General Description
The MAX9940 evaluation kit (EV kit) is an assembled
and tested PCB used to evaluate the MAX9940 high-
voltage signal-line protector for microcontroller ports.
The MAX9940 EV kit demonstrates that microcontroller
ports are protected against high-voltage faults.
The EV kit comes with a MAX9940AXK+ installed.
Features
oOutput Connection to 1-Wire®Device (DS2413)
oPushbutton that Initiates High-Voltage Fault
oLead(Pb)-Free and RoHS Compliant
oProven PCB Layout
oFully Assembled and Tested
Evaluates: MAX9940
MAX9940 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-4520; Rev 0; 3/09
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
C1, C7, C9 3
10μF ±10%, 16V X5R ceramic
capacitors (0805)
KEMET C0805C106K4PACTU
C2, C3, C4 3
0.1μF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
C8 1
1μF ±10%, 16V X5R ceramic
capacitor (0603)
TDK C1608X5R1C105K
C5, C6 2
10pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H100J
D1 1 Green LED (0603)
D2, D3, D4 3 Red LEDs (0603)
D5 0
Not installed, Schottky diode
(3 SOT23)
Fairchild BAT54C
H1 0
Not installed, 2 x 5-pin JTAG
header
JU1 1 3-pin header
R1 1 2k ±5% resistor (0603)
DESIGNATION QTY DESCRIPTION
R2, R3 2 220 ±5% resistors (0603)
R4 1 3k ±5% resistor (0603)
R5 0 Not installed, resistor (0603)
SW1, SW2, SW3 3 Pushbutton switches
U1 1
High-voltage signal-line protector
(5 SC70)
Maxim MAX9940AXK+
U2 1
Microcontroller (68 QFN-EP*)
Maxim MAXQ2000-RAX+
U3 1
LDO regulator (5 SC70)
Maxim MAX8511EXK25+
U4 1
Addressable switch (6 TSOC)
Maxim DS2413P+
Y1 1
16MHz crystal
Hong Kong X’tals
SSM1600000E18FAF
— 1 Shunt
— 1 PCB: MAX9940 Evaluation Kit+
SUPPLIER PHONE WEBSITE
Hong Kong X’tals Ltd. 852-35112388 www.hongkongcrystal.com
KEMET Corp. 864-963-6300 www.kemet.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
TDK Corp. 847-803-6100 www.component.tdk.com
PART TYPE
MAX9940EVKIT+ EV Kit
+
Denotes lead(Pb)-free and RoHS compliant.
1-Wire is a registered trademark of Maxim Integrated Products, Inc.
Note: Indicate that you are using the MAX9940 when contacting these component suppliers.
*
EP = Exposed pad.
Evaluates: MAX9940
MAX9940 Evaluation Kit
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Quick Start
Recommended Equipment
• 3.3V DC power supply
• 28V DC power supply
Procedure
The MAX9940 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on power supplies until all
connections are completed.
1) Connect the 3.3V DC power supply to the VCC and
GND pads on the EV kit.
2) Connect the 28V DC power supply to the FAULT
and GND pads on the EV kit.
3) Verify that a shunt is installed in the 1-2 position on
jumper JU1.
4) Turn on both supplies.
5) Press the START pushbutton (SW2) momentarily
and observe as the green LED (D1) continuously
turns on and off every 500ms for 30 cycles.
6) While the green LED is still blinking, press the
FAULT pushbutton (SW1) and observe as the red
LEDs (D2, D3, and D4) turn on. Once SW1 is deac-
tivated, the red LEDs turn off and the green LED
continues blinking until it reaches the end of its
sequence.
Detailed Description of Hardware
The MAX9940 EV kit is an assembled and tested PCB
used to evaluate the MAX9940 high-voltage signal-line
protector for microcontroller ports. The MAX9940 EV kit
demonstrates that microcontroller ports are protected
against high-voltage faults.
START Pushbutton
Press the START pushbutton (SW2) to start communicat-
ing with the DS2413, dual-channel addressable switch.
The on-board microcontroller commands the DS2413 to
continuously blink the green LED for 30 cycles.
STOP Pushbutton
Press the STOP pushbutton (SW3) to stop communicat-
ing with the DS2413. The green LED should stop blink-
ing if the STOP pushbutton is pressed. If JU1 is in the
2-3 position, then the MAX9940 is also disabled.
FAULT Pushbutton
Press the FAULT pushbutton (SW1) while the microcon-
troller is communicating with the DS2413. The red LEDs
indicate that a voltage is applied to the EXT pin of the
MAX9940.
The absolute maximum voltage of the DATA signal of the
microcontroller (U2) is specified to be (VDDIO + 0.5)V,
i.e., 3.8V.
When the MAX9940 detects a voltage greater than
(VCC + 0.3)V, it automatically turns off, presenting the
high voltage fault signal on its EXT pin from appearing
on the DATA signal line, thus protecting the microcon-
troller from damage.
SHUNT
POSITION DESCRIPTION
1-2* Connects the MAX9940 to the +3.3V supply. Before changing shunt positions, press the STOP pushbutton (SW3).
2-3
Enables the MAX9940 using the MAXQ2000’s GPIO pin, which is used for power saving. Power is only applied when
the START pushbutton (SW2) is pressed. Power is disabled when the MAXQ2000 is done communicating with the
DS2413. Before changing shunt positions, press the STOP pushbutton (SW3). Note: The MAX9940 can withstand
fault voltages even when its VCC = 0.
Table 1. VCC Selection (JU1)
*
Default position.
Evaluates: MAX9940
MAX9940 Evaluation Kit
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Figure 1a. MAX9940 EV Kit Schematic (Sheet 1 of 2)
Evaluates: MAX9940
MAX9940 Evaluation Kit
4 _______________________________________________________________________________________
Figure 1b. MAX9940 EV Kit Schematic (Sheet 2 of 2)
Evaluates: MAX9940
MAX9940 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.
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.
Figure 2. MAX9940 EV Kit Component Placement Guide—
Component Side
Figure 3. MAX9940 EV Kit PCB Layout—Component Side
Figure 4. MAX9940 EV Kit PCB Layout—Solder Side
