tea1753lt NXP Semiconductors, tea1753lt Datasheet - Page 11

• Manufacturer Part Number: tea1753lt
• Description: Tea1753lt Greenchip Iii Smps Control Ic
• Manufacturer: NXP Semiconductors

NXP Semiconductors
TEA1753LT
Objective data sheet
7.2.6 Low power mode
7.2.7 PFC off delay (pin PFCTIMER)
The charging current I
0.5 V. If the voltage on pin PFCSENSE exceeds 0.5 V, the soft start current source starts
limiting current I
source is switched off; see
When the output power of the flyback converter (see
converter switches over to frequency reduction mode. When the maximum switching
frequency of the flyback drops below 48 kHz, 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 also
During low power mode operation the PFCCOMP pin is clamped to a minimal voltage of
3.5 V or 2.5 V, dependent on the voltage on VINSENSE pin, and a maximum voltage of
3.7 V. The lower clamp voltage limits the maximum power that is delivered when the PFC
is switched on again. The upper clamp voltage ensures that the PFC can return to its
normal regulation point in a limited amount of time when returning from low power mode.
As soon as the maximum switching frequency of the flyback converter exceeds 86 kHz,
the power factor correction circuit restores normal operation.
When the maximum switching frequency of the flyback controller drops below 48 kHz, 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 part detects a low power, it enters frequency reduction mode
and the IC outputs a 5 A current to the PFCTIMER pin. When the voltage on the
PFCTIMER pin reaches 3.75 V, 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 1.25 V, the PFC is switched on (see
Fig 5.
Soft start-up of PFC
All information provided in this document is subject to legal disclaimers.
start(soft)PFC
start(soft)PFC
Rev. 01 — 4 March 2011
R SENSE1
S1
. As soon as the PFC starts switching, the I
Figure
R SS1
C SS1
flows as long as the voltage on pin PFCSENSE is below
5.
11
PFCSENSE
I start(soft)PFC ≤ 60 μA
Section 7.2.7
Figure
0.5 V
6).
SOFT START
SOFT STOP
CONTROL
Section
OCP
GreenChip III SMPS control IC
014aaa756
7.3) is low, the flyback
TEA1753LT
start(soft)PFC
© NXP B.V. 2011. All rights reserved.
current
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