TDA9103 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
MFG CO.
'TDA9103' PDF : 27 Pages View PDF
TDA9103
Figure 17 : Output stage simplified diagram,
showing the two possibilities of
connection
21 VCC
20
H-DRIVE
VCC
21 VCC
H-DRIVE
20
The reset of this protection is obtained by VCC
switch off.
S Correction. S Outputs
In the case where the ”S correction” of the horizon-
tal scanning is performed using capacitors, it is
necessary to switch capacitors when the frequency
changes.
For this the outputs S1, 2, 3 and 4 (Pins 9, 8, 7 and
16) give an indication about the horizontalfrequency
by monitoring thecontrolvoltage of the VCO (Pin 12).
The switching of the S outputs occurs for the fol-
lowing value of the control voltage.
S1
2V
S2
2.4V
S3
3V
S4
3.7V
The use of comparators with hysteresis avoids
erratic switching of the Sout outputs if the control
voltage of the VCO remains very close to a switch-
ing reference level.
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 2 (duty cycle adjust)
inhibits the horizontal, vertical and SMPS outputs.
This is not memorised.
X-ray protection : the activation of the X-ray protec-
tion is obtained by application of a high level on the
X-ray input (>1.6V). Consequences of X-ray pro-
tection are :
- Inhibition of H drive output.
- Inhibition of SPMS output.
- Activation of safety blanking output.
SMPS
This unit generates the supply voltage for the hori-
zontal scanning system. This supply voltage is
approximately proportional to the H frequency in
order to keep the scanning amplitude constant
when the frequency changes. More precisely the
amplitude regulation is obtained by detecting and
regulating the ”flyback” amplitude or EHT value.
The power supply is a step-up converter and it uses
the ”current-mode” regulation principle.
The power supply works in synchronism with the
horizontal scanning. The switching power transis-
tor (external to the TDA9103) is switched on at the
beginning of the positive slope of the horizontal
sawtooth. It is switched off as required by the
integrated regulator. The current in the switching
power transistor is monitored and limited, and the
ratio Ton/Ton+Toff of the power transistor is limited
to 75% typically providing a very good reliability to
the power supply.
15/27
Share Link: 
