l6599atn STMicroelectronics, l6599atn Datasheet - Page 24

• Manufacturer Part Number: l6599atn
• Description: Improved High-voltage Resonant Controller
• Manufacturer: STMicroelectronics

Application information
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Figure 13. Line sensing function: internal block diagram and timing diagram
With reference to
(Vin
Equation 11
which, solved for R
Equation 12
While the line undervoltage is active the start-up generator continues working but there is no
PWM activity, thus the V
between the start-up and the UVLO thresholds, as shown in the timing diagram of
Figure 13
As an additional measure of safety (e.g. in cases where the low-side resistor is open or
missing, or in non-power factor corrected systems in cases of abnormally high input voltage)
if the voltage on the pin exceeds 7 V, the L6599AT is shut down. If its supply voltage is
always above the UVLO threshold, the IC restarts as the voltage falls below 7 V.
The LINE pin, while the device is operating, is a high impedance input connected to high
value resistors, thus it is prone to pick up noise, which might alter the OFF threshold or give
origin to undesired switch-off of the IC during ESD tests. It is possible to bypass the pin to
ground with a small film capacitor (e.g. 1-10 nF) to prevent any malfunctioning of this kind. If
ON
) and OFF (Vin
.
Vin
Figure 11
H
ON
and R
R
R
OFF
H
−
H
cc
. 1
=
) thresholds of the input voltage:
24
voltage (if not supplied by another source) continuously oscillates
L
Vin
, the following relationships can be established for the ON
, yield:
=
13
ON
Doc ID 15534 Rev 1
13
⋅
−
10
⋅
10
Vin
−
6
−
6
OFF
+
. 1
;
R
24
L
R
L
=
R
Vin
H
Vin
OFF
R
OFF
. 1
H
−
24
. 1
−
24
. 1
24
=
. 1
R
24
L
L6599AT