19-0519; Rev 1; 2/07
MAX6974 Evaluation Kit
Evaluates: MAX6974
General Description
The MAX6974 evaluation kit (EV kit) is an assembled and
tested printed circuit board (PCB) that demonstrates the
MAX6974/ MAX6975 precision current-sinking, 24-output
PWM LED drivers. The MAX6974/MAX6975 functionality
can be evaluated using the MAX6974 EV kit. The
MAX6975 has 14-bit individual PWM and 5-bit global
PWM, while the MAX6974 has 12-bit individual PWM and
7-bit global PWM. The evaluation kit comes with a
MAX6974ATL+ installed. The Windows
®
98/2000/XP
software supports only the MAX6974.
♦
Proven PCB Layout
♦
Complete Evaluation System
♦
Convenient On-Board Test Points
♦
Fully Assembled and Tested
♦
Multiplexed 4 x 8 RGB (96 LEDs Total) 20mA LED
Matrix
Features
Ordering Information
PART
TYPE INTERFACE REQUIREMENTS
Windows is a registered trademark of Microsoft Corp.
MAX6974EVKIT+ EV kit Windows PC with RS-232 serial port
+Denotes
a lead-free and RoHS-compliant EV kit.
Component List
DESIGNATION QTY
C1
C2, C3
C4, C5, C25
C6–C9
C10–C16
C17, C18
C19–C22
C23, C24
C26
D1–D32
J1
J2
J3
J4
1
2
3
4
7
2
4
2
1
32
0
1
1
0
DESCRIPTION
100µF ±20%, 10V X5R capacitor (1812)
TDK C4532X5R1A107M
100µF ±20%, 6.3V X5R capacitors (1210)
TDK C3225X5R0J107M
10µF ±10%, 6.3V X5R capacitors (0603)
TDK C1608X5R0J106K
0.47µF ±10%, 6.3V X5R capacitors (0402)
TDK C1005X5R0J474K
0.1µF ±10%, 6.3V X5R capacitors (0402)
TDK C1005X5R0J104K
0.001µF ±10%, 25V X5R capacitors (0402)
TDK C1005X5R1E102K
120pF ±5%, 25V C0G capacitors (0402)
TDK C1005C0G1E121J
10pF ±5%, 25V C0G capacitors (0402)
TDK C1005C0G1E100J
0.01µF ±10%, 6.3V X5R capacitor (0402)
TDK C1005X5R1E103K
RGB LED modules
Stanley URGB1308B-10-TF
Not installed
2 x 5 right-angle receptacle (0.1in)
2 x 5 right-angle male header (0.1in)
Not installed
U5
1
DESIGNATION QTY
JU1–JU13
JU14–JU20
P1
Q1–Q4
R1–R8
R9–R12
R13–R16
R17
R18
R19
R20
TP1–TP10
U1, U2
13
7
1
4
8
4
4
1
1
1
1
0
2
DESCRIPTION
2-pin headers
3-pin headers
Female DB9 connector
pnp transistors
Zetex FMMTL717TA (SOT23)
200Ω ±1% resistors (0603)
182Ω ±1% resistors (0603)
562Ω ±1% resistors (0603)
4.99kΩ ±1% resistor (0402)
9.53kΩ ±1% resistor (0402)
249kΩ ±1% resistor (0402)
267kΩ ±1% resistor (0402)
Not installed
24-output LED drivers
Maxim MAX6974ATL+
(40-pin TQFN, 6mm x 6mm EP)
Low-power microcontroller
Maxim MAXQ2000-RAX+
(68-pin QFN, 10mm x 10mm EP)
Dual LVDS line driver
Maxim MAX9112EKA+ (8-pin SOT23)
Dual LVDS line receiver
Maxim MAX9113EKA+ (8-pin SOT23)
U3
1
U4
1
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
MAX6974 Evaluation Kit
Evaluates: MAX6974
Component List (continued)
DESIGNATION QTY
U6
U7, U8
U9
1
2
1
DESCRIPTION
RS-232 transceiver
Maxim MAX3311EUB+ (10-pin µMAX
®
)
LDO linear regulators
Maxim MAX1658ESA+ (8-pin SO)
LDO linear regulator
Maxim MAX1659ESA+ (8-pin SO)
DESIGNATION QTY
Y1
Y2
—
—
1
1
1
20
DESCRIPTION
20MHz crystal
Citizen HCM49-20.000MABJ-UT
32MHz oscillator
ECS ECS-3953M-320-B-TR
PCB: MAX6974 evaluation kit+
Shunts
µMAX is a registered trademark of Maxim Integrated Products, Inc.
Component Suppliers
SUPPLIER
TDK Corp.
Zetex USA
PHONE
847-803-6100
631-543-7100
FAX
847-390-4405
631-864-7630
WEBSITE
www.component.tdk.com
www.zetex.com
Note:
Indicate that you are using the MAX6974 when contacting these component suppliers.
Quick Start
Required Equipment
Before you begin, you need the following equipment:
• Maxim MAX6974EVKIT
•
•
•
DC power supply, 5VDC at 1A
Windows 98/2000/XP-compatible computer with a
serial (COM) port
9-pin I/O extension cable
5) Turn on the power supply. None of the LEDs light
up at this time.
6) Start the MAX6974 program by opening its icon in
the
Start
menu.
7) In the
Select Maxim MAX6974 Evaluation Kit
Software Mode
window, select
Connect to EVKit on
port (Autodetect).
Click
OK.
See Figure 1. Verify that
the blue M test pattern appears (test_0_blue_M.clr).
8) From the
File
menu, select
Load Test Patterns...
and then pick the file
test_01_all_white.clr.
Verify
that all 32 RGB LEDs light up in white.
9) In the
LED0 color
grid, double-click one of the
large round color dots in the 4 x 8 grid (or select
one of the dots and click
OK).
The standard color
selector dialog box appears. Select a color and
click
OK.
Click
Upload All
to write the 4 x 8 color
grid data to the board. Verify that the LEDs light up
in colors corresponding to the software color grid
settings.
10) Set
Global Intensity
to
5/63
and click
Upload All.
Verify that the LEDs are brighter.
Procedure
Do not turn on the power until all connections
are complete.
1) Ensure that all jumpers JU1–JU20 are in 1-2 posi-
tion (see Table 5).
2) Connect a 5VDC power source (7VDC maximum) to
the board at the VLED and GND terminals.
3) Connect a cable from the computer’s serial port to
the EV kit. If using a 9-pin serial port, use a straight-
through, 9-pin female-to-male cable. If the only
available serial port uses a 25-pin connector, a
standard 25-pin-to-9-pin adapter is required.
4) Install the evaluation software on your computer by
launching MAX6974.msi. (The latest software can
be found on Maxim’s website www.maxim-ic.com.)
The program files are copied and icons are created
for them in the Windows
Start
menu.
Detailed Description of Software
The MAX6974 EV kit software controls one or more
MAX6974 EV kit boards, each of which has two
MAX6974s driving a 4 x 8 grid of LEDs.
2
_______________________________________________________________________________________
MAX6974 Evaluation Kit
Universal Options
The
Cascaded Boards
control must be set to the num-
ber of boards that are connected.
When
Multiplexing
is disabled, only the left half of the
4 x 8 grid is driven. See the
Detailed Description
of
Hardware
section.
Clicking the
Upload Control Command Only
button
writes the control command to all cascaded MAX6974s
(see Figure 2). Refer to the MAX6974/MAX6975 data
sheet
Commands
section, Table 15.
Cascading Boards
Two or more MAX6974 EV kit boards can be connected
together in a master-slave configuration, using the mas-
ter/slave connectors, J2 and J3.
1) With power off, connect the J3 pins of one board to
the J2 socket of the next board.
2) The board on the left is the master. On the master
board, set the JU14–JU18 shunts to position 1-2.
On all other boards, set the JU14–JU18 shunts to
position 2-3.
3) The board on the right is the last slave. On the last
slave board, set the JU10–JU13 shunts closed. On
all other boards, remove the JU10–JU13 shunts.
4) Connect 5VDC power to the master board, between
the VLED and GND pads.
5) Connect a cable from the computer’s serial port to
the master board. If using a 9-pin serial port, use a
straight-through, 9-pin, female-to-male cable.
6) Install the evaluation software on your computer by
launching MAX6974.msi. The program files are
copied and icons are created for them in the
Windows
Start
menu.
7) Turn on the power supply. None of the LEDs light
up at this time.
8) Start the MAX6974 program by opening its icon in
the Windows
Start
menu.
9) In the
Select Maxim MAX6974 Evaluation Kit
Software Mode
window, select
Connect to EVKit
on port (Autodetect).
See Figure 1. Click
OK.
10) Set the software’s
Cascaded Boards
to
2, 3, 4,
or
5,
depending on the number of boards used.
11) Set the software’s
Select Board
to 1 to work with
the master board.
12) In the
Board 1 LED Colors
grid, double-click one
of the large round color dots in the 4 x 8 grid (or
select one of the dots and click
OK).
The standard
color selector dialog box appears. Select a color
and click
OK.
13) Click
Upload All
to write the 4 x 8 color grid data to
the board. Verify that the LEDs light up in colors
corresponding to the software color grid settings.
14) Set
Board 1 Global Intensity
to
5/63
and click
Upload All.
Verify that the LEDs are brighter.
15) Set the software’s
Select Board
to 2 to work with
the next board, and repeat the process of setting
LED colors, global intensity, and upload all.
Evaluates: MAX6974
Individual Board Options
The
Individual Board Options
controls apply to the
two MAX6974s on the selected board. If using a single
EV kit board, leave
Select Board
set at 1. See the
Cascading Boards
section.
The
Board Calibration
controls determine the peak
LED current for each group of output ports. Because
the LEDs used on the EV kit board are only rated for
20mA, setting the calibration controls to a value greater
than about 50/255 can exceed the LED’s rated drive
current, causing permanent damage to the LED.
The 4 x 8 grid of circles inside
Board LED Colors
cor-
responds to the 4 x 8 grid of LEDs on the EV kit board.
These can be individually selected by clicking them
with the mouse. The
Change…
button chooses the
color of the single selected LED. Clicking the
Change
All
button sets all 32 LEDs to a chosen color.
Upload All
Clicking the
Upload All
button writes universal and
individual board options to all cascaded MAX6974s.
File-Load Test Patterns
Pressing the key combination Ctrl+T brings up a con-
venient window containing a list of test pattern files
(see Figure 3). All files whose names begin with “test_”
and end with “.clr” are listed as test patterns. Click on a
filename from the list, and the chroma pattern is
immediately loaded. For example, test pattern
test_921_ 2boards_all_white.clr loads a master and one
slave board with a 4 x 16 pattern where all of the LEDs
are on. The test pattern default.clr is loaded at startup.
Disabling LED Multiplexing
As shipped from the factory, the 4 x 8 grid of tricolor LEDs
is multiplexed. To disable multiplexing, and drive only the
left 4 x 4 half of the grid, two steps are necessary. First,
jumpers JU1–JU6 and JU19 and JU20 must be reconfig-
ured. See Table 5. Second, the
Multiplexing
must be set
to
Disabled
in
Universal Options.
_______________________________________________________________________________________
3
MAX6974 Evaluation Kit
Evaluates: MAX6974
Slideshow Demo
The EV kit software can load a sequence of test pat-
terns. From the
Command
menu, select
Slideshow,
then choose a folder containing test pattern files (see
Figure 4). The time between patterns can be adjusted
between 50ms and 30s.
MAX6974 LED display drivers (U1, U2). A 32MHz crys-
tal oscillator (Y2) is used to demonstrate optimum PWM
frequency by driving the LVDS clock signal between
command sequences. During command sequences,
the MAXQ2000 bit bangs the LVDS clock at 2.8MHz.
When used with the software, the MAX3311 (U6) trans-
lates the RS-232 signal levels from the COM port (P1) to
logic-level signals. Resistor-dividers R17/R18 convert
the 5V logic output into 3.3V logic.
When JU14–JU18 are in the 2-3 position, external LVDS
signals must be applied to connector J2. In this slave
configuration, the MAXQ2000 (U3), MAX9112 (U4), and
MAX3311 (U6) are not used.
Detailed Description of Hardware
The MAX6974 precision current-sinking, 24-output PWM
LED drivers (U1, U2) drive a 4 x 8 multiplexed grid of
red-green-blue LEDs in the common-anode configura-
tion. Common-emitter pnp BJTs (Q1–Q4) switch the
LED supply voltage in the multiplexing configuration.
See Tables 1 and 2.
Table 1. LED Nonmultiplexing
IC/PORT
U1 port R
U1 port G
U2 port R
U2 port G
U1 port B
U2 port B
LED DEVICES DRIVEN
D1 to D8
D1 to D8
D9 to D16
D9 to D16
D1 to D8
D9 to D16
COLORS
Red
Green
Red
Green
Blue
Blue
LED Power Dissipation
Peak LED current is set by each port’s LED current cali-
bration register. This 8-bit DAC allows peak LED cur-
rent to be reduced to between 20% and 100% of the
full-scale rating, 30mA. Setting the current calibration
register to a value of 0 limits the peak LED current to
6mA (20% of 30mA). By writing different values to the
red, green, and blue ports’ current calibration registers,
the display’s color balance can be adjusted to compen-
sate for LED efficacy variations.
The evaluation kit is shipped from the factory with an
LED type (Stanley URGB1308B) that has a maximum rat-
ing of 20mA forward current or 84mW power dissipation.
Table 2. LED Multiplexing
IC/PORT
U1 port R
U1 port G
U2 port R
U2 port G
U1 port B
U2 port B
LED DEVICES DRIVEN
D1 to D8
D17 to D24
D1 to D8
D17 to D24
D9 to D16
D25 to D32
D9 to D16
D25 to D32
D1 to D8
D9 to D16
D17 to D24
D25 to D32
COLORS
Red
Green
Red
Green
Blue
Blue
Evaluating the MAX6975
The MAX6974 EV kit’s software and firmware are only
capable of driving 12-bit PWM values. If the EV kit were
used to drive the MAX6975s instead, then the two least
significant bits of the individual pixel PWM values are
not accessible. See Tables 3 and 4.
Table 3. Device Comparison—
Nonmultiplexed Operation
MAX6974
7 bits
MAX6975
5 bits
OPERATION
Global-intensity control PWM resolution
Number of LED current calibration
registers
LED current calibration resolution
Maximum LED drive current
(LED current calibration = 255)
LED drive current
(LED current calibration = 0)
Number of pixels
Individual pixel PWM-intensity-control
resolution
3 (R, G, B) 3 (R, G, B)
8 bits
30mA
6mA
24
12 bits
8 bits
30mA
6mA
24
14 bits
User-supplied DC power between 5V and 7V, applied
between the VLED and GND pads, is regulated by three
MAX1658/MAX1659 low-dropout linear regulators (U7,
U8, and U9) to produce 5V, 3.3V, and 2.5V supply rails.
The MAXQ2000 microcontroller (U3) drives the
MAX9112 LVDS level shifter (U4). When JU14–JU18 are
in the 1-2 position, this microcontroller drives the
4
_______________________________________________________________________________________
MAX6974 Evaluation Kit
Evaluates: MAX6974
Table 4. Device Comparison—
Multiplexed Operation
MAX6974
6 bits
MAX6975
4 bits
OPERATION
Global-intensity control PWM resolution
Number of LED current calibration
registers
LED current calibration resolution
Maximum LED drive current
(LED current calibration = 255)
LED drive current
(LED current calibration = 0)
Number of pixels
Individual pixel PWM-intensity-control
resolution
3 (R, G, B) 3 (R, G, B)
8 bits
30mA
6mA
48
12 bits
8 bits
30mA
6mA
48
14 bits
Table 5. Jumper Functions Table
JUMPER
JU1
JU2
JU3
JU4
JU5
JU6
JU7
JU8
JU9
PINS
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Closed*
Open
Enables LED multiplexing.
Disables LED multiplexing.
Enables LED multiplexing.
Disables LED multiplexing.
Enables LED multiplexing.
Disables LED multiplexing.
Enables LED multiplexing.
Disables LED multiplexing.
Enables LED multiplexing.
Disables LED multiplexing.
Enables LED multiplexing.
Disables LED multiplexing.
Normal operation.
Force LED D1 red open fault condition.
Normal operation.
Force LED D1 green open fault condition.
Normal operation.
Force LED D1 blue open fault condition.
FUNCTION
*Default
jumper setting.
_______________________________________________________________________________________
5
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