Datasheet
3Maxim Integrated
Evaluates: MAX9617
MAX9617 Evaluation Kit
Noninverting Configuration
The MAX9617 EV kit comes preconfigured as a nonin-
verting amplifier. The gain is set by the ratio of R5 and
R1. The MAX9617 EV kit comes preconfigured for a gain
of 11. The output voltage for the noninverting configura-
tion is given by the equation below:
OUT INP
R5
V (1 ) V
R1
= +
Differential Amplifier
To configure the MAX9617 EV kit as a differential amplifi-
er, replace R1, R2, R3, and R5 with appropriate resistors.
When R1 = R2 and R3 = R5, the CMRR of the differential
amplifier is determined by the matching of the resistor
ratios R1/R2 and R3/R5.
OUT INP INM
V GAIN (V V )= −
where:
R5 R3
GAIN
R1 R2
= =
Sallen-Key Configuration
The Sallen-Key topology is ideal for filtering sensor
signals with a second-order filter and acting as a buf-
fer. Schematic complexity is reduced by combining the
filter and buffer operations. The MAX9617 EV kit can be
configured in a Sallen-Key topology by replacing and
populating a few components. The Sallen-Key topology
can be configured as a unity-gain buffer by replacing
R1 and R5 with 0I resistors. The signal is noninverting
and applied to INP. The filter component pads are R2,
R3, R4, and R8, where some have to be populated with
resistors and others with capacitors.
Lowpass Sallen-Key Filter: To configure the Sallen-Key
as a lowpass filter, populate the R2 and R8 pads with
resistors and populate the R3 and R4 pads with capaci-
tors. The corner frequency and Q are then given by:
c
R2 R8 R3 R4
1
f
2RRCC
=
π
R2 R8 R3 R4
R4 R2 R8
RRCC
Q
C (R R )
=
+
Highpass Sallen-Key Filter: To configure the Sallen-
Key as a highpass filter, populate the R3 and R4 pads
with resistors and populate the R2 and R8 pads with
capacitors. The corner frequency and Q are then given
by:
c
R3 R4 R2 R8
1
f
2RRCC
=
π
R3 R4 R2 R8
R3 R2 R8
RRCC
Q
R (C C )
=
+
Capacitive Loads
Some applications require driving large capacitive loads.
To improve the stability of the amplifier in such cases,
replace R6 with a suitable resistor value to improve
amplifier phase margin.