DDA002C
EN2 Input
This enable input is non−latched and thus can be used
either for simple ON/OFF control or, because of its reaction
time that is maximally 120 ns, as an ultra fast over current
To Input Current
Sensing Circuitry
protection input. Connection of the EN 2 comparator can be
seen in Figure 55. Functionality of this input is independent
of any timers i.e. it works immediately when the VCCON
threshold is reached.
R1
EN2
R2
20 ns
RC
Filter
To Gate Drivers
and Internal Logic
VEN2 = 1 V
Figure 55. Internal Connection of the EN2 Comparator
The EN2 comparator incorporates −50 mV hysteresis − it
means that the controller will restore operation via full
start−up period (i.e. PFC delay, preheat and soft−start) when
EN2 input voltage goes below VEN2−0.05 V. Figure 56
shows the EN2 input related operating waveforms.
EN2
EN2 is not blanked and can stop the IC anytime!
Full startup sequence is placed when EN2 re−enabled.
PFC_OK
CIG
SS
DRV_Outputs
100 ms
CIG_End = 5V
SS_not_finished
Vcc
EN2 triggered
IC restarts
Figure 56. EN2 Input Functionality Description Waveforms
The High−voltage Driver
The controller features an internal high voltage driver that
enables direct connection to the half bridge topologies.
Figure 57 shows the internal architecture of the Lgd and Hgd
drivers section. The device incorporates an upper UVLO
circuitry that ensures adequate Vgs is available for the upper
side MOSFET.
http://onsemi.com
24