it outputs 4.00V !! It can’t be a coincidence. Something is wrong.

I just measured mine and it gave me 3.94. It says up to 4.2v is okay, but is that just BS? And should I not use it at 3.94? “3.3V to 4.2V range, 3.6V typical”

Sorry about the confusion. As per page 9 of the manual the module can operate at a maximum of 4.2V. We use resistors with a 1% tolerance on the resistor divider that sets the output voltage of the SPX29302 regulator. So the output voltage should not deviate greatly from the 3.8V it is set for. This means if you are seeing a 200mV rise in output voltage, there is a chance you have damaged the regulator. Sleahey | about 2 years ago 1 If the data sheet says its fine upto 4.2V then its fine… With the components fitted, at 1%, if you read the datasheet for this regulator, you will find the expected output range is Max=~4.06V.. Min=~3.9V.. So, you could say that the 3.8V on the datasheet is wrong, but its close enough… in engineering terms..(+/-10% as a general rule is OK!) If your worried, change R1 to a 20K, which will bring the nominal down to ~3.7V Also, I would recommend replacing the link on the RX UART with a resistor, maybe a 2K2 (0402), to protect the input from 5V signalling…

Correction, Max=~4.14 Min=~3.79 I used this… http://www1.futureelectronics.com/doc/EXAR/SPX29302T5-L__TR.pdf

Mine has the same problem :‘( It worked fine but now it doesn’t. I even notice some marks on the stickers so it seems to really overhet the SM5100B. But… how come it does that. The datasheet says it should be able to handle up to 16V input. I 'only’ used 12 (5A adapter). So how can we damage the regulator?

I inserted that 4.8v on VIN and not on 5v , infact when i tried it by providing voltage on the 5v pin of the shield nothing was there, i mean it was not at all starting , so when i used the same voltage on VIN the module started to work and after that night i just left and power to the shield was cut so in any way it can't be destroyed as such in this way.

i think there is a problem with the SIM cards, but the one that was initially working and now it stopped working without any possible reason , i'm not getting things?

so when i used the same voltage on VIN the module started to work

So Vin has to be at least 7.5V!

but the one that was initially working and now it stopped working without any possible reason

I think you have your logical reason above.

When you kill things they don't always die straight away, sometimes the die on the next power up, sometimes after a few power ups.

See the thing is if anyway it would have been able to start with the basic 3.3v or 5v supply of the arduino then it would have been worked out? but this thing does not even starts with that level or power, only after applying that power it worked.