19-4542; Rev 0; 4/09
MAX4374 Evaluation Kit
General Description
The MAX4374 evaluation kit (EV kit) provides a proven
design to evaluate the MAX4374 low-cost, micropower,
high-side current-sense supervisor that contains a high-
side current-sense amplifier, bandgap reference, and
comparator with latching output. This EV kit demonstrates
the MAX4374 in a 10-pin µMAX
®
package. The MAX4374
is also available in 14-pin SO, but that package is not
compatible with this EV kit.
The MAX4374 EV kit PCB comes with a MAX4374FEUB+
installed, which is the 50V/V gain version. The MAX4374
EV kit can also be used to evaluate the MAX4374T
(20V/V gain version), MAX4374H (100V/V gain version),
MAX4375T (20V/V gain version), MAX4375F (50V/V gain
version), and MAX4375H (100V/V gain version). Contact
the factory for free samples of the pin-compatible
MAX4374TEUB+, MAX4374HEUB+, MAX4375TEUB+,
MAX4375FEUB+, or MAX4375HEUB+ devices.
Features
o
Precision Real-Time Current Monitoring
o
Overcurrent Protection and Reset Circuits
o
Overvoltage Indicator Circuit
o
0 to 28V Input Common-Mode Range
o
50µA Supply Current
o
1mV (max) Input Offset Voltage
o
2% (max) Full-Scale Accuracy
o
Lead(Pb)-Free and RoHS Compliant
o
Proven PCB Layout
o
Fully Assembled and Tested
Evaluates: MAX4374/MAX4375
Ordering Information
PART
MAX4374EVKIT+
TYPE
EV Kit
µMAX is a registered trademark of Maxim Integrated Products, Inc.
+Denotes
lead(Pb)-free and RoHS compliant.
Component List
DESIGNATION QTY
C1
1
DESCRIPTION
0.1µF ±10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C104K
4.7µF ±10%, 6.3V X5R ceramic
capacitor (0603)
Murata GRM188R60J475K
0.22µF ±10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C224K
10µF ±20%, 25V X5R ceramic
capacitor (1206)
Murata GRM31CR61E106K
Not installed, capacitor
30V, 12A p-channel MOSFET (6 SC70)
Vishay SiA421DJ
30V, 2.5A dual n-channel MOSFET
(6 SuperSOT)
Fairchild FDC6561AN
U1
—
1
1
DESIGNATION QTY
R
SENSE
R1, R3
R2
R4
R5
R6
R8
R7, R9
S1
1
2
1
1
1
1
1
2
1
DESCRIPTION
0.075Ω ±1%, 1/2W sensing resistor
(1206)
IRC LRC-LR1206LF-01-R075-F
10kΩ ±5% resistors (0603)
100kΩ ±5% resistor (0603)
20kΩ ±5% resistor (0603)
470kΩ ±5% resistor (0603)
52.3kΩ ±1% resistor (0603)
205kΩ ±1% resistor (0603)
10kΩ ±1% resistors (0603)
Pushbutton switch
Current-sense amplifier (10 µMAX)
Maxim MAX4374FEUB+
PCB: MAX4374 Evaluation Kit+
C2
1
C3
1
C4
C5
M1
1
0
1
M2
1
________________________________________________________________
Maxim Integrated Products
1
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.
MAX4374 Evaluation Kit
Evaluates: MAX4374/MAX4375
Component Suppliers
SUPPLIER
Fairchild Semiconductor
IRC, Inc.
Murata Electronics North America, Inc.
Vishay
PHONE
888-522-5372
361-992-7900
770-436-1300
402-563-6866
www.irctt.com
www.murata-northamerica.com
www.vishay.com
WEBSITE
www.fairchildsemi.com
Note:
Indicate that you are using the MAX4374 when contacting these component suppliers.
Quick Start
Recommended Equipment
•
•
•
•
•
MAX4374 EV kit
5V/10mA DC power supply
12V/1.5A DC power supply
An electronic load capable of sinking 1.1A (e.g., HP
6060B)
Two digital voltmeters
10) Slowly increase the sink current to above 1A. When
the OUT voltage reaches approximately 3.75V, the
comparator output of the part trips the PMOS
switches and shuts off the load-current path.
11) Verify that the overcurrent circuitry shuts off the
load current.
12) Reset the current path by pressing the S1 pushbut-
ton after an overcurrent condition.
Detailed Description of Hardware
Procedure
The MAX4374 evaluation kit (EV kit) provides a proven
design to evaluate the MAX4374 low-cost, micropower,
high-side current-sense supervisor that contains a high-
side current-sense amplifier, bandgap reference, and
comparator with latching output. This EV kit demon-
strates the MAX4374 in a 10-pin µMAX package. The
MAX4374 is also available in 14-pin SO, but that pack-
age is not compatible with this EV kit.
The MAX4374 EV kit is fully assembled and tested.
Follow the steps below to verify the board operation.
Caution: Do not turn on power supply or the elec-
tronic 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 VIN 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 LOAD pad and the negative terminal to the
GND pad.
5) Connect the first voltmeter across the OUT and GND
pads.
6) Connect the second voltmeter across the COUT2
and GND pads.
7) Turn on the power supplies.
8) Turn on the electronic load.
9) Verify that the OUT voltmeter reading is approximately
1.875V and the COUT2 voltmeter is approximately 0V.
Measuring the Load Current
The load current is measured as a voltage drop
(V
SENSE
) across an external sense resistor. This volt-
age is then amplified by the current-sense amplifier and
presented as a voltage at its output pin (OUT). Like all
differential amplifiers, the output voltage has two com-
ponents of error, an offset error and a gain error. The
offset error affects accuracy at low V
SENSE
and the
gain error affects accuracy at large V
SENSE
. By mini-
mizing both offset and gain errors, accuracy can be
optimized over a wide dynamic range.
Output-Voltage Calculation
The MAX4374 EV kit is installed with a MAX4374FEUB+,
which has a gain of 50V/V. The current-sense resistor
(R
SENSE
) value is 0.075Ω with ±1% tolerance. The V
OUT
is given by:
V
OUT
= I
LOAD
x R
SENSE
x A
V
where A
V
is the gain and I
LOAD
is the current load applied
to the device. Note that A
V
for the MAX4374FEUB+ is
50V/V.
2
_______________________________________________________________________________________
MAX4374 Evaluation Kit
Overcurrent Protection Circuit
The MAX4374 evaluation kit (EV kit) has an on-board
overcurrent protection circuit. The overcurrent protec-
tion circuit uses the latched output (COUT1) to control
the external p-channel MOSFET (M1) through a level
translator (M2). M1, controlled by the MAX4374, opens
the current path during overload conditions. When the
load current exceeds 1A, COUT1 turns M1 off. Reset
the current path by pressing the pushbutton (S1) after
an overcurrent condition.
Overvoltage Indicator Circuit
The MAX4374 evaluation kit (EV kit) uses the open-
drain comparator output (COUT2) as the overvoltage
indicator. The COUT2 pin is at 0V when VIN is below
13V. When VIN is above 13V, COUT2 will be pulled
high to VCC by the external pullup resistor.
Evaluates: MAX4374/MAX4375
_______________________________________________________________________________________
3
MAX4374 Evaluation Kit
Evaluates: MAX4374/MAX4375
Figure 1. MAX4374 EV Kit Schematic
4
_______________________________________________________________________________________
MAX4374 Evaluation Kit
Evaluates: MAX4374/MAX4375
Figure 2. MAX4374 EV Kit Component Placement Guide
Figure 3. MAX4374 EV Kit PCB Layout—Component Side
Figure 4. MAX4374 EV Kit PCB Layout—Solder Side
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________
5
© 2009 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.
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