19-1034; Rev 0; 11/07
MAX5474 Evaluation Kit
General Description
The MAX5474 evaluation kit (EV kit) is an assembled
and tested printed-circuit board (PCB) that evaluates
the MAX5474 IC. The MAX5474 is a 32-tap, 50kΩ non-
volatile, linear-taper digital potentiometer. Windows
®
2000/XP/Vista-compatible software is available to pro-
vide a convenient user interface for exercising the
MAX5474 features.
The MAX5474 EV kit provides three options to control
the MAX5474 wiper position using logic-input signals.
The MAX5474 logic-input signals can be controlled by
an on-board USB interface circuit, PCB interfacing
pads, or switches on the EV kit circuit for stand-alone
operation.
The EV kit can operate from a 3.3V source generated
from the USB interface circuit or from a 2.7V to 5.25V
external DC power supply. The EV kit can also evaluate
the MAX5475 (100kΩ) after IC replacement (U1).
Features
♦
2.7V to 5.25V Single-Supply Operation
♦
Power-On Recall of Wiper Position from
Nonvolatile Memory
♦
On-Board USB Interface Circuit
♦
USB Powered
♦
USB-PC Connection (Cable Included)
♦
Stand-Alone Operation Using On-Board Switches
♦
PCB Pads for User-Supplied Microcontroller
Interface Signals
♦
PCB Pads for Potentiometer Signals (L, W, H)
♦
Proven USB-Compatible PCB Layout
♦
Evaluates the MAX5474/MAX5475 in 8-Pin SOT23
Package
♦
Windows 2000/XP/Vista (32-Bit)-Compatible
Software
♦
Fully Assembled and Tested
Evaluates: MAX5474/MAX5475
Ordering Information
PART
MAX5474EVKIT+
+Denotes
lead-free and RoHS-compliant.
TYPE
EV Kit
Component List
DESIGNATION
C1, C3–C10,
C17, C21–C26
QTY
DESCRIPTION
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K
TDK C1608X7R1C104K
10µF ±20%, 6.3V X5R ceramic
capacitors (0805)
Murata GRM21BR60J106M
TDK C2012X5R0J106M
10pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H100J
TDK C1608C0G1H100J
1µF ±10%, 10V X5R ceramic
capacitors (0603)
Murata GRM188R61A105K
TDK C1608X5R1A105K
DESIGNATION
QTY
DESCRIPTION
22pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H220J
TDK C1608C0G1H220J
3300pF ±10%, 50V X7R ceramic
capacitor (0603)
Murata GRM188R71H332K
TDK C1608X7R1H332K
Green LED (0603)
Panasonic LNJ314G8TRA
Not installed, ferrite-bead
inductor—short (PC trace) (0603)
Not installed, dual-row 10-pin (2 x 5)
header
Not installed, dual-row 10-pin (2 x 5)
header—short
3-pin header
3-way, 4-pin headers
16
C18, C19
2
C2, C13, C15
3
C20
1
D1
FB1
H1
J1
JU1
1
0
0
0
1
3
C11, C12
2
C14, C16, C27
3
Windows is a registered trademark of Microsoft Corp.
JU2, JU3, JU4
________________________________________________________________
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.
MAX5474 Evaluation Kit
Evaluates: MAX5474/MAX5475
Component List (continued)
DESIGNATION
JU5, JU6
P1
R1
R2
R3
R4
R5
R6, R7
R8
R9, R10
R11
SW1, SW2
SW3
U1
QTY
2
1
1
1
1
1
1
2
0
2
1
2
1
1
DESCRIPTION
2-pin headers
USB type-B right-angle male
receptacle
0Ω ±5% resistor (0603)
220Ω ±5% resistor (0603)
10kΩ ±5% resistor (0603)
2.2kΩ ±5% resistor (0603)
1.5kΩ ±5% resistor (0603)
27Ω ±5% resistors (0603)
Not installed, resistor (0402)
100kΩ ±5% resistors (0603)
51kΩ ±5% resistor (0603)
Single-pole/double-throw (SPDT)
slide switches
Momentary pushbutton switch
Maxim 32-tap, 50kΩ nonvolatile,
linear-taper digital potentiometer
MAX5474EKA+T (8-pin SOT23)
Maxim microcontroller
Maxim MAXQ2000-RAX+ (68-pin
QFN-EP, 10mm x 10mm)
U9
Y1
Y2
U2
1
—
—
—
1
1
1
6
1
1
U7, U8
2
U5
U6
1
1
U4
1
U3
1
DESIGNATION
QTY
DESCRIPTION
93C46 type 3-wire EEPROM (8-pin
SO), 16-bit architecture
Atmel AT93C46A-10SU-2.7
UART-to-USB converter (TQFP-32L,
7mm x 7mm)
FTDI FT232BL
Maxim 3.3V regulator
MAX8511EXK33+T (5-pin SC70)
Maxim 2.5V regulator
MAX8511EXK25+T (5-pin SC70)
Maxim low-voltage logic-level
translators
MAX3374EEKA+T (8-pin SOT23)
Maxim CMOS switch debouncer
MAX6816EUS+T (4-pin SOT143)
16MHz crystal
Citizen HCM49-16.000MABJ-UT
6MHz crystal
Citizen HCM49-6.000MABJ-UT
Shunts
USB high-speed A-to-B cable, 6ft
PCB: MAX5474 Evaluation Kit+
Component Suppliers
SUPPLIER
Murata Mfg. Co.,
Ltd.
Panasonic Corp.
TDK Corp.
PHONE
770-436-1300
800-344-2112
847-803-6100
WEBSITE
www.murata.com
www.panasonic.com
www.component.tdk.com
MAX5474 EV Kit Software Files
FILE
INSTALL.EXE
MAX5474.EXE
USB_Driver_Help.PDF
FTD2XX.INF
UNINST.INI
DESCRIPTION
Installs the EV kit files on the
computer
Application program
USB driver installation help file
USB driver file
Uninstalls the EV kit software
Note:
Indicate that you are using the MAX5474 when contacting
these component suppliers.
2
_______________________________________________________________________________________
MAX5474 Evaluation Kit
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
•
Maxim MAX5474 EV kit (USB cable included)
•
User-supplied Windows 2000/XP/Vista-compatible
PC with a spare USB port
•
One ohmmeter
Note:
In the following sections, software-related items
are identified by bolding. Text in
bold
refers to items
directly from the EV kit software. Text in
bold and
underlined
refers to items from the Windows operating
system.
nect it. Administrator privileges are required to
install the USB device driver on Windows
2000/XP/Vista.
8) Follow the directions of the
Add New Hardware
Wizard
to install the USB device driver. Choose the
Search for the best driver for your device
option.
Specify the location of the device driver to be
C:\Program Files\MAX5474
(default installation
directory) using the
Browse
button. During device
driver installation, Windows may show a warning
message indicating that the device driver Maxim
uses does not contain a digital signature. This is not
an error condition and it is safe to proceed with
installation. Refer to the USB_Driver_Help.PDF doc-
ument for additional information.
9) Start the MAX5474 EV kit software by opening its
icon in the
Start | Programs
menu.
10) The software automatically searches for the
MAX5474. After successful connection, the EV kit soft-
ware main window appears in the upper-left corner of
the window. Select the
Up/Down
buttons to change
the wiper position, or enter the desired wiper position
into the
Wiper Input
combo box (see Figure 1).
See the
Detailed Description of Software
section for
more information on the software features.
Evaluates: MAX5474/MAX5475
Procedure
The EV kit is fully assembled and tested. Follow the
steps below to verify board operation.
Caution: Do not
turn on the power supply until all connections are
completed.
1) Visit www.maxim-ic.com/evkitsoftware to download
the latest version of the EV kit software,
5474Rxx.ZIP. Save the EV kit software to a tempo-
rary folder and uncompress the ZIP file.
2) Install the EV kit software on the computer by run-
ning the INSTALL.EXE program inside the tempo-
rary folder. The program files are copied and icons
are created in the Windows
Start | Programs
menu.
3) Verify that a shunt is installed on pins 1-2 of jumper
JU1. This configures the MAX5474 IC’s VDD to 3.3V
from the USB interface circuit.
4) Verify that a shunt is installed on pins 1-3 of
jumpers JU2, JU3, and JU4. This configures the
logic-input pins to receive signals from the USB
interface circuit.
5) Verify that no shunt is installed on jumpers JU5 and
JU6, the L PCB pad is not connected to GND, and
the H PCB pad is not connected to the W PCB pad.
6) Connect the ohmmeter across the W and L PCB
pads.
7) Connect the USB cable from the PC to the
MAX5474 EV kit. A
Building Driver Database
win-
dow pops up in addition to a
New Hardware
Found
message when installing the USB driver for
the first time. If a window similar to the one
described above does not appear after 30s,
remove the USB cable from the board and recon-
Figure 1. MAX5474 Evaluation Kit Software Main Window
_______________________________________________________________________________________
3
MAX5474 Evaluation Kit
Evaluates: MAX5474/MAX5475
Detailed Description of Hardware
The MAX5474 EV kit demonstrates the MAX5474, a 32-
tap, 50kΩ nonvolatile, linear-taper digital potentiometer
IC’s features. The EV kit uses a MAX5474 IC in an 8-pin
SOT23 package on a proven two-layer PCB design. The
MAX5474 EV kit provides two options to power the
MAX5474 IC. It can operate from the 3.3V supply gener-
ated from the USB interface circuit, or from a user-sup-
plied 2.7V to 5.25V external DC power supply. The USB
interface circuit features MAX3374 low-voltage logic-
level translators (U7 and U8) for 2.7V to 5.25V operation.
Jumper and Switch Functions
Using an External DC Power Supply
The MAX5474 EV kit can be powered by an external
2.7V to 5.25V DC power supply. To connect the EV kit
to an external power supply, disconnect the USB cable
and install a shunt on pins 2-3 of jumper JU1. Turn off
the power supply and connect the power-supply
ground terminal to the EV kit GND pad and the power-
supply positive terminal to the VIN pad. Table 1 lists the
various options for powering the MAX5474 EV kit.
Nonvolatile Memory
Programming Nonvolatile (NV) Memory in Stand-
Alone Operation
In stand-alone operation, the MAX5474 wiper position
is stored in nonvolatile memory whenever the SPDT
slide switch SW1 (CS) is moved from
EN
to DIS (rising
edge) and the pushbutton switch SW3 (INC) is not
depressed (high). The wiper returns to this stored posi-
tion upon power-up.
Software Operation
In software operation, the MAX5474 wiper position is
stored in nonvolatile memory when the
Store
button is
pressed. The MAX5474 wiper returns to this position
upon power-up. After powering up the EV kit, before
changing the wiper position from the nonvolatile memo-
ry position, press the
Reset
button to reinitialize the
wiper to a known position (midscale).
Reset
does not
overwrite the MAX5474 nonvolatile memory; press the
Factory Default
button to reset the NV memory to the
factory-preset position (midscale). See the
Detailed
Description of Software
section for more information.
Table 1. JU1 Jumper Functions (V
DD
)
SHUNT
POSITION
1-2*
Open
2-3
V
DD
PIN
CONNECTED TO
3.3V
No connect
VIN
EV KIT POWERED
FROM
USB interface circuit
Do not use (EV kit will not
be powered)
External power supply
*Default
position.
Interface Control Signals
The MAX5474 EV kit circuit features three logic-input
signals to control the MAX5474 wiper position. The
chip-select (CS), up/down (U/D), and increment (INC)
interface signals are controlled by the on-board USB
interface circuit or the PCB pads, along with user-sup-
plied external control signals, or stand-alone operation
using switches on the EV kit. Jumpers JU2, JU3, and
JU4 select the interface-signal-control sources for the
MAX5474 IC. Table 2 lists the various options for con-
figuring logic-input signal controls.
Table 2. JU2, JU3, JU4 Jumper Functions (CS, U/D,
INC)
SHUNT
POSITION
1-2
1-3*
INTERFACE CONTROL
SIGNALS CONNECTED TO
PCB pads
USB interface circuit
INTERFACE SIGNALS CONTROLLED BY
User-supplied external signals (EV kit software not updated)
USB interface circuit and EV kit software
Stand-alone operation, switches SW1, SW2, SW3 (EV kit software not updated):
• SW1 controls the
CS
signal
• SW2 controls the U/D signal
• SW3 controls the
INC
signal
Do not use this configuration
1-4
Switches
Open
No connect
*Default
position.
4
_______________________________________________________________________________________
MAX5474 Evaluation Kit
The stand-alone-operation switches can be used to
store the MAX5474 wiper position into nonvolatile mem-
ory. To store the MAX5474 wiper position into non-
volatile memory, set the wiper to the desired position
and slide the SPDT switch SW1 (CS) from
EN
to DIS
(rising edge), while pushbutton switch SW3 (INC) is not
depressed (high). The wiper returns to this stored posi-
tion upon power-up.
Voltage-Divider with Ground Reference
The MAX5474 EV kit provides an option to configure
the MAX5474 as a voltage-divider referenced to ground
(GND). To configure the EV kit as a voltage-divider ref-
erenced to ground, connect the L PCB pad to GND
using jumper JU5, connect the voltage source to the H
PCB pad, and the application input signal to the W PCB
pad. Jumper JU5 connects or disconnects the L signal
from GND. Table 3 lists the JU5 jumper options.
Stand-Alone Operation Switches (SW1, SW2, SW3)
The MAX5474 EV kit features three switches to control
the MAX5474 interface signals for stand-alone opera-
tion. SPDT slide switches SW1 and SW2 control the
CS
and U/D signals, respectively, and pushbutton switch
SW3 controls the
INC
signal. The
CS,
U/D, and
INC
sig-
nals interact to control the wiper position of the
MAX5474. Table 5 lists the functions of switches SW1,
SW2, and SW3 for stand-alone operation. Refer to the
Truth Table
in the MAX5474 IC data sheet for specific
switch sequence.
Evaluates: MAX5474/MAX5475
Table 5. Stand-Alone Operation for SW1,
SW2, SW3 Switch Functions (CS, U/D,
INC
Signals)
SWITCH
SW1
SW2
LOGIC-
INPUT PINS
CS
U/D
LOGIC-INPUT PINS FUNCTION
High = U1 disabled
Low = U1 enabled
High = Increment up
Low = Decrement down
Increment if:
CS
= low, U/D = high,
and
INC
=
↓
Decrement if:
CS
= low, U/D = low,
and
INC
=
↓
Table 3. JU5 Jumper Functions (L Signal
and GND)
SHUNT
POSITION
Not installed*
Installed
L PIN
CONNECTED TO
L PCB pad
GND
EV KIT FUNCTIONS
Potentiometer or
variable resistor
Voltage-divider with
ground reference
SW3
INC
*Default
position.
↓
=
High-to-low transition.
Note:
For stand-alone operation:
1) To power the EV kit, connect an external power
supply to V
IN
and GND and install a shunt on pins
2-3 of jumper JU1 (see Table 1).
2) To utilize the switches, install a shunt across pins 1-
4 of jumpers JU2, JU3, and JU4 (see Table 2).
Variable Resistor or Potentiometer
The MAX5474 EV kit configures the MAX5474 as a
potentiometer by default. The EV kit provides an option
to reconfigure the MAX5474 as a variable resistor by
connecting the MAX5474 IC’s H and W pins. To recon-
figure the MAX5474 as a variable resistor, install a shunt
on jumper JU6. Table 4 lists the JU6 jumper options.
Table 4. JU6 Jumper Functions
(H and W pins)
SHUNT
POSITION
Not installed*
Installed
*Default
position.
H AND W PINS
Not connected
Connected
EV KIT FUNCTIONS
Potentiometer
Variable resistor
Evaluating the MAX5475
The MAX5475 is similar to the MAX5474, but has an
end-to-end resistance of 100kΩ. To evaluate the
MAX5475, order a free sample of the MAX5475 and
replace IC U1. The software is compatible with the
MAX5475 IC.
_______________________________________________________________________________________
5
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