MAX44205 Evaluation Kit
Evaluates: MAX44205
General Description
The MAX44205 evaluation kit (EV kit) provides a
proven design to evaluate the MAX44205, low-noise, low-
distortion fully differential operational amplifier (op amp),
suitable for driving high-resolution SAR ADCs such as the
MAX11905 family of devices.
The EV kit PCB comes installed with a MAX44205ATC+
in a 12-pin, 3mm x 3mm TQFN package with an exposed
pad.
Quick Start
Required Equipment
●
●
●
MAX44205 EV kit
±5V, 100mA dual DC power supply
Low-distortion differential-output signal genera-
tor (i.e., Audio Precision 2700, Stanford Research
DS360)
2-channel oscilloscope
Two SMA cables of equal length
●
●
Benefits and Features
● Fully Differential Amplifier with 130dBc THD
● +2.7V to +13.2V Supply Voltage Range
● Output-Voltage Clamps to Prevent Overranging ADC
● Adjustable Output Common-Mode Voltage
● Evaluate 20-Bit SAR ADC + MAX44205 Amplifier
(refer to the MAX11905 EV Kit)
● Proven PCB Layout
● Fully Assembled and Tested
Procedure
The EV kit is fully assembled and tested. Follow the
steps below to verify the board operation:
1) Verify that all shunts are in their default positions, as
shown in Table 1.
2) Connect the ±5V supply to the VS+, VS-, and GND
test points, respectively.
3) Use the SMA cables and connect the 10kHz,
6.6Vp-p sine, differential input from the signal
generator to the INP and INM SMAs on the EV kit.
4) Turn on the power supplies.
5) Use the oscilloscope and monitor the differential
output at jumper JU6.
Ordering Information
appears at end of data sheet.
19-7058; Rev 0; 9/14
MAX44205 Evaluation Kit
Evaluates: MAX44205
Table 1. Jumper Functions (Ju1–Ju5)
JUMPER
JU1
JU2
JU3
JU4
JU5
SHUNT POSITION
1-2*
2-3
1-2*
2-3
1-2*
2-3
Not installed
Installed*
Not installed*
Installed
Normal operation
SHDN.
MAX44205 is in shutdown mode.
VCLPH is connected to VS+.
External VCLPH. Apply a voltage no greater than (VS+) + 0.42V at the EXT_VCLPH test point.
VCLPL is connected to VS-.
External VCLPL. Apply a voltage no greater than (VS-) + 0.54V at the EXT_VCLPL test point.
User-supplied VOCM. Apply (VS-) + 1.2V to (VS+) - 1.2V at the VOCM test point.
VOCM is connected to GND.
Disconnects VS- from GND.
Connects VS- to GND.
DESCRIPTION
*Default
position.
Note:
Jumper JU6 has no shunt; it is used for probing only.
Detailed Description of Hardware
The MAX44205 EV kit provides a proven design to
evaluate the MAX44205, low-noise, low-distortion, fully
differential op amp, suitable for driving high-
resolution SAR ADCs such as the MAX11905 family of
devices. Features of the EV kit include jumpers for
SHDN
control, VCLPH/VCLPL voltage-clamping options, and
input for output common-mode voltage (VOCM). The EV
kit is meant to work using dual supplies where the voltage
between VS+ and VS- is +2.7V to +13.2V.
common-mode voltage from (VS-) + 1.2V to (VS+) - 1.2V
at the VOCM test point.
Adjusting the Gain
Adjust the gain by replacing R1–R4 on the EV kit with
appropriate resistors. The gain (A
V
) is as follows:
A
=
V
R3 R4
=
R1 R2
Shutdown Mode (SHDN)
When selecting resistors, use 0.1% tolerance and 10ppm
parts when possible.
Jumper JU1 controls the shutdown mode of the device.
The device is in normal operation when the shunt is
installed in the 1-2 position on jumper JU1. To place
the device in shutdown mode, install a shunt in the 2-3
position on JU1. If the shunt on JU1 is removed, the
device is pulled internally to VS+. This option also allows
a pulse to be sent through the
SHDN
SMA.
Input Termination Resistors
The EV kit has 49.9Ω termination resistors populated at
the R7 and R8 pads at the IN+ and IN- inputs. These
resistors should be removed or replaced appropriately to
match the impedance of the signal source.
Input Filter for ADC
Clamping Voltage (VCLPH and VCLPL)
Jumpers JU2 and JU3 allow the options to connect to
the VS+ and VS- supply rails or external supplies (Table
1). When the device is driving an ADC, connect VCLPH
to the reference voltage of the ADC and VCLPL to the
minimum input voltage (or ground).
Replace R5, R6, and populate C12 appropriately when
driving a high-resolution ADC like the MAX11905.
Additional capacitance can be installed at the C17 and
C18 pads. Refer to
Driving a Fully Differential ADC
section in the MAX44205 IC data sheet.
Component List
Output Common-Mode Voltage (VOCM)
Refer to file “evkit_build_bom_max44205_evkit_a.csv”
attached to this PDF for component information.
Jumper JU4 sets the output common-mode voltage to
0V. If the shunt is removed, apply the desired output
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