tea1752t NXP Semiconductors, tea1752t Datasheet - Page 11

• Manufacturer Part Number: tea1752t
• Description: Greenchip Iii Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1752T_LT
Product data sheet
7.2.6 Low power mode
7.2.7 PFC off delay (pin PFCTIMER)
When the output power of the flyback converter (see
converter switches to frequency reduction mode. When the internal switching frequency
limit of the flyback drops below 48 kHz (typical), the power factor correction circuit is
switched off to maintain high efficiency. The switch-off can be delayed by connecting a
capacitor to the PFCTIMER pin (see
During low power mode operation the PFCCOMP pin is clamped to a minimum voltage of
3.5 V (typical) and a maximum voltage of 3.7 V (typical). The lower clamp voltage limits
the maximum power delivered when the PFC is switched on again. The upper clamp
voltage ensures the PFC can return to its normal regulation point in a limited amount of
time when returning from low power mode.
The power factor correction circuit restores normal operation when the internal switching
frequency limit of the flyback converter rises above 86 kHz (typical).
When the internal switching frequency limit of the flyback controller drops below
48 kHz (typical), the PFC is switched off. To prevent the PFC from switching off due to a
fast changing load at the flyback output, the PFC switch-off can be delayed by connecting
a capacitor to the PFCTIMER pin.
When the flyback controller detects a low power, it enters frequency reduction mode and
the IC outputs a 10 μA (typical) current to the PFCTIMER pin. When the voltage on the
PFCTIMER pin reaches 3.6 V (typical), the PFC is switched off by performing a soft stop.
When the flyback controller part leaves the frequency reduction mode, a switch
discharges the PFCTIMER pin capacitor. When the voltage on the PCTIMER pin drops
below 1.27 V (typical), the PFC is switched on (see
Fig 5.
Soft start-up of PFC
All information provided in this document is subject to legal disclaimers.
Rev. 02 — 24 June 2010
R SENSE1
S1
R SS1
C SS1
11
PFCSENSE
I start(soft)PFC ≤ 60 μA
Section
TEA1752T; TEA1752LT
7.2.7).
0.5 V
SOFT START
SOFT STOP
CONTROL
Figure
Section
OCP
GreenChip III SMPS control IC
6).
014aaa756
7.3) is low, the flyback
© NXP B.V. 2010. All rights reserved.
11 of 34