19-4069; Rev 0; 3/08
MAX6620 Evaluation Kit/Evaluation System
General Description
The MAX6620 evaluation system (MAX6620EVCMAXQU+)
consists of the MAX6620 evaluation kit (MAX6620EVKIT+)
and the Maxim CMAXQUSB+ command module.
Windows 2000/XP/Vista
®
-compatible software is also
available for use with the MAX6620 evaluation system (EV
system) and can be downloaded from the Maxim website
(www.maxim-ic.com/evkitsoftware).
The MAX6620 evaluation kit (EV kit) is a fully assembled
and tested printed-circuit board (PCB) that evaluates
the MAX6620 quad linear fan-speed controller. The
MAX6620 controls the speeds of up to four fans using
four independent linear voltage outputs. The EV kit
includes 3-pin fan headers to allow easy fan connection
and an I
2
C/SMBus™-compatible interface that allows
for software control of the drive voltage, tachometer
count, fan configuration, and fan dynamics.
The Maxim CMAXQUSB command module provides
the I
2
C/SMBus interface and is connected to the com-
puter through the universal serial bus (USB) port. The
MAX6620 EV kit software provides a graphical user
interface (GUI) for exercising the MAX6620 features.
♦
3V to 5.5V Supply Voltage Range
♦
Controls Up to Four Independent Fans with Linear
(DC) Drive
♦
Uses Four External Low-Cost PNP Pass
Transistors
♦
Fan-Fail Output
♦
I
2
C/SMBus-Compatible Interface
♦
Fully Assembled and Tested
Features
Evaluate: MAX6620
Ordering Information
PART
MAX6620EVKIT+
MAX6620EVCMAXQU+
TYPE
EV Kit
EV System
+Denotes
lead-free and RoHS-compliant.
Component Lists
MAX6620 EV System
PART
MAX6620EVKIT+
CMAXQUSB+
QTY
1
1
DESCRIPTION
MAX6620 EV kit
I
2
C/SMBus interface command
module
Q1–Q4
R1–R4
4
4
0
1
4
DESIGNATION
QTY
DESCRIPTION
20V, 1A, PNP silicon EPI
transistors
ON Semi BCP69T1G
2.7kΩ ±5% resistors (0603)
Not installed, resistors (0603)
4.7kΩ ±5% resistor (0603)
10kΩ ±5% resistors (0603)
Quad linear fan-speed controller
(28 TQFN-EP*, 5mm x 5mm x
0.8mm)
Maxim MAX6620ATI+
Standard 32.768kHz quartz
crystal, 12.5pF load capacitance
Hong Kong X’tals
3TK0327680D1CF5GX-0A
Shunts
PCB: MAX6620 Evaluation Kit+
MAX6620 EV Kit
DESIGNATION
QTY
DESCRIPTION
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
Murata GRM188R71C104K
TDK C1608X7R1C104K
2 x 10 right-angle receptacle
3-pin headers, 0.1in pitch, vertical,
friction lock
2-pin header
3-pin headers
R5, R6
R7
R8–R11
C1–C6
6
U1
1
J1
J2–J5
JU1
JU2–JU6
1
4
1
5
Y1
1
—
—
6
1
*EP
= Exposed pad.
Windows Vista is a registered trademark of Microsoft Corp.
SMBus is a trademark of Intel Corp.
________________________________________________________________
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.
MAX6620 Evaluation Kit/Evaluation System
Evaluate: MAX6620
Component Suppliers
SUPPLIER
Hong Kong X’tals Ltd.
Murata Mfg. Co., Ltd.
ON Semiconductor
TDK Corp.
PHONE
+852-3511-2388
770-436-1300
602-244-6600
847-803-6100
WEBSITE
www.hongkongcrystal.com
www.murata.com
www.onsemi.com
www.component.tdk.com
Note:
Indicate that you are using the MAX6620 when contacting these component suppliers.
MAX6620 EV Kit Files
FILE
INSTALL.EXE
MAX6620.EXE
TROUBLESHOOTING_USB.PDF
FTD2XX.INF
UNINST.INI
DESCRIPTION
Installs the EV kit files on your computer
Application program
USB driver installation help file
USB driver file
Uninstalls the EV kit software
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• User-supplied PC running Windows 2000/XP/Vista
• Available USB port
• 5V/2A or 12V/2A DC power supply (VFAN)
• One to four brushless DC fans
• MAX6620 EV system
MAX6620 EV kit
CMAXQUSB+ command module (USB cable
included)
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
2000/XP/Vista operating system.
3) Carefully connect the boards by aligning the 20-pin
connector of the MAX6620EV kit with the 20-pin
header on the CMAXQUSB interface board. Gently
press them together.
4) Connect one to four fans appropriately.
Note:
The
EV kit is configured for use with fans that typically
draw up to 400mA. When using larger fans, a differ-
ent pass transistor might be required for proper
operation.
5) With power off, connect the positive terminal of the
DC power supply to the VFAN pad, and the ground
terminal to the FAN_GND pad next to VFAN.
6) Connect the USB cable from the computer’s type-A
USB port to the CMAXQUSB board’s type-B USB
port.
7) Visit www.maxim-ic.com/evkitsoftware to download
the latest version of the MAX6620 EV kit software
and install it on your computer by running the
INSTALL.EXE program. The program files are
copied and icons are created in the Windows
Start
menu.
8) Turn on the power supply and set it to 5V or 12V, as
appropriate.
9) Start the MAX6620 program by opening its icon in
the
Start
menu.
10) Normal device operation is verified when
CMAXQUSB
HW: Connected. MAX6620 device connected.
is
displayed at the bottom left of the MAX6620 EV kit
main window (Figure 1).
Procedure
The MAX6620 EV kit is fully assembled and tested.
Follow the steps to verify board operation.
Caution: Do
not turn on the power supply until all connections
are completed.
1) On the CMAXQUSB command module, ensure that
the shunt on jumper JU1 is in the 3.3V position.
2) To enable the on-board VCC supply, ensure that a
shunt is installed between pins 2-3 on jumper JU2
on the MAX6620 EV kit. Also, verify that the shunt
on JU1 of the EV kit is uninstalled.
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MAX6620 Evaluation Kit/Evaluation System
Detailed Description of Software
User-Interface Panel
The program’s main window contains two tabs,
Fan
Status
and
Fan Configuration/Dynamics,
which pro-
vide controls for the MAX6620 EV kit software’s config-
urable features. The
Fan Status
tab sheet (Figure 1)
provides controls for the
Global Configuration
regis-
ter,
TACH Count, Drive Voltage, Targets,
and
Faults.
The
Fan Configuration/Dynamics
tab sheet (Figure 2)
provides controls for
Fan_ Configuration
and
Fan_
Dynamics.
A status box is also provided at the bottom
of the program’s main window and is used to verify
command module and device connectivity.
VFAN Input Setting (5V or 12V)
The MAX6620 EV kit software can be configured to work
with 5V or 12V DC fans. Manually select the appropriate
fan voltage from the
VFAN
drop-down list (Figure 1).
The default setting is for use with 12V DC fans.
Evaluate: MAX6620
Global Configuration
The
Global Configuration
group box contains several
functions that control general operation. The
I2C Bus
Timeout
checkbox resets the interface if SDA is low for
more than 35ms, when enabled. The
Fans to 100% on
Failure
checkbox, when checked, drives the fans to
full-scale drive voltage when a fan failure is detected.
The
External Xtal
checkbox toggles between the inter-
nal oscillator (unchecked) and the 32.768 kHz on-board
crystal (checked).
Figure 1. MAX6620 EV Kit Software—Fan Status Tab
_______________________________________________________________________________________
3
MAX6620 Evaluation Kit/Evaluation System
Evaluate: MAX6620
Figure 2. MAX6620 EV Kit Software—Fan Configuration/Dynamics Tab
I2C Watchdog
The
I2C Watchdog Period
drop-down list controls the
period that the watchdog monitors SDA and SCL for
valid I
2
C transactions. If there are no valid transactions
between the master and the MAX6620 within the watch-
dog period, all fan output voltages go to full-scale drive
voltage. The
I2C Watchdog Status
indicator monitors
whether a watchdog fault has occurred. This bit is
cleared when read.
TACH Count and Drive Voltage
With polling enabled, the
TACH Count
group box auto-
matically reads the tachometer count for each corre-
sponding fan. With polling disabled, press the
Read
buttons next to each fan’s
TACH_ Count
label.
With polling enabled, the
Drive Voltage
group box
automatically reads the drive voltage for each corre-
sponding fan. With polling disabled, press the
Read
buttons next to each fan’s drive voltage label. When a
fan is driven at full-scale voltage, the drive voltage label
text is displayed the in red font.
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_______________________________________________________________________________________
MAX6620 Evaluation Kit/Evaluation System
Targets
In RPM mode, the
Target TACH_ Count
sets the
desired tachometer count for each corresponding fan.
The MAX6620 then adjusts the fan drive voltage to
achieve this tachometer count. In DAC mode, this fea-
ture has no effect.
In DAC mode, write the desired fan drive voltage to the
Target Drive Voltage_
edit box. The MAX6620 then
drives the fan with this voltage.
RPM/DAC Mode
Select the appropriate
RPM
or
DAC
radio button to set
the fan to either RPM or DAC mode. In RPM mode, the
fan drive voltage is adjusted to produce the tachometer
count value in the Fan_ Target TACH Count register. In
DAC mode, the fan drive voltage is set by the value in
the Fan_ Target Drive Voltage register.
Spin-up
The
Spin-up
drop-down list controls the period of time
that the fan is driven at full-scale voltage before reduc-
ing the drive to the selected value. The default is set
through jumper JU6.
TACH Settings
The
TACH Input Enable
checkboxes enable the TACH
input function and fan-fault detection. When enabled,
select the appropriate radio button to set the TACH
input to either
TACH Count
or
Locked Rotor.
When
using locked rotor input, the
Polarity
can be set at high
or low.
Evaluate: MAX6620
Faults
Fan_ Status
Fan faults are detected through the fan fault register
and displayed in the
Faults
group box. When a fault is
detected, the
Fan_ Status
label changes from
Ok
to
Fault
and displays the text in red font. Since these bits
latch until they are cleared by reading, the option to poll
bits automatically, or manually read status, is offered by
toggling the
Enable Polling
checkbox. Refer to the
MAX6620 IC data sheet for more information regarding
types of faults.
Fan_ Fault Mask
The
Fan_ Fault Mask
checkboxes give the option to
mask faults on selected fans from asserting the
FAN_FAIL
hardware option. When checked, bits do not
assert the
FAN_FAIL
output. Faults are still indicated
through
Fan_ Status.
Fan_ Dynamics
The
Fan_ Dynamics
group box contains controls for
individual fan speed range and DAC rate-of-change.
The
# of tach cycles counted
drop-down list sets the
number of complete tachometer cycles used for count-
ing the number of 8192Hz clock cycles. For example,
by default, this number is set to 4, which means that the
MAX6620 counts the number of 8192Hz clock cycles in
four complete tachometer cycles.
The
DAC rate of change
drop-down list determines the
time interval between output voltage increments. Note
that in RPM mode, a setting of zero would result in an
unstable feedback loop, so a default of 0.0625 is in
effect when zero is selected.
Fan_ Configuration
The
Fan_ Configuration
group boxes (Figure 2) con-
figure the corresponding fan’s
Spin-up
conditions,
TACH Input Enable
settings, and set either RPM or
DAC mode.
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