MAX9638EVKIT+ Maxim Integrated Products, MAX9638EVKIT+ Datasheet - Page 3

• Manufacturer Part Number: MAX9638EVKIT+
• Description: Amplifier Modules & Development Tools MAX9638 KIT MAX9638 KIT
• Manufacturer: Maxim Integrated Products

Specifications of MAX9638EVKIT+

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

To configure the EV kit as a differential amplifier, replace
R1, R2, R3, and R5 with appropriate resistors for op
amp A and R9, R10, R15, and R16 for op amp B. When
R1 = R2 and R5 = R3, and R10 = R9 and R15 = R16,
the CMRR of the differential amplifiers is determined by
the matching of the resistor ratios R1/R2 and R3/R5, and
R9/R10 and R15/R16:
where:
where:
The Sallen-Key topology is ideal for filtering sensor
signals with a 2nd-order filter and acting as a buffer.
Schematic complexity is reduced by combining the filter
and buffer operations. The EV kit can be configured in
a Sallen-Key topology by replacing and populating a
few components. The Sallen-Key topology is typically
configured as a unity-gain buffer, which can be done
by replacing R1 and R5 with 0I resistors for op amp
A. The signal is noninverting and applied to INAP. The
filter component pads are R2, R3, R4, and R8, where
some have to be populated with resistors and others with
capacitors. The same idea applies for op amp B; replace
R10 and R15 with 0I resistors and the filter component
pads are R9, R12, R14, and R16.
V
V
OUTA
OUTB
_______________________________________________________________________________________
GainB
GainA
=
=
GainA (V
GainB (V
=
and
=
R10
R15
R5
R1
Sallen-Key Configuration
INAP
INBP
=
=
R3
R2
R16
R9
Differential Amplifier
−
−
V
V
INBM
INAM
)
)
MAX9638 Evaluation Kit
To configure the op amp A Sallen-Key as a lowpass
filter, populate the R2 and R8 pads with resistors and
populate the R3 and R4 pads with capacitors. The
corner frequency and Q are then given by:
The same idea applies for op amp B by replacing R9,
R12, R14, and R16 with the appropriate components.
To configure the op amp A 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:
The same idea applies for op amp B by replacing R9,
R12, R14, and R16 with the appropriate components.
Some applications require driving large capacitive loads.
To improve the stability of the amplifiers in such cases,
replace R6 and R11 with a suitable resistor value to
improve amplifier phase margin.
f
f
C
C
Q
Q
=
=
=
=
2
2
π
π
R
C
R
R
R3
R
R4
R
R3 R4 R2 R8
R2 R8 R3 R4
R2 R8 R3 R4
R3 R4 R2 R8
(C
R
(R
R
R
R
Highpass Sallen-Key Filter
R2
R2
Lowpass Sallen-Key Filter
1
1
C
C
+
+
C
C
C
R
Capacitive Loads
C
C
R8
R8
C
C
)
)
3