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TDA911x Family Pin Review
AN1290
10/62
STMicroelectronics Confidential
16
When the DC/DC converter is used in the External sawtooth configuration, Pin 16 should receive a sawtooth (less
than 2V peak), either representative of the current in the switch (current mode) or provided by an R/C oscillator (open
loop). In both cases, the power MOS transistor is switched OFF when pin 16 voltage exceeds one-third of the voltage
on pin 14. Biasing Pin 16 with more than 6V will set the so-called “internal sawtooth”, in voltage mode configuration
(TDA9112 only).
17 & 18
High-impedance inputs which control H and V amplitude respectively. Each one should receive an image of the EHT
(for instance, a fraction of the Automatic Beam Limiter voltage) for size compensation versus EHT variations. Both
have the same active range: 1 to 8V, and sign: amplitude increases when pin voltage increases. The gains of the two
channels have to be separately set to the correct values by external resistive dividers.
19
Presents a DC level equal to Vertical sawtooth negative peak, it should be filtered to VGND to improve vertical jitter.
20
The capacitor on pin 20 stores the AGC value to maintain the constant Vertical Sawtooth amplitude regardless of the
frequency. It should be a 0.47µF non-electrolytic capacitor.
21
Vertical ground. In addition to the main GND on pin 27, it should be only connected to Vertical section components.
22
A 0.15µF film capacitor should be connected between Pin 22 and VGND to obtain the Vertical Sawtooth with constant
amplitude (between 2 and 5V).
23
The same sawtooth is available on pin 23, buffered and with adjustable amplitude and offset for the control of vertical
size and position. The middle value of this signal is (3.5/8) of the reference voltage (pin 13). An equal voltage should
be derived from pin 13 through a resistive divider, to bias the Vertical booster positive input.
24
Provides the complete waveform to control Horizontal amplitude, including DC (for H Size, with EHV compensation),
Pincushion, Keystone and symmetric Corner. It has the structure of an Emitter follower; a pull-down resistor (10k
Ω
) is
necessary. Voltage range is 2 V to 8.5 V. The TDA9115 does not have corner correction.
25
High-impedance comparator input for X-ray detection, with 8V threshold. It should be filtered to GND (VGND is
recommended).
26
HOut: open-collector NPN with more than 30mA capability. The NPN is switched OFF (pin 26 High) when the
scanning transistor is to be switched OFF (“Reverse control”). An external pull-up resistor connected to pin 29 is
necessary. Direct control of a bipolar NPN driver is possible.
27
General GND. The general GND track should enter the IC area by this pin, then be connected only to the special H
and V ground tracks.
28
BOut: open-collector NPN, with more than 10mA capability. An external pull-up resistor connected to pin 29 will be
necessary to make the power switch conductive.
Warning! The polarity should be selected by I²C. By default: High level (NPN OFF) is meant to make the power switch
conductive (adapted for N-type power switches).
29
General supply (10.8 V to 13.2 V, 70 mA). It should be filtered to pin 27.
30 & 31
SCL and SDA for the high-speed I²C bus. Threshold voltage is 2.2V typically.
32
Extra V Focus output, to allow separate H Focus and V Focus channels. It provides a parabola at Vertical frequency.
It presents the structure of an emitter follower and requires a 10 k
Ω
pull-down resistor to GND. Quiescent voltage is
4 V.
Warning! The signal polarity may be selected through I²C (Default is: Downwards Concavity
∩
).
Table 2: TDA911x Pin Descriptions (Sheet 2 of 2)
Pin No.
Pin Description