The SANYO CHASSIS 2021 is based around the DIGIVISION ITT TECHNOLOGY and is therefore a digital chassis.
On a monocarrier are fitted all circuits and the digital board is left postioned in a metal shield box.
On the front side is fitted a PCB carrying the system control.
TEA2260 SWITCH MODE POWER SUPPLY CONTROLLER:
.POSITIVE AND NEGATIVE CURRENT UP TO
1.2A and – 2A
.LOW START-UP CURRENT
.DIRECT DRIVE OF THE POWER TRANSISTOR
.TWO LEVELS TRANSISTOR CURRENT LIMITATION
.DOUBLE PULSE SUPPRESSION
.UNDER AND OVERVOLTAGE LOCK-OUT
.AUTOMATIC STAND-BY MODE RECOGNITION
.LARGE POWER RANGE CAPABILITY IN
STAND-BY (Burst mode)
.INTERNAL PWM SIGNAL GENERATOR
The TEA2260/61 is a monolithic integrated circuit
for the use in primary part of an off-line switching
mode power supply.
All functions required for SMPS control under normal
operating,transient or abnormal conditions are
The capability of working according to the ”masterslave”
concept, or according to the ”primary regulation”
mode makes the TEA2260/61 very flexible
and easy to use. This is particularly true for TV
receivers where the IC provides an attractive and
low cost solution (no need of stand-by auxiliary
The TEA2260/61 is an off-line switch mode power
supply controller. The synchronization functionand
the specificoperationin stand-bymodemake itwell
adapted to video applications such as TV sets,
VCRs, monitors, etc...
The TEA2260/61 can be used in two types of
- Master/slave architecture. In this case, the
TEA2260/61 drives the power transistor according
to the pulse width modulated signals generated
by the secondary located master circuit. A
pulse transformer provides the feedback (see
- Conventional architecture with linear feedback
signal (feedback sources : optocoupler or transformer
winding) (see Figure 2).
Using the TEA2260/61, the stand-by auxiliary
power supply, often realized with a small but costly
50Hz transformer, is no longer necessary. The
burst mode operation of the TEA2260/61 makes
possible the control of very low output power (down
to less than 1W) with the main power transformer.
When used in a master/slave architecture, the
TEA2260/61and also the power transistor turn-off
can be easily synchronized with the line transformer.
The switching noise cannot disturb the
picture in this case.
As an S.M.P.S.controller, the TEA2260/61features
the following functions :
- Power supply start-up (with soft-start)
- PWM generator
- Direct power transistor drive (+1.2A, -2.0A)
- Safety functions : pulse by pulse current limitation,
output power limitation, over and under voltage
S.M.P.S. OPERATING DESCRIPTION
Starting Mode - Stand By Mode
Power for circuit supply is taken from the mains
through a high value resistor before starting. As
long as VCC of the TEA2260/61 is below VCC start,
the quiescent current is very low (typically 0.7mA)
and the electrolytic capacitor across VCC is linearly
charged. When VCC reaches VCC start (typically
10.3V), the circuit starts, generating output pulses
with a soft-starting. Then the SMPS goes into the
stand-bymode and the output voltage is a percentage
of the nominal output voltage (eg. 80%).
For this the TEA2260/61 contains all the functions
required for primary mode regulation : a fixed frequency
oscillator, a voltage reference, an error
amplifier and a pulse width modulator (PWM).
For transmission of low power with a good efficiency
in stand-by, an automatic burst generation
system is used, in order to avoid audible noise.
Normal Mode (secondary regulation)
The normal operating of the TV set is obtained by
sending to the TEA2260/61regulation pulses generated
by a regulator located in the secondary side
of the power supply.
This architectureuses the ”Master-slave Concept”,
advantages of which are now well-known especially
the very high efficiency in stand-bymode, and
the accurate regulation in normal mode.
Stand-by mode or normal mode are obtained by
supplying or not the secondary regulator. This can
be ordonneredfor exemple by a microprocessor in
relation with the remote control unit.
Regulation pulses are applied to the TEA2260/61
through a small pulse-transformer to the IN input
(Pin 2). This input is sensitive to positive square
pulses. The typical threshold of this input is 0.85V.
The frequency of pulses coming from the secondary
regulator can be lower or higher than the
frequency of the starting oscillator.
The TEA2260/61has no soft-starting system when
it receives pulses from the secondary. The softstarting
has to be located in the secondary regulator.
Due to the principle of the primary regulation,
pulses generated by the starting system automatically
disappear when the voltage delivered by the
Stand-by Mode - Normal Mode Transition
During the transition there are simultaneously
pulses coming from the primary and secondary
These signals are not synchronizedand some care
has to betaken toensure the safety of theswitching
Avery sure and simple way consist in checking the
transformer demagnetization state.
- A primary pulse is taken in account only if the
transformer is demagnetized after a conduction
of the power transistor required by the secondary
- A secondary pulse is taken in account only if the
transformer is demagnetized after a conduction
of the power transistor required by the primary
With this arrangement the switching safety area of
the power transistor is respected and there is no
risk of transformer magnetization.
The magnetization state of the transformer is
checked by sensing the voltage across a winding
of the transformer (generally the same which supplies
the TEA2261). This is made by connecting a
resistor between this winding and the demagnetization
sensing input of the circuit (Pin 1).
SECURITY FUNCTIONS OF THE TEA2260 (see flow-chart below)
- Undervoltage detection. This protection works
in association with the starting device ”VCC
switch” (see paragraph Starting-mode - standby
mode). If VCC is lower than VCCstop (typically
7.4V) output pulses are inhibited, in order to avoid
wrong operation of the power supply or bad
power transistor drive.
- Overvoltage detection. If VCC exceedsVCCmax
(typically 15.7V) output pulses are inhibited. Restarting
of the power supply is obtained by reducing
VCC below VCCstop.
- Current limitation of the power transistor. The
current is measured by a shunt resistor. Adouble
threshold system is used :
- When the first threshold (VIM1) is reached, the
conduction of the power transistor is stopped
until the end of the period : a new conduction
signal is needed to obtain conduction again.
- Furthermore as long as the first threshold is
reached (it means during several periods), an
external capacitor C2 is charged. When the
voltage across the capacitor reaches VC2 (typically
2.55V) the output is inhibited.This is called
the ”repetitive overload protection”. If the overload
diseappears before VC2 is reached, C2 is
discharged, so transient overloads are tolerated.
- Second current limitation threshold (VIM2).
When this thresholdis reached the output of the
circuit is immediatly inhibited. This protection is
helpfull in case of hard overload for example to
avoid the magnetization of the transformer.
- Restart of the power supply. After stopping due
to VC2, VIM2, VCCMax or VCCstop triggering, restart
of the power supply can be obtained by the
normal operating of the ”VCC switch” but thanks
to an integrted counter, if normal restart cannot
be obtained after three trials, the circuit is definitively
stopped. In this case it is necessary to
reduce VCC below approximately 5V to reset the
circuit. From a practical point of view, it means
that the power supply has to be temporarily disconnected
from any power source to get the
TDA8172 TV VERTICAL DEFLECTION OUTPUT CIRCUIT
The TDA8172 is a monolithic integrated circuit in
HEPTAWATTTM package. It is a high efficiency
power booster for direct driving of vertical windings
of TV yokes. It is intended for use in Color and B &
W television as well as in monitors and displays.
SAB3035 COMPUTER INTERFACE FOR TUNING AND CONTROL (CITAC)
The SAB3035 provides closed-loop digital tuning of TV receivers, with or without a.f.c., as required. lt
also controls up to 8 analogue functions, 4 general purpose I/O ports and 4 high-current outputs for
tuner band selection.
The IC is used in conjunction with a microcomputer from the MAB84OO family and is controlled via a two-wire, bidirectional I2 C bus.
Combined analogue and digital circuitry minimizes the number of additional interfacing components
Frequency measurement with resolution of 50 KHz
Selectable prescaler divisor of 64 or 256
32 V tuning voltage amplifier
4 high-current outputs for direct band selection
8 static digital to analogue converters (DACSI for control of analogue functions
Four general purpose input/output (l/O) ports
Tuning with control of speed and direction
Tuning with or without a.f.c.
Single-pin, 4 MHZ on-chip oscillator
I2 C bus slave transceiver
The SAB3035 is a monolithic computer interface which provides tuning and control functions and
operates in conjunction with a microcomputer via an I2 C bus.
This is performed using frequency-locked loop digital control. Data corresponding to the required tuner
frequency is stored in a 15-bit frequency buffer. The actual tuner frequency, divided by a factor of 256
(or by 64) by a prescaler, is applied via a gate to a 15-bit frequency counter. This input (FDIV) is
measured over a period controlled by a time reference counter and is compared with the contents of the frequency buffer. The result of the comparison is used to control the tuning voltage so that the tuner frequency equals the contents of the frequency buffer multiplied by 50 kHz within a programmable tuning window (TUW).
The system cycles over a period of 6,4 ms (or 2,56 ms), controlled by the time reference counter which is clocked by an on-chip 4 lVlHz reference oscillator. Regulation of the tuning voltage is performed by a charge pump frequency-locked loop system. The charge IT flowing into the tuning voltage amplifier is controlled by the tuning counter, 3-bit DAC and the charge pump circuit. The charge IT is linear with the frequency deviation Af in steps of 50 .
TDA8341 Television IF amplifier and demodulator
The TDA8340;Q and TDA8341;Q are integrated IF
amplifier and demodulator circuits for colour or black/white
television receivers, the TDA8340;Q is for application with
n-p-n tuners and the TDA8341;Q for p-n-p tuners.
The TDA8340;Q and TDA8341;Q are pin-compatible
successors with improved performance to types
TDA2540/2541;Q and TDA3540/3541;Q.
· Full range gain-controlled wide-band IF amplifier
· Linear synchronous demodulator with excellent
· White spot inverter
· Wide-band video amplifier with noise protection
· AFC circuit with AFC on/off switching and
· Low impedance AFC output
· AGC circuit with noise gating
· Tuner AGC output for n-p-n tuners (TDA8340) or p-n-p
· External video switch for switching-off the video output
· Reduced sensitivity for high sound carriers
· Integrated filter to limit second harmonic IF signals
· Wide supply voltage range
· Requires few external components.
TDA2556 QUASI-SPLIT-SOUND CIRCUIT WITH DUAL SOUND DEMODULATORS
The TDA2556 is a monolithic integrated circuit for quasi-split-sound processing, including two FM
demodulators, for two carrier stereo TV receivers and VTR.
First IF (vision carrier plus sound carrier).
0 3 stage gain controlled IF amplifier
0 AGC circuit
0 Reference amplifier and limiter amplifier for vision carrier (V.C.) processing
0 Linear multiplier for quadrature demodulation
Second IF (two separate channels for both FM sound signals).
0 4-stage-limiting amplifier
0 Ouadrature demodulator
0 AF amplifier with de-emphasis
O Output buffer
0 Muting for one or both AF outputs
TDA1521 TDA1521Q 2 x 12 W hi-fi audio power amplifier:
The TDA1521/TDA1521Q is a dual hi-fi audio power amplifier encapsulated in a 9-lead plastic power package.
The device is especially designed for mains fed applications (e.g. stereo tv sound and stereo radio).
· Requires very few external components
· Input muted during power-on and off
(no switch-on or switch-off clicks)
· Low offset voltage between output and ground
· Excellent gain balance between channels
· Hi-fi according to IEC 268 and DIN 45500
· Thermally protected