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12V SMPS Driver Circuit for LED Strip

12V SMPS driver change big AC power from 110V or 220V into small 12V DC.

Circuit is good for LED strip light.

In this DIY we make cheap and strong LED driver.

It can power full 12V LED strip with 100 or 200 LEDs.

Important points to follow:

Circuit uses 230V AC direct which is very dangerous.

Only safety is at short-circuit protection at output.

If we want to make SMPS then first learn well and follow trusted diagram and take safety care.

Only try if having good skill and knowledge in electronics.

Circuit Working:

Parts List:

Component TypeDescriptionQuantity
Resistors (All resistors are 1/4 watt unless specified)
4.7M2
22Ω1
220Ω1
1k1
43k1
12k1
Capacitors
Ceramic 470pF 200V1
Ceramic 100nF 50V1
Electrolytic 22μF 400V1
Electrolytic 10μF 50V1
Electrolytic 470μF 25V1
Semiconductors
IC TNY285DG1
IC PC8171
IC TL4311
SMBJ160A TVS diode1
UF4007 diode1
SB380 schottky diode1
Bridge Rectifier MB10S1
Transformer Ferrite core (see specific requirements)1

First learn how LED strip driver work and its parts.

Circuit is high voltage so we need to keep in strong box for safety.

For learning we have made a simple test on veroboard with no solder.

C1 feedback capacitor control output voltage.

TNY285DG main IC drives transformer and switch 125 kHz.

C2 supply capacitor keeps IC smooth.

R1, R2 are under voltage lockout and they stop IC if input low.

D1, D2 protect IC from spikes.

D3 Schottky SB380 rectify and control current and snubber R3 and C3 protect D3.

C5 output capacitor keeps LED power steady.

PC817 optocoupler isolate high voltage from low to do feedback.

Transformer Construction:

Steps to Make Transformer:

Start winding 85 turns from pin 2 and use 34 AWG single wire with double coated.

Wind clockwise left to right.

Second layer wind right to left.

Next layer clockwise again.

Last layer spread wire evenly and finish at pin 1.

Use 3 layers polyester tape 1 mil and 8.45 mm wide.

Start pin 7 and wind 8 turns 24 AWG triple insulated single wire clockwise.

Spread evenly and finish at pin 6.

Add 2 layers tape over windings.

Put core halves together tight.

No vacuum dip is needed just varnish evenly.

Formulas:

Important Formulas for Designing 12V SMPS Driver for LED Strip with ICs:

1. Turns Ratio (Np/Ns):

Np/Ns = √[Vout∗(Vin−Vout)]/[Vin∗f∗Ae]

where,

2. Peak Primary Current (Ipeak):

Ipeak = Vin∗Dmax/(f∗Ae)

Dmax = Max duty cycle

Use this to find highest current in primary winding.

3. Output Capacitor (Cout):

Cout≥Iout∗(1−D)/(f∗ΔVout)

where,

This helps to choose the right capacitor.

4. Feedback Voltage Divider:

Vout / Vref ​​= Rtop​​ / Rbottom​

where,

5. Efficiency (η):

η = Pout / Pin ​​​× 100%

where,

How to Build:

To build a 12V SMPS Driver Circuit for LED Strip follow the below mentioned steps for connections:

Conclusion:

Making 12V SMPS Driver Circuit for LED Strip is good and useful project.

It works better than linear regulators and saves more power and makes less heat.

But be careful with high voltage is dangerous.

Always unplug before touching any parts, work in good light and ask expert if unsure about electronics.

Start with small low voltage projects first.

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