Power Supply For PCB - Page 1
Forum section: electronics / projects

author: Md_Aslam
author_rank: Contributor
timestamp: September 09, 2022, 06:39:06 am
content: I want to design a circuit on the PCB which requires the power supply of different values like 1.8v, 3.3v, 5v and 12v.I want a single power supply with multiple voltage options as I said. The size should be as small as possible and should be suitable for the PCB, So is there any solution for that?

author: mariush
author_rank: Super Contributor
timestamp: September 09, 2022, 07:27:57 am
content: It's too little information.How much current on each of those voltages? How much space you have on pcb? What's your budget? There's 40$ chips with on package inductors and surface mount components that can produce 4+ voltages or you could have 4 independent switching power supplies that cost 3-5$ each but take up way more space.Depending on the current amounts or what the voltages are used for, it may make more sense to have some hybrid switching / linear power supply - for example produce 12v and 5v using switching regulators, and then produce 1.8v and 3.3v using linear regulators from 5v.If you have FPGAs, then those 1.8v and 3.3v may be higher current than 5v and 12v... so you really need to give more details.There's are also switching regulators with built in low power regulators, for example you could configure main output to 5v and the built in LDO can do 3.3v at 100-500mA (depending on regulator)

author: Md_Aslam
author_rank: Contributor
timestamp: September 09, 2022, 10:01:47 am
content: Quote from: mariush on September 09, 2022, 07:27:57 amI have one Microcontroller LQFP32 package, some ICs based on SPI, GNSS Rx, some serial converters and bunch of buffer gates.Current amounts are in uA to mA and overall size of the PCB is 7cmx7cm.PS: 12v is not required only 1.8v,3.3v and 5v are required.

author: mariush
author_rank: Super Contributor
timestamp: September 09, 2022, 01:43:55 pm
content: Most would simply chose to put a USB connector and power it with a usb charger / phone charger that gives you 5v +/- 5% , which should be good enough.If you absolutely need exactly 5v, then you could put a barrel jack connector and power your board with a 7.5v / 9v / 12v wallwart adapter and you'd need to have an extra 5v dc-dc converter on the pcb.for mA worth of current, just go with linear regulators, you can get fixed output voltage regulators that are very tiny and only need a couple ceramic capacitors on input and output.For example :AP2127 fixed 1.8v output up to 300mA, max 6v input voltage so ideal for 5v input :https://www.digikey.com/en/products/detail/diodes-incorporated/AP2127K-1-8TRG1/4470784NCP161 fixed 1.8v output up to 450mA, but max 5.5v input voltage :https://www.digikey.com/en/products/detail/onsemi/NCP161ASN180T1G/10064748TLV70718 fixed 1.8v output up to 200mA, max 5.5v input but small footprint (1mm x 1mm) :https://www.digikey.com/en/products/detail/texas-instruments/TLV70718PDQNR/2696407All the above only need a couple 1uF ceramic capacitors.Same deal for 3.3vAP2120 fixed 3.3v out, max 6v in :https://www.digikey.com/en/products/detail/diodes-incorporated/AP2120N-3-3TRG1/4470762AP7370 max 18v input (good if you want to get 3.3v from 7.5-12v and then use a fixed 1.8v regulator to get 1.8v from the 3.3v output) :https://www.digikey.com/en/products/detail/diodes-incorporated/AP7370-33Y-13/10235828others:https://www.digikey.com/short/0j0d54mmYou can get linear regulators that output both voltages, here's a couple examplesAP7312 : 6v in , 1.8v up to 150mA , 3.3v up to 150mA :https://www.digikey.com/en/products/detail/diodes-incorporated/AP7312-1833W6-7/2901062MIC5370 : 5.5v in, 1.8v and 3.3v up to 150mA :https://www.digikey.com/en/products/detail/microchip-technology/MIC5370-SGYMT-TR/2020357So you could have a 6v...18v to 5v dc-dc converter to power your board with a barrel jack or something and then use one of the above regulators to get 3.3v and 1.8v from the 5v output of your dc-dc converter.