Driver led circuit (it's correct?)

Thread Starter

ale_disola

Joined Aug 31, 2019
13
Hi. I have made 3 circuits for drive a power leds.
The circuit is power with a 50V continuos.

The circuit is this:

Driver led 2.4v.png

This is for 3W led at 2.4V.

The series of led is represented by LED1 in the circuit.
It is a 7 led in series with a current of 700mA and a voltage of 16.8V
The VCC is 50V.

Driver led 3.4v.png

This is for 3W led at 3.4V.

The series of led is represented by LED2 in the circuit.
It is a 7 led in series with a current of 700mA and a voltage of 23.8V.
The VCC is 50V DC.

Driver led 10w.png

This is for 10W led at 12V.

The series of led is represented by LED3 in the circuit.
It is a 3 led in series with a current of 1010mA and a voltage of 36V.
The VCC is 50V DC.


The circuit is correct? If not, what is the error? Can we explain me the correction?

Thanks in advance
 

TeeKay6

Joined Apr 20, 2019
382
Hi. I have made 3 circuits for drive a power leds.
The circuit is power with a 50V continuos.

The circuit is this:

View attachment 185539

This is for 3W led at 2.4V.

The series of led is represented by LED1 in the circuit.
It is a 7 led in series with a current of 700mA and a voltage of 16.8V
The VCC is 50V.

View attachment 185540

This is for 3W led at 3.4V.

The series of led is represented by LED2 in the circuit.
It is a 7 led in series with a current of 700mA and a voltage of 23.8V.
The VCC is 50V DC.

View attachment 185541

This is for 10W led at 12V.

The series of led is represented by LED3 in the circuit.
It is a 3 led in series with a current of 1010mA and a voltage of 36V.
The VCC is 50V DC.


The circuit is correct? If not, what is the error? Can we explain me the correction?

Thanks in advance
@ale_disola
For your third example, you state that the current is 1010mA. Yet the LM3414 datasheet (page 5, "System Parameters") clearly states that the max allowed current is 0.95A (950mA). I have not yet reviewed other elements of your design.
 

Sensacell

Joined Jun 19, 2012
2,447
I don't think it's a reasonable expectation to ask the forum if this is "correct" or not.

There are way too many complexities involved, it's a days work to dig deep and check all the calculations, not to mention that there are many details missing.

You need to build a physical prototype and test it.
 

TeeKay6

Joined Apr 20, 2019
382
I don't think it's a reasonable expectation to ask the forum if this is "correct" or not.

There are way too many complexities involved, it's a days work to dig deep and check all the calculations, not to mention that there are many details missing.

You need to build a physical prototype and test it.
@Sensacell
I respectfully disagree. I believe that one of the greatest advantages of AAC is that it can prevent wasted labor--such as building prototypes--when there are obvious problems that AAC commenters see. I am keeping in mind that what AAC commenters do or don't do is entirely up to them. They are under no obligation to answer every question a TS posts; they can pick & choose and can answer those questions about which they are knowledgeable. If a TS asks too much or is not clear in their questions or does not supply necessary information (especially after a request), then the TS will likely not get good and useful comments. As in this particular case, I simply noted that one sample design violated the device datasheet. I spent only a few minutes downloading and skimming the datasheet before noting the discrepancy. I would be less likely to help if the TS's question had been the more common "I found this part lying in the road, can someone tell me what product it came from?" :)
 

Sensacell

Joined Jun 19, 2012
2,447
@Sensacell
I respectfully disagree. I believe that one of the greatest advantages of AAC is that it can prevent wasted labor--such as building prototypes--when there are obvious problems that AAC commenters see. I am keeping in mind that what AAC commenters do or don't do is entirely up to them. They are under no obligation to answer every question a TS posts; they can pick & choose and can answer those questions about which they are knowledgeable. If a TS asks too much or is not clear in their questions or does not supply necessary information (especially after a request), then the TS will likely not get good and useful comments. As in this particular case, I simply noted that one sample design violated the device datasheet. I spent only a few minutes downloading and skimming the datasheet before noting the discrepancy. I would be less likely to help if the TS's question had been the more common "I found this part lying in the road, can someone tell me what product it came from?" :)
Very good point- as long as there is zero expectation that all errors will get caught.
I have just been blamed for too many things not being perfect...
 

Thread Starter

ale_disola

Joined Aug 31, 2019
13
@ TeeKay6

Vero, hai ragione, tuttavia posso cambiare la resistenza e osservare la corrente, per restare nel range. Il problema è che non è così possibile può funzionare il circuito

Google translation:
True, you're right, but I can change the resistance and watch the current, to stay in the range. The problem is that it is not possible to operate the circuit

Please restrict your posts to English as this is an English-only site. Thank you -dc
 
Last edited by a moderator:

TeeKay6

Joined Apr 20, 2019
382
@ TeeKay6

Vero, hai ragione, tuttavia posso cambiare la resistenza e osservare la corrente, per restare nel range. Il problema è che non è così possibile può funzionare il circuito
@ale_disola
You say it is not possible to operate the circuit. Have you made any measurements? What troubleshooting have you done? If the circuit does not operate, what does it do? Do LEDs illuminate? Does PWM dimming work? Describe what voltages appear on all pins for a specific mode of operation that you believe is failing. Are you using the inductor brand (Mag Layers) listed in the datasheet? Does your PCB layout follow the guidelines shown in Fig 25 of the datasheet? Initially, do this for one version of the circuit, not all 3 versions. Do you have a voltmeter? An oscilloscope?
 
Last edited:

bertus

Joined Apr 5, 2008
20,051
Hello,

@ale_disola , This is an english only forum.
Please translate ALL posts into english.
You could turn off the auto translate in your browser, as I see it is done by the browser.

Bertus
 

Thread Starter

ale_disola

Joined Aug 31, 2019
13
@ale_disola
You say it is not possible to operate the circuit. Have you made any measurements? What troubleshooting have you done? If the circuit does not operate, what does it do? Do LEDs illuminate? Does PWM dimming work? Describe what voltages appear on all pins for a specific mode of operation that you believe is failing. Are you using the inductor brand (Mag Layers) listed in the datasheet? Does your PCB layout follow the guidelines shown in Fig 25 of the datasheet? Initially, do this for one version of the circuit, not all 3 versions. Do you have a voltmeter? An oscilloscope?

I don't have tested this circuit. It's only theory. But some persons asked me that the circuit is not correct, but I don't know why. For this reason i have answered help here
 
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