Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF HTML

TDA8722 Datasheet(PDF) 5 Page - NXP Semiconductors

Part No. TDA8722
Description  I2C-bus programmable modulator for negative video modulation and FM sound
Download  28 Pages
Scroll/Zoom Zoom In 100% Zoom Out
Maker  PHILIPS [NXP Semiconductors]
Homepage  http://www.nxp.com
Logo 

TDA8722 Datasheet(HTML) 5 Page - NXP Semiconductors

 
Zoom Inzoom in Zoom Outzoom out
 5 / 28 page
background image
1998 Jun 23
5
Philips Semiconductors
Product specification
I2C-bus programmable modulator for
negative video modulation and FM sound
TDA8722
PINNING
SYMBOL PIN
DESCRIPTION
AUDIO
1
audio input
SOSCA
2
sound oscillator A
SOSCB
3
sound oscillator B
UOSCB
4
UHF oscillator B
OGND
5
RF oscillator ground
UOSCA
6
UHF oscillator A
AMP
7
tuning amplifier output
CP
8
charge pump output
XTAL
9
crystal oscillator
DGND
10
digital ground
VDDD
11
digital supply voltage
SCL
12
serial clock input (I2C-bus)
SDA
13
serial data input (I2C-bus)
P0
14
NPN open-collector output Port
RFB
15
asymmetrical RF output B
RFA
16
asymmetrical RF output A
ADJUST
17
modulation depth and picture-to-sound
distance adjustment pin
AGND
18
analog ground
VIDEO
19
video input
VDDA
20
analog supply voltage
Fig.2 Pin configuration.
handbook, halfpage
TDA8722
MBE394
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
CP
DGND
XTAL
SCL
SDA
AMP
P0
UOSCA
RFB
OGND
RFA
UOSCB
ADJUST
SOSCB
AGND
SOSCA
VIDEO
AUDIO
VDDD
VDDA
FUNCTIONAL DESCRIPTION
The TDA8722 is a programmable modulator which can be
divided into two main blocks:
• A modulator for negative video modulation and
FM sound TV standards
• A programmable PLL frequency synthesizer.
The video part of the modulator consists of a clamping
circuit which sets the internal reference voltage to the
bottom of the synchronizing pulse, followed by a white clip
which avoids over modulation in case the video signal is
too strong. Typically, the IC starts to clip the video signal
when the voltage at the video input (pin 19) is
>560 mV (p-p) while the normal voltage at the video input
is 500 mV (p-p). This clipping function ensures that the
video modulation depth is not too high. The modulation
depth is adjusted in the application between at least
65 and 90% by changing the resistor value between pin 17
and ground (R17). The value can change between 47 k
and infinite (R17 removed); see Fig.10.
The video part also contains a test pattern signal generator
to simplify the adjustment of the receiving channel of the
TV set to the required channel of the modulator. The
pattern consists of a synchronization pulse and two
vertical white bars on screen (see Fig.3).
The audio part of the modulator contains an FM sound
modulator. The frequency of the sound subcarrier is set in
the application by external components (C3, L3 and R3).
The difference between the video carrier level and the
sound subcarrier level is adjusted in the application by
changing the value of the capacitor between pin 17 and
ground (C17). The value can change between
0 and 47 pF. The distance between the video carrier and
the sound subcarrier can be adjusted between at least
−10 and −18 dB (see Fig.11).


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28 


Datasheet Download




Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ]  

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Alldatasheet API   |   Link Exchange   |   Manufacturer List
All Rights Reserved© Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn