L6699DTR STMicroelectronics, L6699DTR Datasheet - Page 23

• Manufacturer Part Number: L6699DTR
• Description: AC/DC Switching Converters Enhanced High Volt Res CTRL 600V
• Manufacturer: STMicroelectronics

Specifications of L6699DTR

• Product Category: AC/DC Switching Converters

L6699
Figure 17. How the L6699 can switch off a PFC controller at light load
To help the user meet energy saving requirements even in power-factor-corrected systems,
where a PFC pre-regulator precedes the DC-DC converter, the L6699 allows that the PFC
pre-regulator can be turned off during burst-mode operation, therefore eliminating the no
load consumption of this stage (0.5
EMC regulations on low-frequency harmonic emissions refer to nominal load, no limit is
envisaged when the converter operates with light or no load.
To do so, the L6699 provides pin 8 (PFC_STOP): it is an open drain output, normally open,
that is asserted low when the IC is idle during burst-mode operation. This signal is externally
used for switching off the PFC controller and the pre-regulator as shown in
the L6699 is in UVLO the pin is kept open to allow the PFC controller to start first.
The PFC_STOP pin is also used by some protection functions (OCP, OLP and latched
shutdown). Please refer to the relevant sections for more information.
L6699
Vcc
12
9
PFC_STOP
100 k W
BC547
Doc ID 022835 Rev 2
22 k W
ZCD (L6562)
INV (L6562A)
BC547
-
1 W). There is no compliance issue in that, because
L6562/2A
Operation at no load or very light load
L6564, L6564T/H
L6563S/H
L6699
L4984
Figure 17
9
PFC_STOP
PFC_OK
(AC_OK)
AM11388v1
. When
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