AN10881
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© NXP B.V. 2011. All rights reserved.
Application note
Rev. 2 — 26 September 2011
53 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
8.5.1 HBC Open-Loop Protection (OLP)
The resonant controller of the TEA1713 contains an Open-Loop Protection (OLP). This
protection monitors the voltage on SNSFB. When it exceeds 7.7 V, the protection timer is
started.
In normal operating conditions, the OPTO coupler current is between 0.66 mA and 2.2 mA
which pulls down the voltage at pin SNSFB. Due to an error in the feedback loop, the
current can become less than 260
A which leads to an open-loop protection.
Fig 30. SNSFB V-I characteristics
1.
V
BOOST
= 310 V (DC)
2.
V
BOOST
= 350 V (DC)
3.
V
BOOST
= 390 V (DC)
Fig 31. SNSFB voltage to output power characteristics examples
0
I
SNSFB
V
open
= 8.4 V
0.66 mA
I
fmin
V
RFMAX
2.2 mA
I
fmax
0
0
V
SSHBC
= 8 V
260
μ
A
I
OLP
V
OLP
= 7.7 V
V
fmin
= 6.4 V
V
fmax
= 4.1 V
V
clamp,fmax
= 3.2 V
V
SNSFB
8 mA
I
clamp,max
001aal040
2.5 V
typ
= V
fmax
1.5 V
typ = 0.6
×
V
fmax
Pout (W)
0
250
200
100
150
50
001aal041
5.4
5.6
5.2
5.8
6.0
SNSFB
(V)
5.0
(1)
(2)
(3)
