TDA9105 查看數據表（PDF） - STMicroelectronics
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TDA9105 Datasheet PDF : 32 Pages
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TDA9105
OPERATING DESCRIPTION (continued)
Output Section
The H-drive signal is transmitted to the output
through a shaping block ensuring a duty cycle
adjustable from 30% to 50%. In order to ensure a
reliable operation of the scanning power part, the
output is inhibited in the following circumstances :
- VCC too low,
- Xray protection activated,
- During the horizontal flyback,
- Output voluntarily inhibited through Pin 4.
The output stage is composed of a Darlington NPN
bipolar transistor. Both the collector and the emitter
are accessible (see Figure 16).
The output Darlington is in off-state when the power
scanning transistor is also in off-state.
The maximum output current is 20mA, and the
correspondingvoltage drop of the output darlington
is 1.1V typically.
It is evident that the power scanning transistor
cannot be directly driven by the integrated circuit.
An interface has to be designed between the circuit
and the power transistor which can be of bipolar or
MOS type.
Outputs inhibition
The application of a voltage lower than 1V (typ.) on
Pin 4 (duty cycle adjust) inhibits the horizontal and
vertical outputs. This is not memorised.
Figure 17 : Safety Functions Block Diagram
VCC Checking
VCC
REF
XRAY Protection
XRAY
VCC off
SQ
R
Inhibition
H-Duty cycle
1V
Flyback
0.7V
X-RAY PROTECTION : the activation of the X-ray
protection is obtained by application of a high level
on the X-ray input (>8V). Consequences of X-ray
protection are :
- Inhibition of H drive output,
- Activation of composite blanking output.
The reset of this protection is obtained by VCC
switch off (see Figure 17).
Figure 16 : Output stage simplified diagram,
showing the two possibilities of
connection
21 VCC
20
VCC
H-DRIVE
21
H-DRIVE
20
H OUTPUT
INHIBITION
V OUTPUT
INHIBITION
V-fly
Vsync
V sawtooth
retrace time
H-fly
LOGIC
BLOCK
COMPOSITE
BLANKING
to 2ND PLL
18/32
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