Continue to Site

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.

Register Log in

Optimum decoupling capacitors for Digital ICs

Status
Not open for further replies.
UroBoros

UroBoros

Advanced Member level 2
Joined
May 5, 2004
Messages
642
Helped
19
Reputation
38
Reaction score
8
Trophy points
1,298
Location
Cochin - India
Activity points
6,463
In My PIC Micro Board I am using input output expanders like CD4094 with ULN2803 (O/P) and 74HC165 for input expanding.
The outputs may drive LEDs or relays
I would like to know what is the rule of thumb(if any) for decoupling capacitors. for each IC I have provided one 100nf close to Supply pins.
Should I need any electrolytic caps in parallel with this for these ICs, especially for the ULN2803 which may have to sink substantial current. during switching.
Generally what is the policy in matters like these?
 

ULN2803 has no supply pin, so where would connect a decoupling capacitor? It's a darlington transistor array rather than a logic iC.

100 nF is basically O.K. for standard logic. Larger bypass capacitors can be useful but don't need to be placed directly at the ICs, presume they are present somewhere in your circuit anyway.
 
I have filter capacitors (1000uF) on the board. So that part may be ok.
And regarding the ULN2803, I got the point, the common pin is not a current flowing path. So no point in decoupling that Pin. Correct?
Thanks for the info.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top