1 watt to 12 watt SMPS LED Driver

Here we study a very simple 120V/220V smps LED driver circuit which can be used for driving high watt LEDs rated anywhere between 1 watt to 12 watts directly from any domestic AC mains outlet.

Main Features

The proposed smps LED driver circuit is extremely versatile and specifically suited for driving high watt LEDs, however being a non-isolated topology does not provide safety from electric shocks at the LED side of the circuit.

Apart from the above drawback, the circuit is flawless and is virtually protected from all possible mains surge related dangers.

Although a non-isolated configuration may look a bit undesirable, it relieves the constructor from winding complex primary/secondary sections on E-cores, since the transformer here is replaced with a couple of simple ferrite drum type of chokes.

The main component here responsible for the execution of all the features is the IC VIPer22A from ST microelectronics, which has been specifically designed for such small transformerless compact 1 watt LED driver applications.

Circuit Diagram

Simulation and Working

The circuit functioning of this 1 watt to 12 watt LED driver can be understood as given under:

The input mains 220V or 120V AC is half wave rectified by D1 and C1.

C1 along with the inductor L0 and C2 constitute a pie filter network for cancelling EMI disturbances.

D1 should be preferably replaced with two diodes in series for sustaining the 2kv spikes bursts generated by C1 and C2.

R10 ensures some level of surge protection and acts like a fuse during catastrophic situations.

As can be seen in the above circuit diagram, the voltage across C2 is applied to the internal mosfet drain of the IC at pin5 to pin8.

An inbuilt constant current source of the VIPer IC delivers a 1mA current to pin4 of the IC which is also the Vdd pin of the IC.

At about 14.5V at Vdd, the current sources gets switched OFF and forces the IC circuitry into an oscillatory mode or initiates pulsing of the IC.

The components Dz, C4 and D8 become the circuit regulation network, where D8 charges C4 to the peak voltage in the freewheeling period and when D5 is forward biased.

During the above actions, the source or the reference of the IC is set to about 1V below ground.

For a comprehensive info about the circuit details of the 1 watt to 12 watt LED driver, please go through the following pdf document presented by ST microelectronics.

Complete Datasheet


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jideofor5050 said…
Please sir, i have two woofers with 6 ohms impedance each, and i need a simple IC based amplifier circuit that can produce wall vibrations and a heart-thumping effect when connected to the woofer with 6 ohms impedance. Please suggest to me the circuit to use. Thanks
Swagatam said…
jideofor, you can try the following circuit:

jideofor5050 said…
Please sir, the circuit you suggested is a complex design to me, i am still a beginner, and i do not have access to a PCB where i can fix the circuit during design, so that was why i requested an IC based circuit and not MOSFET transistor based circuit. Please sir i need a simpler one like the one you discussed in one of your post here titled "Outstanding home theatre" using TDA1521, because you indicated a woofer in one of it's channel. Please sir, can the above IC produce the result i need? Or suggest a better TDA series that is very simple because the TDA1521 can even be designed without PCB due to its simplicity. Or can any of these produce the wall vibrations i need in case the TDA1521 can't=(TDA7294, TDA7295, TDA1514, TDA2050, TDA7560 or TDA2030).
jideofor5050 said…
Please sir, can NE555 ic produce a lower frequency of about 0.000011574Hz? If not what is the highest period it can reach
Swagatam said…
in simple words you are asking whether the IC555 can be used for making a long duration timer or not?

No, it wont work accurately.
jideofor5050 said…
But can i use an electrolytic capacitor(eg. 100uf, 16v) as the capacitor in the NE555 frequency determining network that comprises R1, R2 and C? Because in NE555 circuits i have seen, the "C" is usually a ceramic capacitor, my question is can i use an electrolytic capacitor there instead of ceramic or mylar?
Swagatam said…
higher value elect caps would mean greater leakage, less efficiency, inaccurate results, you can try it.
Aditya said…
I’m very newbie.
I am trying to connect two 10w LEDs and I need to build LED driver circuit.
LED are
Voltage : 9 - 12 V DC
Current : 600 - 900 mA
I searched your blog and could find one which matches exactly.
Swagatam said…
the above design is a non-isolated type, you can try the following:


adjust R6 to obtain 24V at the output and connect the two LEDs in series
jil jain said…
Dear sir,
I am beginner for led driver circuits. I want to make universal driver of 3w ,5w,7w whose power factor is around .87 to .9 and efficiency is 87%
Swagatam said…
Dear JIl,

I will try to post it soon in my site, thanks
Hi Swagatam, I have VIPer12A chip, so I have a question;
1. Can that chip give an output 12V / 300mA (for driving 3 x 1Watt LED in series)...?
2. Can that chip give an output 18V / 300mA?

Best regards.
Swagatam said…
Hi Samuel, yes definitely the IC is capable of providing those outputs.
thank said…
Yes So So Think......
Unknown said…
i want to make high power led street light, so i buy 10 led every led is 10 w .but the question is that i have a old 15v 1.05A dc power supply which i use walkies talkie charging system.can i use this with those leds .if yeas so how.and if no so what driver circuit i have to use..please suggest..
Swagatam said…
sorry a 1amp power supply will not be able to power even 2nos of 10 watt LEDs...you can illuminate one 10 watt LED with this power supply
rohit hazra said…
yeas sir you are right.so do you have any circuit in which i can drive atlist 5 led together with full glow.i have another power source of 24 v 7.2A can i use this?
sir one more question.what is the different between AC to DC aduptor and led driver..
please reply as soon as possible.
Swagatam said…
You can use the 24V 7amp power supply for driving 5 LEDs.

make 3 strings of LEDs containing 2 LEDs each, and connect them in parallel to the supply.

use the following circuit in between the led and the power supply, by properly calculating the value of R1:


if you use the above current limiter circuit with any adapter then it will become an led driver
Unknown said…
Hello and good day Swagatam,
Can you possibly post a reliable / doable circuit diagram for a driver of 30 volts LED, 30 Watts, 0.600 ampere rating? or much better if raised to 1 ampere rating? the input voltage would be 12 volts. Thanks.
Swagatam said…
Hello Good day,

You can try the first circuit from the the following article:


it's a boost converter circuit with built-in optimization controls, which you can use to set the correct supply for the LEDs.
Madhusudhan said…
Hi Mr Swagatham,

Thanks for sharing the circuit of Viper22A. Pls let me know whether all the diodes in the circuit can be replaced with smd diodes.. If yes, pls let me know the part number of the smd diodes..
Swagatam said…
Hi Madhusudan,

the indicated numbers are of the SMD version, so you can procure exactly the indicated ones to get them in the SMD form.
Hello Mr.Swagatam
Can I know whether the above circuit with the viper22AE produces a constant current of 350mA (like a LED driver) or produces a maximum current of 350mA(and supplies only the current required by the load)?
Sachintha Weerasinghe
Swagatam said…
Hello Sachintha, the "E" version of Viper IC is specified to provide 350ma max current, so it's the max capacity of the IC
Madhusudhan said…
Hi Swagatam,
Pls let me know how to get pf 0.9 with the above ic

Swagatam said…
Hi Madhusudan, the PF is already well optimized in the design through the passive L0, C1, C2 pi-filter, so I don't think we need to worry about this, especially since it's designed by the ST engineers.
Atif Nizam Butt said…
dear sir i need a (10w / 20w L.E.D Driver or buck converter ) and want to fix in motor buick Headlight
can you send me this link or diagram circuit then i make, this is my email
( buttji82@gmail.com ) plz reply me soon
Swagatam said…
dear Atif, the bike already has 12V so buck converter is not required...you will only need a current limiter circuit as explained below:

Swagatam said…
hello, sorry I don't think that's correct, it cannot handle more than 1 amp between 1V and 30V...please show me where the 2amp value is specified in the datasheet
vishal kumar said…
thanks for circuit knowledge
Hussain vengara said…
Hello Swagatam Majumdar

Thankfully your task work
I am searching low price transistor based 12v, 1 amp SMPS circuit with feed back.
Swagatam said…
you can refer to this


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