jean@maxwell.Concordia.CA ( JEAN GOULET ) (08/03/89)
I am looking for a chip which satisfies the following:
-There are two inputs (composite video signals, actually).
-There is one output (one of the above).
-There is a TTL control line which selects one of the two inputs.
In other words it's just a multiplexer. However, I've only used a 4066, and
that thing doesn't work at high frequencies. Any suggestions?
Oh, and in case you're wondering why I need this, it's for my home computer.
I got this external graphics box for $20 that generates sharp text, but slowly,
while my regular graphics output is fast (but has lower resolution). What
I want to do is switch between the two video outputs under program control so
that I can switch between quickly-drawn menus and slow-but-clear text.
Oh, and thanks in advance to those who will post a suggestion.
Jean Goulet
Electrical Engineering
Class of '89
Concordia University
Montreal, Canadabarry@hprmokg.HP.COM (Barry Fowler) (08/08/89)
How about a Signetics TDA8440 Video and Audio Switch IC. It can switch two groups of two audio inputs and one group of two video inputs. That is, two "SPDT" audio switches and one "SPDT" video switch in effect. The chip is described on page 11-46 of the 1989 Signetics Linear Data Manual Volume 3 (the video manual).
mrb1@cbnewsh.ATT.COM (maurice.r.baker) (08/15/89)
In article <1058@clyde.Concordia.CA>, jean@maxwell.Concordia.CA ( JEAN GOULET ) writes: > I am looking for a chip which satisfies the following: > > -There are two inputs (composite video signals, actually). > -There is one output (one of the above). > -There is a TTL control line which selects one of the two inputs. > Try contacting Maxim Integrated Products, Inc., 120 San Gabriel Drive, Sunnyvale, California 94086. They are at 408-737-7600. The product you may be interested in is the MAX453/454/455 series of video multiplexer/ amplifiers. (The 453 has 2 input channels, 454 has 4 input channels, and the 455 has 8 input channels) They are TTL controllable, and will drive a 75 ohm coax cable. These ICs do require a split +/-5 VDC supply. Maxim is pretty good about supplying parts in small sample quantities. While you are at it, make sure to get a copy of the 1988/89 Seminar Applications Book and the 1989 Integrated Circuits Data Book. Both very useful. It seems to me that Intersil also makes a similar IC, but it may be harder getting info., etc. on it what with all the turmoil in the GE/RCA/Intersil/ Harris melting pot. A quick look at a recent Harris data book "Integrated Circuits for Linear Applications" reveals a part called the CA3256 (listed as "Product Preview") which would do the job quite nicely....it even has LED Drivers to show which of the 4 input channels has been selected! It was originally developed as an RCA part. Hope this helps! M. Baker AT&T-Bell Labs, Holmdel hoqub!mrb