# LED series parallel combination problem

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#### shiva007nand

Joined Sep 25, 2015
38
Hello, I am using non isolated constant current source driver,
I am using 0.2 watt 2835 package LED which drops 2.5 volts.

I have some data which I had checked myself practically.
Input Voltage Type Output Voltage Type Output Voltage without load Output Current Load Power
230 AC 73.4 DC 110.7 99mA 48 LED 7.3 W

230 AC 77 DC 95.8 131mA 48 LED 10.087

LEDs are connected in the way of 2 parallel and one serial, so total 48 LED. Like 24 LED in series with 2 LED parallel for each combination.

Input Voltage Type Output Voltage Type Output Voltage without load Output Current Load Power
230 AC 74.2 DC 100 249.5mA 96 LED 18.51 W
LEDs are connected in the way of 4 parallel and one serial, so total 96 LED. Like 24 LED in series with 4 LED parallel for each combination.

I do not know How output voltage varies or what is combination for it.
How can I apply KCL for above combination ??

#### TheButtonThief

Joined Feb 26, 2011
237
LED output voltage?
Input voltage type?
Output voltage type?

Sir, thou speaketh in riddles.

#### AnalogKid

Joined Aug 1, 2013
10,799
Do you really think you can accurately describe series/parallel arrangements of 48 and 96 LEDs in one sentence each? In a foreign language? Think. This is an electrical engineering forum, and a schematic diagram is the universal language. No schematic, no answer.

And, what does KCL mean?

ak

#### shiva007nand

Joined Sep 25, 2015
38
Okay,
KCL is Kirchoffs current law.
I am trying to upload schematic diagram but I do not know what is problem
It is showing me a block message on top of it.

#### shiva007nand

Joined Sep 25, 2015
38
LED output voltage?
Input voltage type?
Output voltage type?

Sir, thou speaketh in riddles.
Input voltage 230 volt Alternating Current
Output voltage type is Direct current
output current value
and load means combination of LED series and parallel - how much LED are connected with it
Power - It means how much energy it consumes in watt

#### TheButtonThief

Joined Feb 26, 2011
237
Input voltage 230 volt Alternating Current
Fine

Output voltage type is Direct current
How do LEDs have an output voltage?

output current value
Again, how does an LED output a current?

and load means combination of LED series and parallel - how much LED are connected with it
Yep, I Know what a load is. However, "output current load power" doesn't make sense

Power - It means how much energy it consumes in watt

#### dl324

Joined Mar 30, 2015
16,206
I am trying to upload schematic diagram but I do not know what is problem [sic] It is showing me a block message on top of it.
Are you trying to post a photo format?

#### dl324

Joined Mar 30, 2015
16,206
Input Voltage Type Output Voltage Type Output Voltage without load Output Current Load Power
230 AC 74.2 DC 100 249.5mA 96 LED 18.51 W
Some of your formatting was lost. What are the three lines of information for?

#### shiva007nand

Joined Sep 25, 2015
38
Are you trying to post a photo format?
Yes I was trying to post images
Anyways here I have attached schematic diagram,I you still find it difficult to understand
I will make required changes in it.

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#### dl324

Joined Mar 30, 2015
16,206
You shouldn't connect LEDs in parallel without ballast resistors; even very small differences in Vf can result in objectionable differences in brightness.

What is the operating current for the LEDs, how many will you have in series, and what are the power supply output specs?

#### shiva007nand

Joined Sep 25, 2015
38
Fine

How do LEDs have an output voltage?

Again, how does an LED output a current?

Yep, I Know what a load is. However, "output current load power" doesn't make sense

#### Attachments

• 49.9 KB Views: 11

#### shiva007nand

Joined Sep 25, 2015
38
You shouldn't connect LEDs in parallel without ballast resistors; even very small differences in Vf can result in objectionable differences in brightness.

What is the operating current for the LEDs, how many will you have in series, and what are the power supply output specs?
Operating current is constant for LED 115 mA to 249 mA as per need, different watt.
I have 24 led in series, as per above attached schematic diagram.
power supply output is direct current it varies according to your load i.e. series parallel combination of LED

#### dl324

Joined Mar 30, 2015
16,206
Operating current is constant for LED 115 mA to 249 mA as per need, different watt.
I thought it was established in your other thread that max current for your LEDs was 90mA continuous and 120mA peak for < 100uS at a 20 or 25% duty cycle.

#### shiva007nand

Joined Sep 25, 2015
38
I thought it was established in your other thread that max current for your LEDs was 90mA continuous and 120mA peak for < 100uS at a 20 or 25% duty cycle.
90 mA is maximum forward current for LED package of 2835.
so if we use more than 90 mA, we have to get current divided using parallel combinations.
continuous current range of my drivers is from 60 mA to 249 mA

#### TheButtonThief

Joined Feb 26, 2011
237
My brain is fried.

I'm still unsure what the OP is asking us...

#### shiva007nand

Joined Sep 25, 2015
38
My brain is fried.

I'm still unsure what the OP is asking us...
see I am asking about I know the current which is I am giving to the circuit, I know the
schematic diagram of it.
But I am lagging to find out that how much voltage it needs ??
If I get simple formula for one schematic diagram which is attached above, I can make other every possible combination to find output voltage

I am trying to use kirchoffs current law for above schematic diagram.

#### TheButtonThief

Joined Feb 26, 2011
237
But I am lagging to find out that how much voltage it needs ??
Are you asking us to tell you what voltage you need to supply to the circuit?

If I get simple formula for one schematic diagram which is attached above, I can make other every possible combination to find output voltage
By "output voltage" do you mean "supply voltage"?

I am trying to use kirchoffs current law for above schematic diagram.
Why? What are you hoping to calculate?

#### ScottWang

Joined Aug 23, 2012
7,389
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