GSM Man
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vamsi.kodati said:Hi,
I am working on an avr-gsm project and am using sim300. I would like to know if sim300 can be operated by a 3.7 Li-ion battery with a boost converter to 4.2V??? Can anyone heelp me with this issue???
galama said:Hi all !
Anyone help me , I'm working with sim300d module for our GPS tracking system but it seems that I can't make the sim300d module work .
When I try connect my circuit ( I design by my self ) with PC , sim300d module didn't send anything to Hyper Terminal . I attach schematic of our project here .
Please show me what I wrong in my circuit . Thanks in advanced.
I've never seen that version of the manual, but I sell about 200 boards a month with the SIM300/340 and I can tell you from experince that anything less than 220uF is not reliable for all modules. Some modules work with smaller caps on them, some are intermittent, and some don't work at all.pisoiu said:I use 100nF and works well. Simcom documentation for SIM300, version 4.01, page 45 indicates a schematic with 100nF from SIM_VDD to GND.
/pisoiu
The power supply of SIM300 is from a single voltage source of VBAT= 3.4V...4.5V. In some case, the ripple in a transmit burst may cause voltage drops when current consumption rises to typical peaks of 2A, So the power supply must be able to provide sufficient current up to 2A.
For the VBAT input, a local bypass capacitor is recommended. A capacitor (about 100μF, low ESR) is recommended. Multi-layer ceramic chip (MLCC) capacitors can provide the best combination of low ESR and small size but may not be cost effective. A lower cost choice may be a 100 μF tantalum capacitor (low ESR) with a small (1 μF to 10μF) ceramic in parallel, which is illustrated as following figure. And the capacitors should put as closer as possible to the SIM300 VBAT pins.
Please pay special attention to the supply power when you are designing your applications. Please make sure that the input voltage will never drops below 3.4V even in a transmit burst during which the current consumption may rise up to 2A. If the power voltage drops below 3.4V, the module may be switched off. Using the board-to-board connector will be the best way to reduce the voltage drops. You should also take the resistance of the power supply lines on the host board or of battery pack into account.
vamsi.kodati said:Well i use RPS for my board right now and during transmit burst i saw current shooting upto 1.9A and my voltage was also constant and it didnt drop. Moreover sim300 didnt stop working or shut down at 3.6V but its not responding to AT commands properly even when sim300 is on at 3.6V...
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