Datasheet

3-1
EVM Applications
EVM Applications
Example applications are presented in this chapter. These applications
demonstrate the most popular circuits, but many other circuits can be
constructed. The purpose of the EVM board is for the user to experiment with
different circuits, exploring new and creative design techniques, which is the
function of an evaluation board.
3.1 Default Configuration
Figure 3-1. Default Configuration
Vs-
-
+
U1
2
3
6
7
4
J2
Vin+
J4
Vout
R7
R3
R6
R4
R2
0
Vs+
R5
249 
453 
49.9 
249 
49.9 
Note: This schematic reflects the default THS4271EVM configuration.
Power supply decoupling not shown.
The EVM output provides a 500-Ω load to the output of the EVM to provide
optimum performance (per the data sheet). The load is implemented as a
453-Ω resistor (R6) in series with the output to J4 (V
out
), and a 49.9-Ω output
load resistor (R7) from J4 to ground. The total of these two resistors is close
to 500 Ω, which is the standard load impedance.
When the EVM is monitored with a high input impedance instrument, R7 can
remain on the board, and the EVM provides a 10:1 attenuation of the input
signal.
When the EVM is monitored with an instrument that has an input impedance
of 50 Ω, R7 must be removed. The EVM again provides a 10:1 attenuation.
Chapter 3