7W dual output offline flyback converter using VIPer0P

The negative voltage setup is extremely simplified thanks to an embedded error amplifier, whose accurate 1.2 V internal reference (FB pin) is referred to a separate ground (EAGND pin) that can drift down to -12.5 V with respect to the signal ground of the IC (SGND). The negative output (OUT1) is obtained by just connecting EAGND to the negative rail and a voltage divider between FB, EAGND and SGND. The positive output (OUT2) is obtained from OUT1 through the turn ratio of the secondary windings of the transformer.
To achieve extremely low input power consumption, the IC is biased through a diode coming from the OUT2, which maintains the V_CC voltage high enough (> 4.5 V) to prevent the activation of the internal HV current source.