The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
From: Winfield Hill
Subject: Re: Is this chip suitable for video signal switching?
Date: 18 Jan 2003 04:56:24 -0800
Organization: Rowland Institute
X-Newsreader: Direct Read News 4.20
> BarryNL wrote:
>> I pulled an MC14066B chip out of an old video ...
> A 74hc4066 will do much better, but has a 5 volt power supply
> max I think. At max voltage these things work fastest.
Even better suited are the 74hc4053 and 74hc4052 types of chips
(3PDT and DP4T, resp.) which can be run from +/-5V with signals
at 0V. http://www.onsemi.com/pub/Collateral/MC74HC4051A-D.PDF
and http://www-s.ti.com/sc/psheets/schs122c/schs122c.pdf Note
that TI offers free samples.
The hc4052 4:1 switch has an on resistance of about 30 ohms with
+/-5V supplies and a self capacitance of 45pF max, allowing over
30MHz bandwidth (don't forget the 75-ohm source impedance), much
more than you need.
Although these cmos switches can be used by themselves for video
switching, it's a good idea to buffer the switch's output with
an opamp or other 2x gain circuit, to which you can add a 75-ohm
series output resistor to match coax and termination impedances.
Use an opamp with an f_T or GBW of at least 20MHz.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup