Can I use this device ?

[milan.rajik]

I need to design a battery operated device. I will be using the circuit of mikroE Li-Po charger to charge the 3.7V 6600 mAh Li-Po battery from USB port (5V 500 mA) or external 5V 500 mA USB adapter. The PIC32 and SIM900A circuits need 3.3V and SIM900A circuit needs 2A burst current while sending SMS (short period < 200 ms). So, Can I use this device ?

https://www.linear.com/product/LTC3113

This will be connected to battery terminals and based on whether the battery is not charging or charging or fully charged the voltage at the battery terminals may vary from 3.3V to 4.5V. So can I use the above device to provide power to PIC32 and SIM900 circuits from battery power ?

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Edit:

Can I use this ?

TPS65266


[url]https://www.ti.com/product/tps65266
[/URL]

It has Vin range of 2.7 to 6.5V and my Vin range will be 3.3V to 4.5V.
It gives 3 V constant output. 3V is enough to power PIC32 and SIM900 circuits.
It can provide 3A which is sufficient for burst 2A requirement for SIM900A.

 

[milan.rajik]

Can I use these ?

https://www.digikey.com/us/en/ph/texas-instruments/tps63020.html?WT.z_Tab_Cat=Featured Products

or LM2576 3.3 ?

 

[ashugtiwari]

U can use TI part or any part that provides the required current. But since USB can only provide 500mA which may not be sufficient to provide 2A at output, u can simple put a 3300uF 100V electrolytic capacitor to Vcc near SIM300. During SMS, the capacitor will act as battery and will not load the USB. The exact value of capacitor can be found from the duration of burst, the value of burst. This will provide time constant for capacitor discharge and capacitor value can be found.

hope that helps.

 

[milan.rajik]

Thank you ashugtiwari.

In my circuit. USB power goes to battery charging circuit and out of battery charging circuit goes to battery and also power supply circuit which converts 2.7V to 4.5V of battery to constant 3.3V. Earlier I decided to use 3.7V 2200 mAh Li-Po battery from mikroElektronika and they said that it can be used for battery powered GSM devices and it can provide 2A burst current required for GSM. But now I am using 3.7V 4000 mAh single Li-ion cell but I don't have any experience in designing battery powered circuits. So, my question was can I use above mentioned devices to get 3.3V and 3A burst current from 3.7V battery connected to them. I need to get 3 or 3.3V output. It should not exceed 3.3V. The SIM900A will only be powered when required. Only PIC32 will be running all the time.

USB will not be used to power the PIC32 and SIM900A. USB will also be used for device firmware update.

So, if anybody has experience with designing battery powered devices then please tell me what device will be best for me to put between battery terminals and power connector for PIC32 and SIM900A.


Edit:

In this document on page 21 it provides a circuit. The Vin is from 1.8 to 4.5V and output is 3.3V 3A. Can I use this between my battery terminals and PIC32 and SIM900 power terminals ? If yes, it had RUN and BURST pins. How to use them ?

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More help needed in deciding the right device. Please read this thread.

http://www.microchip.com/forums/m716305.aspx


Edit 2:

What about TPS603020 or TPS603021 ?

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What about this ? www.intersil.com/content/dam/Intersil/documents/isl9/isl91110.pdf

I think this is better than others.

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Edit 4:

What about LTC 3785 ? Is this better than all others ?

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I think this will be ok for my requirement. http://cds.linear.com/docs/en/demo-board-schematic/957asch.pdf

Please give me a confirmation.

Can't use Intersil component because it is a BGA component. It was a good device.

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I have made a circuit and want to post it here and ask if it is fine. The Manage Attachment page is not loading for me. Please fix it so that I can post attachment.

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I have one question. Pin no. 23 of LTC 3785 is Vcc ? What voltage should be provided to it ? I am using Li-Ion battey which can give 3V to 4.5 V based on battery charge, battery fully charged or battery is charging. Can I just provide 3.7V from battery to Vcc pin of LTC3785 ?

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The pin is an output pin. I don't need it. I will ground it with a 4.7uF capacitor.

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Edit 6:

Finally I will use LTC 3785, A 3.7V 4000 mAh Li-Ion battery, PIC32MX and SIM900A. SIM900A will be in OFF state most of the time and only turned ON when required by PIC32MX and also PIC32MX will be in sleep state most of the time. INTx pin is used to activate the GSM Alerter. PIC32 wakes on external interrupt and starts a 2 minute timer. If the same button (INTx) is pressed again before the 2 min timer expires then system will go to deactivated state and PIC32 will power down SIM900A and then goes to sleep. If timer expires then PIC32 will power ON SIM900A and the GAM alerter session starts. Once activated only by sending SMS from owner mobile it can be deactivated.

Can SIM900A be jammed ? If yes, is there any GSM and GPS with anti-jamming feature ?

 

[milan.rajik]

Another device is TPS63060 but LTC 3785 is better.

 

[D.A.(Tony)Stewart]

You could use the tps65266 triple output Buck or this single output one as well
https://www.ti.com/product/tps62130/description

 

[milan.rajik]

Thank you SunnySkyGuy. You showed the right device. Now I can reduce PCB size and less components are needed.