TEA1753T All information provided in this document is subject to legal disclaimers. © NXP B.V. 2012. All rights reserved.
Product data sheet Rev. 3. — 24 August 2012 19 of 32
NXP Semiconductors
TEA1753T
HV start-up flyback controller with integrated PFC controller
Accurate OVP detection is made possible by adjusting the value of R
FBAUX
to the turns
ratio of the transformer.
7.3.9 Overcurrent protection (FBSENSE pin)
The primary peak current in the transformer is measured accurately cycle-by-cycle using
the external sense resistor R
sense2
. The OCP circuit limits V
FBSENSE
to a level set by V
fbctrl
(see Section 7.3.3
). The OCP detection is suppressed during the leading-edge blanking
period, t
leb
, to prevent false triggering due to switch-on spikes.
7.3.10 Overpower protection
During the primary stroke of the flyback converter, the input voltage is measured by
sensing the current drawn from the FBAUX pin.
The current information is used to limit the maximum peak current of the flyback
converter, measured from the FBSENSE pin. The internal compensation is such, that a
maximum output power is realized which is almost independent of the input voltage.
The OPP curve is given in Figure 16
.
7.3.11 Driver (FBDRIVER pin)
The driver circuit to the power MOSFET gate has a current sourcing capability of 500 mA
and a current sink capability of 1.2 A. These capabilities permit fast switching of the power
MOSFET, thus ensuring efficient operation.
Fig 15. OCP leading-edge blanking
t
leb
OCP level
V
FBSENSE
t
014aaa022
Fig 16. Overpower protection curve
−360
0−100
014aaa749
0.65
0.46
I
FBAUX
(μA)
V
FBSENSE
(V)