General Description
The MAX6639 evaluation kit (EV kit) is an assembled and
tested PCB used to evaluate the MAX6639 dual tempera-
ture sensor/fan controller. The MAX6639 monitors its own
die temperature and the junction temperature of one
external diode-connected transistor, or the junction tem-
peratures of two external diode-connected transistors. It
converts the temperature to 8-bit or 11-bit 2-wire serial
data that can be accessed over a 2-wire serial bus.
The MAX6639 EV kit includes both external diode-connect-
ed transistors (2N3906) soldered to the board, which can
be bypassed to connect the board through a twisted pair
to remote diodes close to your system.
The temperature data is also used by the internal dual
PWM fan-speed controller to adjust the speed of up to
two cooling fans. Speed control is accomplished by
tachometer feedback from the fan.
The EV kit also includes Windows®2000/XP- and
Windows Vista®-compatible software, which provides a
simple user interface for exercising the features of the
MAX6639. The program is menu-driven and offers a
graphical user interface (GUI) complete with control but-
tons. The EV kit comes with the MAX6639AEE+ installed.
Contact the factory for free samples of the pin-compatible
MAX6639FAEE+ and MAX6640AEE+.
The MAX6639 EV kit also evaluates the MAX6640. The
MAX6640 is not recommended for new designs.
Features
oTwo Thermal-Diode Inputs
oLocal Temperature Sensor
oProgrammable Temperature Alarms
oTwo PWM Outputs for Fan Drive
oUp to 25kHz PWM Output Frequency
oProgrammable Fan-Control Characteristics
o3-Wire and 4-Wire Fan Configurations
oOn-Board Microcontroller to Generate
SMBus™/I2C Commands
oUSB-PC Connection (Cable Included)
oWindows 2000/XP- and Windows Vista
(32-Bit)-Compatible Software
oEasy-to-Use, Menu-Driven Software
oLead(Pb)-Free and RoHS Compliant
oFully Assembled and Tested
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-4448; Rev 0; 1/09
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
DESIGNATION QTY DESCRIPTION
C1, C12, C14 3
10µF ±10%, 16V X5R ceramic
capacitors (0805)
Murata GRM21BR61C106K
C2, C3 2
22pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H220J
C4 1
0.033µF ±10%, 25V X7R ceramic
capacitor (0603)
TDK C1608X7R1E333K
C5–C10 , C17,
C18, C19 9
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
C11, C13, C22 3
1µF ±10%, 16V X5R ceramic
capacitors (0603)
TDK C1608X5R1C105K
C15, C16 2
10pF ±5%, 50V C0G ceramic
capacitors (0603)
Murata GRM1885C1H100J
DESIGNATION QTY DESCRIPTION
C20, C21 2
2200pF ±10%, 50V X7R ceramic
capacitors (0603)
Murata GRM188R71H222K
D1, D2, D3 3 Red LEDs (0603)
D4 1 Green LED (0603)
H1 0 Not installed, dual-row (2 x 5)
10-pin JTAG header
J1, J2 2 3-pin headers, 0.1in pitch, vertical,
friction lock
J3, J4 2 4-pin headers, 0.1in pitch, vertical,
friction lock
JU1–JU7 7 3-pin headers
JU8–JU13 0 Not installed, 2-pin headers—shorted
by PCB trace
L1 1 Ferrite bead (0603)
TDK MMZ1608R301A
PART TYPE
MAX6639EVKIT+ EV Kit
+
Denotes lead(Pb)-free and RoHS compliant.
Windows and Windows Vista are registered trademarks of
Microsoft Corp.
SMBus is a trademark of Intel Corp.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
2 _______________________________________________________________________________________
Component Suppliers
SUPPLIER PHONE WEBSITE
Central Semiconductor Corp. 631-435-1110 www.centralsemi.com
Fairchild Semiconductor 888-522-5372 www.fairchildsemi.com
Hong Kong X’tals Ltd. 852-35112388 www.hongkongcrystal.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
TDK Corp. 847-803-6100 www.component.tdk.com
Note: Indicate that you are using the MAX6639 when contacting these component suppliers.
Component List (continued)
DESIGNATION QTY DESCRIPTION
N1, N2 2
n-channel MOSFET, 1.4A, 30V
(3 SOT23)
Fairchild NDS351AN
P1 1 USB type-B right-angle PC-mount
receptacle
Q1, Q2 2 2N3906-type pnp transistors (SOT23)
Central Semi CMPT3906
R1, R2 2 27Ω ±5% resistors (0603)
R3, R19, R20,
R21 41.5kΩ ±5% resistors (0603)
R4 1 470Ω ±5% resistor (0603)
R5 1 2.2kΩ ±5% resistor (0603)
R6, R16, R18 3 10kΩ ±5% resistors (0603)
R7 1 169kΩ ±1% resistor (0603)
R8 1 100kΩ ±1% resistor (0603)
R9–R13 0 Not installed, resistors—shorted by
PCB trace (0402)
R14 1 47Ω ±5% resistor (0603)
R15, R17, R22,
R23, R24 54.7kΩ ±5% resistors (0603)
R25, R26, R27 0 Not installed, resistors (0603)
DESIGNATION QTY DESCRIPTION
R28 1 220Ω ±5% resistor (0603)
U1 1 Temp sensor fan controller (16 QSOP)
Maxim MAX6639AEE+
U2 1 Microcontroller (68 QFN-EP*)
Maxim MAXQ2000-RAX+
U3 1 LDO regulator (5 SC70)
Maxim MAX8511EXK25+
U4 1
Adjustable output LDO regulator
(5 SC70)
Maxim MAX8512EXK+
U5 1 UART-to-USB converter (32 TQFP)
U6 1 93C46 EEPROM (8 SO)
Y1 1
16MHz crystal (HCM49)
Hong Kong X’tals
SSM1600000E18FAF
Y2 1
6MHz crystal (HCM49)
Hong Kong X’tals
SSL600000E18FAF
— 7 Shunts
— 1 USB high-speed A-to-B cable, 6ft
— 1 PCB: MAX6639 Evaluation Kit+
MAX6639 EV Kit Files
*
EP = Exposed pad.
FILE DESCRIPTION
INSTALL.EXE Installs the EV kit files on your
computer
MAX6639.EXE Application program
FTD2XX.INF USB driver file
UNINST.INI Uninstalls the EV kit software
USB_Driver_Help.PDF USB driver installation help file
Quick Start
Recommended Equipment
• A MAX6639 EV kit (USB cable included)
• A user-supplied Windows 2000/XP- or Windows
Vista-compatible PC with a spare USB port
• A power supply to power the fans (the voltage and
current depend on the fans used, but the voltage
must not exceed 30V)
• One or two 3-pin DC fans with tachometer outputs
(each fan must not draw more than 1.4A continuous)
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 under-
lined refers to items from the Windows operating system.
Procedure
The MAX6639 EV kit is fully assembled and tested.
Follow the steps below to verify board operation.
Caution: Do not turn on power supply until all con-
nections are completed.
1) Visit www.maxim-ic.com/evkitsoftware to down-
load the latest version of the EV kit software,
6639Rxx.ZIP. Save the EV kit software to a tempo-
rary folder and uncompress the ZIP file.
2) Install the EV kit software on your 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 all jumpers (JU1–JU7) are in their default
positions, as shown in Table 1.
4) Connect the fan(s) to J1 and J2 on the EV kit board.
5) Connect the fan power supply to the pads labeled
VFAN and FAN_GND.
6) Connect the USB cable from the PC to the EV kit
board. A New Hardware Found window pops up
when installing the USB driver for the first time. If a
window is not seen that is similar to the one
described above after 30s, remove the USB cable
from the board and reconnect it. Administrator priv-
ileges are required to install the USB device driver
on Windows.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
_______________________________________________________________________________________ 3
Table 1. MAX6639 EV Kit Jumper Description Table (JU1–JU7)
JUMPER SHUNT
POSITION DESCRIPTION
1-2* Connects the MAX6639 to the on-board 3.3V supply
JU1 2-3 Connects the MAX6639 to the user-supplied 3.0V to 3.6V supply
1-2* Connects the MAX6639 to the on-board SCL
JU2 2-3 Connects the MAX6639 to the user-supplied SCL
1-2* Connects the MAX6639 to the on-board SDA
JU3 2-3 Connects the MAX6639 to the user-supplied SDA
1-2* Connects the MAX6639 to the on-board ALERT
JU4
2-3 Connects the MAX6639 to the user-supplied ALERT
1-2* Connects pin ADD of the MAX6639 to VCC. Address = 0x5E. If the MAX6640 is used, always use
this jumper in the 1-2 position.
Open Pin ADD of the MAX6639 left unconnected. Address = 0x5C.
JU5
2-3 Connects pin ADD of the MAX6639 to ground. Address = 0x58. Not allowed on the MAX6640.
1-2* Connects the pullup resistor for the TACH1 signal to the voltage VFAN, which is used for 3-wire fans
JU6
2-3 Connects the pullup resistor for the TACH1 signal of the MAX6639 to the voltage VIN, which is used
for 4-wire fans
1-2* Connects the pullup resistor for the TACH2 signal of the MAX6639 to the voltage VFAN, which is
used for 3-wire fans
JU7
2-3 Connects the pullup resistor for the TACH2 signal of the MAX6639 to the voltage VIN, which is used
for 4-wire fans
*
Default position.
Evaluates: MAX6639/MAX6639F
7) 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\MAX6639 (default installation
directory) using the Browse button. During device
driver installation, Windows may show a warning
message indicating that the device driver provided
by Maxim 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
document included with the software for additional
information.
8) Turn on fan power supply.
9) Start the EV kit software by opening its icon in the
Start | Programs menu. The EV kit software main
window should appear as shown in Figure 1. Observe
as the program automatically detects the address of
the MAX6639 and starts the main program.
Detailed Description of Software
User Interface
The user interface is easy to operate. Each button cor-
responds to bits in the command and configuration
byte. By pressing them, the correct I2C-compatible
write operation is generated to update the internal reg-
isters of the MAX6639.
Automatic Read
The program polls the device for the new temperature
and status data a maximum of two times per second
(2Hz). To disable the polling of data, uncheck the Auto
Read checkbox located at the top of the program.
Data Logging
Check the Data Logging checkbox located at the top of
the program to activate data logging. Data logging saves
temperature, voltage, and status data to a text file that
includes a time/date stamp next to each data point. If the
Auto Read checkbox is checked, data is sampled at
2Hz. When the Auto Read checkbox is unchecked, the
MAX6639 Evaluation Kit
4 _______________________________________________________________________________________
Figure 1. MAX6639 EV Kit Software Main Window (Temperature Tab)
data is logged each time Read All is selected from the
Options menu bar. To stop data logging, uncheck the
Data Logging checkbox.
Temperature
The MAX6639 monitors its own die temperature and the
junction temperature of one external diode-connected
transistor, or the junction temperature of two external
diode-connected transistors. The temperature mea-
surements are capable of either 8-bit or 11-bit (extend-
ed) resolution; 8-bit resolution results in a temperature
resolution of 1°C/LSB. Extended resolution results in a
temperature resolution of 0.125°C/LSB and is enabled
by checking the Enable Extended Resolution (0x05)
checkbox (Figure 1).
Read the temperatures by pressing the Read buttons
within the Temperature tab sheet (Figure 1). The tem-
perature is shown to the right of the buttons.
External Diodes
The MAX6639AEE remote temperature sensor is opti-
mized for use with a diode-connected transistor whose
ideality factor is equal to 1.008. Transistors with different
ideality factors produce different remote temperature
readings. Some typical discrete transistors may produce
readings that vary approximately 3°C from the correct
value. Refer to Application Note 1057:
Compensating for
Ideality Factor and Series Resistance Differences Between
Thermal Sense Diodes
for additional information.
ALERT
,
THERM
, and
OT
Temperature Limits
The MAX6639 has ALERT, THERM, and overtempera-
ture (OT) limit registers. Temperatures exceeding the
ALERT limit register generate an alert interrupt.
Exceeding the THERM or OT limits sets the THERM or
overtemperature bit in the status register and asserts
the THERM or OT output pin.
Read a limit by pressing the Read button (Figure 1). The
value (in Celsius) is shown to the right of the button.
Change a limit by entering the value (in Celsius) into the
appropriate edit field and pressing the Write button.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
_______________________________________________________________________________________ 5
Figure 2. MAX6639 EV Kit Software Main Window (Global Configuration Tab)
Evaluates: MAX6639/MAX6639F
Fan-Start Temperature
The minimum fan-start temperature register contains
the temperature at which fan control begins. Note: This
applies only to automatic RPM mode. Refer to the
MAX6639 IC data sheet for more information on auto-
matic RPM mode operation.
Read the minimum fan-start temperature by pressing
the Read button (Figure 1). The value (in Celsius) is
shown to the right of the button. Change the minimum
fan-start temperature by entering the values (in Celsius)
into the edit boxes and pressing the Write buttons.
Global Configuration
The global configuration register has several functions.
Figure 2 displays the checkboxes that configure the
register. Each checkbox corresponds to a bit in the
register. Table 2 describes the function of each check-
box. Read the global configuration register by pressing
the Read button. Change the global configuration reg-
ister by checking or unchecking the desired function
checkbox and pressing the Write button.
Mask
The mask register enables or disables the ALERT, OT,
THERM, or FANFAIL outputs. Figure 3 displays the
checkboxes that configure the register. Each checkbox
corresponds to a bit in the register. Table 3 describes
the function of each checkbox. Read the mask register
by pressing the Read button. Change the mask by
selecting or deselecting the desired masks and press-
ing the Write button.
Status
The Status (0x02) group box displays the critical and
fault conditions that occur. Each line corresponds to a
bit in the registers. See Table 4 for a list of the status
conditions.
Read the status by pressing the Read Status button
within the Status (0x02) group box.
Fan 1 and Fan 2 Configuration 1
The fan 1 Configuration 1 (0x10) and fan 2
Configuration 1 (0x14) group boxes control the modes
of operation of the fans (Figure 4). The Configuration 1
(0x14) group box is not shown, but can be accessed
by navigating to the Fan 2 tab sheet from Figure 4.
These group boxes contain four items: Mode, Rate of
Change, Control, and RPM Range.
The Mode drop-down list has two options: PWM mode
or RPM mode. Select PWM mode to control the PWM
duty cycle manually. RPM mode allows for either man-
ual or automatic control of the fan’s RPM.
The Rate of Change drop-down list sets the time
between adjustments of the duty cycle. Each adjust-
ment is 1/120 of the PWM period. By adjusting the Rate
MAX6639 Evaluation Kit
6 _______________________________________________________________________________________
Table 2. Global Configuration Register Checkboxes
BIT NAME STATE DESCRIPTION
Checked Places the MAX6639 in software standby mode
7STOP Unchecked* Places the MAX6639 in operational mode
Checked
Resets all registers to their default values, including the global configuration
register. After selecting the POR checkbox, the checkbox returns to the
unchecked state.
6POR
Unchecked* Normal operation
Checked* Enables the SMBus timeout
5SMB Timeout
Enabled Unchecked Disables the SMBus timeout, as well as the alert response, thus providing true
I2C compatibility
Checked* The local sensor on the MAX6639 is the source for channel 2
4Channel 2
Source = Local Unchecked The remote sensor connected to DXP2 and DXN is the source for channel 2
Checked Enables high-frequency PWM output on the MAX6639
3High-Freq Enabled
(MAX6639 only) Unchecked* Enables low-frequency PWM output
2Reserved N/A Not used
1Reserved N/A Not used
0Reserved N/A Not used
*
Power-on-reset (POR) state.
of Change drop-down list, audibility of fan-speed
changes can be traded for response time. There are
eight possible options: 0s, 0.0625s, 0.125s, 0.25s,
0.5s, 1s, 2s, or 4s.
The Control drop-down list sets the temperature chan-
nels that control the fan in RPM mode. There are four
options under the control drop-down list: None,
Channel1, Channel2, or Both. Selecting None allows
for manual control of the fan’s RPM. Selecting Channel1,
Channel2, or Both, allows the fan’s RPM to be con-
trolled by the temperature of the selected channel(s).
The RPM Range drop-down list scales the tachometer
counter by setting the maximum (full-scale) value of the
RPM range. There are four possible selections: 2000
RPM, 4000 RPM, 8000 RPM, or 16000 RPM. Select the
closest value that is greater than the fan’s full-speed RPM.
Read the configuration 1 register by pressing the Read
button. Change the configuration by selecting the
desired options and pressing the Write button.
Fan 1 and Fan 2 Configuration 2A
The fan 1 Configuration 2A (0x11) and fan 2
Configuration 2A (0x15) group boxes apply to the
automatic RPM mode (Figure 4). The Configuration 2A
(0x15) group box is not shown, but can be accessed
by navigating to the Fan 2 tab sheet from Figure 4.
These group boxes contain four items: RPM step-size
A, Temp step-size, Positive PWM Polarity, and Min.
speed.
The RPM step-size A drop-down list selects the number
of tachometer counts that the target value decreases for
each temperature-step increase above the fan-start
temperature. The value can be set between 1 and 16.
The Temp step-size drop-down list selects the temper-
ature adjustment for fan control. For each temperature-
step increase, the target tachometer count decreases
by the value of RPM step-size A. The temperature step-
size value can be set to 1 C, 2 C, 4 C, or 8 C.
The Positive PWM Polarity checkbox sets the PWM
output polarity. Checking the Positive PWM Polarity
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
_______________________________________________________________________________________ 7
Figure 3. MAX6639 EV Kit Software Main Window (Mask Tab)
Evaluates: MAX6639/MAX6639F
checkbox results in the PWM output being high at
100% duty cycle. Unchecking the Positive PWM
Polarity checkbox results in the PWM output being low
at 100% duty cycle.
The Min. speed drop-down list selects the value of the
minimum fan speed (when the temperature is below the
fan-start temperature in the automatic RPM mode).
There are two possible selections: 0% duty cycle or
Set by Start TACH. Selecting 0% duty cycle results in
the fan being off when the temperature is below the
fan-start temperature value. Selecting Set by Start
TACH (0x22) or Set by Start TACH (0x23) results in
the fan operating at the minimum speed set for fan 1 or
fan 2.
Read the configuration 2A register by pressing the
Read button. Change the configuration by selecting the
desired options and pressing the Write button.
Fan 1 and Fan 2 Configuration 2B
The fan 1 Configuration 2B (0x12) and fan 2
Configuration 2B (0x16) group boxes also apply to the
automatic RPM mode (Figure 4). The Configuration 2B
(0x16) group box is not shown, but can be accessed
by navigating to the Fan 2 tab sheet from Figure 4.
These group boxes set the tachometer step sizes and
number of steps for step-size A to step-size B slope
changes.
The RPM step-size B drop-down list selects the number
of tachometer counts that the target value decreases for
each temperature-step increase above the fan-start
temperature. The value can be set between 1 and 16.
The Number of steps drop-down list sets the number
of temperature/tachometer steps above the fan-start
temperature at which step-size B begins. The number
of steps can be set between 1 and 16. Read the config-
uration 2B register by pressing the Read button.
Change the configuration by selecting the desired
options and pressing the Write button.
Fan 1 and Fan 2 Configuration 3
The fan 1 Configuration 3 (0x13) and fan 2
Configuration 3 (0x17) group boxes control fan spin-
up, THERM to fan full speed, pulse stretching, and
PWM output frequency (Figure 4). The Configuration 3
(0x17) group box is not shown, but can be accessed
by navigating to the Fan 2 tab sheet from Figure 4.
The fan spin-up feature ensures that the fan starts.
Whenever the fan starts up from zero drive, it is driven
with 100% duty cycle for 2s to ensure that it starts. Fan
spin-up is enabled by default. To disable this feature,
check the Fan Spin Up Disable checkbox.
When the THERM to Fan Full Speed checkbox is
checked, THERM going low—either by being pulled low
MAX6639 Evaluation Kit
8 _______________________________________________________________________________________
Table 3. Mask Register Checkboxes
BIT NAME STATE DESCRIPTION
Checked Disables the channel 1 ALERT interrupts
7Channel 1 ALERT
Mask Unchecked* Enables the channel 1 ALERT interrupts
Checked Disables the channel 2 ALERT interrupts
6Channel 2 ALERT
Mask Unchecked* Enables the channel 2 ALERT interrupts
Checked Prevents OT from being asserted by channel 1 fault
5Channel 1 OT Mask Unchecked* Allows OT to be asserted by channel 1 fault
Checked Prevents OT from being asserted by channel 2 fault
4Channel 2 OT Mask Unchecked* Allows OT to be asserted by channel 2 fault
Checked Prevents THERM from being asserted by channel 1 fault
3Channel 1 THERM
Mask Unchecked* Allows THERM to be asserted by channel 1 fault
Checked Prevents THERM from being asserted by channel 2 fault
2Channel 2 THERM
Mask Unchecked* Allows THERM to be asserted by channel 2 fault
Checked* Prevents FANFAIL from being asserted by channel 1 fault
1FAN 1 Fault Mask Unchecked Allows FANFAIL to be asserted by channel 1 fault
Checked* Prevents FANFAIL from being asserted by channel 2 fault
0FAN 2 Fault Mask Unchecked Allows FANFAIL to be asserted by channel 2 fault
*
Power-on-reset (POR) state.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
_______________________________________________________________________________________ 9
Figure 4. MAX6639 EV Kit Software Main Window (Fan Controls | Fan 1 | Configuration Tab)
Table 4. Status Register
BIT NAME DESCRIPTION
7 Channel 1 ALERT The temperature of channel 1 is above the value set in the channel 1 ALERT limit register.
6 Channel 2 ALERT The temperature of channel 2 is above the value set in the channel 2 ALERT limit register.
5 Channel 1 OT The temperature of channel 1 has exceeded the value set in the channel 1 OT limit register. This bit
returns to zero when the temperature of channel 1 drops 5°C below the channel 1 OT limit.
4 Channel 2 OT The temperature of channel 2 has exceeded the value set in the channel 2 OT limit register. This bit
returns to zero when the temperature of channel 2 drops 5°C below the channel 2 OT limit.
3 Channel 1 THERM The tem p er atur e of channel 1 has exceed ed the val ue set i n the channel 1 THE RM l i m i t r eg i ster . Thi s
b i t r etur ns to zer o w hen the tem p er atur e of channel 1 d r op s 5°C b el ow the channel 1 THE RM l i m i t.
2 Channel 2 THERM The tem p er atur e of channel 2 has exceed ed the val ue set i n the channel 2 THE RM l i m i t r eg i ster . Thi s
b i t r etur ns to zer o w hen the tem p er atur e of channel 2 d r op s 5°C b el ow the channel 2 THE RM l i m i t.
1 Fan 1 Fault A fault has been detected on fan 1. Refer to the MAX6639 IC data sheet for a detailed description.
0 Fan 2 Fault A fault has been detected on fan 2. Refer to the MAX6639 IC data sheet for a detailed description.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
10 ______________________________________________________________________________________
Figure 5. MAX6639 EV Kit Software Main Window (Fan Controls | Fan 1 | Tachometer Tab)
externally or by the temperature exceeding the THERM
limit—forces the fan to full speed at the rate determined
by the rate-of-change setting in configuration 1.
Pulse stretching is used with a pulse-modulated power
supply powering the fan. When modulating the fan’s
power supply with the PWM signal, the PWM pulses are
periodically stretched to keep the tachometer’s signal
available for one full revolution. Check the Pulse
Stretching Disable checkbox to disable this feature.
Always disable pulse stretching when using 4-wire fans.
The PWM Frequency drop-down list sets the frequen-
cy that drives the pulse-modulated power supply. The
frequency can be set to 20Hz, 33.33Hz, 50Hz, or
100Hz. If the High Freq. Enabled (MAX6639 only)
checkbox is checked within the Global Configuration
tab sheet, then the frequency can be set to 5kHz,
8.33kHz, 12.5kHz, or 25kHz.
Read the configuration 3 register by pressing the Read
button. Change the configuration by selecting the
desired options and pressing the Write button.
Fan 1 and Fan 2 Tachometer Count
The fan 1 Tachometer Count (0x20) and fan 2
Tachometer Count (0x21) group boxes control the dif-
ferent tachometer counts (Figure 5). The Tachometer
Count (0x21) group box is not shown, but can be
accessed by navigating to the Fan 2 tab sheet from
Figure 5. The tachometer count value is inversely pro-
portional to the fans’ speed.
Read the tachometer count by pressing the Read button.
Fan 1 and Fan 2 Start or Target
Tachometer Count
The fan 1 Start or Target Tachometer Count (0x22)
and fan 2 Start or Target Tachometer Count (0x23)
group boxes set either the starting tachometer count for
the fan when operating in automatic RPM mode, or the
target tachometer count when operating in manual
RPM mode (Figure 5). The Start or Target Tachometer
Count (0x23) group box is not shown, but can be
accessed by navigating to the Fan 2 tab sheet from
Figure 5. Read the count by pressing the Read button.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
______________________________________________________________________________________ 11
Change the count by entering the value into the
Tachometer count edit box and pressing the Write
button.
Fan 1 and Fan 2 Pulses per Revolution
and Min Tach Count
The fan 1 Pulses per Revolution and Min Tach Count
(0x24) and fan 2 Pulses per Revolution and Min Tach
Count (0x25) group boxes set the number of tachome-
ter pulses per revolution of the fan and the minimum
allowable tachometer count (maximum speed) for the
fan (Figure 5). The Pulses per Revolution and Min
Tach Count (0x25) group box is not shown, but can be
accessed by navigating to the Fan 2 tab sheet from
Figure 5.
The Tach. Pulses per Rev. drop-down list setting has
four options: 1, 2, 3, or 4.
The Min tachometer count edit box can be set to any
value between 0 and 63. Read the pulses per revolu-
tion and minimum tachometer count by pressing the
Read button. Change the pulses per revolution by
selecting the desired number from the drop-down list.
Change the minimum tachometer count by entering the
value into the edit box. Press the Write button to apply
the changes.
Fan 1 and Fan 2 Duty Cycle
The Duty Cycle tab sheet (Figure 6) contains the PWM
duty cycle value. When operating in RPM mode, this
value is controlled by the MAX6639. In PWM mode, this
is the desired (target) PWM duty-cycle value. The value
can be set between 0 and 120. Any number above 120
is changed to 120.
Read the duty-cycle value by pressing the Read but-
ton. Change the duty cycle by entering the value into
the edit box and pressing the Write button.
Alert
The message ALERT appears in the alert box when an
interrupt condition occurs, unless the configuration reg-
ister is set to mask the alert. The cause of the interrupt
is shown in the Status (0x02) group box. To clear the
interrupt, first eliminate the condition that caused it and
then press the Read Alert button.
Figure 6. MAX6639 EV Kit Software Main Window (Fan Controls | Fan 1 | Duty Cycle Tab)
Evaluates: MAX6639/MAX6639F
Save Settings
The MAX6639 EV kit software allows the user to save
desired GUI settings by selecting File | Save Settings
from the menu bar. GUI setting files can be saved only
as .INI files.
Load Settings
To restore a saved GUI setting, select File | Load
Settings from the menu bar. Next, select the .INI file
with the desired GUI settings and observe as the GUI
reconfigures appropriately.
Advanced User Interface
There are two methods for communicating with the
MAX6639, through the normal user-interface main win-
dow or through the SMBus/I2C commands available by
selecting Options | Interface (Advanced Users) from
the menu bar. An Advanced User Interface window
pops up with the 2-wire interface tab selected, which
allows the SMBus/I2C-compatible protocols, such as
read byte and write byte, to be executed. The only
SMBus/I2C-compatible protocols used by the MAX6639
are:
1 - SMBusWriteByte(addr,cmd,data8)
4 - SMBusReadByte(addr,cmd) -> data8
The combo and edit boxes accept numeric data in
hexadecimal and should be prefixed by 0x. See Figure
7 for an example of this tool.
In this example, the software is reading from Device
Address 0101111 r/w (binary), and register address
0x00.
MAX6639 Evaluation Kit
12 ______________________________________________________________________________________
Figure 7. Simple SMBusReadByte Operation Using the Advanced User Interface
Detailed Description of Hardware
The MAX6639 EV kit is an assembled and tested PCB
used to evaluate the MAX6639 dual-temperature sen-
sor/fan controller. The MAX6639 monitors its own die
temperature and the junction temperature of one exter-
nal diode-connected transistor, or the junction tempera-
tures of two external diode-connected transistors. It
converts the temperature to 8-bit or 11-bit 2-wire serial
data that can be accessed over a 2-wire serial bus.
Slave Address
The slave address can be changed by moving jumper
JU5. See Table 1 for address selection.
3-Wire and 4-Wire Fan Configurations
The MAX6639 EV kit is configured for a 3-wire fan by
default when the shunts are placed in the 1-2 position
of jumpers JU6 and JU7.
For 4-wire fan configuration, the user must move the
shunts to the 2-3 position of jumpers JU6 and JU7.
Replacing Diodes
Jumpers JU11 and JU12 connect the 2N3906 transistor
as the external diodes. To use different diodes, cut the
trace, short the two pins of JU11 and JU12, and con-
nect the diodes (through twisted-pair wire) to the DXP1,
DXN, and DXP2 pads.
User-Supplied I2C Interface
To use the MAX6639 with a user-supplied I2C interface,
first move JU2, JU3, and JU4 to the 2-3 position. Then,
connect SCL, SDA, and ALERT to the corresponding
pads on the MAX6639 EV kit.
User-Supplied Power Supply
The MAX6639 EV kit is powered completely from the
USB port by default. Move the shunt of JU1 to the 2-3
position and apply a user-supplied 3.0V to 3.6V power
supply at the EXT_VIN and GND pads.
The fan supply is provided by the user and varies
depending on different fans.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
______________________________________________________________________________________ 13
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
14 ______________________________________________________________________________________
Figure 8a. MAX6639 EV Kit Schematic (Sheet 1 of 2)
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
______________________________________________________________________________________ 15
Figure 8b. MAX6639 EV Kit Schematic (Sheet 2 of 2)
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
16 ______________________________________________________________________________________
Figure 9. MAX6639 EV Kit Component Placement Guide—Component Side
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
______________________________________________________________________________________ 17
Figure 10. MAX6639 EV Kit PCB Layout—Component 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.
18
__________________
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2009 Maxim Integrated Products Maxim is a registered trademark of Maxim Integrated Products, Inc.
Evaluates: MAX6639/MAX6639F
MAX6639 Evaluation Kit
SPRINGER
Figure 11. MAX6639 EV Kit PCB Layout—Solder Side
