SMPS USING TNY267 (12V 1A)

Design Challenge:

Design and development of 12V 1A SMPS using TNY267. Capable for delivering power up to 12W.

Application:

1. Suitable for Transducer and sensors.

2.DC Motors and Actuators.

3.Power unit for Micro-controller.

4.up to 12W

  
Theory:

1. The popular TNY267 small switch IC is used in the aforementioned simple smps design.
   
2. It's a little mosfet-based 120V to 220V switching oscillator IC that simply needs a ferrite transformer and a stepped down Vdd operational voltage to work.
3. The design is so simple that simply visualizing the schematic is enough to instantly tell us how it works.
4. After rectifying the mains 220V through 1N4007 diodes and the 10uF/400V filter capacitor, the stepped down start voltage is obtained by stabilizing the network using 180V zener diodes and the rapid recovery diode BA159.
5. The IC starts oscillating as soon as this voltage is provided, and its inbuilt mosfet switches the ferrite transformer primary at the predetermined oscillating frequency.
6. Because the secondary is a flyback design, it begins conducting during the primary's OFF cycles through mutual induction and generates the required 12V voltage at the output side.
7. Because this voltage may not be stable, an opto-coupler-based feedback is used, and the link is configured with the IC's exclusive shut down pinout 4.
8. This ensures that the output never exceeds the 12V 1 amp proportion and remains constant.     
   

Circuit:

Pcb layout: