The MAX44298 evaluation kit (EV kit) provides a proven
design to evaluate the MAX44298 current, voltage, and
power monitor. The device offers a precision power monitor
with very low offset for low-side monitoring. This EV kit
demonstrates the MAX44298 in an ultra-small, 2.4mm x
2.4mm, 16-bump wafer-level package (WLP) with 0.5mm
bump spacing.
The EV kit PCB is preconfigured with the CSA full-scale
input voltage range (V
SENSE
) of 10mV and 100µA of
output current ranges, but can be reconfigured to
10mV/5mV of FS V
SENSE
or 50µA of output current by
changing a few jumpers.
The EV kit comes with a MAX44298EWE+ and a voltage
divider to provide a forced full-scale V
SENSE
of 10mV
range at the CSA inputs installed.
Quick Start
Required Equipment
●
MAX44298 EV kit
●
+3V to +5.5V, 100mA DC power supply
●
+0.4V to +1.005V DC power supply
●
Precision DC voltage source
●
Five digital multimeters (DMMs)
Before beginning, the following equipment is needed:
Procedure
The EV kit is fully assembled and tested. Follow the steps
below to verify board operation.
Caution: Do not turn on
power supply until all connections are made.
1)
Set the +3V to +5.5V supply to +3.3V and turn it off.
Connect the positive terminal of the supply to the
VDD test point and the negative terminal of the
supply to the nearest GND test point.
Set the +0.4V to +1.005V supply to +1V and turn it
off. Connect the positive terminal of the supply to
the VIN test point and the negative terminal of the
supply to the nearest GND test point.
Set the precision DC voltage source to 5mV and turn
it off. Apply this voltage source across the V
SENSE
inputs as a forced voltage V
SENSE
(i.e., connect the
positive terminal of the DC voltage source to the
RS+ test point and connect its negative terminal to
the RS- test point).
Connect one DMM across RS+ and RS- to monitor the
V
SENSE
input. Connect each DMM to each output of
the device (IOUT, VOUT, POUT, and REF) to monitor
the output voltages.
Enable all supplies.
Observe the output voltage from all four digital
voltmeter displays. Verify that V
IOUT
= 1.2V,
V
VOUT
= 2.4V, V
POUT
= 1.2V and V
REF
= 2.4V.
Features
● Precision Real-Time, Low-Side Current /Voltage/
Power Monitoring
● +3V to +5.5V Single-Supply Voltage Range
●
Proven PCB Layout
●
Fully Assembled and Tested
Ordering Information
appears at end of data sheet.
2)
3)
4)
5)
6)
19-7855; Rev 0; 11/15
MAX44298 Evaluation Kit
Evaluates: MAX44298
Table 1. Jumper Description
JUMPER
JU1
(ISET)
SHUNT
POSITION
1-2
1-3
1-4*
1-2
1-3
1-4*
JU3
(G0)
1-2
1-3
1-4*
1-2*
2-3
1-4
Sets the full-scale output current to 50µA.
Reserved
Sets the full-scale output current to 100µA.
Enters calibration mode, sets the output current to 10µA (for IOUT, VOUT, and POUT) and
full-scale output current set by JU1 (for the REF).
Reserved
Sets the device in normal operation mode and the output current full scale is set by JU1.
Connects G0 to logic 1 to set the full-scale sensing voltage range (VFS). See Table 2.
Reserved
Connects G0 to logic 0 to set the full-scale sensing voltage range (VFS). See Table 2.
Connect G1 to logic1 to set the full-scale sensing voltage range (VFS). See Table 2.
Reserved
Connect G1 to logic 0 to set the full-scale sensing voltage range (VFS). See Table 2.
DESCRIPTION
JU2
(CAL)
JU4
(G1)
*Default configuration
Table 2. Full-Scale V
SENSE
Range Selection
G1
(JU4)
0
1*
1
0
*Default configuration
G0
(JU3)
1
0*
1
0
FS V
SENSE
5mV
10mV*
20mV
R
SENSE
= 1mΩ
5A
10A
20A
R
SENSE
= 2mΩ
2.5A
5A
10A
R
SENSE
= 10mΩ
0.5A
1A
2A
Device enters power-down mode
Detailed Description of Hardware
The MAX44298 EV kit low-side current-sensing measures
the load current by using a precision CSA, allowing
accurate full-scale V
SENSE
ranges of 5mV, 10mV, and
20mV, providing scaled output current at IOUT. The floating
source voltage is measured through a user-selectable
resistive-divider (dividing the source input voltage down
to a full-scale VIN of 1.00V) and provides scaled output
current at VOUT. The device monitors the instantaneous
input power by internally multiplying the scaled load
current by a scaled fraction of the load voltage, providing
scaled output current at POUT. The device also provides
a reference output current at the REF output. All four
output currents are converted to voltages by using scaled
resistors (R3–R6).
Output-Scaling Resistors:
R3, R4, R5, R6, and the ISET Input
The output-scaling resistors should all be the same value
and be of a type with very low temperature coefficients,
with metal film types being recommended. Metal foil is
more effective, though significantly more expensive. The
chosen values of these resistors will depend on the ISET
setting. JU1 determines the full-scale output current range.
When ISET is connected to ground (JU1: 1-2), the full-
scale output current from all four outputs will be 100µA.
When ISET is connected to VDD (JU1: 1-4), the full-scale
current will be 50µA. This can be a simple and convenient
way to change all four scaling resistors simultaneously. The
EV kit is shipped with all four 24kΩ scaling resistors.
www.maximintegrated.com
Maxim Integrated
│
2
MAX44298 Evaluation Kit
Evaluates: MAX44298
Calibration
JU2 sets the device in operational mode (or CAL) mode.
The EV kit is shipped with JU2 in 1-4 position for operational
mode. Set JU2 in 1-2 position to place the device in CAL
mode.
Applying the Source Voltage
The EV kit supports a full-scale sense voltage drop of 5mV,
10mV, and 20mV (see
Table 2
for selections). The EV kit
defaults to the 10mV full-scale setting. For different full-scale
sense ranges and full-scale load current arrangements, the
equation above can be used to determine the appropriate
sense-resistor value.
Other options to evaluate the current-sensing capability
of the MAX44298 are to create a voltage across RS+ and
RS- without applying heavy load current going through
these two test points. Apply a negative voltage to the
VNEG test point (using the resistive-divider R12 and
R13) or a direct precision voltage source across RS+
and RS-. In either case, ensure that the sense voltage
across RS+ and RS- is within its set full-scale range. The
device is shipped with a voltage-divider formed by R12
= 4.99kΩ and R13 = 10Ω. When using this option, the
users should note that there exists approximately 100µA
bias current coming out of the RS- pin due to the CSA
internal gain settings. This input bias current should be
taken into account for error when sensing small currents
in milli-ampere ranges. Therefore, measuring the actual
drop across RS+ and RS- is necessary for accuracy. For
example, applying a negative supply voltage of -5V at the
VNEG test point would give about 9mV across RS+ and
RS- instead of 10mV, theoretically.
For 5mV and 20mV full-scale sense ranges, R12 and R13
should be re-scaled accordingly.
The two options for applying source voltage are through
an external voltage divider (R1 and R2) or as a direct
voltage input (VIN). For using an R1–R2 voltage-divider:
apply the source voltage to IN+ and IN-. For a maximum
input source voltage of say 57V, R1 could be 560kΩ with
R2 being 10kΩ. The voltage-divider, formed by R1 and
R2, provides 1V at the VIN input test point. The second
option is to apply the voltage directly to the VIN test point.
In either configuration, care must be taken not to apply
a voltage greater than 1V to the VIN input of the device.
The EV kit is shipped with the voltage-divider formed by
R1 (560kΩ) and R2 (10kΩ), and a VIN test point as well.
Measuring the Low-Side Load Current
The device measures the unidirection load current
(flowing from RS+ to RS-) as a voltage drop (V
SENSE
)
across an external sense resistor (R14, not installed) and
provides scaled output at IOUT. To ensure proper load
current measurements, the sense resistor must be cho-
sen so that its voltage drop does not exceed the full-scale
sense voltage of the device. The full-scale sense voltage
should be reached when the full-scale load current is
being supplied to the load. The external sense resistor
R14 is determined by setting the full-scale load current
and selecting a full-scale sense voltage that does not
exceed the full-scale sense-voltage rating of the IC:
R
14
=
V
SENSE_FS
I
LOAD_FS
Monitoring the Load Power
The device monitors the instantaneous input power by
internally multiplying the scaled load current and a scaled
fraction of the load voltage and provides scaled output at
POUT.
www.maximintegrated.com
Maxim Integrated
│
3
MAX44298 Evaluation Kit
Evaluates: MAX44298
Component List, PCB Layout, and
Schematic
●
MAX44298 EV BOM
●
MAX44298 EV PCB Layout
●
MAX44298 EV Schematic
Ordering Information
PART
MAX44298EVKIT#
#RoHS-compliant
TYPE
EV Kit
See the following links for component information, PCB
layout diagrams, and schematics.
www.maximintegrated.com
Maxim Integrated
│
4
MAX44298 Evaluation Kit
Evaluates: MAX44298
Revision History
REVISION
NUMBER
0
REVISION
DATE
11/15
Initial release
DESCRIPTION
PAGES
CHANGED
—
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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