Power supply
Consists of two completely separate sections:
" Stand-by power supply
" Main power supply
Stand-by power supply
This is an SMPS (Switch Mode Power Supply) operating at about 50 kHz with primary
side control and stabilisation performed by the integrated circuit VIPer20A (ICP10), which
provides exclusively the voltages required by the appliance in stand-by mode.
In these conditions the main power supply is completely deactivated, which allows for an
exceptionally low overall consumption (< 1 W), far lower than even the most stringent
standards.
The transformer TRP2 performs the dual function of isolating the appliance from the
mains power supply and generating on the secondary winding the supply voltage + 5 Vsb
which powers the IR receiver (IRH1), the microcontroller (ICR1), the NVM memory (ICR3),
the reset circuit (ICR6) and the EPROM (ICR2) containing the software. A duplicator
circuit is used to obtain a voltage of about 20 V used for turning off the electromagnetic
mains switch (optional).
Main power supply
This is an SMPS (Switch Mode Power Supply) operating at about 45 kHz with secondary
side control and stabilisation performed by the integrated circuit TEA2262 (ICP1).
The transformer TRP1 performs the dual function of isolating the appliance from the
mains power supply and generating the correct supply voltages on the various secondary
windings.
In stand-by the TRIAC DP2 does not conduct, so the circuit (including the PTC powering
the degaussing coil) is completely disconnected from the power supply and therefore has
no power consumption.
When it is turned on by means of the photo-coupler ICP3, the TRIAC DP2 is made to
conduct and the rectified and smoothed mains voltage across CP14, via winding 5/2 of
transformer TRP1, is present on the collector of TP1, which does not conduct because
ICP1 is not yet powered.
Simultaneously CP16 is charged from mains via RP3. As soon as the voltage across it
reaches a value of about 10 V, the integrated circuit begins to operate and generates on
pin 14 the driving pulses for making transistor TP1 conduct.
Current therefore begins to flow in the primary winding 5/2 of the transformer and across
the winding 1/7 there are formed pulses which are rectified by DP4 and smoothed by
CP16 and ensure a complete power supply of ICP1.
At the same time currents are also induced in the secondary windings; after being rectified
and smoothed these currents generate the various power supply voltages.
A voltage taken from across CP37 by way of the voltage divider made up of
RP35/RP29/RP23/RP33/PP1 is applied to the base of TP4 and causes a proportional
current to flow in the photodiode contained in the optocoupler ICP2.
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ACEC
