tea2028b

tea2028b, Ham- CB Radio, Karty katalogowe

[ Pobierz całość w formacie PDF ]
TEA2028B
COLOR TV SCANNING AND POWER SUPPLY PROCESSOR
.
CERAMIC 500kHz RESONATOR FRE-
QUENCY REFERENCE
DESCRIPTION
The TEA2028B is a complete (horizontal and ver-
tical) deflection processor with secondary to pri-
mary SMPS control for color TV sets.
.
NO LINE AND FRAME OSCILLATOR AD-
JUSTMENT REFERENCE
.
DUAL PLL FOR LINE DEFLECTION
.
HIGH PERFORMANCE SYNCHRONIZATION
.
SUPER SANDCASTLE OUTPUT
.
FRAME BLANKING WITH SAFETY CIRCUIT
.
VIDEO IDENTIFICATION CIRCUIT
.
AUTOMATIC 50/60Hz STANDARD IDENTIFI-
CATION
.
EXCELLENT INTERLACING CONTROL
.
SPECIAL PATENTED FRAME SYNCHRO DE-
VICE FOR VCR OPERATION
.
FRAME SAW-TOOTH GENERATOR
SMPS CONTROL
.
SYNCHRONIZATION WITH HORIZONTAL
DEFLECTION
DIP28
(Plastic Package)
.
SECURITY CIRCUIT AND START-UP PROC-
ESSOR
ORDER CODE :
TEA2028B
.
OUTPUT PULSES ARE SENT TO THE PRI-
MARY SMPS IC TEA2261 THROUGH A LOW
COST SYNCHRO PULSE TRANSFORMER
PIN CONNECTIONS
LINE MONOSTABLE CAPACITOR
SAFETY FRAME BLANKING INPUT
FRAME SAW-TOOTH OUTPUT
FRAME BLANKING OUTPUT
FRAME RAMP GENERATOR
GROUND POWER
SWITCH MODE POWER SUPPLY OUTPUT
1
2
3
4
5
6
7
8
9
10
28
27
26
SAFETY INPUT
VIDEO INPUT
H. SYNCHRO CAPACITOR (tip level)
VIDEO IDENTIFICATION CAPACITOR
MUTING + 50/60Hz IDENT. OUTPUT
V.C.R. INPUT
PHASE COMPARATOR
25
24
23
22
21
F
1 CAPACITOR
V
CC
GROUND SUBSTRAT
FRAME SYNCHRO ADJ USTMENT CAPACITOR
V.C.O. INPUT
V.C.O. OUTPUT
V.C.O. 90
S.M.P.S. INPUT REGULATION
HORIZONTAL OUTPUT
S. SANDCASTLE OUTPUT
HORIZONT AL FLYBACK INPUT
HORIZO NTAL SAW-TOOTH
CURRENT REFERENCE
20
19
18
17
16
15
11
12
REF.
PHASE COMPARATOR
13
14
F
2 CAPACITOR
STARTING AND SAFETY CAPACITOR
August 1993
1/9
DEFLECTION
.
ERROR AMPLIFIER AND PHASE MODULA-
TOR
°
50/60Hz
MUTING OUTPUT
VCR SWITCHING
INPUT
503kHz
SUBSTRAT
GROUND
25
24
23
22
21
20
19
18
TEA2028B
H. SYNC
SUBST
26
HORIZONTAL
SYNCHRO
AND FRAME
SYNCHRO
VCR
INPUT
j
1 DET
VCO 500kHz
17
27
VIDEO
IDENTIFICATION
j
1 INHIBITION TIME
CONSTANT SWITCHING
VIDEO INPUT
2
m
s
2
16
SAFETY
INPUT
j
28
FRAME TIMING
IDENTIFICATION LOGIC
HORIZONTAL
LOGIC TIMING
LINE
MONOSTABLE
V
R
1.26V
15
V
CC
50/60Hz
1
REFERENCE
CURRENT
VOLTAGE
3.3k
W
V
R
1.26V
14
SWITCH ON/OFF
SAFETY CIRCUIT
2
FRAME ERROR
AMPLIFIER
SAFETY
LOGIC
H. SAWTOOTH
GENERATOR
13
FRAME
BLANKING
SAFETY
FRAME
SAWTOOTH
OUTPUT
50/60
Hz
SOFT STARTING
CIRCUIT
3
SUPER
SANDCASTLE
H. OUTPUT
H. INHIBIT
12
FRAME
SAWTOOTH
OUTPUT
FRAME
BLANK
OUTPUT
S.M.P.S.
V
R
1.26V
HORIZONTAL
FLYBACK
INPUT
FRAME
SAFETY
S.M.P.S.
OUTPUT
j
MODULAT.
4
5
6
7
8
9
10
11
V
CC
V
CC
S SC OUTPUT
POWER
GROUND
HORIZONTAL
OUTPUT
FRAME
BLANKING
OUTPUT
FRAME
SAWTOOTH
2028B-02.EPS
TEA2028B
GENERAL DESCRIPTION
Introduction
This integrated circuit uses I
2
L bipolar technology
and combines analog signal processing with digital
processing.
Timing signals are obtained from a voltage-control-
led oscillator (VCO) operating at 500kHz by means
of a cheap ceramic resonator. This avoids the
frequency adjustment normally required with line
and frame oscillators.
A chain of dividers and appropriate logic circuitry
produce very accurately defined sampling pulses
and the necessary timing signals.
The principal functions implemented are :
- Horizontal scanning processor.
- Frame scanning processor :
B Class Power stage using an external power
amplifier with fly back generator such as the
TDA8170.
- Secondary switch mode power regulation.
- The SMPS output synchronize a primary I.C.
TEA2261 at the mains part.
- This concept allows ACTIVE STANDBY facilities.
- Line and frame synchronization separation.
- Dual phase-locked loop horizontal scanning.
- High performance frame and line synchronization
with interlacing control.
- Video identification circuit.
- Super sandcastle.
- Automatic 50-60Hz standard identification.
- VCR input for PLL time constant and frame syn-
chro switching.
- Frame saw-tooth generator.
- Frame blanking output.
- Switching mode regulated power supply compris-
ing error amplifier and phase modulator.
- Security circuit and start-up processor.
- 500kHz VCO.
The circuit is supplied in a 28 pin DIP case.
V
CC
= 12V.
Synchronization Separator
Line synchronization separator is clamped to black
level of input video signal with synchronization
pulse bottom level measurement.
The synchronization pulses are divided centrally
between the black level and the synchronization
pulse bottom level, to improve performance on
video signals in noise conditions.
Frame Synchronization
Time constant of Frame Separator can be adjusted
by adding a capacitor pin 20.
The frame timing identification logic permits auto-
matic adaptatio to 50 - 60Hz standards or non-in-
terlaced video.
An automatic synchronization window width sys-
tem provides :
- fast frame capture (6.7ms wide window),
- good noise immunity (0.4ms narrow window).
The internal generator starts the discharge of the
saw-tooth generator capacitor so that it is not dis-
turbed by line fly-back effects.
Thanks to the logic control, the beginning of the
charge phase does not depend on any disturbing
effect of the line fly-back.
A32
m
s timing is automatically applied on standardi-
zed transmissions, for perfect interlacing.
In VCR mode, the discharge time is controlled by
an internal monostable independent of the line
frequency and gives a direct frame synchroniza-
tion.
Horizontal Scanning
The horizontalscanning frequency is obtainedfrom
the 500kHz VCO.
The circuit uses two phase-locked loops (PLL) :
the first one controls the frequency, the second one
controls the relative phase of the synchronization
and line fly-back signals.
The frequency PLL has two switched time con-
stants to provide :
- capture with a short time constant,
- good noise immunity after capture with a long
time constant.
The output pulse has a constant duration of 29
m
s
(with C(pin 1) = 3.3nF), independent of V
CC
and
delay in switching off the scanning transistor.
Video Identification
The horizontal synchronization signal is sampled
by a 2
m
s pulse within the synchronization pulse.
The signal is integrated by an external capacitor.
The identification function provides three different
levels :
- 0V : no video identification
- 6V : 60Hz video identification
- 12V : 50Hz video identification
This information may be used for timing research
in the case of frequency or voltage synthetizer type
receivers and for audio muting.
Super Sandcastle
with 3 levels : burst, line fly-
back, frame blanking
In the event of vertical scanning failure, the frame
blanking level goes high to protect the tube.
Frame blanking time (start with reset of frame
divider) is 21 lines.
VCR Input
This provides for continuous use of the short time
constant of the first phase-locked loop (frequency).
In VCR mode, the frame synchronization window
widens out to a search window and there is no
delay of frame fly-back (direct synchronization).
3/9
TEA2028B
Frame Saw-tooth Generator
The current to charge the capacitor is automatically
switched to 60Hz operation to maintain constant
amplitude.
Security Circuit And Start-up Processor
When the security input (pin 28) is at a voltage
below 1.26V the two outputs are simultaneously cut
off until this voltage reaches the 1.26V threshold
again. In this case the switch mode power supply
is restarted by the ”soft start” system.
If this cycle is repeated three times, the two outputs
are cut off definitively. To reset the safety logic
circuits, V
CC
must be lower than 3.5V.
This circuit eliminates the risk to switch off the TV
receiver in the event of a flash affecting the tube.
On starting up the horizontal scanning function
comes into operation at V
CC
= 6V. The power
supply then comes into operation progressively.
On shutting down, the two functionsare interrupted
simultaneously after the first line fly back.
Frame Blanking Safety
(Pin 2)
The frame blanking safety checks the normal of
frame scanning.
In case of any problem pin 4 and pin 11 is at a high
level (frame blanking) in order to protect the tube.
Switch Mode Power Supply
(S.M.P.S)
Sec-
ondary to Primary Regulation
This power supply uses a differential error amplifier
with an internal reference voltage of 1.26V and a
phase modulator operating at the line frequency.
The power transistor is turned off bythe falling edge
of the horizontal saw-tooth.
The ”soft start” device imposes a very small con-
duction angle on starting up, this angle progres-
sively increases to its nominal regulation value.
The maximum conduction angle may be monitored
by forcing a voltage on pin 15. This pin may also
be used for current limitation.
The output pulse is sent to the primary I.C.
TEA2261 via a low cost synchro transformer.
ABSOLUTE MAXIMUM RATINGS
(limiting values) (T
amb
=25
o
C unless otherwise noted)
Symbol
Parameter
Min.
Max.
Unit
Supply Voltage (pin 8)
14
V
V
CC
Operating Supply Voltage (pin 8)
Starting threshold
13.2
V
I
24
Video Identification Current (pin 24)
10
mA
V
12
Positive voltage (pin 12)
– 5
V
I
12
Line retrace current (pin 12)
+ 10
mA
I
10
Line Output Current (pin 10)
– 10
40
mA
I
3
Frame Saw-tooth Generator (pin 3)
20
mA
I
4
Frame Blanking Input Current (pin 4)
100
mA
I
7
SMPS Output Current (pin 7)
– 40
mA
I
28
Safety Input Current (pin 28)
5
mA
V
28
Safety Input Voltage (pin 28)
V
CC
THERMAL DATA
Symbol
Parameter
Value
Unit
R
th (j-a)
Junction-ambient Thermal Resistance
55
°
C/W
ELECTRICAL OPERATING CHARACTERISTICS
T
amb
=25
o
C, V
CC
= 12V (unless otherwise noted) Pulse duration at 50% of the ampifier
Symbol
Parameter
Min. Typ. Max. Unit
I
CC
Supply Current (pin 8) (frame, line and SMPS output without load)
50
80
mA
SYNC SEPARATOR (Pins 26-27)
Positive Video Input AC Coupled (output impedance of signal source < 200
W
)
0.2
1.8
3
V
PP
–I
27
Negative Clamping Current (during sync pulse)
-25 -40
-55
m
A
I
27
Clamping Current
3
6
9
m
A
Pin for slicing level 0.2V < V
27pp
< 2V (50% of sync amplitude)
–I
26
Negative Current
0
-750 -1000
m
A
I
26
Positive Current
17
25
36
m
A
4/9
TEA2028B
ELECTRICAL OPERATING CHARACTERISTICS
(continued)
T
amb
=25
o
C, V
CC
= 12V (unless otherwise noted) Pulse duration at 50% of the ampifier
Symbol
Parameter
Min.
Typ.
Max. Unit
FRAME SYNCHRO ADJUSTMENT (Pin 20) (V
20
= 2.5V)
I
20H
High Output Current (V
27
= 12V)
7.2
m
A
I
20L
Low Output Current (V
27
= 0V)
– 2.8
m
A
VCO (Pins 17-18 and 19)
Frequency control range after line divider (ceramic resonator : 503kHz)
15.30 to
16.10
kHz
PHASE COMPARATOR
1 (Pin 22)
Output Current Low Loop Gain
j
±
0.35
±
0.50
±
0.65 mA
Output Current High Loop Gain
±
1
±
1.5
±
2A
Window Pulse Width
7
10
13
m
s
VCR SWITCHING (Pin 23)
Threshold Voltage VCR Operating
1.7
2.2
2.7
V
I
23
Input Current (V
23
=0, V
CC
= 12V)
-0.030
-0.25
-1
mA
VIDEO IDENTIFICATION (Pin 24)
V
24
Output Saturation Voltage (without video signal, I
24
= 3mA)
0.2
0.6
V
V
24
Output Voltage (with 60Hz video signal, I
24
= 2.5mA)
5
6.5
7.5
V
V
24
Output Voltage (with 50Hz video signal, I
24
=10
m
A)
11.0
11.5
V
VIDEO IDENTIFICATION (Pin 25)
I
25
Output Current (charging the capacitor)
0.5
0.75
1
mA
t
25
Identification Time (charging the capacitor)
1.3
1.7
2.2
m
s
V
25
Threshold (voltage changing from lower to higher value)
4
4.5
5
V
L
HYS
Hysteresis
350
mV
H-RAMP GENERATOR (Pin 13)
I
ch13
Charge Current
185
200
215
m
A
V
I13
Base Voltage of Saw-tooth
0.5
V
I
dis13
Discharge Current
3.5
7.0
mA
SUPER SANDCASTLE (Pin 11)
V
B11
Burst key pulse level Output Voltage (I
11
= – 5mA)
9
V
V
L11
Line Blanking Pulse Level Output Voltage (I
11
= – 5mA)
4
4.5
5
V
V
BT11
Frame Blanking Pulse Level Output Voltage (and frame out of function)
(I
11
= – 5mA)
2
2.5
3
V
SUPER SANDCASTLE
T
B11
Delay between middle of synch pulse (Pin 27) and leading edge of burst
key pulse
2.3
3.0
m
s
Duration of burst key pulse
3.7
4
5
T
O11
Delay Between SSC Cutting Level at Pin 12 and Line Blanking Pulse
0.35
Frame Blanking Time (start with reset of frame divider)
21
Line
POSITIVE LINE FLY BACK INPUT (Pin 12)
Delay between middle of synch pulse and middle of line retrace
2.1
2.6
3.1
m
s
Threshold for SMPS Safety
1.1
V
V
bI12
Threshold for Blanking
0.3
V
V
j
12
Threshold for PLL2
3
V
I
12
Input Current – 0.4 V < V
12
<V
bI12
-20
m
A
I
12
Input Current VbI12 < V
12
<V
j
12
-10
m
A
I
12
Input Current V
j
12
<V
12
<V
CC
0
1
m
A
5/9
[ Pobierz całość w formacie PDF ]