L6599 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'L6599' PDF : 36 Pages View PDF
Application information
L6599
Figure 32. Line sensing function: internal block diagram and timing diagram
With reference to Figure 32 the following relationships can be established for the ON
(VinON) and OFF (VinOFF) thresholds of the input voltage:
V-----i--n---O----N-----–----1----.-2----5--
RH
=
15 ⋅
10–6 + 1----.-2----5--
RH
V-----i--n---O----F---F-----–----1----.-2----5-
RH
=
1----.-2----5--
RH
which, solved for RH and RL, yield:
RH=
-V----i--n---O----N-----–----V-----i--n---O----F---F--
15 ⋅ 10–6
RL
= RH ⋅
-------------1----.-2----5--------------
VinOFF – 1.25
While the line undervoltage is active there is no PWM activity, thus the VCC voltage (if not
supplied by another source) continuously oscillates between the start-up and the UVLO
thresholds, as shown in the timing diagram of Figure 32.
As an additional measure of safety (e.g. in case the low-side resistor is open or missing, or
in non-power factor corrected systems in case of abnormally high input voltage) if the
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