TEA2029C 데이터 시트보기 (PDF) - STMicroelectronics
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TEA2029C Datasheet PDF : 9 Pages
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TEA2029C
widens out to a search window and there is no
delay of frame fly-back (direct synchronization).
Frame Scanning
FRAME SAW-TOOTH GENERATOR. The current
to charge the capacitor is automatically switched to
60Hz operation to maintain constant amplitude.
FRAME PHASE MODULATOR (WITH TWO DIF-
FERENTIAL INPUTS). The output signal is a pulse
at the line frequency, pulse width modulated by the
voltage at the differential pre-amplifier input.
This signal is used to control a thyristor which
provides the scanning current to the yoke. The
saw-tooth output is a low impedance, however, and
can therefore be used in class B operation with a
power amplifier circuit.
Switch Mode Power Supply (SMPS) Secon-
dary 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 conductionangle may be monitored
by forcing a voltage on pin 15. This pin may also
be used for current limitation.
The outputpulse is sent to the primary S.M.P.S. I.C.
(TEA2261) via a low cost synchro transformer.
Security Circuit and Start Up Processor
When the security input (pin 28) is at a voltage
exceeding 1.26V the three outputs are simultane-
ously cut off until this voltage drops below 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 three
outputs are cut off definitively. To reset the safety
logic circuits, VCC must be zero volt.
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 and vertical scanning
functions come into operation at VCC = 6V. The
power supply then comes into operation progres-
sively.
On shutting down, the three functions are inter-
rupted simultaneously after the first line fly-back.
ABSOLUTE MAXIMUM RATINGS (limiting values) Tamb = 25 °C (unless otherwise noted)
Symbol
VCC
I20
I24
V12
I12
I10
I3
I4
I7
I28
V28
V1/V2
Parameter
Supply Voltage (pin 8)
Operating Supply Voltage (pin 8)
AGC Current (pin 20)
Video Identification Current (pin 24)
Negative Line Retrace Voltage (pin 12)
Line Retrace Current (pin 12)
Line Output Current (pin 10)
Frame Saw-tooth Generator (pin 3)
Frame Output Current (pin 4)
SMPS Output Current (pin 7)
Safety Input Current (pin 28)
Safety Input Voltage (pin 28)
Common Mode Range (pins 1-2)
Min.
Max.
Unit
14
V
Starting threshold
13.2
V
5
mA
10
mA
– 20
V
+ 10
mA
– 10
40
mA
20
mA
100
mA
– 40
40
mA
5
mA
VCC
10
V
THERMAL DATA
Symbol
Rth (j-a)
Parameter
Junction-ambient Thermal Resistance
Value
55
Unit
°C/W
ELECTRICAL OPERATING CHARACTERISTICS
Tamb = 25°C VCC = 12V (unless otherwise noted) Pulse duration at 50% of the ampl.
Symbol
Parameter
ICC Supply Current (pin 8, frame, line and SMPS output without load)
SYNCH SEPARATOR (Pins 26-27)
Min. Typ. Max. Unit
50 80 mA
Positive Video Input AC Coupled (output impedance of signal source < 200Ω)
0.2 1.8 3 Vpp
– I27 Negative Clamping Current (during synch, pulse)
- 25 - 40 - 55 µA
I27 Clamping Current - Pin for slicing level 0.2V < V27pp < 2V (50% of sync amplitude) 3
6
9 µA
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