Figure 1. Connection diagram
Table 1. Pin description
Ground and MOSFET source. Connection of both the source of the internal MOSFET and the return of
GND the bias current of the device. All of the groundings of bias components must be tied to a trace going to
this pin and kept separate from the pulsed current return.
N. C. Not connected. When designing the PCB, this pin can be soldered to GND.
Controller Supply. An external storage capacitor has to be connected across this pin and GND. The
pin, internally connected to the high-voltage current source, provides the VCC capacitor charging current
at startup. A small bypass capacitor (0.1 μF typ.) in parallel, placed as close as possible to the IC, is also
recommended, for noise filtering purposes.
Not available for user. This pin is mechanically connected to the controller die pad of the frame. In order
to improve noise immunity, it is highly recommended to connect it to GND.
Undervoltage Protection. If VUVP falls below the internal threshold VUVP_th (0.4 V typ.) for more than
tUVP_DEB time (30 ms, typ.), the IC is disabled, and its consumption reduced to ultra-low values. When
VUVP rises above VUVP_th, the device waits for a tUVP_REST time interval (30 ms, typ.) then resumes
switching. The pin can be used to realize an input undervoltage protection or as a disabling input for the
entire SMPS, with ultra-low residual input power consumption. If the feature is not required, the pin must
be left open, which excludes the function.
Overvoltage protection. If VOVP exceeds the internal threshold VOVP_th (4 V typ.) for more than
tOVP_DEB time (250 μsec, typ.), the PWM is disabled in auto-restart for tOVP_REST (500 msec, typ.) until
the OVP condition is removed, after that it restarts switching with soft-start phase. OVP pin can be used
to realize an input overvoltage protection (or, in non-isolated topologies, an output overvoltage
If the feature is not required, the pin must be connected to GND, which excludes the function.
Direct feedback. It is the inverting input of the internal transconductance E/A, internally referenced to
1.2 V with respect to GND. In non-isolated converter, the output voltage information is directly fed into the
pin through a voltage divider. In primary regulation, the FB voltage divider is connected to the VCC. The
E/A is disabled if FB is connected to GND pin.
DS13285 - Rev 2