Hi,
Background
My basic circuit consists of 2 x 'mid-power' high-intensity warm white LEDs hooked-up in series with a current limiting resistor sitting in-between and 2 x ceramic bypass capacitors (one for each LED), all of which are driven by a 12VDC power supply, as depicted in the following drawing:
Despite the simplicity of this circuit, I'm unclear about several points and would very much appreciate the input of more experienced members of this forum.
Circuit Technical Details:
D1A & D2A : high-intensity warm white smd LEDs (GW PSLMS1.EC-GSGU-5O8Q-1, product page, datasheet)
R1A : smd resistor (100R/0.5W, 0805 package)
C1A & C2A : smd ceramic capacitor (0.1uF/50V, 0805 package)
Reverse Polarity Protection
I'd like to add reverse current protection for the LEDs in this circuit. However, due to severe space limitations, the best I can do atm is fit a single diode in reverse-series with the power lines as shown in the follow diagram:
The diode which I have on hand and would like to use is the following:
D3A : smd general purpose diode (BAS321, 0805 package, product page, datasheet)
Space limitations also mean I cannot fit any additional component into the circuit.
Questions
Given all of the above, these are the open questions I'm hoping to get advice on:
(1) Would the said diode (D3A), fitted in the above position, provide decent reverse current protection for the LEDs? and if not, what would be the most minimal adjustment I could make to achieve such protection?
(2) The 100R/0.5W resistor (R1A) was selected so as to drive the 2 LEDs at 0.65mA (if I'm not mistaken, at this current level, each LED introduces 3.3V forward voltage drop, so there should be plenty of headroom with a 12V power supply). Is this calculation correct? and, would this current level be a good choice for long-term operation these LEDs? and, finally, if not, what would be a better current level and why?
(3) The 2 LEDs are packed into a very compact space and I'm worried about their temperature rising to a level that would compromise the encasing structure (made of 3D printed PLA or similar material). Can someone help me figure out from the datasheet what would be the temperature of the LEDs when operating in the above conditions (0.65mA)? Moreover, any additional advice on thermal considerations re this circuit would be much appreciated.
(4) Of course, any input/correction/advice on the circuit as a whole would be very welcome!
Thank you very much in advance,
SnowCrash
Background
My basic circuit consists of 2 x 'mid-power' high-intensity warm white LEDs hooked-up in series with a current limiting resistor sitting in-between and 2 x ceramic bypass capacitors (one for each LED), all of which are driven by a 12VDC power supply, as depicted in the following drawing:
Despite the simplicity of this circuit, I'm unclear about several points and would very much appreciate the input of more experienced members of this forum.
Circuit Technical Details:
D1A & D2A : high-intensity warm white smd LEDs (GW PSLMS1.EC-GSGU-5O8Q-1, product page, datasheet)
R1A : smd resistor (100R/0.5W, 0805 package)
C1A & C2A : smd ceramic capacitor (0.1uF/50V, 0805 package)
Reverse Polarity Protection
I'd like to add reverse current protection for the LEDs in this circuit. However, due to severe space limitations, the best I can do atm is fit a single diode in reverse-series with the power lines as shown in the follow diagram:
The diode which I have on hand and would like to use is the following:
D3A : smd general purpose diode (BAS321, 0805 package, product page, datasheet)
Space limitations also mean I cannot fit any additional component into the circuit.
Questions
Given all of the above, these are the open questions I'm hoping to get advice on:
(1) Would the said diode (D3A), fitted in the above position, provide decent reverse current protection for the LEDs? and if not, what would be the most minimal adjustment I could make to achieve such protection?
(2) The 100R/0.5W resistor (R1A) was selected so as to drive the 2 LEDs at 0.65mA (if I'm not mistaken, at this current level, each LED introduces 3.3V forward voltage drop, so there should be plenty of headroom with a 12V power supply). Is this calculation correct? and, would this current level be a good choice for long-term operation these LEDs? and, finally, if not, what would be a better current level and why?
(3) The 2 LEDs are packed into a very compact space and I'm worried about their temperature rising to a level that would compromise the encasing structure (made of 3D printed PLA or similar material). Can someone help me figure out from the datasheet what would be the temperature of the LEDs when operating in the above conditions (0.65mA)? Moreover, any additional advice on thermal considerations re this circuit would be much appreciated.
(4) Of course, any input/correction/advice on the circuit as a whole would be very welcome!
Thank you very much in advance,
SnowCrash