A look inside a 40W LED lamp with 660 LEDs.

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A very interesting lamp that uses a HUGE array of standard surface mount LEDs wired as 66 parallel strings of ten series LEDs. The use of multiple parallel circuits of ten LEDs seems to be a very common driving technique, as used in most of the 20-100W LED floodlights.
The driver is surprisingly chunky in this lamp, and has a lot of interference suppression circuitry on both the incoming mains and the outgoing DC to the LEDs.
Demo of lamp at
The main control chip is an SN03A driver chip dedicated to the function of driving LED lighting loads with very good power factor. It doesn't seem to use significant smoothing on the incoming rectified mains, but rides the waveform, switching the transformer with a single MOSFET. The transformer has a second winding on the primary side to power the chip itself after it has started running. Current in the primary is monitored on each switching cycle via a sense resistor in series with the MOSFET.
There is opto-isolated feedback from the secondary side with efficient low-loss current detection being implemented using an LM258 op-amp. The secondary rectification and smoothing is based around a TO220 style diode package on a heatsink and two paralleled smoothing capacitors.
There is an auxiliary secondary winding on the transformer for a cooling fan (not fitted on this model), which uses a single rectification diode and a 22uF capacitor to create a simple unregulated DC supply.
The LEDs are probably run at a current of 1200mA split across 66 parallel circuits, giving a typical LED current of around 18mA.