Green mode power supply

This is a cheap 5V / 5W power supply with regulated output. This device uses a FSDM311A integrated circuit that includes a PWM modulator and a high voltage FET transistor. This chip is designed to use minimum external components.

- flyback type converter
- input voltage: 230 VAC / 50 Hz
- output voltage: 5 VDC (fixed)
- maximum output current: 1A
- output current protection (hiccup mode) at approx. 1.2 A
- output over voltage protection
- line regulation: max 2%
- efficiency: min 70%
- operating frequency: 67 kHz

Figure 1
Schematic (PDF)
Figure 2
Figure 3

In the FSDM311A datasheet you will find links to the documents that will help you to design this type of power supply. Please note that FSDM311 is obsolete since 23-Sep-2010. However there are available now equivalent or similar ICs that have the same functions (manufactured by Fairchild or other IC producers). My comments are extended also to these integrated circuits.

Warning: The manufacturer gave the commercial name "Green Mode Power Switch" to FSDM311A, so don't blame me if I named this power supply in the same way.

This type of power supply MUST NOT BE USED in industrial applications, for the following reasons:
-flyback power supplies are designed for white goods (any component malfunction could lead to destruction of the entire powered equipment)
-many of them have hiccup over current protection (automatic recovery attempts), wich will lead in some circumstances (frequently) to the destruction of the entire powered system
-I saw in my career too many examples of industrial automation systems powered with this type of power supply (they wanted economy, but they not knew the consequences): electronic paperless recorders made by Honeywell, substation automations, SCADA systems, data acquisition systems and so on. In some of this cases, I saw also the destruction of the equipment because of the power supply used.

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[1] - FSDM311 datasheet