Datasheet

L6591 Application information
Doc ID 14821 Rev 6 27/41
Figure 46. Hiccup mode OCP: timing diagram (device self-supplied)
6.5 Latched shutdown
The L6591 is equipped with a comparator having the non-inverting input externally available
at the DIS pin (#2) and with the inverting input internally referenced to 4.5 V. As the voltage
on the pin exceeds the internal threshold, the IC is immediately shut down and its
consumption reduced to a low value.
The information is latched and it is necessary to let the voltage on the Vcc pin go below the
UVLO threshold to reset the latch and restart the IC. To keep the latch supplied as long as
the converter is connected to the input source, the HV generator is activated periodically so
that Vcc oscillates between the startup threshold V
ccON
and V
ccON
– 1 V. It is then
necessary to disconnect the converter from the input source to restart the IC. This operation
is shown in the timing diagram of
Figure 47 . Activating the HV generator in this way cuts its
power dissipation approximately by three (as compared to the case of continuous
conduction) and keeps peak silicon temperature close to the average value.
AM13262v1
Vc c
LVG, HVG
OCP latch
Sec on dary di od e i ssho rted he re
t
t
t
t
V
C S
Vcc_OK
t
1.5 V
PFC _S top
t
Vcc
on
Vcc
off
Vc c
resta rt