General Description
The MAX9928 evaluation kit (EV kit) provides a proven
design to evaluate the MAX9928 uni-/bidirectional, high-
side, current-sense amplifier, which offers precision accu-
racy specifications of VOS < 400µV and gain error
< 1.0%. This EV kit demonstrates the MAX9928 in an ultra-
small, 1mm x 1.5mm x 0.6mm, 6-bump UCSP™ package.
The MAX9928 is also available in an 8-pin µMAX®, but
that package is not compatible with this EV kit.
The MAX9928 EV kit PCB comes with a MAX9928FABT+
installed, which is the 5µA/mV gain version. The
MAX9928 EV kit can also be used to evaluate the
MAX9928T, MAX9929F, and MAX9929T (2µA/mV, 50V/V,
and 20V/V, respectively). This EV kit can also evaluate
the MAX4372 in a footprint-compatible UCSP package.
Contact the factory for free samples of the pin-compatible
MAX9928TABT+, MAX9929FABT+, or MAX9929TABT+
devices.
Features
oPrecision Real-Time Current Monitoring
o-0.1V to +28V Input Common-Mode Range
oEvaluates MAX9928, MAX9929, and MAX4372
oVOS < 0.4mV; Gain Error < 1%
oSIGN Bit to Show Charge/Discharge Current Flow
oLead(Pb)-Free and RoHS Compliant
oProven PCB Layout
oFully Assembled and Tested
Evaluates: MAX9928/MAX9929/MAX4372
MAX9928 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-4397; Rev 0; 12/08
Component List
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.
Ordering Information
Component Suppliers
DESIGNATION QTY DESCRIPTION
CIN, COUT 0 Not installed, capacitors (0603)
C3 1
0.1μF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H104K
C4 1
1μF ±10%, 50V X5S ceramic
capacitor (0603)
Taiyo Yuden UMK107C5105KA
DESIGNATION QTY DESCRIPTION
RSENSE 1
0.1 ±1%, 1/2W sensing resistor
(1206)
Vishay/Dale WSL1206R1000FEB18
RIN1, RIN2 0 Not installed, resistors—short
ROUT 1 10k ±1% resistor (0603)
U1 1
Precision current-sense amplifier
(6 UCSP)
Maxim MAX9928FABT+
— 1 PCB: MAX9928 Evaluation Kit+
SUPPLIER PHONE WEBSITE
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Taiyo Yuden 800-348-2496 www.t-yuden.com
Vishay 402-563-6866 www.vishay.com
PART TYPE
MAX9928EVKIT+ EV Kit
+
Denotes lead(Pb)-free and RoHS compliant.
UCSP is a trademark and µMAX is a registered trademark of Maxim Integrated Products, Inc.
Note: Indicate that you are using the MAX9928 when contacting these component suppliers.
Evaluates: MAX9928/MAX9929/MAX4372
MAX9928 Evaluation Kit
2 _______________________________________________________________________________________
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• MAX9928 EV kit
• 5V/10mA DC power supply
• 12V/1A DC power supply
• An electronic load capable of sinking 800mA (e.g.,
HP 6060B)
• Two digital voltmeters
Procedure
The MAX9928 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on the power supply or the
electronic load until all connections are completed.
1) Connect the positive terminal of the 5V supply to
the VCC pad. Connect the negative terminal of the
5V supply to the GND pad.
2) Connect the positive terminal of the 12V supply to
the RS+ pad. Connect the negative terminal of the
12V supply to the GND pad.
3) Set the electronic load to sink 500mA.
4) Connect the electronic load’s positive terminal to
the RS- pad and the negative terminal to the GND
pad.
5) Connect the first voltmeter across the OUT and the
GND pads.
6) Connect the second voltmeter across the SIGN and
the GND pads.
7) Turn on the power supplies.
8) Turn on the electronic load.
9) Verify that the OUT voltmeter reading is approximate-
ly 2.5V and the SIGN voltmeter is approximately 5V.
Take care not to load the internal 1MΩpullup resistor
on the SIGN pin when measuring this voltage.
Detailed Description of Hardware
The MAX9928 evaluation kit (EV kit) provides a proven
design to evaluate the MAX9928 uni-/bidirectional,
high-side, current-sense amplifier, which offers preci-
sion accuracy specifications of VOS < 400µV and gain
error < 1.0%.
Output Voltage Calculation
The MAX9928 EV kit is installed with a MAX9928FABT+,
which has a gain of 5µA/mV. The current-sense resistor
(RSENSE) value is 0.1Ωwith ±1% tolerance. The VOUT is
given by:
VOUT =I
LOAD x RSENSE x Gmx ROUT
where Gm is the gain and ILOAD is the current load
applied to the device. Vary ROUT to change the effec-
tive voltage gain.
Applying VCC and VRS+ Supply Voltages
The normal operating range for VCC is 2.5V to 5.5V for
MAX9928/MAX9929. The normal operating range for
VCC is 2.7V to 28V for MAX4372.
The normal input common-mode range at VRS+ and
VRS- is -0.1V to +28V for MAX9928/MAX9929. The
MAX4372 operates with an input range of 0V to 28V,
but the total OUT error at 0V can be up to 28%.
Measuring the Load Current
The load current is measured as a voltage drop
(VSENSE) across an external sense resistor. This volt-
age is then amplified by the current-sense amplifier
and presented as a current at its output pin and con-
verted to a voltage by ROUT. Like all differential ampli-
fiers, the output voltage has two components of error:
an offset error and a gain error. The offset error affects
accuracy at small VSENSE and a gain error affects
accuracy at large VSENSE. By minimizing both offset
and gain errors, accuracy can be optimized over a
wide dynamic range.
Evaluates: MAX9928/MAX9929/MAX4372
MAX9928 Evaluation Kit
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Figure 1. MAX9929F EV Kit Schematic
Evaluating SIGN Output for
MAX9928/MAX9929
The MAX9928 and MAX9929 have a digital SIGN out-
put to indicate the direction of the load current flow
(charge vs. discharge current for a battery).
To evaluate current flowing in the opposite direction,
swap the position of the 12V supply and the electronic
load (connect the 12V supply to RS- and connect the
electronic load to RS+). Verify that the OUT voltmeter
still reads approximately 2.5V and the SIGN voltmeter
has changed to 0V.
Evaluating MAX9929 or MAX4372
The MAX9929 and MAX4372 are voltage output
devices with an internal 10kΩROUT resistor. When
evaluating these devices, leave the MAX9928 EV kit
ROUT open.
Refer to the MAX9928/MAX9929 IC data sheet and/or
the MAX4372 IC data sheet for more information.
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.
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Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX9928/MAX9929/MAX4372
MAX9928 Evaluation Kit
Figure 2. MAX9928 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX9928 EV Kit PCB Layout—Component Side
Figure 4. MAX9928 EV Kit PCB Layout—Solder Side
