General Description
The MAX16826 evaluation kit (EV kit) provides a proven
design to evaluate the MAX16826, a four-string, I2C pro-
grammable high-brightness LED (HB LED) driver with
PWM dimming control. The EV kit also includes
Windows®2000/XP/Vista®-compatible software that
provides a simple graphical user interface (GUI) for
exercising the features of the MAX16826. The
MAX16826 EV kit PCB comes with a MAX16826ATJ+
installed. The EV kit is configured in a boost application.
This EV kit can be modified by changing component
values on the board for other configurations (including
RGB LED applications). Refer to the MAX16826 IC data
sheet for more information.
Features
oFour Independently Controllable LED Strings
o7 LEDs Per String Configuration
oIndependently Programmable 50mA to 150mA
String Current
o7.5V to 22V Input Voltage
oCan Withstand Automotive Load Dump Up to 40V
for 400ms
o0% to 100% DIM Duty Cycle Range
oShorted LED Protection and Detection
oOpen LED String Detection
oAdaptive Boost-Stage Voltage Optimization
oConvenient Breakaway LED Driver Board Easily
Adaptable to End Application
oLow Mechanical Profile
oWindows 2000/XP/Vista (32-Bit)-Compatible
Software
oUSB-PC Interface
oUSB-to-I2C On-Board Circuitry
oFully Assembled and Tested
oLead-Free and RoHS Compliant
Evaluates: MAX16826
MAX16826 Evaluation Kit
________________________________________________________________
Maxim Integrated Products
1
19-4271; Rev 0; 9/08
Component List
LED Driver Board Specification
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
PARAMETER DESCRIPTION
Configuration 7 white LEDs/string
Number of Strings 4 strings
LED Current Adjustment Range 50mA to 150mA
Total Maximum LED Power 16.8W
VIN (min) 7.5V
VIN (max) 22V
Load Dump 40V for < 400ms
Nominal Boost Voltage Adjustment
Range 22.4V to 32V
Nominal OVP Trip Threshold 35V
Boost Stage Switching Frequency 350kHz
DESIGNATION QTY DESCRIPTION
C1, C2, C3, C5–
C8, C12, C15,
C17, C23, C24
12
100nF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
C9 1
33nF ±10%, 50V X7R ceramic
capacitor (0603)
TDK C1608X7R1H333K
C10, C11 2
22pF ±5%, 50V C0G ceramic
capacitors (0603)
TDK C1608C0G1H220J
C13, C14,
C18–C21 6
1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C105K
C16, C25 2
10µF ±10%, 10V X5R ceramic
capacitors (1210)
Murata GRM32FR61A106K
DESIGNATION QTY DESCRIPTION
C26, C28 2
10µF ±20%, 50V X5R ceramic
capacitors (2220)
Murata GRM55DR61H106K
C27 1
10µF ±20%, 50V X7S ceramic
capacitor (1210)
Taiyo Yuden UMK325BJ106MM-T
C29 1
2.2nF ±5%, 50V C0G ceramic
capacitor (0603)
Murata GRM1885C1H222K
C30 1
1µF ±10%, 50V X7R ceramic
capacitor (1210)
Murata GRM32RR71H105K
C32 1
4.7µF ±10%, 6.3V X5R ceramic
capacitor (0603)
Murata GRM188R60J475K
PART TYPE
MAX16826EVKIT+ EV Kit
+
Denotes lead-free and RoHS compliant.
Windows and Windows Vista are registered trademarks of Microsoft Corp.
Evaluates: MAX16826
MAX16826 Evaluation Kit
2 _______________________________________________________________________________________
Component List (continued)
DESIGNATION QTY DESCRIPTION
C33 1
2200pF ±10%, 50V X7R ceramic
capacitor (0402)
Murata GRM155R71H222K
C34, C35 2
47µF ±20%, 50V electrolytic
capacitors
Panasonic EEE-FK1H470XP
C36, C37 0 Not installed, capacitors (0603)
C38 1
1000pF ±5%, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H102JA01D
C39 1
220pF ±5%, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H221J
C40 1
100pF ±5%, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H101J
C41–C44 4
0.01µF ±10%, 50V X7R ceramic
capacitors (0402)
Murata GRM155R71H103K
C45 0 Not installed, capacitor (0402)
D1 1 60V, 1A Schottky diode (SMB)
Diodes, Inc. B160B-13-F
J1 1 USB series-B right-angle PC-mount
receptacle
J2, J3 0 Not installed
JU2–JU8 7 3-pin headers
L1 1 Ferrite bead (0603)
TDK MMZ1608R301A
L2 1 22µH ±20%, 5A, 52mΩ inductor
Coilcraft MSS1260-223Ml
LED1 1 Red LED (0603)
Panasonic LNJ208R8ARA
P1, P2 2 Connectors, FFC/FPC 18-pos, 1mm
P3 1 Connector, FFC/FPC 6-pos, 1mm
Q1 1
40V, 9A, 2.5W n-channel MOSFET
(8 SO)
International Rectifier IRF7469
Q2–Q5 4
55V, 1.9A, 160mΩ n-channel
MOSFETs (SOT223)
Inter nati onal Recti fi er IRFL014N P b F
R1 1 220Ω ±5% resistor (0603)
R2 1 2.2kΩ ±5% resistor (0603)
R3, R9, R10 3 1.5kΩ ±5% resistors (0603)
R4, R5 2 27Ω ±5% resistors (0603)
R6 1 470Ω ±5% resistor (0603)
R7 1 100kΩ ±5% resistor (0603)
R8 1 7.5kΩ ±1% resistor (0603)
R11 1 68Ω ±1%, 0.25W resistor (1206)
DESIGNATION QTY DESCRIPTION
R12 1
0.04Ω ±1%, 0.5W sense resistor
(2010)
Vishay/Dale WSL2010R0400FEA
R13 1 215kΩ ±1% resistor (0402)
R14, R16 2 10kΩ ±1% resistors (0402)
R15 1 249kΩ ±1% resistor (0402)
R17 1 1.27kΩ ±1% resistor (0603)
R18 1 182kΩ ±1% resistor (0603)
R19 1 2kΩ ±1% resistor (0402)
R20, R22,
R24, R26 4 100kΩ ±1% resistors (0402)
R21, R23,
R25, R27 4 16.5kΩ ±1% resistors (0402)
R28–R31 4
2.2Ω ±1%, 100mW sense resistors
(0603)
Panasonic ECG ERJ-3RQF2R2V
R32, R33 2 0Ω ±5% resistors (0603)
R34–R37 4 0Ω ±5% resistors (0402)
R38 1 12.1Ω ±1% resistor (0805)
R39 1 470Ω ±5% resistor (0402)
R40 1 10kΩ ±5% resistor (0603)
R41–R44 4 237kΩ ±1% resistors (0603)
U1 1 LED driver (32 TQFN)
Maxim MAX16826ATJ+
U2, U8 2 Microcontrollers (68 QFN-EP*)
Maxim MAXQ2000-RAX+
U3 1 UART-to-USB converter (32 TQFP)
FTDI FT232BL
U4 1 93C 46A 3- w i r e E E P ROM ( 8 S O )
Atmel AT93C46A-10SU-2.7
U5 1
p-channel MOSFET power switch
(8 SO)
Maxim MAX890LESA+
U6 1 LDO regulator (5 SC70)
Maxim MAX8511EXK25+T
U7 1 LDO regulator (5 SC70)
Maxim MAX8511EXK33+T
Y1 1 20MHz crystal oscillator
Y2 1
6MHz crystal
Hong Kong X’tals
SSL6000000E18FAF
—1C ab l e, fl at fl ex 18- p osi ti on, 1m m , 5i n
— 7 Shunts
—1
USB high-speed A-to-B cable,
5ft (1.5m)
— 1 PCB: MAX16828 Evaluation Kit+
*
Exposed pad.
Quick Start
Recommended Equipment
Before beginning, the following equipment is needed:
• MAX16826 EV kit (USB cable included)
• A user-supplied Windows 2000/XP/Vista PC with a
spare USB port
• 7V to 24V, 5A DC power supply
• Four strings of white LEDs (7 LEDs/string)
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 MAX16826 EV kit is fully assembled and tested.
Follow the steps below to verify board operation:
1) Visit www.maxim-ic.com/evkitsoftware to down-
load the latest version of the EV kit software,
16826Rxx.ZIP (xx in the filename denotes the soft-
ware version number). Save the EV kit software to a
temporary folder and uncompress the ZIP file.
2) Install the EV kit software on your computer by run-
ning the INSTALL.EXE program inside the temporary
folder. The program files are copied and icons are
created in the Windows Start | Programs menu.
3) Verify that all jumpers (JU2–JU8) are in their default
positions, as shown in Table 1.
4) 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 you
do not see a window that is similar to the one
described above after 30 seconds, remove the USB
cable from the board and reconnect it. Administrator
privileges are required to install the USB device
driver on Windows.
5) 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\MAX16826 (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
document included with the software for additional
information.
6) Set the output of the power supply to 12V. Turn off
the power supply.
7) Connect the positive terminal of the power supply to
the VIN pad of the LED driver board.
Evaluates: MAX16826
MAX16826 Evaluation Kit
_______________________________________________________________________________________ 3
Component Suppliers
SUPPLIER PHONE WEBSITE
Coilcraft, Inc. 847-639-6400 www.coilcraft.com
Diodes, Inc. 805-446-4800 www.diodes.com
Hong Kong X’tals Ltd. 852-35112388 www.hongkongcrystal.com
International Rectifier 310-322-3331 www.irf.com
Murata Electronics North America, Inc. 770-436-1300 www.murata-northamerica.com
Panasonic Corp. 800-344-2112 www.panasonic.com
Taiyo Yuden 800-348-2496 www.t-yuden.com
TDK Corp. 847-803-6100 www.component.tdk.com
Vishay/Dale 402-563-6866 www.vishay.com
Note: Indicate that you are using the MAX16826 when contacting these component suppliers.
FILE DESCRIPTION
INSTALL.EXE Installs the EV kit files on your
computer
MAX16826.EXE Application program
FTDIBUS.INF USB device driver file
FTDIPORT.INF VCP device driver file
UNINST.INI Uninstalls the EV kit software
USB_Driver_Help.PDF USB driver installation help file
MAX16826 EV Kit Files
Evaluates: MAX16826
8) Connect the negative terminal of the power supply
to the PGND pad of the LED driver board.
9) Ensure that the supplied ribbon cable is firmly con-
nected to the P1 and P2 connectors.
10) Connect the anode ends of the LED strings to the
P3-1 pin of the P3 connector.
11) Connect the cathode ends of the LED strings to the
P3-2 to P3-5 pins of the P3 connector.
12) Turn on the power supply
13) Start the MAX16826 EV kit software by opening its
icon in the Start | Programs menu. The EV kit soft-
ware main window appears, as shown in Figure 1.
14) Press the Start button to start the LED driver.
15) Verify that all of the LEDs are lit.
MAX16826 Evaluation Kit
4 _______________________________________________________________________________________
Table 1. MAX16826 EV Kit Jumper Descriptions (JU2–JU8)
JUMPER SHUNT POSITION DESCRIPTION
1-2* On-board PWM signal for Ch1
JU2 2-3 Connect user-supplied PWM signal for Ch1 to the on-board DIM1 pad
1-2* On-board PWM signal for Ch2
JU3 2-3 Connect user-supplied PWM signal for Ch2 to the on-board DIM2 pad
1-2* MAX16826 SDA signal connected to on-board microcontroller
JU4 2-3 Connect user-supplied SDA signal to the on-board SDA pad
1-2* MAX16826 SCL signal connected to on-board microcontroller
JU5 2-3 Connect user-supplied SCL signal to the on-board SCL pad
1-2* MAX16826 SYNC/EN signal connected to on-board microcontroller
JU6 2-3 Connect user-supplied SYNC/EN signal to the on-board SYNC/EN pad
1-2* On-board PWM signal for Ch3
JU7 2-3 Connect user-supplied PWM signal for Ch3 to the on-board DIM3 pad
1-2* On-board PWM signal for Ch4
JU8 2-3 Connect user-supplied PWM signal for Ch4 to the on-board DIM4 pad
*
Default position.
Detailed Description of Software
The MAX16826 evaluation kit software has all the func-
tions to evaluate the MAX16826 IC. To start the
MAX16826 EV kit software, click Start | Programs |
Maxim MAX16826 Evaluation Kit | Maxim MAX16826
Evaluation Kit that is created during installation. The
GUI main window appears as shown in Figure 1.
Evaluates: MAX16826
MAX16826 Evaluation Kit
_______________________________________________________________________________________ 5
Figure 1. MAX16826 EV Kit Software Main Window
Evaluates: MAX16826
String Current Set
The String Current Set group box is located at the
upper left corner of the main window. Use the scroll-
bars to adjust the current of the LED strings. The corre-
sponding values of the current will be shown in the
adjacent edit boxes. Press the Read button to read the
values from the linear regulator output registers of the
MAX16826. The equivalent values of the output current
will be shown in the edit boxes.
Boost Output Control
The Boost Output Control Mode group box has the
functions to control the boost output voltage.
To control the boost output voltage manually, click on
the radio button next to the Manual Control group box.
Use the scrollbar to adjust the output voltage, and the
voltage value will be displayed in the adjacent edit box.
The actual boost output voltage can be seen in the
Read Back Values group box.
To use the software automatic control, click on the
radio button next to the Software Control group box.
The edit box next to the Set button is used to change
the Drain to GND regulated voltage of the current sink
FETs on the LED string with the highest voltage drop.
This voltage setting will depend on how much overhead
the user is willing to have. If the set value is too low, the
LED currents will no longer be well regulated and may
indeed drop because the boost voltage might fall too
low. The scrollbar in this mode will move automatically
to compensate and regulate the output voltage. The
update rate is approximately once per second. In any
case, the channel with the lowest voltage across the
sink FET will be regulated to the value in the edit box.
DIM Pulse Width Modulation (DPWM)
The DPWM group box is located at the center of the
main window. The four DIM PWM signals generated by
the on-board MAXQ2000 microcontrollers are used to
control the brightness of the LEDs. Adjust the scrollbars
in the DPWM Duty Cycle group box to change the duty
cycles of the PWM signals and the values of the duty
cycle (%) are shown in the adjacent edit boxes. Check
the Set All Channels to 100% Duty Cycle checkbox to
force all channel duty cycles to 100%.
In the DPWM Frequency group box, change the
DPWM frequency by adjusting the scrollbar position
and press the Set button. The frequency value will be
shown in the edit box.
To guarantee that the leading edge of all the DIM sig-
nals are synchronized, press the Set button in the
DPWM Frequency group box.
Press the Start button to start to generate the PWM signals.
Press the Stop button to stop all PWM signals.
Status
The Status group box is located at the right of the main
window. The software reads the external FET drain volt-
age measurements, and the boost output voltage mea-
surement from the ADC output registers of the
MAX16826. The software multiplies the measured val-
ues by the appropriate scaling factor and then displays
them in the Read Back Values group box.
Enter the values into the edit boxes in the Fault Level
Set group box to set the fault-detection values. When
the value in the Read Back Values group box is less
than the fault-detection value, then the color of the
read-back value changes to dark green. When the
read-back value is 0 to 10% higher than the fault-detec-
tion value, the read-back value turns a lime color. If the
read-back value is more than 10% higher than the fault-
detection value, then the read-back value turns purple.
The read-back value turns red when it is more than
20% higher than the fault-detection value.
The software also reads the fault register to detect the
fault conditions. If a fault condition exists, it will be
shown in the String Fault Status group box. See Table
2 for the fault-condition explanations.
Press the Read button to update the Status group box.
By checking the Automatic Read checkbox, the
Status group box will be automatically updated every
second.
Enable/Disable
The Enable/Disable group box controls the signal on
the SYNC/EN pin. Click on the Enable radio button to
set the signal high and enable the MAX16826. Click on
the Disable radio button to set the signal low and dis-
able the MAX16826.
Standby
Check the Standby checkbox to set the MAX16826 to
standby mode. Refer to the MAX16826 IC data sheet
for more information regarding standby mode.
MAX16826 Evaluation Kit
6 _______________________________________________________________________________________
Table 2. Fault Conditions
FAULT NAME CONDITION
TO ADC conversion timeout; also corresponds
to open string condition*
Open LED string open
Short LED string shorted
OVP Overvoltage
*
Open LED string detection may require multiple flag examination.
Scaling Factors
The calculations for the LED string current, boost out-
put voltage, and the read-back values are based on the
scaling factors. You can change the scaling factor by
selecting the Scaling Factor menu item under the
Scaling Factors menu bar. In the pop-up window
shown in Figure 2, enter the appropriate scaling factor.
See Table 3 for the formulas for the scaling factors.
These values can be used for calibration against actual
read values with external instruments.
When the default values are changed, they are stored
in the software. Re-enter the default values to bring the
software back to the default setting.
Evaluates: MAX16826
MAX16826 Evaluation Kit
_______________________________________________________________________________________ 7
Table 3. Scaling Factor
SCALING FACTOR FORMULA DEFAULT
VALUE
DR1 (ADC read-back voltage
across Drain and GND for the
sink FET on Ch1)
1 + (R20/R21) 7.046
DR2 (ADC read-back voltage
across Drain and GND for the
sink FET on Ch2)
1 + (R22/R23) 7.046
DR3 (ADC read-back voltage
across Drain and GND for the
sink FET on Ch3)
1 + (R24/R25) 7.046
DR4 (ADC read-back voltage
across Drain and GND for the
sink FET on Ch4)
1 + (R26/R27) 7.046
Read Back VBoost (ADC read-
back boost output voltage) 1 + (R15/R16) 25.900
String Current Set Ch1 (LED
string current for Ch1) R31 2.200
String Current Set Ch2 (LED
string current for Ch2) R30 2.200
String Current Set Ch3 (LED
string current for Ch3) R29 2.200
String Current Set Ch4 (LED
string current for Ch4) R28 2.200
VBoost (Boost output voltage) 1 + (R13/R14) 22.500
Figure 2. Scaling Factor Window
Evaluates: MAX16826
Detailed Description of Hardware
The MAX16826 EV kit board provides a proven layout for
evaluating the MAX16826 IC. This EV kit consists of a
controller board and an LED driver board. The break-
away slots at the center of the EV kit make it easier for
the user to break and separate the controller board from
the LED driver board. This is done so that once the eval-
uation is complete with the included software, the driver
board can easily be used in the target application envi-
ronment with the target system microcontroller.
To connect the power, ground, PWM, and the I2C inter-
face signals of the boards, attach the ribbon cable to
the P1 connector of the controller board and attach the
other end of the ribbon cable to the P2 connector of the
LED driver board.
Controller Board
The controller board acts as the bridge between the
software in the PC and the actual LED driver board
containing the MAX16826. In addition to the USB con-
nectivity, it generates the four adjustable PWM DIM sig-
nals that control the brightness of the LEDs. The con-
troller board communicates with the driver board
through the I2C interface, and is able to read or change
the values of the registers in the MAX16826.
The user can use the MAX16826 evaluation kit software
to control the controller board.
See Table 1 to control the MAX16826 with a user-sup-
plied PWM signal.
LED Driver Board
The LED driver board is able to drive up to four LED
strings (7 LEDs/string). LED strings can be connected
to the LED driver board through the P3 connector by
using a ribbon cable. Connect all of the anode ends of
the LED strings to the P3-1 pin (which connects to the
boost output) of the P3 connector. Then connect the
cathode ends of the LED strings to the P3-2 to P3-5
pins (that connects to the drains of the sink FETs) of the
P3 connector.
User-Supplied I2C Interface
To use the MAX16826 EV kit with a user-supplied I2C
interface, install the shunts on pins 2-3 of JU4 and JU5.
Connect SDA, SCL, and GND lines from the user-
supplied I2C interface to the SDA, SCL, and PGND
pads on the MAX16826 controller board.
After the LED driver board has broken away from the
controller board, the user may connect their supplied
I2C, DIM, and power signals to the LED driver board
through the P2 connector using a ribbon cable. See
Table 4 for the pin description of the P2 connector.
MAX16826 Evaluation Kit
8 _______________________________________________________________________________________
Table 4. Pin Description for P2 Connector
PIN NUMBER DESCRIPTION
P2-1 to P2-5 Connect to the VIN pin of the MAX16826
P2-6 Not connected
P2-7 to P2-11 Connect to the ground
P2-12 Connects to the SYNC/EN pin of the
MAX16826
P2-13 Connects to the SDA pin of the MAX16826
P2-14 Connects to the SCL pin of the MAX16826
P2-15 Connects to the DIM4 pin of the MAX16826
P2-16 Connects to the DIM3 pin of the MAX16826
P2-17 Connects to the DIM2 pin of the MAX16826
P2-18 Connects to the DIM1 pin of the MAX16826
Evaluates: MAX16826
MAX16826 Evaluation Kit
_______________________________________________________________________________________ 9
Figure 3. MAX16826 EV Kit LED Driver Board Schematic
Evaluates: MAX16826
MAX16826 Evaluation Kit
10 ______________________________________________________________________________________
Figure 4a. MAX16826 EV Kit Controller Board Schematic (Sheet 1 of 2)
Evaluates: MAX16826
MAX16826 Evaluation Kit
______________________________________________________________________________________ 11
Figure 4b. MAX16826 EV Kit Controller Board Schematic (Sheet 2 of 2)
Evaluates: MAX16826
MAX16826 Evaluation Kit
12 ______________________________________________________________________________________
Figure 5. MAX16826 EV Kit Component Placement Guide—Component Side
Evaluates: MAX16826
MAX16826 Evaluation Kit
______________________________________________________________________________________ 13
Figure 6. MAX16826 EV Kit PCB Layout—Component Side
Evaluates: MAX16826
MAX16826 Evaluation Kit
14 ______________________________________________________________________________________
Figure 7. MAX16826 EV Kit PCB Layout—Layer 2
Evaluates: MAX16826
MAX16826 Evaluation Kit
______________________________________________________________________________________ 15
Figure 8. MAX16826 EV Kit PCB Layout—Layer 3
Evaluates: MAX16826
MAX16826 Evaluation Kit
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.
16
__________________
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.
Figure 9. MAX16826 EV Kit PCB Layout—Solder Side
