I'm looking to make some IR LED arrays and was wondering if someone could help me with a couple questions.
I know it depends on current but but wondering (as is the case is logic level FETs) if there are a few common or "standard" current driver chips someone could recommend. I'd be making my own PCB for the LED's and driver.
The datasheet says the max permissible forward current is 1.0 A. Does that means I want my driver to supply 1.0 Amps to each LED or should it deliver something lower then the max like 800 mA, etc?
If I wanted to have the brightness of the light come on slowly from minimum to maximum brightness over 5ish seconds, what's the best way to do that? Thanks in advance!
not sure how many LED's will be in the array until I test how much light they throw
Are you using an array to get more brightness?
If so a matrix is the wrong way to go about it. This is because all the LEDs are flashing on and off, so the brightness you can achieve is much less than if you were to drive them directly.
Grumpy_Mike:
Are you using an array to get more brightness?
If so a matrix is the wrong way to go about it. This is because all the LEDs are flashing on and off, so the brightness you can achieve is much less than if you were to drive them directly.
Grumpy Mike! You helped me with some addressable RGB LED's on these forums probably 5 years ago. Glad to see you are still around!
They will be IR lights for an IR security camera all of which will be run off a battery so not setup in a matrix. I was thinking I would have a power bus so one LED Driver regulated the current for all the lights. Something like the attached image. If there's a better way to do it I'd love to learn.
Well, that is not a diagram of a LED driver, as LED drivers are constant-current drivers with all the LEDs in series and the output definitely does not have a connection to ground. Unless the input voltage is greater than the total voltage of the LEDs in series, you will require a purpose-designed switchmode "boost" converter.
Those LEDs are rated at 2.5 W (1 A at about 2.5 V) so you would not likely be using many. You could probably drive four in series at 12 V from a constant-current driver such as this (noting that you would have to use a different transistor for 800 mA):
IR LEDs have a low forward voltages, you'd always string them in series, even at 3.3V supply.
Either you need constant current drive or a current-limiting resistor per string.
