|
|
PDF LM1044 Data sheet ( Hoja de datos )
| Número de pieza | LM1044 | |
| Descripción | Analog Video Switch | |
| Fabricantes | National Semiconductor | |
| Logotipo |  |
|
Hay una vista previa y un enlace de descarga de LM1044 (archivo pdf) en la parte inferior de esta página. Total 10 Páginas | ||
|
No Preview Available !
www.DataSheet4U.com
June 1992
LM1044 Analog Video Switch
General Description
Primarily intended for but not restricted to the switching of
video signals the LM1044 is a monolithic DC controlled an-
alog switch with buffered outputs allowing the selection of
three 5 MHz bandwidth 6 dB gain channels or two
RGBaSync 30 MHz bandwidth 0 dB gain channels Chan-
nel selection is achieved via latched TTL compatible logic
inputs which may be controlled by microprocessor derived
signals The device is supplied in a 24 pin dual in line plastic
package
Features
Y Wide RGB bandwidth typically 30 MHz
Y High signal to noise ratio typically 60 dB
Y Excellent channel isolation typically b60 dB 5 MHz
Y High RGB output currents typically 4 mA peak
Y RGB channels may be DC restored or clamped
Y Logically compatible with the LM1038 stereo audio
switch IC
Block Diagram
Order Number LM1044N
See NS Package Number N24A
TL H 9252 – 1
C1995 National Semiconductor Corporation TL H 9252
RRD-B30M115 Printed in U S A
1 page  
Pin Description
Note The pin designations CV R G B and Sync are as-
signed for the convenience of description and are not in-
tended to be a limitation For example RGB could be YUV
or they could all be independent signal sources
Pin 1
Composite video input 1 (CV1) biased internally
via 1 8 kX to VS a 1V
2
Pin 2 Composite video input 2 (CV2) biased as for pin
1 (CV1) above
Pin 3 Composite video input 3 (CV3) biased as for pin
1 (CV1) above
Pin 4
RGB input R1 This pin is internally biased via
a clamp circuit to VS a 1V and should be AC
2
coupled to a low impedance source
The input coupling capacitor also acts as a
clamp capacitor see application notes
Pin 5 RGB input G1 biased as for pin 4 (R1) above
Pin 6 RGB input B1 biased as for pin 4 (R1) above
Pin 7
Sync input S1 biased internally via 2 5k to
VS a 1V
2
Pin 8 RGB input R2 biased as for pin 4 (R1) above
Pin 9 RGB input G2 biased as for pin 4 (R1) above
Pin 10 RGB input B2 biased as for pin 4 (R1) above
Pin 11 Sync input S2 biased as for pin 7 (S1) above
Pin 12 Negative supply (GND)
Pin 13 Connect a capacitor to GND to decouple the
internal bias of the RGB amplifiers
Pin 14 Internal bias for the CV and Sync Amplifiers
decouple with a capacitor to GND
Pin 15 B Output
Pin 16 G Output
Pin 17 R Output
Pin 18
This is the clamp pulse input pin A positive
going pulse activates the RGB input bias
clamps
See application notes
Pin 19 Channel select input control C
Pin 20 Channel select input control B
Pin 21 Channel select input control A
Pin 22
Enable input for control latches Channel
selection is locked while this input is low and is
updated when high The minimum enable pulse
width is 5 ms
Pin 23 CV output or Sync output when an RGB channel
is selected
Pin 24
Supply pin (VS) This pin should be well
decoupled at high frequencies a 100 nF
capacitor connected close to the supply pins is
normally adequate
Application Notes
DEVICE DESCRIPTION
The LM1044 video switch circuit has a configuration as illus-
trated in Figure 1 and consists of a 3 input to 1 output 5
MHz switch with 6 dB gain three 2 input to 1 output 30
MHz 0 dB gain switches coupled together with a 2 input to
1 output switch sharing the 3 way switch output All switch
stages are current switched differential amplifers with feed-
back providing low impedance buffered outputs Latched
logic inputs with control decoding are provided for switch
control and a DC clamp facility is available on the 30 MHz
channels
The principle application of this device is the selection be-
tween various composite video (CV) or Red Green and
Blue (RGB) sources now found in video systems using vari-
ous signal sources e g VCR’s satellite receivers home
computers and video games Other possible application ex-
amples for example security camera switching are shown
towards the end of these notes
The 5 MHz channels are ideally suited for the switching of
composite video sources and have a gain of 6 dB to allow
amplification from terminated inputs back up to internal sig-
nal levels The 30 MHz channels are suitable for direct RGB
inputs to display high quality graphics and will also handle
high quality linear signals The fourth switch channel shares
the CV output pin and is ideal for routing synchronization
signals from the RGB YUV sources into the path to the
sync separator and timebase circuits
CHANNEL SELECTION
The switch selections are made via the enable and 3 logic
control inputs according to the truth table shown on the
following page This gives a choice of 3 CV video signal
sources or 2 RGB plus Sync signals on the video display
FIGURE 1
TL H 9252 – 3
5
5 Page | ||
| Páginas | Total 10 Páginas | |
| PDF Descargar | [ Datasheet LM1044.PDF ] | |
Hoja de datos destacado
| Número de pieza | Descripción | Fabricantes |
| LM104 | Negative Regulator | National Semiconductor |
| LM1040 | DUAL DC OPERATED TONE / VOLUME / BALANCE CIRCUIT | National Semiconductor |
| LM1042 | Fluid Level Detector | National Semiconductor |
| LM1042 | LM1042 Fluid Level Detector (Rev. A) |  Texas Instruments |
| Número de pieza | Descripción | Fabricantes |
| SLA6805M | High Voltage 3 phase Motor Driver IC. |
 Sanken |
| SDC1742 | 12- and 14-Bit Hybrid Synchro / Resolver-to-Digital Converters. |
 Analog Devices |
|
DataSheet.es es una pagina web que funciona como un repositorio de manuales o hoja de datos de muchos de los productos más populares, |
| DataSheet.es | 2020 | Privacy Policy | Contacto | Buscar |