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

Basic question about driving LEDs

Status
Not open for further replies.
A

AmatSaragih

Newbie level 1
Joined
Oct 29, 2004
Messages
1
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,281
Activity points
9
Basic LED question

Suppose I have a HC logic gate that can sink 20mA at 5V.
I'm sure I can use it to drive a 2V 20mA Led (with 100ohm Resistor).

But I wonder if I use it to drive a 3V 30mA Led (with R).
Is this 30mA Led can destroy my logic IC ?

Amat Saragih
 

Re: Basic LED question

You should look at the details of the logic data sheet. The maximum current is frequently quoted for the highest voltage that will be interpreted as a logic zero. There is probably also another absolute maximum current limit.

You can also parallel two HC gates in the same package to double the output current ratings.
 

Re: Basic LED question

Most of logic ICs are designed in such a way that you can safely shorten their outputs to GND line (but not to +V) so don't worry you wll not damage your driver and, as Flatulent said, you can parallel 2 or more HC gates if you wish to drive 1, 2 or more high current LEDs (each with R).
 

Basic LED question

Or simply drive your LED at reduced current. It won't be quite as bright.
 

Re: Basic LED question

You could also drive the LED through a BJT Transistor, to keep the LED bright and the Logic safe.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top