General Description
The MAX16806 evaluation kit (EV kit) demonstrates the
features of the MAX16806 high-current LED driver,
capable of delivering regulated current of up to a total
of 350mA to one or more strings of high-brightness
LEDs with high accuracy. This EV kit operates at supply
voltages between 5.5V to 40V and temperatures rang-
ing from 0°C to +70°C.
The MAX16806 EV kit provides a user-selectable three-
level LED current setting, connection to the 5V-regulat-
ed output, and a momentary switch to enable or disable
the dimming function. This EV kit features wide-range
dimming, controllable through a PWM input or analog
input generated using an on-board trim pot. The
MAX16806 EV kit is a fully assembled and tested PCB.
The MAX16806 EV kit provides access to the I2C inter-
face of the MAX16806 IC, through which the internal
dynamic registers and the EEPROM are written/read to
control various device features. A CMAXQUSB board
can be used to enable PC communication using the I2C
2-wire interface. Windows®98SE/2000/XP-compatible
GUI software is provided to access the MAX16806 IC.
The MAX16806 EV kit can also be interfaced directly to
a user-provided I2C system.
The MAX16806 evaluation system (EV system) consists
of the MAX16806 EV kit and a companion CMAXQUSB
serial-interface board. The CMAXQUSB interface board
allows a PC to control an I2C interface using the USB
port. Order the MAX16806EVCMAXQU+ for a complete
PC-based evaluation of the MAX16806. Order the
MAX16806EVKIT+ if you already have a CMAXQUSB
interface board, or if you have your I2C interface, or do
not require PC-based evaluation of the MAX16806.
Features
o5.5V to 40V Supply Voltage Range
oJumper Selectable 150mA, 250mA, or 350mA
Output Current
o5V-Regulated Output
oWide-Range Dimming Control with PWM or
Analog Control Signal
oOn-Board Trim Pot to Provide Analog Control
Voltage for PWM Dimming
oTactile Momentary Switch
oPC-Based Evaluation of Features Using I2C
Interface
oLED Current Thermal Foldback with Connection
for Optional Thermal Sensor
oWindows 98SE/2000/XP-Compatible GUI Software
oPackage Dissipates Up to 2.760W at TA= +70°C
oLead-Free and RoHS Compliant
oFully Assembled and Tested
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
________________________________________________________________
Maxim Integrated Products
1
19-0682; Rev 3; 11/08
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.
Windows is a registered trademark of Microsoft Corp.
Note: The MAX16806 EV kit software is included with the
MAX16806 EV kit, but is designed for use with the complete EV
system. The EV system includes both the Maxim CMAXQUSB+
interface board and the EV kit. If the evaluation software will
not be used, the EV kit board can be purchased without the
Maxim CMAXQUSB+ board.
Figure 1. MAX16806 EV Kit Board
Component Lists
MAX16806 EV System
PART
QTY
DESCRIPTION
MAX16806EVKIT+
1 MAX16806 EV kit
CMAXQUSB+ 1 I2C interface board
Ordering Information
PART TYPE
MAX16806EVKIT+ EV Kit
MAX16806EVCMAXQU+ EV System
+
Denotes lead-free and RoHS compliant.
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
2 _______________________________________________________________________________________
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• Power supply 1: 0 to 30V, 0.5A rated
• Power supply 2: 0 to 5V rated
• Multimeter to measure current
• MAX16806 EV system
One LED rated for at least 350mA
MAX16806 EV kit
Maxim CMAXQUSB interface board (USB cable
included)
• Windows 98/2000/XP-compatible PC with a spare
USB port
• USB I/O extension cable and I2C interface cable
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.
Procedure
The MAX16806 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 con-
nections are completed.
Hardware-Only Configuration
1) Connect an LED rated for at least 350mA between
LED+ and LED-.
2) Connect the DC power supply 1 (0V to 30V or
above, 0.5A) to VIN.
Component Suppliers
Component Lists (continued)
MAX16806 EV Kit
DESIGNATION
QTY
DESCRIPTION
C1
1
0.1µF, 10V X7R ceramic capacitor
(0402)
Murata GRM155R71C104KA88D
KEMET C0402C104K8RACTU
C2
1
0.1µF, 50V X7R ceramic capacitor
(0603)
Murata GRM188R71H104KA93D
TDK C1608X7R1H104K
C3
1
Not installed, capacitor
CFD, PWM,
RSNS, TFIN,
VIN, V5
6
0.1in 2-pin headers (through hole)
I2C
1
0.1in 4-pin header (through hole)
J1, J2, J3
3
0.1in 3-pin headers (through hole)
LED+, LED-
2
0.1in 1-pin headers (through hole)
DESIGNATION
QTY
DESCRIPTION
R1
1
0.82Ω ±1%, 1/4W resistor (0805)
Susumu RP2012T-R82-F
R2
1
0.56Ω ±1%, 1/4W resistor (0805)
Susumu RP2012T-R56-F
R3
1
100kΩ ±20%, 3MM trim pot
BI Technologies 22AR100KLFTR
R4
1
Short (PCB trace)
R5, R6
2
50kΩ ±1%, 1/8W resistors (0603)
S1
1
SMD tactile momentary switch
ALPS SKRAACE010
U1
1
H i g h- cur r ent LE D d r i ver ( 20 TQFN - E P *)
M axi m M AX 16806ATP +
—
1
PCB: MAX16806 Evaluation Kit+
SUPPLIER PHONE WEBSITE
ALPS Electric 408-361-6400 www.alps.com
BI Technologies 714-447-2345 www.bitechnologies.com
KEMET Corporation 978-658-1663 www.kemet.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Susumu International USA 208-328-0307 www.susumu-usa.com
TDK Corp. 847-390-4373 www.component.tdk.com
Note: Indicate that you are using the MAX16806 when contacting these component suppliers.
*
EP = Exposed pad.
3) Open all the pins of J1 to select 150mA LED current.
4) Place jumper J2 between pins 2-3 to enable U1.
5) Place jumper J3 between pins 2-3 to enable analog
dimming.
6) Short the CFD jumper to disable current foldback.
7) Turn on the power supply and increase the input
voltage above 5.5V. The LED glows and the bright-
ness depends on the analog dimming input voltage
set by the trim pot (R3). If the LED is not glowing,
check by turning R3 in a counterclockwise direction
to increase analog dimming voltage.
8) Press the momentary switch (S1) to disable dim-
ming and get full brightness. Measure the LED cur-
rent. It should be 150mA ±3%. Input current can be
used to measure LED current, as the input current
will be only 0.7% more than the LED current.
9) Press the momentary switch again to enable dim-
ming. Turn the trim pot (R3) fully in a counterclock-
wise direction to get full brightness. Measure the
LED current, which should be 150mA ±3%.
10) Increase the supply voltage to 16V and check
whether the LED current is stable at 150mA ±3%.
Hardware and Software Configuration
1) Visit www.maxim-ic.com/evkitsoftware to down-
load the latest version of the EV kit software,
MAX16806EVSYS_GUI_setup.exe.
2) Install the MAX16806 evaluation software on the PC
by running the MAX16806EVSYS_GUI_setup.exe.
The program files are copied and icons are created
in the Windows Start menu. Restart the computer
when prompted. For Windows 2000/XP, you may
need administrator privileges.
3) Power up the MAX16806 EV kit by applying 10V to
VIN. Leave TFIN open and connect the I2C interface
of CMAXQUSB+ board to the I2C interface of
MAX16806 EV kit using the 3-wire connector included
(in correct direction). Function of each pin of the I2C
connector is indicated on both boards.
4) Set both CMAXQUSB+ interface board SW1 switches
to the ON position. These components provide pullup
resistors for the SDA and SCL 2-wire bus signals.
5) Connect the included USB cable from the PC to the
CMAXQUSB+ interface board. The CMAXQUSB+
board is powered through the computer’s USB port.
A Building Driver Database window pops up in
addition to a New Hardware Found message. If
you do not see a window that is similar to the one
described above within 30 seconds, remove the
USB cable from the CMAXQUSB+ interface board
and reconnect it again. Administrator privileges are
required to install the USB device driver on
Windows 2000/XP.
6) 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 as
C:\Program Files\MAX16806 by using the Browse
button. Refer to the TROUBLESHOOTING_USB.PDF
document included with the software if you have any
problems during this step.
7) Start the MAX16806 EV kit software by opening its
icon in the Start menu.
8) In the pulldown File menu, select Connect. The
MAX16806 software communicates with the
MAX16806 device and displays the contents of all
the dynamic registers in the corresponding pulldown
menu. The EV kit and the software are then ready for
evaluation. If a Connection failed message is dis-
played, check the USB and I2C interface connec-
tions and whether the MAX16806 board is powered
up.
See the
Detailed Description of Software
section in this
document for more information on the software GUI
features.
Detailed Description of Hardware
The MAX16806 EV kit demonstrates a high output-
current linear LED driver with accurate current control
based on the MAX16806 current regulator. This EV kit is
capable of supplying regulated output currents up to a
total of 350mA and operates at supply voltages
between 5.5V to 40V. Note: If the supply voltage is
above the total operating voltage of the LED string by
more than 7.5V, the maximum output current should be
set so the device does not enter into thermal shutdown
due to excessive power dissipation.
The MAX16806 uses a feedback loop to control the out-
put current. The differential voltage across the current-
sense resistors (R1 and R2) is compared with an internal
fixed reference and the error is used to control the output
drive. The voltage across the sense resistors is measured
differentially to achieve high immunity to common-mode
noise. The MAX16806 uses a factory-set reference of
198mV ±3% that is adjustable through the binning adjust-
ment register. See the
Detailed Description of Software
section in this document for more information on access-
ing the binning adjustment register through I2C interface.
Two-pin TFIN input provided on-board takes a
temperature-dependent voltage signal from the
MAX6613 temperature sensor, or an equivalent device
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
_______________________________________________________________________________________ 3
for thermal foldback function. The MAX16806 EV kit
also includes connection for the 5V-regulated output
and access to the on-board current-sense resistors.
PWM Dimming
The MAX16806 EV kit features wide-range dimming to
control the LED brightness by varying the duty cycle of a
PWM input signal, or by varying the amplitude of an ana-
log input voltage. Trim pot R3 generates the analog volt-
age needed to evaluate the analog-control PWM dimming
from the regulated 5V output, whereas the PWM signal
should be driven externally. For the analog-control PWM
dimming, an internal 200Hz ramp is compared against
the analog input and the output is chopped at 200Hz. The
peak value of the internal ramp can be adjusted through
I2C interface and is explained in the
Detailed Description
of Software
section
.
When an external PWM signal is used for dimming, the
chopping frequency is between 100Hz to 2kHz, and the
PWM amplitude is between 4V to 40V. An on-board
momentary switch provides active-low signal to the
switch input when pressed, and activates a bistable
latch in the MAX16806 to enable or disable the analog
dimming function. The momentary switch does not dis-
able dimming by the external PWM control signal or
dimming caused by thermal or LED current foldback.
Output Current Setting
Users select between three output current levels by set-
ting jumper J1 (see Table 1 for jumper settings). The
output current can be set to 150mA, 250mA, or 350mA.
The current-sense resistor is accessible through the
RSNS connector. The output current is adjusted by
removing R2 or R3, opening all the pins of J1, and con-
necting a resistor across RSNS with values calculated
using the following equation:
where RSNS is the external current-sense resistor,
0.198V is the factory-set current-sense reference, and
IOUT is the desired output current. If the current-sense
reference voltage is changed using binning adjustment,
the numerator of the above equation has to be modified
with the selected reference voltage.
Power Dissipation
Thermal shutdown turns off the device if power dissipa-
tion in the IC causes the junction temperature to reach
+155°C (typ). An external resistor can be added at the
input to the device or in series with LED to reduce the
power dissipation in the IC. The resistor’s power rating
should be higher than I2R. (I is the input current or LED
current, and R is the value of the added resistor.)
Use the following equation to calculate the maximum
LED current that can be drawn from the device without
causing a thermal shutdown:
where 2.760W is the maximum power dissipation capa-
city of the device when mounted on a multilayer board,
as per JEDEC specifications, with ambient temperature
below +70°C. VIN is the input-supply voltage and VLED
is the total operating voltage of the LED string.
5V-Regulated Output
The +5V regulator is used to power other components
from the V5 connector. The 5V output supplies up to
0.5mA of current and is not disabled during PWM off.
Jumper Selection
Three-pin jumper J1 selects between three different out-
put current settings. Three-pin jumper J2 controls the EN
pin of the MAX16806 and enables or disables the device.
Three-pin jumper J3 selects between the on-board ana-
log voltage and external PWM signal for dimming. Close
CFD to disable the current foldback function. Table 1 lists
the jumper options.
Detailed Description of Software
The MAX16806 EV kit GUI software is used to
evaluate the features of the MAX16806 device that are
controllable through the I2C interface. The software uses
the CMAXQUSB+ board to generate the I2C interface
signals at 400KHz to communicate to the MAX16806
device. The software writes data into, as well as reads
data from, the dynamic registers and the nonvolatile
EEPROM registers of the MAX16806. Modifying contents
of the dynamic registers directly controls the respective
device function. Writing to EEPROM stores all the
dynamic register contents to the corresponding
EEPROM registers, which are copied to dynamic re-gis-
ters every time during power-up.
IVV
LEDMAX IN LED
=−
2 760.
RSNS =0 198.
IOUT
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
4 _______________________________________________________________________________________
Table 1. Jumpers J1, J2, J3 and CFD
Functions
SHUNT POSITION AND FUNCTION
1-2 2-3 Open
J1 350mA 250mA 150mA
J2
U1 disabled
U1 enabled —
J3
PWM dimming Analog dimming
—
CFD Closed: current foldback disabled
Open: current foldback enabled
Note: Text in bold are user-selectable features in the
MAX6964 EV kit software. A mouse or the keyboard’s tab
key is used to navigate various items on the main window.
Software Startup
During power-up, the MAX16806 device loads the
factory-set or last-stored contents of the EEPROM reg-
isters to the corresponding dynamic registers. After the
PC-based evaluation setup is made, as described in
the Quick Start
Hardware and Software Configuration
section, start the MAX16806 program by opening its
icon in the Start menu. Use the pulldown File menu
and select Connect. The MAX16806 software commu-
nicates with the MAX16806 device and displays the
contents of all the dynamic registers in the correspond-
ing pulldown menu. Figure 2 shows the GUI software
startup window.
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
_______________________________________________________________________________________ 5
Figure 2. MAX16806 EV Kit Software—Startup Window
Evaluate: MAX16806
Programming Dynamic Registers
Dynamic register contents directly control the respec-
tive features of the MAX16806 device. During power-
up, the contents of the EEPROM registers are loaded to
the six dynamic registers. To modify the contents of any
of the dynamic registers, simply pull down the respec-
tive menu and select the required value. As soon as a
value is selected, the pulldown menu disappears and
the software writes the equivalent binary code into the
corresponding dynamic register location through the
I2C interface, and verifies the register contents after the
write operation. The data and last address written are
displayed in hex in the bottom-left corner of the GUI
window (see Figure 3).
MAX16806 Evaluation Kit/
Evaluation System
6 _______________________________________________________________________________________
Figure 3. MAX16806 EV Kit Software—Writing to Dynamic Registers
Binning Adjustment
Binning Adjustment takes 16 different values from
103mV to 198mV, and this voltage is used as the cur-
rent-sense reference for controlling the LED current.
Ramp Peak value takes eight different values from
1.55V to 2.88V, and this voltage decides the peak volt-
age of the internal 200Hz reference ramp. Changing
the ramp peak voltage affects the analog dimming and
the dimming during current and thermal foldback.
Current Foldback Threshold
Current Foldback Threshold takes eight values from
11.4V to 16.4V, and this value decides the supply volt-
age above which the current foldback feature starts
dimming LEDs (if the CFD jumper is open to enable
current foldback). The current foldback range is 1.2
times the ramp peak value if bit 3 of the current fold-
back threshold register is not set. The Double Current
Foldback Range checkbox sets bit 3 of the current
foldback threshold register when checked to make the
current foldback range 2.4 times the ramp peak value.
Thermal Foldback Knee Point
Thermal Foldback Knee Point takes 16 different values
from +60°C to +136°C, controlling the thermal foldback
feature based on the voltage level at the TFIN input.
Temperature-sense input TFIN is compatible to the out-
put of the MAX6613 temperature sensor, or an equiva-
lent device. Each temperature setting corresponds to a
reference voltage internal to the MAX16806 that is equal
to the output voltage generated by a MAX6613, or an
equivalent device. When the voltage at the TFIN input
reduces to the voltage corresponding to the selected
thermal foldback knee-point temperature, the thermal
foldback feature starts dimming the LED. Connect the
output of a MAX6613 temperature sensor, or an equiva-
lent device, to the TFIN input or apply the respective
voltage to TFIN to evaluate this feature. Disconnect the
I2C interface when connecting signals to TFIN, as both
the functions use the same device pins.
Thermal foldback knee point inputs TFN/TFP should not
be left open when not used, as it will enable the thermal
foldback function and reduce the LED brightness. In the
MAX16806 EV kit, resistors R5 and R6 provide the nec-
essary biasing for TFN/TFP inputs and disable the ther-
mal foldback function. The TFN input is connected to
GND through R6 (50kΩ) and the TFP input is connected
to +5V through R5 (50kΩ). These resistors do not affect
the normal functionality of the thermal foldback input, as
well as the I2C interface, and should be used in the end-
user application circuit for proper operation.
Thermal Foldback Slope
Thermal Foldback Slope takes four different
values, and the selected value is multiplied with the dif-
ference between the voltage input at TFIN and the inter-
nal reference voltage that corresponds to the thermal
foldback knee point (this difference voltage is a mea-
sure of the set thermal foldback knee point and the
sensed temperature), with the resultant voltage used to
decide the dimming. As this resultant voltage increases,
the LED brightness reduces. When it becomes equal to
the peak amplitude of the internal ramp, the dimming is
complete and the LED is fully off.
Thermal Foldback Clamp Level
Thermal Foldback Dim Clamp takes eight values
between 40% and 100%. This value is the minimum per-
centage of the output brightness that will be reached
when MAX16806 is dimming during thermal foldback.
Programming EEPROM Registers
To program the EEPROM registers, the input supply
voltage should be kept at 22V. Open the CFD jumper to
enable current foldback to prevent excessive power
dissipation due to high input voltage. Load the values
to be stored into the EEPROM to dynamic registers by
using the respective pulldown menu and the check-
box. Click on the Program Data button. The software
writes hex code 0xCA to the password register (0xFF)
to enable EEPROM programming, and then makes a
write operation to the EEPROM program enable register
to initiate the EEPROM programming cycle. Data written
into the EEPROM program enable register does not
have any significance. The MAX16806 stores the con-
tents of the dynamic registers to EEPROM. A
Programming EEPROM Data Successful message
appears. This indicates that the dynamic register con-
tents are stored into the EEPROM and programming is
complete.
If the current foldback is not disabled and the LED is on, it
is turned off during EEPROM programming. During the
next power-up, the new EEPROM contents are loaded
into the dynamic registers. To load the EEPROM contents
to dynamic registers during normal operation, click on the
Recall Data button. The software makes a write operation
to EEPROM content transfer register (0x06). This initiates
the transfer of EEPROM contents to dynamic registers.
The data written to the EEPROM content transfer register
do not have any significance. The dynamic register con-
tents are displayed after the transfer is complete.
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
_______________________________________________________________________________________ 7
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
8 _______________________________________________________________________________________
MAX16806
U1
GND N.C. GNDTFN/SDATFP/SCL
678910
N.C. DIM GNDENOUT
20 19 18 17 16
1
2
3
4
5
15
14
13
12
11
TFIN
R6
50kΩ
R5
50kΩ
OUT
IN
IN
CFD
DGND
S1
SKRAACE010
C2
0.1μF
50V
C3
OPEN R3
100kΩ
V5
CS-
CS+
V5
SW
4
I2C
321
SCL
GND
SDA
2
+
1
+2
1
CFD
+
2
C1
0.1μF
10V
1
V5
LED+
R1
0.82Ω
1%
R2
0.56Ω
1%
LED-
2
1
LED
2
1
RSNS
+2
1
VIN
+2
1
PWM R4
SHORT
2
3
1
J2
2
3
1
2
3
1
J3
2
3
1
J1
Figure 4. MAX16806 EV Kit Schematic
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
_______________________________________________________________________________________ 9
Figure 5. MAX16806 EV Kit Component Placement Guide—Component Side
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
10 ______________________________________________________________________________________
Figure 6. MAX16806 EV Kit PCB Layout—Component Side
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
______________________________________________________________________________________ 11
Figure 7. MAX16806 EV Kit PCB Layout—Solder 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.
12
____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Evaluate: MAX16806
MAX16806 Evaluation Kit/
Evaluation System
REVISION
NUMBER
REVISION
DATE DESCRIPTION PAGES
CHANGED
0 11/06 Initial release —
1 3/07 — 1, 2, 3, 7–11
2 12/07 Updated Ordering Information table format; corrected errors in Quick Start
section; various style edits. 1, 2, 3, 7
3 11/08 Removed LED from EV kit. 1, 2
Revision History