TEA1751T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2013. All rights reserved.
Product data sheet Rev. 3 — 10 January 2013 26 of 31
NXP Semiconductors
TEA1751T
HV start-up flyback controller with integrated PFC controller
11. Application information
A power supply with the TEA1751T consists of a power factor correction circuit and a
flyback converter. See Figure 16
.
Capacitor C
VCC
buffers the IC supply voltage. The IC is powered from the high voltage
rectified mains during start-up and the auxiliary winding of the flyback converter during
operation. Sense resistors R
SENSE1
and R
SENSE2
convert the current through the
MOSFETs S1 and S2 into a voltage at pins PFCSENSE and FBSENSE. The values of
R
SENSE1
and R
SENSE2
define the maximum primary peak current in MOSFETs S1 and S2.
In the example given, the LATCH pin is connected to a Negative Temperature Coefficient
(NTC) resistor. The protection is activated when the resistance drops below a value
calculated as follows:
(8)
A capacitor C
TIMEOUT
is connected to the FBCTRL pin. R
LOOP
is added so that the
time-out capacitor does not interfere with the normal regulation loop.
R
S1
and R
S2
are added to prevent the soft-start capacitors from being charged during
normal operation due to negative voltage spikes across the sense resistors.
Resistor R
AUX1
is added to protect the IC from damage during lightning events.
V
prot LATCH
I
OLATCH
-------------------------------
15.6 k=
Fig 16. Typical application diagram for the TEA1751T
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