19-4052; Rev 0; 2/08
MAX16825 Evaluation Kit
The MAX16825 evaluation kit (EV kit) demonstrates a
high-voltage, 3-channel, linear high-brightness LED (HB
LED) driver using the MAX16825 IC. This EV kit is configured to supply an LED current of 100mA per channel and
operates from a 0.5A, 6.5V to 28V rated power supply.
The MAX16825 EV kit uses a standard 4-wire SPI™
interface for independently controlling each of the three
LED channels. The MAX16825 EV kit also integrates a
USB-to-SPI interface circuit based on Maxim’s
MAXQ2000 microcontroller. The EV kit includes
Windows 2000/XP/Vista®-compatible software that provides a simple graphical user interface (GUI) for exercising the features of the MAX16825. The EV kit can
also interface with a user-supplied SPI circuit for standalone operation.
Features
o Operates from a 6.5V to 28V, 0.5A Supply
o 3 Channels for Driving High-Brightness LEDs
o 100mA LED Current per Channel
o Evaluates a Stand-Alone 4-Wire SPI Interface
o USB-PC Interface (Cable Included)
o Windows 2000/XP/Vista (32-Bit)-Compatible
Software
o Fully Assembled and Tested
Ordering Information
PART
TYPE
MAX16825EVKIT+
EV Kit
+Denotes lead-free and RoHS-compliant.
Component List
DESIGNATION
C1, C3–C10, C17
QTY
10
C2, C13, C15
3
C11, C12
2
C14, C16, C22
3
C18, C19
2
C20
1
C21
1
DESCRIPTION
0.1µF ±10%, 16V X7R ceramic
capacitors (0603)
TDK C1608X7R1C104K
10µF ±20%, 6.3V X5R ceramic
capacitors (0805)
TDK C2012X5R0J106M
10pF ±5%, 50V C0G ceramic
capacitors (0603)
TDK C1608C0G1H100J
1µF ±10%, 10V X5R ceramic
capacitors (0603)
Murata GRM188R61A105K
22pF ±5%, 50V C0G ceramic
capacitors (0603)
TDK C1608C0G1H220J
3300pF ±10%, 50V X7R ceramic
capacitor (0603)
TDK C1608X7R1H332K
1µF ±10%, 50V X7R ceramic
capacitor (1210)
Murata GRM32ER71H105K or
TDK C3325X7R1H105K
DESIGNATION
QTY
D1
1
FB1
0
H1, J1
0
J2
0
P1
1
R1
R2
R3
R4
R5
R6, R7
1
1
1
1
1
2
R8, R9, R10
3
R11
0
DESCRIPTION
Green LED (0603)
Panasonic LNJ314G8TRA
Not installed, ferrite-bead inductor
(0603)
Not installed, dual-row (2 x 5) 10pin headers
Not installed, dual-row (2 x 4) 8pin header
USB type-B right-angle female
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)
2Ω ±1%, 0.25W sense resistors
(1206)
IRC WCR-WCR1206LF-2R00-F
Not installed, resistor (0402)
SPI is a trademark of Motorola, Inc.
Windows Vista is a registered trademark of Microsoft Corp.
________________________________________________________________ Maxim Integrated Products
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.
1
Evaluates: MAX16825
General Description
MAX16825 Evaluation Kit
Evaluates: MAX16825
Component List (continued)
DESIGNATION
U1
QTY
1
DESCRIPTION
SPI-controlled linear HB LED
driver (16-pin TSSOP-EP*)
Maxim MAX16825AUE+
SUPPLIER
PHONE
WEBSITE
IRC, Inc.
361-992-7900 www.irctt.com
Murata Mfg. Co.,
Ltd
770-436-1300 www.murata.com
1
Low-power 16-bit microcontroller
(68-pin QFN-EP*, 10mm x 10mm)
Maxim MAXQ2000-RAX+
Panasonic
800-344-2112 www.panasonic.com
TDK Corp.
847-803-6100 www.component.tdk.com
U3
1
93C46 type 3-wire EEPROM
(8-pin SO)
Note: Indicate that you are using the MAX16825 when contacting these component suppliers.
U4
1
UART-to-USB converter
(32-pin TQFP, 7mm x 7mm)
1
3.3V regulator (5-pin SC70)
Maxim MAX8511EXK33+T
(Top Mark: AEI)
1
2.5V regulator (5-pin SC70)
Maxim MAX8511EXK25+T
(Top Mark: ADV)
U2
U5
U6
Y1
1
16MHz crystal
Y2
1
6MHz crystal
—
1
USB high-speed A-to-B cable, 6ft
—
1
PCB: MAX16825 Evaluation Kit+
*EP = Exposed paddle.
Quick Start
Required Equipment
Before beginning, the following equipment is needed:
• MAX16825 EV kit (USB cable included)
• 6.5V to 28V, 0.5A adjustable DC power supply
• User-supplied Windows 2000/XP/Vista PC with a
spare USB port
• Three LED loads, each rated as follows:
Current rating ≥ 100mA
Total LED string forward voltage VFLED ≤ 26.3V
• See the LED Load Configuration section for more
information
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 MAX16825 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.
2
Component Suppliers
MAX16825 EV Kit Files
FILE
INSTALL.EXE
DESCRIPTION
Installs the EV kit files on
your computer
MAX16825.EXE
Application program
FTD2XX.INF
USB device driver file
UNINST.INI
Uninstalls the EV kit
software
TROUBLESHOOTING_USB.PDF
USB driver installation help
file
1) Visit www.maxim-ic.com/evkitsoftware to download
the latest version of the EV kit software,
16825Rxx.ZIP. Save the EV kit software to a temporary folder and uncompress the ZIP file.
2) Install the EV kit software on your computer by running the INSTALL.EXE program inside the temporary folder. The program files are copied and icons
are created in the Windows Start | Programs
menu. All EV kit files are automatically installed.
3) Set the power-supply output to over VFLED + 1.7V.
4) Disable the power-supply output.
5) Connect the power-supply ground to the GND pad
next to the VIN pad.
6) Connect the power-supply positive output to the
VIN pad.
7) Connect one LED load anode to each LED output
pad (LED1+, LED2+, or LED3+).
8) Connect each LED load cathode to the corresponding LED input pad (LED1-, LED2-, or LED3-).
9) 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
_______________________________________________________________________________________
MAX16825 Evaluation Kit
12) Start the EV kit software by opening its icon in the
Start | Programs menu. The MAX16825 EV kit software main window appears, as shown in Figure 1.
13) Select the Output Enable checkbox and any of the
Channel_ checkboxes.
14) Verify that the corresponding attached LEDs are
illuminated.
The software features a demo mode that is available by
selecting the View | Demo Mode menu item. When
operating in demo mode, all software communication to
the EV kit hardware is disabled and most of the software’s GUI is functional. This feature enables the user
to evaluate the software without hardware connectivity.
The left-bottom status bar provides the USB-to-SPI
communication status. The right-bottom status bar provides the current program status. The MAX16825 EV kit
software configures the on-board SPI communication to
8kHz by default.
Software Startup
Upon starting the program, select the Output Enable
checkbox to enable the LED outputs. Deselecting the
Output Enable checkbox disables all three LED outputs. The Channel_ checkboxes enable and disable
individual channels.
General-Purpose 3-Wire (SPI) Interface Utility
The general-purpose 3-wire interface utility (Figure 2)
can also be used to communicate with the MAX16825
using low-level SPI commands. Select the Options |
Interface menu item and select the 3-wire interface tab
to access the utility. The utility configures the 3-wire serial-interface parameters, such as MSB position, CPOL,
CPHA, MOSI/MISO inverted logic, CS active state (high
or low), SPI clock (SCLK) speed, and custom selection
of SPI signal pins. The data to be sent is 8-bit data represented by a two-digit hexadecimal code. The code is
entered in the Data bytes to be written edit box and
transmitted by clicking on the Send Now button.
General Troubleshooting
Problem: Software reports it cannot find the interface circuit.
• Is power LED D1 lit?
Figure 1. MAX16825 Evaluation Kit Software—Graphical User
Interface (GUI)
Detailed Description of Software
Graphical User Interface
The main window’s GUI (Figure 1) is simple to use. A
mouse or the keyboard’s tab key is used to navigate
through the controls. The correct SPI write operation is
generated to update the internal registers of the
MAX16825 when any of these controls are used.
• Is the USB cable connected to the PC and EV kit?
• Is power applied to the VIN PCB pad?
• Has Windows plug-and-play detected the board?
Bring up the Control Panel > System > Device
Manager, and look at what device nodes are indicated for USB. If there is an unknown device node
attached to the USB, delete it. This process forces
plug-and-play to try again.
_______________________________________________________________________________________
3
Evaluates: MAX16825
described above after 30s, remove the USB cable
from the board and reconnect it. Administrator privileges are required to install the USB device driver
on Windows.
10) 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\MAX16825 (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 TROUBLESHOOTING_USB.PDF document
included with the software for additional information.
11) Enable the power-supply output.
Evaluates: MAX16825
MAX16825 Evaluation Kit
Figure 2. The 3-Wire Interface Window Provides Direct, Low-Level Access to the MAX16825 and 3-Wire Serial Interface
4
_______________________________________________________________________________________
MAX16825 Evaluation Kit
The MAX16825 EV kit demonstrates a high-voltage, 3channel, linear high-brightness LED driver using the
MAX16825 IC in a 16-pin TSSOP surface-mount package. This EV kit is configured to supply an LED current
of 100mA per channel. The MAX16825 IC controls the
LED current by maintaining a 200mV drop across each
external sense resistor (R8, R9, and R10). The EV kit
operates from a 0.5A, 6.5V to 28V rated power supply.
The MAX16825 EV kit uses a standard 4-wire SPI interface for independently controlling each of the three
individual channels. Only the components in the Figure
3 schematic are required when using a user-supplied
SPI interface. The MAX16825 integrates a USB-to-SPI
interface circuit that is based on Maxim’s MAXQ2000
16-bit microcontroller. The EV kit includes Windows
2000/XP/Vista-compatible software that provides a GUI
for exercising the MAX16825 features. The components
on the Figure 4 schematic are only required for PC
evaluation and are not needed for an HB LED design.
The MAX16825 features an exposed paddle that uses
the top-layer and bottom-layer PCB copper as a
heatsink. The exposed paddle connects to GND.
LED Load Configuration
The MAX16825 EV kit can drive three separate LED
loads. Each LED load can consist of multiple LEDs connected in series. The LED load’s forward voltage can
be up to 26.3V. The EV kit drives LEDs rated for at least
100mA. Proper heat sinking of the LEDs is important for
optimum LED performance and durability.
Output Current Setting
The current for each MAX16825 EV kit LED channel
(ILED1, ILED2, and ILED3) is configured to 100mA by
three sense resistors (R8, R9, and R10, respectively).
See the equation below to select a different LED current
and a new resistor value. If designing for a higher LED
current, verify that the desired current setting does not
exceed the power rating of the corresponding resistor
(R8, R9, R10) or the LED load. Do not set the LED current above 150mA. Use the following equation to calculate the value of the new resistor:
R_ =
200mV
ILED _
where ILED_ is the desired LED current and R_ is the
resistor value required to set the desired current of the
LED channel.
_______________________________________________________________________________________
5
Evaluates: MAX16825
Detailed Description of Hardware
Evaluates: MAX16825
MAX16825 Evaluation Kit
High Input Voltage
and Thermal Protection
User-Supplied SPI Interface
The user may control the MAX16825 EV kit directly with a
user-supplied, 5V logic, 4-wire SPI interface for standalone operation. Cut open header J2’s shorting traces
located on the PCB’s bottom layer. Connect the user-supplied CS, SCLK, DIN, and a control signal to the OE, CLK,
DIN, and LE pads, respectively, on the MAX16825 EV kit.
Refer to the Electrical Characteristics, SPI Interface section of the MAX16825 IC data sheet for more information
on the MAX16825’s SPI communication requirements.
The MAX16825 IC operates in linear mode. As a result,
the IC can dissipate significant power if operated using a
high input voltage and a small VFLED. High-power dissipation may cause the IC to go into thermal shutdown.
Refer to the Thermal Protection section in the MAX16824/
MAX16825 IC data sheet for more information.
VIN
LED1+
VIN
LED2+
GND
C21
1μF
LED3+
GND
3
GND
IN
7
DIN
DIN
8
LE
LE
9
OE
OE
10
DOUT
6
CLK
CLK
4
VREG
GND
C22
1μF
OUT1
DIN
U1
LE
OUT2
MAX16825 OUT3
OE
DOUT
CS1
CLK
CS2
REG
CS3
N.C. N.C. GND
5 14
11
1
LED1-
16
LED2-
12
LED3-
2
15
13
R10
2Ω
1%
R9
2Ω
1%
R8
2Ω
1%
Figure 3. MAX16825 EV Kit Schematic—LED Driver Circuit
6
_______________________________________________________________________________________
6
5
+5V
C17
0.1μF
C16
1μF
+5V
3
1
U5 OUT
GND
N.C.
ORG
VCC
SHDN
GND
2
5
DO
D1
SK
CS
U3
AT93C46A
4
MAX8511
5
7
6
8
GND
IN
2
1
D+ 3
D-
VBUS
USB TYPE B
SHIELD
SHIELD
P1
1
IN
32
28
27
4
+3.3V
4
C15
10μF
R3
10kΩ
+5V
3
C14
1μF
SHDN
2
5
TEST
+2.5V
EEDATA
EESK
EECS
XTOUT
XTIN
RESET
RSTOUT
USBDP
USBDM
GND
MAX8511
U6 OUT
31
2
+5V
5
7
8
6
AVCC
3V3OUT
3
C13
10μF
29
AGND
VCC
TDI
H1-10
H1-9
OPEN
H1-2
H1-8
H1-7
H1-5
H1-6
TMS
H1-4
H1-3
10
H1-1
H1
JTAG
SLEEP
PWREN
15
14
11
12
16
18
19
20
21
22
23
24
TCK
17
GND
PWRCTL
RXLED
TXLED
TXDEN
RI
DCD
DSR
DTR
CTS
RTS
RXD
13
VCCIO
25
TXD
+3.3V
R2
220Ω
RI
DCD
DSR
DTR
CTS
RTS
RXD
TXD
RESET
D1
DTR
RTS
RI
DIN
LE
OE
J2-5
J2-3
J2-1
J2-6
J2-4
J2-2
SS
U1_64
SHORT
CLK
J2-7
J2-8
SCLK
MOSI
HEADER 2x4
J2
SHORT
62
23
DSR
22
DCD
21
J1-8
20
63
J1-10
J1-6
J1-4
J1-2
19
64
J1-9
J1-5
J1-3
J1-1
HEADER 2x5
J1
18
65
J1-7
GND
GND
SEG27/P3.3
SEG26/P3.2
SEG25/P3.1
SEG24/P3.0
SEG23/P2.7
SEG22/P2.6
SEG21/P2.5
SEG20/P2.4
SEG19/P2.3
SEG18/P2.2
SEG17/P2.1
SEG16/P2.0
SEG15/P1.7
SEG14/P1.6
SEG13/P1.5
SEG12/P1.4
SEG11/P1.3
VDD
66
TDI
42
28
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
49
SEG9/P1.1
TCK
TMS
TDO
RESET
+3.3V
C9
0.1μF
+2.5V
SEG10/P1.2
67
SEG30/P3.6/INT6
68
SEG8/P1.0
SEG28/P3.4/INT4
C8
0.1μF
SEG34/COM2
24
61
25
60
U2
MAXQ2000
26
59
58
SEG0/P0.0
SEG1/P0.1
+3.3V
TDO
9
GND
U4
FT232BL
VCC
26
C7
0.1μF
SEG7/P0.7/INT3
SEG29/P3.5/INT5
+5V
SEG6/P0.6/INT2
SEG31/P3.7/INT7
30
C6
0.1μF
SEG5/P0.5/INT1
SEG32
+5V
SEG4/P0.4/INT0
SEG33/COM3
C5
0.1μF
57
VADJ
TCK
29
P4.0/TCK/INT8
R1
0Ω
56
VLCD2
TDI
30
P4.1/TDI/INT9
C4
0.1μF
3
+5V
C18
22pF
Y2
6MHz
C19
22pF
+5V
1
R4
2.2kΩ
R5
1.5kΩ
C20
3300pF
C3
0.1μF
2
1
R6
27Ω
R7
27Ω
C2
10μF
55
VLCD1
TMS
31
P4.2/TMS
54
53
52
RXD
P6.5/TO/WKOUT 1
HFXOUT
HFXIN
VDDIO
32KOUT
32KIN
P5.2/RX1/INT10
P5.3/RX1/INT11
P5.4/SS
P5.5/MOSI
P5.6/SCLK
P5.7/MISO
P6.0/T1B/INT12
P6.1/T1/INT13
P6.2/T2B/OW_OUT
P6.3/T2/OW_IN
P6.4/TOB/WKOUT 0
TXD
TDO RESET
32
33
+3.3V
VLCD
P4.3/TD0
FB1
SHORT
SEG3/P0.3
SEG35/COM1
C1
0.1μF
SEG2/P0.2
COM0
P7.0/TXO/INT14
U1_64
P7.1/RXO/INT15
RESET
35
34
36
37
38
39
40
41
43
44
45
46
47
48
50
51
27
RTS
DTR
SS
MOSI
SCLK
R11
OPEN
C12
10pF
C11
10pF
Y1
16MHz
+3.3V C10
0.1μF
CTS
DSR
Evaluates: MAX16825
+5V
MAX16825 Evaluation Kit
Figure 4. MAX16825 EV Kit Schematic—USB and SPI Interface Circuit
_______________________________________________________________________________________
7
Evaluates: MAX16825
MAX16825 Evaluation Kit
Figure 5. MAX16825 EV Kit Component Placement Guide—Component Side
8
_______________________________________________________________________________________
MAX16825 Evaluation Kit
Evaluates: MAX16825
Figure 6. MAX16825 EV Kit PCB Layout—Component Side
_______________________________________________________________________________________
9
Evaluates: MAX16825
MAX16825 Evaluation Kit
Figure 7. MAX16825 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.
10 ____________________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.
Boblet