AN10881
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Application note
Rev. 2 — 26 September 2011
43 of 102
NXP Semiconductors
AN10881
TEA1713 resonant power supply control IC with PFC
Example:
Required: t
discharge
< 600 ms, with:
•
R1 = R2 = 2 M
•
R3 = 560 k
•
R4 = 47 k
(22)
Where:
•
C = 220 nF
•
The time constant equals: t
discharge
= R
discharge
C = 2465 k
220 nF = 542 ms
7.6.3 SNSMAINS open pin detection
The SNSMAINS pin, which senses the mains input voltage, has an integrated protection
circuit to detect an open pin. When the pin is not connected, an internal current source of
33 nA either pulls the pin down below the stop level of 0.9 V or keeps it below the start
level of 1.15 V.
When the SNSMAINS pin is shorted to ground, the results are similar.
R
disch
e
arg
R1
R2
R3
R4
+
R2
R3
R4
+
+
--------------------------------------
2
M
2
M
560
k
47
k
+
2
M
560
k
47
k
+
+
-------------------------------------------------------------------
2465
k
=
+
=
+
=
