[SOLVED] Best power source for PCB

[ahmed hossam]

Hello,

I am building a battery powered application using one cell LIPO battery which is 2500mAh, I am using a system on chip for GSM and BLE, GPS module, MCU IC, some sensors. I want to know what's the best design tips to power this application from battery please?
is it good to power every module/Chip using a separate buck-boost converter ? or i can use just one buck-boost for the whole design?
is load switches important for my design?

Any help is much appreciated, Thank you!

 

[KlausST]

Hi,

How can we decide this?
Without circuit diagram, without power requirements (of each individual device), without any part name...

Without any information what you mean with "best"...
Is it low cost? Or high power efficency, or lowest noise, or smallest size?

Klaus

 

[ahmed hossam]

Hello Klaus,

Thank you for your response. I want to use the UBLOX m8Q GPS module, texas instruments TM4C123GH6PMI MCU, MT2502 GSM+BLE. i didn't choose the LCD yet, but mainly i want it to be about 3 inches with 640x480 resolution. i want to use a LIPO battery pack which is rated at 3.7v 2500mAh for this application.
I didn't work on the schematic yet, now it's just the component selection. I want to use a separate buck-boost converter for every IC like using the TPS63010 to power the MT2502 from the battery, and use something like the TPS63030DSKR to power the LCD and another TPS63030DSKR to power the GPS and some low power sensors like ultrasonic.

Also cost is not a consideration for me, i want high performance and a medium size. about the noise, i know that all buck-boost or switching DC-DC converters will generate high frequency noise and needs filtering, so i appreciate if you have any tips on how to filter this noise on PCB efficiently.

I saw a laptop board schematic which is using a separate Buck-Boost and LDO to provide power for every stage on the board. i don't know exactly if this is done to raise the efficiency of every buck-boost converter or if it produce higher performance or what's the exact purpose of such topology. here is the link to the referred schematic, page 4 include the details which i'm talking about.
https://www.dropbox.com/s/zjmub0k6c71e8m1/Quanta_R08_V08_MB_20120213-1_Dell V3460-N5420.pdf?dl=0

so what i mean by "best" is :
assume that all the above mentioned components work on 3.3v (which is not true), then what's better for me, using one buck-boost converter to power all my components, or using a separate buck-boost for powering every component ?

and in the real case where some components works with 3.3 and others may work with lower voltage, i have to use separate buck-boost for every required voltage of course.

Looking forward to hearing from you soon.

Thank you,
Ahmed Hossam

 

[KlausST]

Hi,

I saw a laptop board schematic

As far as I can see there are independent power supplies for every generated supply_voltage.
There´s no way around this.

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In your case: You also will need individual power supplies for individual supply voltages.

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If multiple devices have the same power supply voltage, then there is no need for separate power supplies.

****
SMPS noise:
I have a PCB with a 16 bit ADC, 10kSmpl/s, input amplifiers with gain of 25, 3kHz bandwidth, 3VRef. Supplied with the same 3V3 as the microcontroller, all the periferals and PLD..
The ADC values jump only on one LSB. (1 LSB is 2uV).
BUT the 3V3 supply of the analog circuitry has additional RC filters to decouple it from the 3V3 microcontroller supply (SMPS output).

The key is: good ground(plane) concept. Knowledge of high frequency current flow on your PCB, splits in the GND plane, device placement ..... --> PCB Layout.

Klaus