totty@flute.cs.uiuc.edu (Brian Totty) (12/03/90)
I need an RS232 driver chip to send data to a Sparc station. The Sparc seems to have data between a range of +5 and -5 volts. I have a +5/-5 volt power supply here, but my 1488 drivers seem to want a 6 or 7 volt supply minimum. What I want is to take a TTL input, provide +5 and -5 volt supplies and get a -5 to +5 output. Anyone want to suggest me a chip? / Brian Totty o o /__ __ o 1304 W. Springfield Avenue o / / / / Urbana, IL 61801 \_/ "We have corn in /__/ / / totty@cs.uiuc.edu Massachusetts too!"
ftpam1@acad3.alaska.edu (MUNTS PHILLIP A) (12/03/90)
In article <1990Dec2.220302.10794@julius.cs.uiuc.edu>, totty@flute.cs.uiuc.edu (Brian Totty) writes... > > I need an RS232 driver chip to send data to a Sparc station. The > Sparc seems to have data between a range of +5 and -5 volts. I have > a +5/-5 volt power supply here, but my 1488 drivers seem to want a > 6 or 7 volt supply minimum. What I want is to take a TTL input, > provide +5 and -5 volt supplies and get a -5 to +5 output. Anyone > want to suggest me a chip? > > > / Brian Totty o o > /__ __ o 1304 W. Springfield Avenue o > / / / / Urbana, IL 61801 \_/ "We have corn in >/__/ / / totty@cs.uiuc.edu Massachusetts too!" There are a number of possibilities, with tradeoffs between cost and complexity. First, you can use 14C88 drivers from National Semiconductor. These are supposed to be able to run off +/- 5V. They have the advantage of being pin compatible with the standard 1488. Motorola makes a device, the 145406 (I think), which is a new CMOS design that isn't compatible with anything else. It has both drivers and receivers on one chip and runs on +/- 5V. Finally, you can use the MAX232 which also has both drivers and receivers on one chip. This can run on a single 5V supply but you need to add 4 small capacitors for the on board voltage generators. The advantage of the MAX232 is it has many more sources than either of the others. There is also a MAX233, my personal favorite, that has the capacitors integrated, but it is single sourced from Maxim, as far as I know. Digi-Key catalogs the MAX232 (listed as ICL232) at $4.80. JDR Microdevices lists it at $7.95. Jameco lists the 14C88 at $1.19. I couldn't find a hobbyist source for the 145406. Philip Munts N7AHL NRA Extremist, etc. University of Alaska, Fairbanks
ron_pool@nysaes.cornell.edu (Ron Pool) (12/04/90)
In article <1990Dec3.054329.5931@hayes.ims.alaska.edu> ftpam1@acad3.alaska.edu (MUNTS PHILLIP A) writes: > Finally, you can use the MAX232 which also has both drivers and receivers > on one chip. This can run on a single 5V supply but you need to add 4 small > capacitors for the on board voltage generators. The advantage of the MAX232 > is it has many more sources than either of the others. There is also a MAX233, > my personal favorite, that has the capacitors integrated, but it is single > sourced from Maxim, as far as I know. Active Electronics lists the MAX233. I think they have a $25 minimum but will sell to individuals. The 800 number directory assistance should have Active's number (call 1-800-555-1212 and ask for the 800 # for Active). - - - - - Ron Pool, Extension Electronic Technology Group CENET: RON POOL Internet: ron_pool@nysaes.cornell.edu - - - - -
totty@flute.cs.uiuc.edu (Brian Totty) (12/04/90)
Looks like MAX232/3 is the clear winner. Thanks for all the suggestions! --- Bri