MAX6974EVKIT+ - Maxim Integrated

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.

Features

♦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

Evaluates: MAX6974

MAX6974 Evaluation Kit

________________________________________________________________ Maxim Integrated Products 1

19-0519; Rev 1; 2/07

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.

Ordering Information

PART

TYPE

INTERFACE REQUIREMENTS

MAX6974EVKIT+

EV kit

Windows PC with RS-232 serial port

DESIGNATION QTY DESCRIPTION

C1 1 100µF ± 20%, 10V X 5R cap aci tor ( 1812)

TD K C 4532X 5R1A107M

C2, C3 2 100µF ±20%, 6.3V X 5R cap acitor s ( 1210)

TD K C 3225X 5R0J107M

C4, C5, C25 3 10µF ± 10% , 6.3V X 5R cap aci tor s ( 0603)

TD K C 1608X 5R0J106K

C6–C9 4 0.47µF ± 10%, 6.3V X5R cap aci tors ( 0402)

TD K C 1005X 5R0J474K

C10–C16 7 0.1µF ± 10%, 6.3V X 5R cap aci tor s ( 0402)

TD K C 1005X 5R0J104K

C17, C18 2 0.001µF ±10%, 25V X5R capacitors (0402)

TD K C 1005X5R1E 102K

C19–C22 4 120p F ± 5% , 25V C 0G cap aci tor s ( 0402)

TD K C 1005C 0G1E 121J

C23, C24 2 10p F ± 5%, 25V C 0G cap aci tor s ( 0402)

TD K C 1005C 0G1E 100J

C26 1 0.01µF ± 10%, 6.3V X 5R cap aci tor ( 0402)

TD K C 1005X 5R1E 103K

D1–D32 32 RGB LED modules

Stanley URGB1308B-10-TF

J1 0 Not installed

J2 1 2 x 5 right-angle receptacle (0.1in)

J3 1 2 x 5 right-angle male header (0.1in)

J4 0 Not installed

Windows is a registered trademark of Microsoft Corp.

Component List

DESIGNATION

QTY

DESCRIPTION

JU1–JU13

2-pin headers

JU14–JU20

3-pin headers

Female DB9 connector

Q1–Q4

pnp transistors

Zetex FMMTL717TA (SOT23)

R1–R8

200Ω ±1% resistors (0603)

R9–R12

182Ω ±1% resistors (0603)

R13–R16

562Ω ±1% resistors (0603)

R17

4.99kΩ ±1% resistor (0402)

R18

9.53kΩ ±1% resistor (0402)

R19

249kΩ ±1% resistor (0402)

R20

267kΩ ±1% resistor (0402)

TP1–TP10

Not installed

U1, U2

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)

+Denotes a lead-free and RoHS-compliant EV kit.

Evaluates: MAX6974

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

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.

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.

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.

MAX6974 Evaluation Kit

2 _______________________________________________________________________________________

DESIGNATION

QTY

DESCRIPTION

RS - 232 tr anscei ver

M axi m M AX 3311E U B+ ( 10- p i n µM AX

)

U7, U8

LDO linear regulators

Maxim MAX1658ESA+ (8-pin SO)

LDO linear regulator

Maxim MAX1659ESA+ (8-pin SO)

Component List (continued)

DESIGNATION

QTY

DESCRIPTION

20MHz crystal

Citizen HCM49-20.000MABJ-UT

32MHz oscillator

ECS ECS-3953M-320-B-TR

—

PCB: MAX6974 evaluation kit+

—

Shunts

Component Suppliers

SUPPLIER PHONE FAX WEBSITE

TDK Corp. 847-803-6100 847-390-4405 www.component.tdk.com

Zetex USA 631-543-7100 631-864-7630 www.zetex.com

Note: Indicate that you are using the MAX6974 when contacting these component suppliers.

µMAX is a registered trademark of Maxim Integrated Products, Inc.

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.

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.

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

MAX6974 Evaluation Kit

_______________________________________________________________________________________ 3

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.

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.

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

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.

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

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.

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.

MAX6974 Evaluation Kit

4 _______________________________________________________________________________________

Table 1. LED Nonmultiplexing

IC/PORT LED DEVICES DRIVEN COLORS

U1 port R D1 to D8 Red

U1 port G D1 to D8 Green

U2 port R D9 to D16 Red

U2 port G D9 to D16 Green

U1 port B D1 to D8 Blue

U2 port B D9 to D16 Blue

Table 2. LED Multiplexing

IC/PORT LED DEVICES DRIVEN COLORS

D1 to D8

U1 port R D17 to D24 Red

D1 to D8

U1 port G D17 to D24 Green

D9 to D16

U2 port R D25 to D32 Red

D9 to D16

U2 port G D25 to D32 Green

D1 to D8

U1 port B D9 to D16 Blue

D17 to D24

U2 port B D25 to D32 Blue

Table 3. Device Comparison—

Nonmultiplexed Operation

M A X6 9 7 4

M A X6 9 7 5

O PER A T I O N

7 b i ts 5 b i ts

G l ob al - i ntensi ty contr ol P W M r esol uti on

3 ( R, G , B)

N um b er of LE D cur r ent cal i b r ati on

r eg i ster s

8 b i ts 8 b i ts LE D cur r ent cal i b r ati on r esol uti on

30m A30m AM axi m um LE D d r i ve cur r ent

( LE D cur r ent cal i b r ati on = 255)

6m A6m ALE D d r i ve cur r ent

( LE D cur r ent cal i b r ati on = 0)

24 24 N um b er of p i xel s

12 b i ts 14 b i ts Ind i vi d ual p i xel P W M - i ntensi ty- contr ol

r esol uti on

Evaluates: MAX6974

MAX6974 Evaluation Kit

_______________________________________________________________________________________ 5

Table 4. Device Comparison—

Multiplexed Operation

M A X6 9 7 4

M A X6 9 7 5

O PER A T I O N

6 b i ts 4 b i ts

G l ob al - i ntensi ty contr ol P W M r esol uti on

3 ( R, G , B)

N um b er of LE D cur r ent cal i b r ati on

r eg i ster s

8 b i ts 8 b i ts LE D cur r ent cal i b r ati on r esol uti on

30m A30m AM axi m um LE D d r i ve cur r ent

( LE D cur r ent cal i b r ati on = 255)

6m A6m ALE D d r i ve cur r ent

( LE D cur r ent cal i b r ati on = 0)

48 48 N um b er of p i xel s

12 b i ts

14 b i ts Ind i vi d ual p i xel P W M - i ntensi ty- contr ol

r esol uti on

Table 5. Jumper Functions Table

JUMPER

PINS FUNCTION

Closed*

Enables LED multiplexing.

JU1 Open Disables LED multiplexing.

Closed*

Enables LED multiplexing.

JU2 Open Disables LED multiplexing.

Closed*

Enables LED multiplexing.

JU3 Open Disables LED multiplexing.

Closed*

Enables LED multiplexing.

JU4 Open Disables LED multiplexing.

Closed*

Enables LED multiplexing.

JU5 Open Disables LED multiplexing.

Closed*

Enables LED multiplexing.

JU6 Open Disables LED multiplexing.

Closed*

Normal operation.

JU7 Open Force LED D1 red open fault condition.

Closed*

Normal operation.

JU8 Open Force LED D1 green open fault condition.

Closed*

Normal operation.

JU9 Open Force LED D1 blue open fault condition.

*Default jumper setting.

Evaluates: MAX6974

MAX6974 Evaluation Kit

6 _______________________________________________________________________________________

Table 5. Jumper Functions Table (continued)

JUMPER

PINS FUNCTION

Closed*

Single board mode: R9 terminates CLKO; nothing connects to J3.

JU10 Open No CLKO termination, allowing slave board to connect to J3.

Closed*

Single board mode: R9 terminates CLKO; nothing connects to J3.

JU11 Open No CLKO termination, allowing slave board to connect to J3.

Closed*

Single board mode: R10 terminates DOUT; nothing connects to J3.

JU12 Open No DOUT termination, allowing slave board to connect to J3.

Closed*

Single board mode: R10 terminates DOUT; nothing connects to J3.

JU13 Open No DOUT termination, allowing slave board to connect to J3.