Data Translation Knowledge Base
Additional resistance spec's , DT340
A) Are both channels terminated in a 100 ohm series impedance
B) A 74ALS244 is specified for Channels 4,5,6,7. What is the driver
for Channels 0,1,2,3?
The DT340 is a very high speed I/O Counter
Timer Board. In order to meet the FCC and ce EMI requirements on the clocks we had to properly
terminate the output signals. Channels 0-3 have a C244 driver
with a series 150 ohm resistor. On the output side there is a 301 ohm resistor to ground
. This works out to be a 100 ohm output impedance
. Channels 4-7 are the same except the series resistor is 100 ohms for an output impedance
of 75 ohms. *Dated 07/24/01.