12V 2A Switch Mode Power Supply with LP2704A

12 Volt 2 Amp switch mode power supply takes an AC input of 100-240V and gives stabilized 12V 2A DC output with low ripple and low interference.

The circuit uses an integrated circuit LP2704A of a series of circuits LP2703A/LP2703A./LP2704A package (SOP8).

Optimized circuit design with high rationality combined with high performance and price ratio SOI production process for cost-effective AC to DC converters.

With the usual PWM (pulse wide modulation) controller is different, it uses a simple on/off control method to stabilize the output voltage.

Integrate a 700 V power MOSFET, the working frequency is 140 kHz, high voltage switches current source, current limiting, and thermal shutdown circuit.

The thermal shutdown circuit detects the temperature of the junction, the threshold is set at 130 °C (typical) and has a hysteresis range of 55 °C (typical).

In the Undervoltage state, the prohibition time of power MOSFET switching exceeds the usual 1.2 seconds until the end of the Undervoltage state.

This power controller can work in a typical small flyback supply and it doesn't even need an auxiliary winding.

Circuit Diagram

Schematic of 12V 2A Switch-mode power supply circuit with IC LA2704A shown below.

Transformer Details

The transformer is a small ferrite EE16 BE010 model whose central column has an air gap of 0.4 mm. Primary (P) has 165 turns of wire diameter 0.15 mm. Secondary (S) has 2x 20 turns of wire 0.4 mm.

Switching supply is not for beginners, because most of its circuits are connected to fatal mains voltage. When bad design, the mains voltage can reach the output! Capacitors can remain charged to dangerous voltage even after disconnected from mains. Everything you do at your own risk, for any injury to health or property I do not take responsibility.


  1. Hi where can I find this IC TLP2704. Can you share link for IC?

    1. TLP2704 is a High Speed Optocoupler, 30V 5000Vrms. You can also use TLP281-4 or TLP291-4.


If you have any doubts or questions, please let me know. Don't add links as it goes to spam. Share your valuable feedback. Thanks