參數資料
型號: TDA4885
廠商: NXP SEMICONDUCTORS
元件分類: 消費家電
英文描述: 150 MHz video controller with I2C-bus
中文描述: SPECIALTY CONSUMER CIRCUIT, PDIP32
封裝: 0.400 INCH, PLASTIC, SOT-232-1, SDIP-32
文件頁數: 18/56頁
文件大小: 396K
代理商: TDA4885
1997 Nov 25
18
Philips Semiconductors
Product specification
150 MHz video controller with I
2
C-bus
TDA4885
3.
Definition of output signals (see Fig.6):
Colour signal
: all positive voltages referred to black level at signal outputs.
Nominal colour signal
: colour signal with nominal input signal (0.7V
b-w
), nominal contrast setting and maximum
gain setting.
Video signal
: all positive voltages referred to reference black level at signal outputs. The video signal is the
superposing of the brightness information (
V
bl
) and the colour signal.
The total supply current I
P
= I
7
+ I
29
+ I
24
+ I
19
depends on the supply voltage with a factor of approximately 10 mA/V
and varies in the temperature range of
20 to +70
°
C by approximately
±
10% (V
30, 25, 20
= 0.7 V).
The channel supply current depends on the signal output current, the channel supply voltage and the signal output
voltage. With I
px
= I
29, 24, 19
at V
P1, 2, 3
= 8 V and V
30, 25, 20
= 0.7 V:
3.1mA
4.
5.
6.
Pin 5 should be used for input clamping and blanking during vertical retrace (signal blanking, brightness blanking and
if control bit PEDST = 1 pedestal blanking). With a fast clamping pulse (transition between V
5
= 1.2 to 3.5 V and vice
versa in less than 75 ns/V) no blanking will occur during input clamping.
For 75 ns/V < t
r/f5
280 ns/V the generation of the internal vertical blanking pulse is uncertain, for t
r/f5
> 280 ns/V the
internal blanking pulse will be generated.
Pin 5 open-circuited will activate permanent input clamping and undefined blanking.
Input voltages less than
0.1 V can produce internal substrate currents which disturb the leakage currents at the
signal inputs. An internal protection circuit creates a current for pin voltages of approximately 0 V or less. Feeding
clamping/blanking pulses via a resistor of some k
protects the pin from negative voltages.
Pin 11 should be used for output clamping and/or blanking. Pin 11 open-circuited will activate permanent blanking
and output clamping.
The DC voltage during input clamping is temperature dependent with a factor of approximately 0.5 V/100
°
C (3V
BE
).
10. Composite signals will not disturb normal operations because an internal clipping circuit cuts all signal parts below
input reference black level (see Fig.3).
11. Contrast control acts on internal colour signals under I
2
C-bus control; subaddress 02H
(bit resolution 1.6% of contrast range).
7.
8.
9.
12.
dB
A
x
: colour signal output amplitude in channel x at any contrast setting.
A
x0
: colour signal output amplitude in channel x at nominal contrast and same gain setting.
13. When OSD fast blanking is active and V
2, 3, 4
are HIGH (V
1
> 1.7 V, V
2, 3, 4
> 1.7 V) the OSD colour signals will be
inserted in front of the gain potentiometers. This assures a correct grey scale of all video signals. The amplitudes of
the inserted OSD signals can be controlled simultaneously by OSD contrast via I
2
C-bus.
14. Typical pulse at fast blanking input (pin 1) and response at signal outputs (pins 30, 25 and 20) with nominal input
signals at pins 6, 8 and 10.
15. Typical pulse at fast blanking input (pin 1) as well as OSD inputs (pins 2, 3 and 4) and response at signal outputs
(pins 30, 25 and 20) during OSD fast blanking for maximum OSD contrast, maximum gain adjustment and pins 12,
13 and 14 grounded. Small internal threshold and delay differences between fast blanking and signal insertion might
cause short signal distortion at begin and end of signal insertion (see Fig.10).
16. OSD contrast control acts on inserted OSD colour signals under I
2
C-bus control; subaddress 03H
(bit resolution 6.7% of OSD contrast range).
I
29, 24, 19
I
px
I
30, 25, 20
-V
V
P1, 2, 3
8 V
(
)
×
2.5mA
-V
V
30 25 20
0.7 V
(
)
×
+
+
G
track
20
maximum of
A
1
A
10
--------
A
A
2
--------
×
log
A
1
A
10
--------
A
A
3
--------
×
log
A
2
A
20
--------
A
A
3
--------
×
log
;
;
×
=
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