General Description
The MAX4208 evaluation kit (EV kit) simplifies evalua-
tion of the MAX4208 ultra-low offset/drift, adjustable
gain, precision instrumentation amplifier in a µMAX®
package. The MAX4208 features high-impedance dif-
ferential inputs optimized for small voltages (±100mV
max) and provides rail-to-rail output. The MAX4208 EV
kit is configured for a gain of 148V/V. The EV kit oper-
ates from a single-supply voltage between 2.85V and
5.5V, or dual supplies providing ±1.425V to ±2.75V.
The MAX4208 EV kit can also be used to evaluate the
MAX4209 fixed-gain amplifiers. The MAX4208 IC tem-
perature range is -40°C to +125°C.
The MAX4209 EV kit, available separately, evaluates the
100V/V fixed-gain MAX4209 amplifier without external
gain-setting resistors.
Note: To evaluate a MAX4209 IC featuring internal
gain-setting resistors, order a MAX4209EVKIT+ or
request a free sample of the MAX4209 IC along with the
MAX4208EVKIT+. See the
Part Selection Table
for IC
ordering information.
Features
oSingle- or Dual-Supply Operation
2.85V to 5.5V Single-Supply Operation
±1.425V to ±2.75V Dual-Supply Operation
oAdjustable Voltage Gain Configured to 148V/V
oRail-to-Rail Output
oConfigurable Reference Voltage: Externally or
Internally Buffered
oOptional Current-Sense Mode
oFully Assembled and Tested
Evaluates: MAX4208/MAX4209
MAX4208 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-0997; Rev 0; 9/07
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
Component List Ordering Information
Part Selection Table
PART TYPE
MAX4208EVKIT+ EV Kit
PART GAIN (V/V)
MAX4208AUA+ Adjustable
MAX4209TAUA+ 10
MAX4209HAUA+ 100
MAX4209KAUA+ 1000
DESIGNATION QTY DESCRIPTION
C1, C3 2
10µF ±10%, 10V X5R ceramic
capacitors (0805)
Murata GRM21BR61A106K
KEMET C0805C106K8PAC
C2, C4, C5 3
0.1µF ±10%, 10V X5R ceramic
capacitors (0402)
Murata GRM155R61A104K
KEMET C0402C104K8RACTU
C6, C7 0 Not installed, capacitors (0603)
C8 1
1000pF ±10%, 16V X5R ceramic
capacitor (0402)
Murata GRM155R61C102K
JU1 1 4-pin header
JU2, JU3 2 2-pin headers
R1 1 1kΩ ±0.1% resistor (0805)
IRC PCF-W0805LF-03-1001-B
R2 1 147kΩ ±0.1% resistor (0805)
IRC PCF-W0805LF-03-1473-B
R3, R4 2 4.99kΩ ±1% resistors (0603)
R5, R6 0 Not installed, resistors—short (0603)
R7 0 Not installed, resistor (1206)
U1 1 MAX4208AUA+ (8-pin µMAX)
— 3 Shunts
— 1 PCB: MAX4208 Evaluation Kit+
+
Denotes lead-free and RoHS-compliant
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX4208/MAX4209
MAX4208 Evaluation Kit
2 _______________________________________________________________________________________
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• 5V, 1A-rated DC power supply
• Function generator
• Oscilloscope
Procedure
The MAX4208 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on the power supply until all
connections are completed.
1) Verify that a shunt is installed across pins 1-4 of
jumper JU1 (on-board buffered-reference mode).
2) Verify that a shunt is installed on jumper JU2 (single-
supply operation).
3) Verify that a jumper is not installed on jumper JU3
(buffered-reference mode).
4) Set the DC power-supply output to 5V and disable
the output.
5) Set the function generator output to a 10mVP-P,
200Hz, 0V DC offset sine wave. Terminate the func-
tion generator as needed.
6) Connect the power-supply positive output to the
VDD PCB pad on the EV kit.
7) Connect the power-supply ground to the GND PCB
pad next to VDD on the EV kit.
8) Connect the function generator output across the
differential input PCB pads, IN+ and IN-.
9) Connect the IN- PCB pad to the GND PCB pad with
a wire.
10) Connect the oscilloscope to the OUT PCB pad and
the oscilloscope ground clip to the GND PCB pad.
11) Enable the DC power supply and the function gen-
erator.
12) Verify that the oscilloscope measures a 1.48VP-P,
200Hz, 2.5V DC offset sine wave.
Detailed Description
The MAX4208 EV kit evaluates the MAX4208 instrumenta-
tion amplifier that features adjustable gain with gain-
setting resistors R1 and R2, low offset voltage, and low
offset voltage drift. The output-voltage range is from VSS
+ 100mV, to VDD - 100mV. The MAX4208 EV kit voltage
gain is configured to 148V/V. The EV kit operates from a
single-supply voltage between 2.85V and 5.5V or from
a dual-supply voltage providing ±1.425V to ±2.75V.
The MAX4208 EV kit can evaluate the fixed-gain
MAX4209 ICs in the 8-pin µMAX package by replacing
the MAX4208 IC U1 and removing resistors R1 and R2.
Power Supply
The MAX4208 EV kit jumper JU2 must be configured
properly for single-supply or dual-supply operation. For
single-supply operation, a single power supply is con-
nected to VDD and GND. For dual-supply operation,
connect a positive supply to VDD, a negative supply to
VSS, and supply ground to GND. See Table 1 to config-
ure jumper JU2.
Component Suppliers
Table 1. Power-Supply Configuration
(Jumper JU2)
Note: Indicate that you are using the MAX4208 or MAX4209 when contacting these component suppliers.
SUPPLIER PHONE WEBSITE
IRC 361-992-7900 www.irctt.com
KEMET Corp. 864-963-6300 www.kemet.com
Murata Mfg. Co., Ltd. 770-436-1300 www.murata.com
SHUNT
POSITION VSS PIN EV KIT FUNCTION
Installed Connected to
GND
Single-supply operation.
Power only VDD.
Not installed Not connected Dual-supply operation.
Power VDD and VSS.
REFIN/MODE Operation Modes
The EV kit jumper JU1 configures the MAX4208 for direct
reference, buffered reference, or shutdown mode. The
reference voltage at REF sets the output voltage DC sig-
nal, OUT, when the differential input signal VIN+ - VIN-
equals zero. In direct-reference-mode operation, con-
nect a user reference voltage directly to the REF PCB
pad. In buffered-reference-mode operation, connect a
user reference voltage to the REFIN/MODE input PCB
pad or use the resistor-divider network R3 and R4 to
provide a reference voltage for REFIN/MODE, scaled
from VDD. The network is configured to scale the volt-
age at REFIN/MODE to one-half of VDD. Replace resis-
tors R3 and R4 to modify the voltage applied to
REFIN/MODE using the following equation:
where VDD is the input supply voltage to the EV kit.
In buffered-reference mode, the MAX4208 internally
buffers the REFIN/MODE voltage onto REF.
Note: Do not connect an external source to the REF PCB
pad in buffered-reference mode. See Table 2 for jumper
JU1 configurations.
REF Input
The EV kit’s jumper JU3 must be configured properly
for appropriate reference-voltage operation. In direct
reference mode, install a shunt on jumper JU3 to con-
nect REF to the on-board ground (GND), or remove the
shunt to connect a user reference voltage to the REF
input PCB pad. For either buffered-reference mode,
REF must not be connected to a reference voltage;
thus, the shunt on jumper JU3 must not be installed.
See Table 2 for jumper JU3 configurations.
Optional capacitor C6 can be used for reference-volt-
age stability/filtering. Choose an appropriate value as
needed.
On-Board Current Sensing
The MAX4208 EV kit can be configured for on-board
current sensing by installing a surface-mount 1206
sense resistor at R7, located between the IN+ and IN-
PCB pads. Use the following equation to select the
value for resistor R7:
where IIN is the maximum current flowing across resis-
tor R7 and 30mV is a suggested sense voltage. 30mV x
148V/V gives a 4.4V output swing. Refer to the
R7 30mV
IIN
=
V VDD x R4
R3 R4
REFIN/MODE =+
⎛
⎝
⎜⎞
⎠
⎟
Evaluates: MAX4208/MAX4209
MAX4208 Evaluation Kit
_______________________________________________________________________________________ 3
Table 2. Jumpers JU1 and JU3 Configurations
MODE JU1 SHUNT
POSITION
REFIN/MODE
PIN
JU3 SHUNT
POSITION REF PIN EV KIT FUNCTION
Installed Connected to
GND
JU1 disables the internal REF buffer.
JU3 sets the REF voltage to GND.
Direct-reference-mode
operation 1-2 Connected to
VSS
Not installed
Connected to
user reference
voltage
JU1 disables the internal REF buffer.
JU3 allows the user to set the REF
voltage directly. Apply a user reference
voltage to the REF PCB pad in the 0V
and VDD - 1.6V range.
Shutdown mode 1-3 Connected to
VDD — — Entire IC is in shutdown. ICC < 5µA.
Buffered-reference-
mode operation
(on-board reference)
1-4 Connected to
VDD / 2 Not installed Not connected
The IC buffers the on-board VDD / 2
onto REF. Do not install JU3 or connect
an external source to the REF PCB pad.
Buffered-reference-
mode operation (user
reference)
Not installed
Connected to
user reference
voltage
Not installed Not connected
The IC buffers a user reference voltage
onto REF. Apply a user reference
voltage to the REFIN/MODE PCB pad in
the range of VSS + 200mV and VDD -
1.6V. Do not install JU3 or connect an
external source to the REF PCB pad.
Evaluates: MAX4208/MAX4209
MAX4208/MAX4209 IC data sheet for application
details. Verify that the selected resistor is rated for the
appropriate current and power levels.
For high-power applications, use the IN+ and IN- PCB
pads as sense connections to an off-board current-
sense resistor.
Differential Input Filter
The MAX4208 EV kit features an optional balanced-dif-
ferential resistor-capacitor filter across the MAX4208
IN+ and IN- input pins. Use the surface-mount 0603
PCB pads for installing resistors R5, R6, and capacitor
C7, which form the filter. Before installing resistors R5
and R6, cut open the shorting PCB trace located at the
respective pads.
Gain Setting
The MAX4208 EV kit gain is configured to 148V/V by
resistors R1 and R2. Replacing these resistors with
high-precision, surface-mount 0805 resistors can
change the gain. Tolerance of ±0.1% or better is rec-
ommended for optimum performance. Use the follow-
ing equation to select values for resistors R1 and R2:
R2 = R1 x (Gain - 1)
where R1 ≤1kΩand the sum of R1 + R2 is 10kΩ≤(R1 +
R2) ≤500kΩ.
Evaluating the MAX4209
The MAX4208 EV kit can be used to evaluate the fixed-
gain MAX4209 IC in the 8-pin µMAX package by replac-
ing the MAX4208 IC U1 and removing resistors R1 and
R2. The MAX4209 IC features fixed gains of 10V/V,
100V/V, or 1000V/V. See the
Part Selection Table
for
ordering information.
The MAX4209 EV kit is also available separately.
MAX4208 Evaluation Kit
4 _______________________________________________________________________________________
C2
0.1μF
C8
1000pF
R2
147kΩ
0.1%
R1
1kΩ
0.1%
OUT
GND
REF
JU3
C6
OPEN
5
6
7
8
VDD
OUT
FB
REF
REFIN/MODE
IN-
IN+
VSS
4
3
2
1
C4
0.1μF
C7
OPEN
C5
0.1μF
C3
10μF
JU2
GND
VSS
VSS
R6
SHORT
R5
SHORT
IN+
IN-
R7
OPEN
REFIN/MODE
GND
1
23
4
JU1
R4
4.99kΩ
1%
R3
4.99kΩ
1%
VSS
C1
10μF
MAX4208
U1
VDD
GND
Figure 1. MAX4208 EV Kit Schematic
Evaluates: MAX4208/MAX4209
MAX4208 Evaluation Kit
_______________________________________________________________________________________ 5
Figure 2. MAX4208 EV Kit Component Placement Guide—
(Component Side)
Figure 3. MAX4208 EV Kit PCB Layout—Component Side
Evaluates: MAX4208/MAX4209
MAX4208 Evaluation Kit
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
6
_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2007 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Figure 4. MAX4208 EV Kit PCB Layout—Solder Side
