19-2479; Rev 0; 6/02
MAX1238 Evaluation Kit
General Description
The MAX1238 evaluation kit (EV kit) is designed to eval-
uate the MAX1238. The MAX1238 is a 12-bit, 12-chan-
nel (six differential-channel) ADC with a 2-wire serial
interface. The MAX1238 EV kit board supports three
standard 2-wire interface speeds: standard mode
(S-Mode), fast mode (F-Mode), and high-speed mode
(HS-Mode). The software provided with this EV kit only
supports S-Mode.
The provided Windows
®
95/98 software uses the paral-
lel (printer) port of an IBM-compatible PC to emulate a
processor with a 2-wire interface (S-Mode). The
Windows software also provides a friendly graphical-
user interface (GUI) to exercise the features of the
MAX1238 with control buttons and menus.
Order the MAX1238 EV kit for comprehensive evaluation
of the MAX1238 using a personal computer with an
available parallel port.
o
Proven PC Board Layout
o
Windows 95/98 Evaluation Software
o
2-Wire Serial Interface
o
Fully Assembled and Tested
Features
Evaluates: MAX1238
Ordering Information
PART
MAX1238EVKIT
TEMP RANGE
0°C to +70°C
IC PACKAGE
16 QSOP
MAX1238 EV Kit Files
INSTALL.EXE
MAX1238.EXE
Installation program
Application program
Component Suppliers
SUPPLIER
Diodes Inc.
TDK
PHONE
805-446-4800
847-803-6100
WEBSITE
www.diodes.com
www.component.tdk.com
Windows is a registered trademark of Microsoft Corp.
Note:
Please indicate you are using the MAX1238 when contact-
ing these component suppliers.
Component List
DESIGNATION
C1–C4,
C10–C17
QTY
12
DESCRIPTION
0.22µF ±10%, 10V X7R ceramic
capacitors (0603)
TDK C1608X7R1A224KT
100pF ±5%, 50V COG ceramic
capacitor (0603)
TDK C1608C0G1H101JT
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104KT
10µF ±20%, 16V X5R ceramic
capacitors (1210)
TDK C3225X5R1C106M
Zener diodes, Vz = 5.1V
Diodes Inc. BZX84C5V1
3-pin SOT23 top mark KZ2
Surface-mount ferrite bead
(0603)
TDK MMZ1608B601C
DESIGNATION
J1
R1–R4, R17–R24
R5, R7
R6, R8, R9,
R13
R10, R12, R14,
R16
R11, R15
U1
U2
None
None
None
QTY
1
12
2
4
4
2
1
1
1
1
1
DESCRIPTION
Male DB-25 right-angle plug
Mouser 152-3325
14Ω ±1% resistors (0603)
Open (1206) (not installed)
47kΩ ±5% resistors (1206)
100Ω ±5% resistors (1206)
4.7kΩ ±5% resistors (0603)
MAX1238EEE (16-pin QSOP)
Open-collector logic inverter
(14-pin SO)
SN74HC05D
PC board, MAX1238 EV kit
3.5in software disk,
MAX1238 EV kit
MAX1238 data sheet
C5
1
C6, C9
2
C7, C8
2
D1–D4
4
FB1
1
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642,or visit Maxim’s website at www.maxim-ic.com.
MAX1238 Evaluation Kit
Evaluates: MAX1238
Quick Start
Recommended Equipment
Before you begin, the following equipment is needed:
• A fixed +5VDC power supply
• An IBM-compatible PC with Windows 95/98
• An available parallel port (DB-25 female connector on
back of PC)
• A standard 25-pin, straight-through, male-to-female
cable to connect the computer’s parallel port to the
MAX1238 EV kit board
3) Connect a +5VDC power supply between the +5V
and the GND pads of the MAX1238 EV kit board.
4) Start the MAX1238 EV kit program by clicking its
icon in the
Programs
section within the
Start
menu.
5) Apply an analog input voltage (0V to +V
REF
)
between the AIN0 and GND pads of the MAX1238
EV kit board.
6) The program automatically detects the MAX1238
EV kit board and displays
2-Wire Hardware
Detected
in green. The
AIN0
label automatically
displays the voltage applied to the pad labeled
AIN0 on the MAX1238 EV kit board.
Procedure
1) Connect a cable from the computer’s parallel port
to the MAX1238 EV kit board. Use a 25-pin straight-
through, female-to-male cable.
2) Install the MAX1238 EV kit software on your computer
by running the INSTALL.EXE program on the floppy
disk. The program files are copied and icons are cre-
ated in the
Programs
section within the
Start
menu.
Detailed Description
of Software
The evaluation software’s main window (shown in
Figure 1) controls the setup byte and configuration
byte. It also displays the voltage and output code of the
input signal(s), depending on the configuration of the
MAX1238.
Figure 1. MAX1238 Evaluation Software Main Window
2
_______________________________________________________________________________________
MAX1238 Evaluation Kit
Read ADC
The
Read ADC
button manually reads the MAX1238
while using the current setup and configuration byte set-
tings. When the
AutoRead
checkbox is checked, the
software automatically reads the MAX1238 approxi-
mately every 300ms.
AutoRead
allows users to modify
the setup and configuration bytes on-the-fly without hav-
ing to manually press the
Read ADC
button each time.
Detailed Description
of Hardware
The MAX1238 is a 12-channel (six differential-channel)
12-bit ADC with a 2-wire serial interface. The open-col-
lector inverter (U2) interfaces the PC parallel port to the
2-wire serial interface. U2 and the associated circuitry
are only required when interfacing to the parallel port.
Power the MAX1238 EV kit from a +5VDC power sup-
ply. To prevent damage to the MAX1238 EV kit, do not
exceed +5.5VDC on the supply.
Evaluates: MAX1238
Setup Byte
The
Setup Byte
always begins with a start bit value of
one. The
SEL2, SEL1,
and
SEL0
bits control the state
of the reference. The
CLK
bit selects either internal
clock or external clock mode. The
UNI/BIP
bit selects
either unipolar or bipolar mode. Setting
RST
to zero
resets the configuration register. The setup register
remains unchanged. The
X Don’t Care
bit can be
ignored. Refer to the MAX1238 data sheet for more
information on the
SEL2, SEL1,
and
SEL0
bits within
the
Setup Byte.
User-Supplied 2-Wire Interface
The MAX1238 EV kit provides a proven PC board lay-
out and software to evaluate the features of the
MAX1238. The Windows software only supports a
2-wire serial interface in S-Mode. To evaluate the
MAX1238 with a user-supplied 2-wire serial interface in
F-Mode or HS-Mode, do the following:
1) Disconnect the MAX1238 EV kit from the PC parallel
port.
2) Install 3kΩ resistors at locations R5 and R7. (This
resistor value may require optimization for each
system.)
3) Connect the user-supplied 2-wire bus to the SDA,
SCL, and GND pads. (Connect to the GND pad
nearest the 5V pad on the MAX1238 EV kit board.)
4) Refer to the MAX1238 data sheet to ensure all tim-
ing specifications are met.
Config Byte
The
Config Byte
always begins with a start bit value of
zero. The
SCAN1
and
SCAN0
bits select the scanning
mode. The CS3, CS2, CS1, and CS0 bits select one of
the 12 analog input channels. The
SE/DIFF
bit selects
either single-ended or differential mode. Refer to the
MAX1238 data sheet for more information on the
SCAN1, SCAN0, CS3, CS2, CS1,
and
CS0
bits within
the
Config Byte.
Reference Voltage
The evaluation software assumes a +4.096V reference
voltage, unless otherwise specified. To override the
internal 4.096V reference value, ensure bit
SEL2
equals zero and bit
SEL1
equals one within the
Setup
Byte.
Then, apply the new reference voltage at the
VREF pad on the board, type in the new reference volt-
age, without the volt unit, and press the Set
V
ref
button.
The EV kit software uses the value typed in the V
ref
field
to translate the digital code to a voltage.
Keyboard Navigation
When you type on the keyboard, the system must know
which control should receive the keys. Press the
TAB
key to move the keyboard’s focus from one control to
the next. The focused control is indicated by a dotted
outline.
SHIFT + TAB
moves the focus to the previously
focused control. Buttons respond to the keyboard’s
SPACE
bar. Some controls respond to the keyboard’s
UP
and
DOWN
arrow keys. Activate the program’s
menu bar by pressing the
F10
key, and then press the
letter of the menu item you want. Most menu items have
one letter underlined, indicating their shortcut key.
_______________________________________________________________________________________
3
MAX1238 Evaluation Kit
Evaluates: MAX1238
DVDD
+5V
SDA
SDA
10
SCL
SCL
R1
14Ω
1%
R2
14Ω
1%
R3
14Ω
1%
R4
14Ω
1%
R17
14Ω
1%
R18
14Ω
1%
C1
0.22µF
2
C2
0.22µF
3
C3
0.22µF
4
C4
0.22µF
5
C10
0.22µF
6
C11
0.22µF
AIN1
AIN10
9
SCL
AIN8
16
C14
0.22µF
15
C15
0.22µF
14
C16
0.22µF
R24
14Ω
1%
C17
0.22µF
R20
14Ω
1%
C13
0.22µF
7
C12
0.22µF
R19
14Ω
1%
SDA
V
DD
12
C5
100pF
C6
0.1µF
R21
14Ω
1%
R22
14Ω
1%
C7
10µF
FB1
+5V
AIN8
AIN0
1
AIN0
AIN9
U1
AIN9
AIN1
MAX1238
R23
14Ω
1%
AIN10
VREF
AIN2
AIN2
REF/AIN11
AIN3
GND
13
11
AIN11
GND
AIN3
AIN4
AIN4
AIN7
8
AIN7
AIN5
AIN8
AIN5
AIN6
Figure 2. MAX1238 EV Kit Schematic (Sheet 1 of 2)
4
_______________________________________________________________________________________
MAX1238 Evaluation Kit
Evaluates: MAX1238
J1-5
DVDD
J1-13
J1-18
J1-11
J1-19
J1-20
J1-21
J1-22
J1-23
J1-24
J1-DB-25 CONNECTOR
J1-25
J1-3
1
3
1
D1
R12
100Ω
3
D2
R11
4.7kΩ
U2-B
74HC05
3
4
14
C9
0.1µF
C8
10µF
11
R10
100Ω
R9
U2-A
47kΩ
74HC05
2
1
R6
47kΩ
R5
OPEN
SDA
U2-E
74HC05
10
DVDD
DVDD
DVDD
J1-1
J1-4
J1-6
J1-7
J1-8
J1-9
J1-10
J1-14
J1-15
J1-16
J1-17
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
N.C.
DVDD
DVDD
DVDD
13
7 12
U2-F
74HC05
J1-12
R14
100Ω
3
1
D3
R16
100Ω
3
J1-2
D4
1
R13
U2-C
47kΩ 74HC05
6
5
R8
47kΩ
R7
OPEN
SCL
U2-D
74HC05
9
R15
4.7kΩ
8
N.C.
N.C.
Figure 2. MAX1238 EV Kit Schematic (Sheet 2 of 2)
_______________________________________________________________________________________
5
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