Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Power Regulator capacitors

Status
Not open for further replies.

bunrockter

Newbie level 6
Joined
Oct 10, 2010
Messages
12
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,283
Activity points
1,364
When looking at reference designs for power regulators (LDO/Linear, switching, etc.) why are the input and ceramic output capacitors generally a 1206 case size? I can find a capacitor that is 0402 or 0603 with the same/similar voltage and ESR, the only difference I see is the temperature (X5R Vs. X7R).

The chip that I am looking at specifically calls out an 0805 P/N as an example in the datasheet, and the reference board that uses it populated a 1206 P/N. I found a 0603 that has the same ESR and the rated voltage is a little less but is still 4x more than the output voltage.


Thanks.
 

SunnySkyguy

Advanced Member level 5
Joined
Sep 26, 2007
Messages
6,744
Helped
1,675
Reputation
3,348
Reaction score
1,644
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
50,737
As I recall;
the smaller the part, the higher the SRF for ceramic caps, but also geometry of MLM is a big factor, layers and stack orientation.
Choose types for SMPS rated for such with ESR or ripple current and never Gen Purpose.

Size may affect heat loss rating but also ESL

>=1206 for >=1kV and more ripple current, less leakage
<=805 for VHF,
<=603 for UHF , microwave

bigger parts tend to have higher voltage ratings and lower ESR with cheaper materials.
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top