TEA1541P PHILIPS [NXP Semiconductors], TEA1541P Datasheet - Page 6

• Manufacturer Part Number: TEA1541P
• Description: SMPS control IC with synchronization function
• Manufacturer: PHILIPS [NXP Semiconductors]

Philips Semiconductors
5
6
The TEA1541 is intended as the controller for a compact
flyback converter for CRT monitor applications. The IC is
situated on the primary side of the output transformer.
Output power is determined by the current in the primary
winding. The voltage across an auxiliary winding in the
transformer is converted to a current by resistor R
used by the IC to derive the current in the primary winding.
This winding is also used for continuous mode protection,
overvoltage protection, and to power the IC after start-up.
The IC can operate in either synchronized or
unsynchronized mode. In synchronized mode, the IC
synchronizes the converter switching frequency to the
monitor line frequency to prevent interference.
Line synchronizing pulses are applied to pin CTRL.
Each operating cycle of the converter comprises a primary
stroke followed by a secondary stroke. During the primary
stroke, current flows in the primary winding.
The secondary stroke transfers the energy stored in the
transformer core to the secondary winding. In either
synchronized or unsynchronized mode, the primary stroke
only starts at the end of the secondary stroke when the
transformer is demagnetized to ensure zero switching
primary current. If no synchronizing pulses are present
(unsynchronized mode), the IC will operate at its minimum
switching frequency.
2003 Aug 11
V
GND
CTRL
DEM
I
DRIVER
HVS
VIN
sense
CC
SMPS control IC with
synchronization function
SYMBOL
PINNING
FUNCTIONAL DESCRIPTION
PIN
1
2
3
4
5
6
7
8
supply voltage
ground
control input
input from auxiliary winding
for demagnetization timing,
OVP and overpower
protection (OPP)
programmable current sense
input
gate driver output
high voltage safety spacer,
not connected
input for start-up current and
mains voltage recognition
DESCRIPTION
DEM
and
6
The IC has an internal frequency divider which allows it to
operate in synchronized mode at a lower frequency than
the synchronizing pulses supplied to pin CTRL by the
application. The limited frequency range allows an
economical design of the transformer.
In unsynchronized mode, when the power that is drawn
from the converter decreases, the converter switching
frequency also decreases. At very low power (standby)
levels, the frequency of the VCO decreases from 25 kHz
to the minimum value of approximately 6 kHz as shown by
the slope of Fig.4. In a typical application it is possible to
obtain an input power of less than 3 W with an output
power of 100 mW.
handbook, halfpage
CTRL
GND
DEM
V CC
Fig.3 Pin configuration.
1
2
3
4
TEA1541P
MDB084
8
7
6
5
Product specification
VIN
HVS
DRIVER
I sense
TEA1541