NXP Semiconductors AN10907, Примечание к применению

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AN10907 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2010. All rights reserved.
Application note Rev. 1 — 28 December 2010 60 of 82
NXP Semiconductors
AN10907
TEA1613T resonant power supply control IC
A possible reset by external control (for example microcontroller) is available using the
SSHBC/EN function.
10.3 SNSOUT/PFCON protection
10.3.1 OverVoltage Protection (OVP) output
The TEA1613T has overvoltage protection intended for monitoring the HBC output
voltage. It is one of the functions that is combined on the SNSOUT/PFCON pin.
10.3.1.1 Auxiliary winding
When dealing with a mains insulated converter, the HBC output voltage can be measured
via the auxiliary winding of the resonant transformer. To accurately measure the
secondary voltage of the primary circuit auxiliary winding, a special transformer
construction is needed.
To facilitate correct working, it is important that this winding has a good coupling with the
secondary winding(s) and a minimum coupling with the primary winding. In this way a
good representation is obtained of the output voltage situation. For more details refer to
Section 6.3.3.1 and Figure 6 .
To meet the mains insulation requirements, triple insulated wire can be used.
10.3.1.2 Principle of operation
The voltage is sensed at the SNSOUT/PFCON pin via an external rectifier and resistive
divider. Overvoltage is detected when the SNSOUT/PFCON voltage exceeds 3.5 V. After
detecting OVP the TEA1613T goes to the latched protection shutdown state.
10.3.1.3 Connecting external measurement circuits
When latched protection is needed for other detection circuits, it can be added on
SNSOUT/PFCON by means of a series diode. For example: external overtemperature
protection.
Fig 45. SNSOUT protection
001aal468
100
μ
A
1.5 V
SNSOUT/PFCON
SUPREG
V
aux
TEA1613
OVP
latched shutdown
3.5 V
COMP
UVP
protection timer
2.35 V
COMP
Θ