19-0534; Rev 0; 5/06
KIT
ATION
EVALU
E
BL
AVAILA
16-Output PWM LED Drivers
for Message Boards
Features
♦
16 LED Current Sink Outputs (Two Banks of Eight
Outputs)
♦
32 LED Drive Option When Multiplexing
♦
33MHz Clock Supports Up to 63 Frames per
Second of Video
♦
Constant Output Current Calibration from 11mA
to 55mA in 256 Steps
♦
EZCascade™ Interface Simplifies Multiple Driver
Cascading Without External Buffers
♦
12-Bit or 14-Bit Individual PWM LED Intensity
Controls
♦
7-Bit or 5-Bit Panel PWM-Intensity Control
♦
+3V to +7V LED Power Supply
♦
+3.0V to +3.6V Logic Supply
♦
Open-Circuit LED Fault Detection
♦
Optional Watchdog Timer Blanks Display if
Interface Fails
♦
Standard -40°C to +125°C Operating Temperature
Range
General Description
The MAX6972/MAX6973 precision current-sinking,
16-output PWM LED drivers drive red, green, and/or blue
LEDs for full-color graphic message boards and video
displays. Each output has an individual 12-bit (MAX6972)
or 14-bit (MAX6973) PWM-intensity (hue) control and
7-bit (MAX6972) or 5-bit (MAX6973) global PWM intensity
(luminance) control. The MAX6972/MAX6973 also fea-
ture open-circuit LED fault-detection circuitry, as well as
a watchdog timer.
The driver has two banks of eight outputs, with each bank
intended to drive a different color in RGB applications.
The standard application uses three MAX6972/
MAX6973s to drive eight RGB LEDs. The full-scale current
for each bank of eight outputs is adjustable from 11mA
to 55mA in 256 steps (0.3125% per step) to calibrate
each color.
The MAX6972/MAX6973 can optionally multiplex by
using outputs
MUX0
and
MUX1,
which each drive an
external pnp transistor. Multiplexing doubles the
MAX6972/MAX6973 drive capability to 32 LEDs.
The MAX6972/MAX6973 operate from a 3.0V to 3.6V
power supply. The LED power supply can range from
3V to 7V. The LED drivers require only 0.8V headroom
above the LEDs’ forward-voltage drop. Using a sepa-
rate LED supply voltage for each LED minimizes power
consumption.
The serial interface uses differential signaling for the
high-speed clock and data signals to reduce EMI and
improve signal integrity. The MAX6972/MAX6973 buffer
all interface signals to simplify cascading devices in
modules that use a large number of drivers.
An internal watchdog timer, when enabled, automatically
clears the pixel-data registers and blanks the display if
any of the signal inputs fail to toggle within 40ms.
The MAX6972/MAX6973 are available in 32-pin TQFN
packages and operate over the -40°C to +125°C
temperature range.
Refer to the MAX6974/MAX6975 data sheet for a
24-output, 6mA to 30mA software-compatible device.
EZCascade is a trademark of Maxim Integrated Products, Inc.
MAX6972/MAX6973
Ordering Information
PART
MAX6972ATJ+
MAX6973ATJ+
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
PIN-
PACKAGE
32 TQFN-EP*
32 TQFN-EP*
PKG
CODE
T3255-5
T3255-5
*EP
= Exposed paddle.
+Denotes
lead-free package.
Pin Configuration
DOUT+
CLKO+
V
DD
17
16
EP*
15
14
13
Y7
Y6
Y5
Y4
Y3
Y2
Y1
Y0
12
11
10
9
1
V
DD
2
MUX0
3
CLKI+
4
CLKI-
5
DIN+
6
DIN-
7
LOADI
8
I.C.
TOP VIEW
24
Z7 25
Z6 26
Z5 27
Z4 28
Z3 29
Z2 30
Z1 31
Z0 32
23
22
21
20
19
18
MAX6972ATJ
MAX6973ATJ
Applications
LED Video Display Panels
LED Message Boards
Variable Message Signs (VMS)
Signs
Graphic Panels
Typical Operating Circuit appears at the end of data sheet.
+
*EP = EXPOSED PADDLE.
TQFN
5mm x 5mm
________________________________________________________________
Maxim Integrated Products
LOAD0
DOUT-
CLKO-
MUX1
AGND
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.
16-Output PWM LED Drivers
for Message Boards
MAX6972/MAX6973
ABSOLUTE MAXIMUM RATINGS
(All voltages with respect to GND.)
V
DD
........................................................................-0.3V to +4.0V
Y0–Y7, Z0–Z7,
MUX0,
and
MUX1
.........................-0.3V to +8.0V
All Other Pins..............................................-0.3V to (V
DD
+ 0.3V)
Continuous Power Dissipation (T
A
= +70°C)
32-Pin TQFN (derate 34.5mW/°C over +70°C) ..........2857mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
DD
= 3.0V to 3.6V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
DD
= 3.3V, T
A
= +85°C.) (Note 1)
PARAMETER
Operating Supply Voltage
LEDs Anode Voltage
(Y0–Y7, Z0–Z7,
MUX0,
and
MUX1)
SYMBOL
V
DD
V
O
f
CLKI
= 0Hz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0x01
Supply Current
I
DD
f
CLKI
= 0Hz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0xFF
f
CLKI
= 32MHz; CLKO_, DOUT_ loaded 200Ω;
calibration DACs set to 0xFF
Input High Voltage LOADI
Input Low Voltage LOADI
Differential Input Voltage Range
CLKI_, DIN_
Common-Mode Input Voltage
CLKI_, DIN_
Differential Input High Threshold
Differential Input Low Threshold
Differential Output Voltage
CLKO_, DOUT_
Differential Output Offset
CLKO_, DOUT_
Input Leakage Current
CLKI_, DIN_, LOADI
Input Capacitance
CLKI_, DIN_, LOADI
Output Low Voltage LOADO
Output High Voltage LOADO
Output Slew Time LOADO
V
OLC
V
OHC
I
SINK
= 5mA
I
SOURCE
= 5mA
20% to 80%, 80% to 20%, load = 10pF
V
DD
- 0.5
V
IHC
V
ILC
V
ID
V
CM
VDIFF
TH
VDIFF
TL
V
OD
V
OS
I
IH
, I
IL
Termination 200Ω at receiver _+ and _- inputs
Termination 200Ω at receiver _+ and _- inputs
-65
±190
1.125
-1
10
0.05
V
DD
- 0.2
3
0.25
1.25
±0.15
|V
ID
/ 2|
8
-8
±550
1.375
+1
0.7
x V
DD
0.3
x V
DD
±1.20
2.4
65
21
40
42
CONDITIONS
MIN
3.0
TYP
MAX
3.6
7
35
55
60
V
V
V
V
mV
mV
mV
V
µA
pF
V
V
ns
mA
UNITS
V
V
2
_______________________________________________________________________________________
16-Output PWM LED Drivers
for Message Boards
MAX6972/MAX6973
ELECTRICAL CHARACTERISTICS (continued)
(V
DD
= 3.0V to 3.6V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
DD
= 3.3V, T
A
= +85°C.) (Note 1)
PARAMETER
Output Low Voltage
MUX_
Open-Circuit Detection
Output Slew Time
Y0–Y7, Z0–Z7
Full-Scale Port Output Current
Y0–Y7, Z0–Z7
I
SINKFS
SYMBOL
V
OLM
V
OCD
80% to 20%, load = 50pF,
calibration DACs set to 0xFF
V
DD
= 3.3V, V
O
= 1.2V,
calibration DACs set to 0xFF
T
A
= +85°C
T
A
= T
MIN
to T
MAX
T
A
= +125°C
(Note 3)
T
A
= +85°C
T
A
= -40°C
(Note 3)
54
52.5
55
55
±0.5
±0.5
±0.7
±1
31.0
30.0
33
33
0.3
I
SINK
= 40mA
200
100
56
58.0
±1.8
±1.2
±2.3
±2
35.5
36.5
1.15
mA/V
T
A
= T
MIN
to T
MAX
T
A
= +85°C
T
A
= T
MIN
to T
MAX
0.6
1.5
1.7
mA/V
2.0
%
mA
%
CONDITIONS
MIN
TYP
MAX
0.4
UNITS
V
mV
ns
mA
Port-to-Port Current Matching
Y0–Y7, Z0–Z7
∆I
SINK
V
DD
= 3.3V, V
O
= 1.2V,
calibration DACs set to 0xFF
I
SINK
= 55mA (Note 2)
Device-to-Device Current Matching
Y0–Y7, Z0–Z7
Half-Scale Port Output Current
Y0–Y7, Z0–Z7
Output Load Regulation
∆I
AVG
I
SINKHS
V
DD
= 3.3V, V
O
= 1.2V, calibration DACs set to 0xFF,
I
SINK
= 55mA, T
A
= +85°C (Note 3)
V
DD
= 3.3V, V
O
= 1.2V,
calibration DACs set to 0x80
V
DD
= 3.3V, V
O
= 1.2V to
3.0V, calibration DACs set to
0x80, I
SINK
= 33mA
V
DD
= 3.0 V to 3.6V,
V
O
= 1.2V, calibration DACs
set to 0x80, I
SINK
= 33mA
T
A
= +85°C
T
A
= T
MIN
to T
MAX
T
A
= +85°C
∆I
OLR
Output Power-Supply Rejection
∆I
OPSR
TIMING CHARACTERISTICS
(V
DD
= 3.0V to 3.6V, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at 3.3V, T
A
= +85°C.) (Note 1)
PARAMETER
CLKI_ Input Frequency
CLKI_ Duty Cycle
CLKO_ Output Delay
DIN_ Setup Time
DIN_ Hold Time
DOUT_ Output Delay
LOADO Output Delay
LOADI Setup Time
LOADI Hold Time
Watchdog Period
t
PD-CLKO
t
SU-DIN
t
HD-DIN
t
PD-DOUT
t
PD-LOADO
t
SU-LOADI
t
HD-LOADI
When enabled
-3
8
40
125
300
0.5
5
15
18
SYMBOL
f
CLKI
40
CONDITIONS
MIN
TYP
MAX
33
60
16
UNITS
MHz
%
ns
ns
ns
ns
ns
ns
ns
ms
Note 1:
All parameters tested at T
A
= +85°C. Specifications over temperature are guaranteed by design.
Note 2:
Specification limits apply to devices at the same T
A
for T
A
= T
MIN
to T
MAX
.
Note 3:
Guaranteed by design.
_______________________________________________________________________________________
3
16-Output PWM LED Drivers
for Message Boards
MAX6972/MAX6973
Typical Operating Characteristics
(V
DD
= 3.3V, T
A
= +25°C, unless otherwise noted.)
OPERATING CURRENT CONSUMPTION
vs. SUPPLY VOLTAGE V
DD
MAX6972/73 toc01
OPERATING CURRENT CONSUMPTION
vs. SUPPLY VOLTAGE V
DD
f
CLKI
= 0MHz
CALDAC = 0x00
T
A
= -40°C
I
DD
(mA)
21
T
A
= +25°C
MAX6972/73 toc02
47
f
CLKI
= 32MHz
CALDAC = 0xFF
T
A
= +25°C
T
A
= -40°C
25
45
I
DD
(mA)
23
43
19
41
T
A
= +125°C
39
3.0
3.1
3.2
3.3
3.4
3.5
3.6
SUPPLY VOLTAGE V
DD
(V)
T
A
= +85°C
T
A
= +125°C
17
T
A
= +85°C
15
3.0
3.1
3.2
3.3
3.4
3.5
3.6
SUPPLY VOLTAGE V
DD
(V)
LED OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
MAX6972/73 toc03
LED OUTPUT SINK CURRENT
vs. OUTPUT VOLTAGE
V
DD
= +3.0V
MAX6972/73 toc04
70
60
50
I
SINK
(mA)
T
A
= -40°C
70
60
50
I
SINK
(mA)
40
30
20
10
0
0
1
2
T
A
= +125°C
T
A
= +25°C
40
30
20
10
0
V
DD
= +3.3V
T
A
= +85°C
V
DD
= +3.6V
3
4
5
6
7
0
1
2
3
4
5
6
7
OUTPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
4
_______________________________________________________________________________________
16-Output PWM LED Drivers
for Message Boards
Pin Description
PIN
1,17
2
3
4
5
6
7
8
9–16
18
19
20
21
22
23
24
25–32
EP
NAME
V
DD
MUX0
CLKI+
CLKI-
DIN+
DIN-
LOADI
I.C.
Y0–Y7
LOADO
DOUT-
DOUT+
CLKO-
CLKO+
MUX1
AGND
Z7–Z0
GND
FUNCTION
Positive Supply Voltage. Bypass V
DD
to GND with a 0.1µF ceramic capacitor.
Multiplex 0 Active-Low, Open-Drain Output. Use
MUX0
to drive a pnp transistor.
PWM and Serial-Interface Noninverting Clock LVDS Input
PWM and Serial-Interface Inverting Clock LVDS Input
Serial-Interface Noninverting Data LVDS Input
Serial-Interface Inverting Data LVDS Input
Serial-Interface Load CMOS Input
Internally Connected. Connect to GND.
Y LED Drive Outputs. Y0 to Y7 are open-drain, constant-current sinks.
Serial-Interface Load CMOS Output
Serial-Interface Inverting Data LVDS Output
Serial-Interface Noninverting Data LVDS Output
PWM and Serial-Interface Inverting Clock LVDS Output
PWM and Serial-Interface Noninverting Clock LVDS Output
Multiplex 1 Active-Low, Open-Drain Output. Use
MUX1
to drive a pnp transistor.
Analog Ground. Connect to GND.
Z LED Drive Outputs. Z0 to Z7 are open-drain, constant-current sinks.
Power Ground. Exposed pad on package underside must be connected to GND.
MAX6972/MAX6973
_______________________________________________________________________________________
5
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