AN10881
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Application note
Rev. 2 — 26 September 2011
21 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
The coupling of the auxiliary winding with the primary winding must be as small as
possible to avoid a primary voltage component on the auxiliary voltage. Place the auxiliary
winding on the secondary winding(s) and as physically remote as possible from the
primary winding to obtain this. See differences in results given by comparison on
secondary side position in
5.3.4 Difference between UVP on SNSOUT and SNSCURHBC OCP/OCR
In a system that uses output voltage sensing with the SNSOUT function, there can be an
overlap in functionality in an over power or short-circuit situation. In such a situation, often
both the SNSOUT UVP and the OCP/OCR on SNSCURHBC, activate the protection
timer.
There are basic differences between both functions:
•
SNSOUT monitors (indirectly) the HBC output voltage or another external protection
circuit (such as NTC temperature measurement)
•
OCP/OCR monitors the power in the system by sensing the primary current in detail
SNSOUT is a more general usable protection input while SNSCURHBC is specifically
designed for HBC operation. In addition, SNSOUT also offers three other functions:
•
OVP (latched)
•
hold HBC
•
hold HBC + PFC (for Burst mode)
Fig 8.
Position the auxiliary winding for good output coupling
001aal020
secondary side
primary side
V
aux
V
aux
V
aux.new
V
aux.new
V
O
V
O
V
O
Bad coupling V
aux
to V
O
at high
output current
Good coupling
V
aux.new
to V
O
at
high output current
