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Need suggestion or recommendation for Constant Current Source Circuit or IC

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AzharElectronics

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For one of my Aerospace Application I need suggestion or recommendation for Constant Current Source Circuit to Drive LED, recommendation may include what type of circuit can be used either Analog Discrete component or any specific off the shelf IC. My Current requirement is 0.55mA to 25mA and I have power supply of +5V DC.
 

If it's for an Aerospace Application, do you need Mil or Space qualified parts?

What is the control signal that varies the current from 0.55ma to 25mA?
 

I have four Set of requirement to drive four different LEDs i:e one to four LEDs needs fix current values from 0.65mA, 2.55mA, 19mA and 24mA. Should be Mil qualified Part.
Supply to LED is +5V and Discrete Enable Signal to Turn on the LEDs is +28V (Which I will be processing to +5V, internal to my PC board).
 

Hi,

LED driver ICs with multiple outputs which can be configured for individual current levels do what you need.

You could get a transistor array and make a (cascode or Full Wilson) current source and mirror the different current's needed from the source but I don't think it's good for temperature performance. The REF200 is a "Dual Current Source and Current Sink" that is very versatile and alongside the max 400uA it puts out, "External circuitry can obtain virtually any current." It's an example, the LM334 is another.
I'd personally look at LED driver ICs.
 

Additional questions for you to consider, in part selection:

- is the current "DC", changeable or modulated (signal)?
- does the larger system prefer analog control, or serial digital?
- how accurate does it have to be? I see up to 3 significant
digits on some values, implying 0.1% range accuracy but
think this is not likely really the case.

Switched resistors could be a simple and foolproof approach
if the circuit is operated linear - you're going to waste current
anyhow, same difference. And if "aerospace" means "space",
the relative ease of finding radiation tolerant COTS switch
devices is sure higher than finding an analog part that
doesn't drift unacceptably.
 

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