TEA1713T_11 NXP [NXP Semiconductors], TEA1713T_11 Datasheet - Page 17

• Manufacturer Part Number: TEA1713T_11
• Description: Resonant power supply control IC with PFC
• Manufacturer: NXP [NXP Semiconductors]

NXP Semiconductors
TEA1713T
Product data sheet
7.7.5 PFC frequency and off-time limiting
7.7.6 PFC soft start and soft stop (pin SNSCURPFC)
Valleys are detected by the valley sensing block connected to the SNSAUXPFC pin. This
block measures the voltage at the auxiliary winding of the PFC transformer, which is a
reduced and inverted copy of the MOSFET drain voltage. When a valley of the drain
voltage (= top at SNSAUXPFC voltage) is detected, the MOSFET is switched on.
If no top is detected on the SNSAUXPFC pin (= valley at the drain) within t
(typ. 4 μs) after demagnetization was detected, the MOSFET is forced to switch on.
For transformer optimization and to minimize switching losses, the switching frequency is
limited to f
system will switch to Discontinuous conduction mode. The PFC MOSFET is switched on
when the drain-source voltage is at a minimum (valley switching).
The minimum off-time is limited to t
under all circumstances.
The PFC controller features a soft start function which slowly increases the primary peak
current at start-up and a soft stop function which slowly decreases the transformer peak
current, before operations are halted. This is to prevent transformer rattle at start-up or
during Burst mode operation.
Fig 8.
Demagnetization and valley detection
max(PFC)
(= top for detection)
Demagnetization
All information provided in this document is subject to legal disclaimers.
V
demag(SNSAUXPFC)
(V
. If the frequency for quasi-resonant operation is above f
Boost
GATEPFC
Aux(PFC)
demagnetized
Dr(PFC)
l
Tr(PFC)
magnetized
Rev. 2 — 9 February 2011
Valley
− V
V
Rect
V
Rect
V
Boost
Rect
)/N
on
off
/N
0
0
0
off(PFC)min
Resonant power supply control IC with PFC
to ensure proper control of the PFC MOSFET
TEA1713T
014aaa856
© NXP B.V. 2011. All rights reserved.
max(PFC)
to(vrec)
t
, the
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