TEA1750T/N1,518 NXP Semiconductors, TEA1750T/N1,518 Datasheet - Page 9

• Manufacturer Part Number: TEA1750T/N1,518
• Description: IC PFC CONTROLLER DCM16SOIC
• Manufacturer: NXP Semiconductors
• Series: GreenChip™ IIIr

Specifications of TEA1750T/N1,518

• Mode: Discontinuous Conduction (DCM)
• Frequency - Switching: 125kHz
• Current - Startup: 60µA
• Voltage - Supply: 14 V ~ 22 V
• Operating Temperature: -40°C ~ 150°C
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 935282967518; TEA1750T-T; TEA1750T-T

NXP Semiconductors
TEA1750_2
Product data sheet
7.2.3 Frequency limitation
7.2.4 Mains voltage compensation (VINSENSE pin)
7.2.5 Soft start-up (pin PFCSENSE)
For applications with high transformer ringing frequencies (after the secondary stroke),
the PFCAUX pin should be connected via a capacitor and a resistor to the auxiliary
winding. A diode must than be placed from the ground connection to the PFCAUX pin.
To optimize the transformer and minimize switching losses, the switching frequency is
limited to f
limit, the system switches over to discontinuous conduction mode. Also here, the PFC
MOSFET is only switched on at a minimum voltage across the switch (valley switching).
The mathematical equation for the transfer function of a power factor corrector contains
the square of the mains input voltage. In a typical application this results in a low
bandwidth for low mains input voltages, while at high mains input voltages the Mains
Harmonic Reduction (MHR) requirements may be hard to meet.
To compensate for the mains input voltage influence, the TEA1750 contains a correction
circuit. Via the VINSENSE pin the average input voltage is measured and the information
is fed to an internal compensation circuit. With this compensation it is possible to keep the
regulation loop bandwidth constant over the full mains input range, yielding a fast transient
response on load steps, while still complying with class-D MHR requirements.
In a typical application, the bandwidth of the regulation loop is set by a resistor and two
capacitors on the PFCCOMP pin.
To prevent audible transformer noise at start-up or during hiccup, the transformer peak
current, I
inserting R
An internal current source charges the capacitor to V
voltage is limited to V
The start level and the time constant of the increasing primary current level can be
adjusted externally by changing the values of R
The charging current I
below 0.5 V (typ). If the voltage on pin PFCSENSE exceeds 0.5 V, the soft start current
source starts limiting current I
I
start(soft)PFC
SoftStart
DM
=
sw(PFC)max
SS1
, is increased slowly by the soft start function. This can be achieved by
current source is switched off; see
3
and C
R
SS1
. If the frequency for quasi-resonant operation is above the f
SS1
Rev. 02 — 15 December 2008
start(soft)PFC
start(soft)PFC
C
SS1
between pin PFCSENSE and current sense resistor, R
start(soft)PFC
.
flows as long as the voltage on pin PFCSENSE is
. As soon as the PFC starts switching, the
Figure
SS1
and C
PFCSENSE
5.
GreenChip III SMPS control IC
SS1
.
= I
start(soft)PFC
TEA1750
© NXP B.V. 2008. All rights reserved.
R
sw(PFC)max
SENSE1
SS1
. The
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