TheFishMan65
New member
Sounds like maybe a bad connection to the PWM pin. Let us know what you find.
DIY LED driver for reef lighting
- Thread starter der_wille_zur_macht
- Start date
SUMMERS
Premium Member
Doyou guys know if this driver will work? http://www.canakit.com/24v-3a-regulated-power-supply-kit-ck331v24-uk331v24.html
sanddune600
Premium Member
looks like it would work but you would have to supply it with 24 to 28 volts AC if you want to plug it into the wall you would also need other parts have seen these they are cheaper ready to go and have more amps
http://www.circuitspecialists.com/prod.itml/icOid/9590
http://www.circuitspecialists.com/prod.itml/icOid/9590
Hi all,
I want to build CAT4101 drivers for my planned LED light, but I'm deciding between 42, 56 and 72 XP-E RB leds.
a) For 42 and 72 I can divide it by 6 so I can use strings of 6 XP-E and according to datasheet from Cree there should be 3.3V voltage drop at 500ma and 3.4V at 700mA. So in the end I need power supply able to adjust between 20.3V and 21V if I add 0.5 voltage drop of Cat4101
b) But I would rather go for 56 where I need to create strings of 7 XP-E and that would mean 23.6V to 24.3V which is really close to 25V Cat4101 limit.
Can someone confirm the voltage drops of XP-E RB 500mW at 700mA?
I want to build CAT4101 drivers for my planned LED light, but I'm deciding between 42, 56 and 72 XP-E RB leds.
a) For 42 and 72 I can divide it by 6 so I can use strings of 6 XP-E and according to datasheet from Cree there should be 3.3V voltage drop at 500ma and 3.4V at 700mA. So in the end I need power supply able to adjust between 20.3V and 21V if I add 0.5 voltage drop of Cat4101
b) But I would rather go for 56 where I need to create strings of 7 XP-E and that would mean 23.6V to 24.3V which is really close to 25V Cat4101 limit.
Can someone confirm the voltage drops of XP-E RB 500mW at 700mA?
TheFishMan65
New member
I don't have any handy, what I can say is that the XR-E varied 3.2 -3.6 (IIRC) in the same string for different LEDs (much larger than I expected). So you may need to balance your string to get everything at 700ma, but it is still pretty close. IMHO you might get lucky, but I don't think you will get 7 XP-E on a CAT.
Thank you for answer.
At what current did you measure the voltage drops? Because XR-E should have at 3.3V at 350mA, 3.5 at 700mA and 3.7V at 1000mA, with maximum 3.9V.
Whereas XP-E should have 3.2V, 3.4V and 3.5 at same currents with the same maximum 3.9V. So in average 0.1V less, so it could be below 25V for 7 leds + CAT4101.
But I will probably go for 72 leds, will try to find 56 leds with lower voltage drop and sell remaining.
TheFishMan65
New member
I think I was running 500 ma. It has been a while I posted in the big thread, but I don't remember when. Why 56? How about 54?
56 because I want to use triangular grid and for 50"x24" led same size over tank 14, 28, 42, 56 or 72 leds are suitable. In triangular grid the led is eqaully distant from other 6 leds. The "circles" of led optics better cover surface.
Practical example for better understanding. Try to imagine how you inscribe circle into square and how you inscribe it into hexagos. Which one leaves less "void" space?
The graph has incorect scale x/y - Excel
TheFishMan65
New member
Well what happens when you mix blue and white? They won't be equidistance any more. It might be fine, but it may cuase you to rethink things.
sanddune600
Premium Member
I havent quite pinpointed the whole problem yet if I dont use the pwm that I was using and tie it into another it seems to work fine I think my issue is that my avr chip may have a short from it to the header for the pwm that I am using I will need to get an ohm meter on it to know for sure:mad2::hammer:
This is just grid of RB with 24 degree optics, there will be 28 CW and 28 NW in other two triangular grids with 46 degree optics. So the light should be nice mixed.
I have calculated that I should get about 210 PAR from RB, and about 110 PAR from each white at water surface 14".
I am thinking about SP-240-24 power supply for RB, because it is only SP power supply which has 20-28V adjustment - 6 or 7 RB in string - 21V or 24.5V at 700mA.
For CW and NW I consider two ELN-100-24 because you can adjust it from 20.4 to 24V - 7 CW/NW in strings - about 23V at 700mA.
perikaruppan
Member
Are these reading correct? ..
1.
Made a 8 in 1 CAT 4101 Design and it has been working brilliantly on my Edision LEDs.
used the same PCB for the newly purchased XPGs (CW/NW) and XPE (RBs) and used only 4 CATs to drive 24 LEDs, but came across this problem:
@ the power supply the voltage is 22.6V, at the input of the CAT Board it is 20.2V and the output of the CAT is 19.2V(about 3.2V per LED, got 6 on them) and 19.7V(got 3 XPGs and 3 XPEs on this)....and current is constant at 700mA...
To attain this, i slowly increased the Voltage from 20V(thats the min) from the Input Power Supply so that i reach exactly 700mA and then measured all the above parameters...
is the above reading correct? will there be so much voltage drop across the input power supply and input voltage to the CAT? its just a wire that is between the input power supply and the CAT PCB...
2.
Initially when i just just drive 1 LED the input voltage is not that high, it is only 21.6V and the current is 700mA, but when i start getting the 2nd string in place, the Amps drop to 0.63, then to 0.56A when all 4 are connected, @ this juncture the CAT is perfectly cool as cucumber... but when i crank up the input voltage to about 22.6V to get the 700mA as the current, the CAT is slightly warm... but when i use another board with different resistors to drive at 1A, the CAT gets kinnda hot ...
Is this common for the current to drop when more strings are attached?
the LED strings attached to the board are in this sequence...
1. First 6 XPG CWs - 700mA
2. Second, 5 XPGCW and 1XPGNW, 0.64mA
3. Third, 6 XPG CWs - 0.59 ma
4. Finnally, 5 XPERB's and 1 XPGCW , 0.56mA
Always the current was measured across the 1st string only...
1.
Made a 8 in 1 CAT 4101 Design and it has been working brilliantly on my Edision LEDs.
used the same PCB for the newly purchased XPGs (CW/NW) and XPE (RBs) and used only 4 CATs to drive 24 LEDs, but came across this problem:
@ the power supply the voltage is 22.6V, at the input of the CAT Board it is 20.2V and the output of the CAT is 19.2V(about 3.2V per LED, got 6 on them) and 19.7V(got 3 XPGs and 3 XPEs on this)....and current is constant at 700mA...
To attain this, i slowly increased the Voltage from 20V(thats the min) from the Input Power Supply so that i reach exactly 700mA and then measured all the above parameters...
is the above reading correct? will there be so much voltage drop across the input power supply and input voltage to the CAT? its just a wire that is between the input power supply and the CAT PCB...
2.
Initially when i just just drive 1 LED the input voltage is not that high, it is only 21.6V and the current is 700mA, but when i start getting the 2nd string in place, the Amps drop to 0.63, then to 0.56A when all 4 are connected, @ this juncture the CAT is perfectly cool as cucumber... but when i crank up the input voltage to about 22.6V to get the 700mA as the current, the CAT is slightly warm... but when i use another board with different resistors to drive at 1A, the CAT gets kinnda hot ...
Is this common for the current to drop when more strings are attached?
the LED strings attached to the board are in this sequence...
1. First 6 XPG CWs - 700mA
2. Second, 5 XPGCW and 1XPGNW, 0.64mA
3. Third, 6 XPG CWs - 0.59 ma
4. Finnally, 5 XPERB's and 1 XPGCW , 0.56mA
Always the current was measured across the 1st string only...
TheFishMan65
New member
1) What gauge wire are you using for the power supply to the CAT and what is the length? It sounds like you are using the power supply to adjust the current - you should use the resistor to set the current.
2) if you are supply 21.6 volt to drive 1 LED the CAT should get very hot. What is the current limit on the suuply? It sounds like you are overloading it. No the current should not drop. I think there is a solder error or short on the new boards. Check the powr supply leads.
What power supply are you using?
2) if you are supply 21.6 volt to drive 1 LED the CAT should get very hot. What is the current limit on the suuply? It sounds like you are overloading it. No the current should not drop. I think there is a solder error or short on the new boards. Check the powr supply leads.
What power supply are you using?
perikaruppan
Member
perikaruppan
Member
This is my PCB of Single sided 8 in 1 driver...
TheFishMan65
New member
Can you test with the other board?
perikaruppan
Member
i did 2 more boards and this is what i found out...
1. when i connect just one set of led, and then connect the next set of LED, there is variation on the Resistance value, but when all the 4 LED sets are connected the Resistance is what i had soldered!!!... so my assumption is that when the CAT circuit is open it give out resistance into the Circuit?
2. Checked the resistance on my wire from the SMPS to CAT Board, it is about 2 Ohms, the wire is 6meters long!!!.
3. At the SMPS it is 23.5V, at the CAT input it is 20.2V, and at the CAT output it is 19.5V.. so this says there is a drop of 0.7V at the CAT and 2.3V between the Board and the SMPS!!! but how can this be? but the CAT gets super Hot!!!!... i think the total 3V is dropping across the CAT... this is the voltages that is required to get to the CURRENT as per the Resistance rating.
4.But if i further increase the SMPS IN voltage, the Current increases!!!, isint the CAT supposed to make it constant based on the resistance??
1. when i connect just one set of led, and then connect the next set of LED, there is variation on the Resistance value, but when all the 4 LED sets are connected the Resistance is what i had soldered!!!... so my assumption is that when the CAT circuit is open it give out resistance into the Circuit?
2. Checked the resistance on my wire from the SMPS to CAT Board, it is about 2 Ohms, the wire is 6meters long!!!.
3. At the SMPS it is 23.5V, at the CAT input it is 20.2V, and at the CAT output it is 19.5V.. so this says there is a drop of 0.7V at the CAT and 2.3V between the Board and the SMPS!!! but how can this be? but the CAT gets super Hot!!!!... i think the total 3V is dropping across the CAT... this is the voltages that is required to get to the CURRENT as per the Resistance rating.
4.But if i further increase the SMPS IN voltage, the Current increases!!!, isint the CAT supposed to make it constant based on the resistance??
kcress
New member
Slow down a bit. Your description is making no sense to me. Nothing "gives out resistance".
Why 6m? That's just asking for trouble. Shorten it to 20cm while you figure this out.
Just focus on ONE channel first. You're trying to fly before you can fall.
These parts need a "voltage headroom" to regulate. If you don't provide it the part doesn't regulate. This means the part becomes a fancy nonlinear resistor that's very confusing. Get a little fan running across your board while you figure out what's going on. That will allow you more power dissipation on the CAT before you have a thermal problem.
The ONE LED string you should be working with has been fully tested and works correctly? You sure don't want to be troubleshooting both at the same time. Move that same string around to the different channels as you sort each channel out.
Turn up the supply to 24VDC and LEAVE IT THERE until everything is working the way you think it should.
When you can definitively say each channel works as expected then and ONLY then start adding more strings.
TheFishMan65
New member
+1 on everything kcress said
But I have one more point of confusion.
Pin 1 is the PWM it should be 0 or +5
Pin 2 is Vin and should be 5 volts
Pin 3 is ground and should read 0
Pin 4 is for the set resistor and IIRC is 1.2 volts
Pin 5 is the LED - and should be a few volts at most. It should be the supply voltage (24 volts) minus the string voltage (6 * 3.3 = 19.8) is what this pin should read (24 - 19.8 = 4.2 volts - kind of high but this is just a test case)
So where are you getting a CAT input of 20.2?
I just looked back at your board. It appears that the plane the tab is soldered to is not or loosely connected to ground. If so this may cause heat problem, but should not affect operation of the board.
But I have one more point of confusion.
This sound bad
Pin 1 is the PWM it should be 0 or +5
Pin 2 is Vin and should be 5 volts
Pin 3 is ground and should read 0
Pin 4 is for the set resistor and IIRC is 1.2 volts
Pin 5 is the LED - and should be a few volts at most. It should be the supply voltage (24 volts) minus the string voltage (6 * 3.3 = 19.8) is what this pin should read (24 - 19.8 = 4.2 volts - kind of high but this is just a test case)
So where are you getting a CAT input of 20.2?
I just looked back at your board. It appears that the plane the tab is soldered to is not or loosely connected to ground. If so this may cause heat problem, but should not affect operation of the board.
