General Description
The MAX6983 serial-interfaced LED driver provides 16
open-drain, constant-current-sinking LED driver outputs
rated at 36V. The MAX6983 operates from a 3V to 5.5V
supply. The MAX6983 supply and the LEDs’ supply can
power up in any order. The constant-current outputs
are programmed together to up to 55mA using a single
external resistor. The MAX6983 operates with a 25Mb,
industry-standard, 4-wire serial interface.
The MAX6983 includes circuitry that automatically
detects open-circuit LEDs. Fault status is loaded into the
serial-interface shift register when LE goes high and is
automatically shifted out on DOUT when the next data
transmission is shifted in.
The MAX6983 includes a fail-safe feature for safetyrelated applications, which blanks the display if the serial interface fails. If the serial interface becomes
inactive for more than 1s, all driver output latches are
automatically cleared. This turns off all LEDs connected
to the outputs. The shift register data is not disturbed.
The outputs remain off until the driver output latches are
updated with data turning them on, so recovery is automatic if the transmission failure is temporary. The
watchdog function requires no software change to the
application driving the MAX6983.
The MAX6983 uses the industry-standard shift-registerplus-latch-type serial interface. The driver accepts data
shifted into a 16-bit shift register using data input DIN
and clock input CLK. Input data appears at the output
DOUT 16 clock cycles later to allow cascading of multiple MAX6983s. The latch-enable input, LE, loads the 16
bits of shift-register data into a 16-bit output latch to set
which LEDs are on and which are off. The outputenable input, OE, gates all 16 outputs on and off, and is
fast enough to be used as a PWM input for LED intensity control.
The MAX6983 is one of a family of 12 shift-register-pluslatch-type LED drivers. The family includes 8-port and
16-port types, with 5.5V- or 36V-rated LED outputs, with
and without open-circuit LED detection and watchdog.
All versions operate from a 3V to 5.5V supply, and are
specified over the -40°C to +125°C temperature range.
Features
♦ 25Mb Industry-Standard, 4-Wire Serial Interface
♦ 3V to 5.5V Logic Supply
♦ 16 Constant-Current LED Outputs Rated at 36V
♦ Up to 55mA Continuous Current per Output
♦ Output Current Programmed by Single Resistor
♦ 3% Current Matching Between Outputs
♦ 6% Current Matching Between ICs
♦ Watchdog Clears Display if Interface Fails
♦ Reports Open-Circuit LED Faults
♦ High-Dissipation, 24-Pin Packages
♦ -40°C to +125°C Temperature Range
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
________________________________________________________________ Maxim Integrated Products 1
Pin Configuration
Ordering Information
19-3751; Rev 0; 7/05
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.
Typical Application Circuit and Selector Guide appear at
end of data sheet.
Applications
Variable Message Signs
Marquee Displays
Point-of-Order Signs
Traffic Signs
Gaming Features
Architectural Lighting
PART TEMP RANGE PIN- PACKAGE
MAX6983AUG -40°C to +125°C 24 TSSOP —
MAX6983ANG -40°C to +125°C 24 Narrow PDIP —
PK G
C O D E
TOP VIEW
GND
DIN
CLK
OUT0
OUT1
OUT2
OUT4
OUT5
OUT6
1
2
3
4
5
6
MAX6983AUG
7
MAX6983ANG
8
9
10
11
12
TSSOP/PDIP
V+
24
SET
23
DOUT
22
OELE
21
20
OUT15
19
OUT14
18
OUT13
17
OUT12OUT3
16
OUT11
15
OUT10
14
OUT9
13
OUT8OUT7
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
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.
Voltage (with respect to GND)
V+ .............................................................................-0.3V to +6V
OUT_ ......................................................................-0.3V to +40V
DIN, CLK, LE, OE, SE ..................................-0.3V to (V+ + 0.3V)
DOUT_ Current .................................................................±10mA
OUT_ Sink Current ..............................................................60mA
Total GND Current ............................................................960mA
Continuous Power Dissipation (TA= +70°C)
24-Pin PDIP (derate 13.3mW/°C over +70°C)............1067mW
24-Pin TSSOP (derate 12.2mW/°C over +70°C) .........975mW
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
ELECTRICAL CHARACTERISTICS
(Typical Operating Circuit, V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V+ = 5V, TA= +25°C.)
(Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Operating Supply Voltage V+ 3.0 5.5 V
Output Voltage V
Standby Current
(Interface Idle, All Output Ports
High Impedance, R
Standby Current
(Interface Running, All Output
Ports High Impedance,
R
= 360Ω)
SET
Supply Current
(Interface Idle, All Output Ports
Active Low, R
Input High Voltage
DIN_, CLK_, LE_, OE_
Input Low Voltage
DIN_, CLK_, LE_, OE_
Hysteresis Voltage
DIN_, CLK_, LE_, OE_
Input Leakage Current
DIN_, CLK_, LE_, OE_
Output High-Voltage DOUT_ V
Output Low-Voltage V
Output Current OUT_ I
Output Leakage Current OUT_ I
Watchdog Timeout t
SET
= 360Ω)
SET
= 360Ω)
OUT
V
V
∆V
I
IH
OUT
LEAK
WD
I
+
I
+
I
+
IH
, I
OH
OL
IL
I
IL
All logic inputs at V+ or GND, DOUT_
unloaded
f
CLK
or GND, DOUT_ unloaded
All logic inputs at V+ or GND,
DOUT_ unloaded
I
SOURCE
I
SINK
V+ = 3V - 5.5V, V
R
OE = V+ 1 µA
= 25MHz, OE = V+, DIN and LE = V+
= 4mA
= 4mA 0.5 V
= 360Ω
SET
36 V
5.7 8 mA
6 6.5 mA
18 25 mA
0.7 x V+ V
0.3 x V+ V
0.8 V
-1 +1 µA
V +
- 0.5V
= 0.8V - 2.5V,
OUT
37 50 61 mA
0.1 1 2.5 s
V
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
_______________________________________________________________________________________ 3
5V TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 4.5V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted.) (Notes 1, 2)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
CLK_ Clock Period t
CLK_ Pulse-Width High t
CLK_ Pulse-Width Low t
DIN_ Setup Time t
DIN_ Hold Time t
DOUT_ Propagation Delay t
DOUT_ Rise and Fall Time C
LE Setup Time t
LE Rising to OUT_ Rising Delay t
LE Rising to OUT_ Falling Delay t
CLK_ Rising to OUT_ Rising
Delay
CLK_ Rising to OUT_ Falling
Delay
OE_ Rising to OUT_ Rising Delay t
OE_ Falling to OUT_ Falling Delay t
LED Output OUT_ Turn-On Fall
Time
LED Output OUT_ Turn-Off Rise
Time
CP
CH
CL
DS
DH
DO
LRR
LRF
t
CRR
t
CRF
OEH
OEL
LS
t
t
f
r
DOUT
(Note 3) 100 ns
(Note 3) 300 ns
(Note 3) 100 ns
(Note 3) 310 ns
(Note 3) 100 ns
(Note 3) 320 ns
80% to 20%; pullup resistor = 65Ω (Note 3) 120 ns
20% to 80%; pullup resistor = 65Ω (Note 3) 120 ns
40 ns
19 ns
19 ns
4ns
8ns
12 32 ns
= 10pF, 20% to 80% 10 ns
10 ns
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
4 _______________________________________________________________________________________
Typical Operating Characteristics
(TA = +25°C, unless otherwise noted.)
3.3V TIMING CHARACTERISTICS
(Typical Operating Circuit, V+ = 3V to 5.5V, TA= T
MIN
to T
MAX
, unless otherwise noted.) (Notes 1, 2)
Note 1: All parameters tested at TA= +25°C. Specifications over temperature are guaranteed by design.
Note 2: See Figure 3.
Note 3: A 65Ω pullup resistor is connected from OUT_ to 5.5V.
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
CLK_ Clock Period t
CLK_ Pulse-Width High t
CLK_ Pulse-Width Low t
DIN_ Setup Time t
DIN_ Hold Time t
DOUT_ Propagation Delay t
CP
CH
CL
DS
DH
DO
DOUT_ Rise and Fall Time C
LE Setup Time t
LS
LE Rising to OUT_ Rising Delay (Note 3) 120 ns
LE Rising to OUT_ Falling Delay (Note 3) 310 ns
C LK_ Ri si ng to OU T_ Ri si ng D el ay (Note 3) 120 ns
C LK_ Ri si ng to OU T_ Fal l i ng D el ay (Note 3) 330 ns
OE_ Rising to OUT_ Rising Delay t
OE_ Falling to OUT_ Falling Delay t
LED Output OUT_ Turn-On Fall
Time
LED Output OUT_ Turn-Off Rise
Time
OEH
OEL
t
f
t
r
52 ns
24 ns
24 ns
4ns
8ns
12 50 ns
= 10pF, 20% to 80% 12 ns
DOUT
15 ns
(Note 3) 120 ns
(Note 3) 330 ns
80% to 20% (Note 3) 120 ns
20% to 80% (Note 3) 120 ns
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF, R
2.00
TA = +125°C
1.95
1.90
SUPPLY CURRENT (mA)
1.85
1.80
3.0 5.5
SUPPLY VOLTAGE (V)
TA = +85°C
TA = +25°C
TA = -40°C
= 720Ω)
SET
5.04.54.03.5
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF, R
3.70
MAX6983 toc01
3.65
3.60
SUPPLY CURRENT (mA)
3.55
3.50
TA = +125°C
TA =-40°C
3.0 5.5
SUPPLY VOLTAGE (V)
TA = +85°C
TA = +25°C
= 360Ω)
SET
5.04.54.03.5
(INTERFACE IDLE, ALL OUTPUTS ON, R
MAX6983 toc02
SUPPLY CURRENT (mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
= 720Ω)
45
40
TA = +125°C
35
30
25
20
TA = -40°C
15
3.0 5.5
SUPPLY VOLTAGE (V)
SET
TA = +85°C
TA = +25°C
5.04.54.03.5
MAX6983 toc03
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
_______________________________________________________________________________________ 5
Typical Operating Characteristics (continued)
(TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS ON, R
45
40
TA = +125°C
35
30
25
SUPPLY CURRENT (mA)
20
15
3.0 5.5
TA = -40°C
SUPPLY VOLTAGE (V)
TA = +85°C
= 360Ω)
SET
TA = +25°C
5.04.54.03.5
MAX6983 toc04
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
= 720Ω, V+ = 5.0V)
(R
SET
30
TA = -40°C
25
20
TA = +25°C
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
= 720Ω, V+ = 3.3V)
(R
30
25
20
15
10
PORT OUTPUT CURRENT (mA)
SET
TA = -40°C
TA = +25°C
TA = +85°C
TA = +125°C
5
0
0 3.0
PORT OUTPUT VOLTAGE (V)
2.52.01.51.00.5
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
= 360Ω V+ = 5.0V)
(R
SET
TA = -40°C
TA = +25°C
MAX6983 toc07
60
50
40
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
= 360Ω, V+ = 3.3V)
(R
60
MAX6983 toc05
50
40
30
20
PORT OUTPUT CURRENT (mA)
10
SET
TA = -40°C
TA = +25°C
TA = +85°C
TA = +125°C
0
0 3.0
PORT OUTPUT VOLTAGE (V)
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
= 720Ω, V
(R
SET
25.0
MAX6983 toc08
24.5
TA = +125°C
= 2V)
OUT
TA = +85°C
MAX6983 toc06
2.52.01.51.00.5
MAX6983 toc09
15
10
PORT OUTPUT CURRENT (mA)
5
0
0 3.0
TA = +85°C
TA = +125°C
PORT OUTPUT VOLTAGE (V)
PORT OUTPUT CURRENT vs. PORT OUTPUT VOLTAGE
(R
49
48
47
PORT OUTPUT CURRENT (mA)
46
SET
TA = -40°C
TA = +125°C
3.0 5.5
2.52.01.51.00.5
= 360Ω, V
OUT
TA = +25°C
TA = +85°C
SUPPLY VOLTAGE (V)
30
20
PORT OUTPUT CURRENT (mA)
10
0
0 3.0
= 2V)
5.04.54.03.5
TA = +85°C
TA = +125°C
PORT OUTPUT VOLTAGE (V)
MAX6983 toc10
24.0
TA = +25°C
23.5
PORT OUTPUT CURRENT (mA)
2.52.01.51.00.5
23.0
PORT OUTPUT CURRENT vs. R
3.0 5.5
SET
TA = -40°C
5.04.54.03.5
PORT OUTPUT VOLTAGE (V)
RESISTANCE
(V+ = 5.0V)
50
40
30
20
PORT OUTPUT CURRENT (mA)
10
0
05
R
RESISTANCE (kΩ)
SET
4321
MAX6983 toc11
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
6 _______________________________________________________________________________________
Pin Description
Figure 1. Block Diagram
PIN NAME FUNCTION
1 GND Ground
2 DIN Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.
3 CLK Serial-Clock Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.
Load-Enable Input. Data is loaded transparently from the internal shift register(s) to the output latch(es)
4LE
5–20 OUT0–OUT15 LED Driver Outputs. OUT0 to OUT15 are open-drain, constant-current sinking outputs rated to 28V.
while LE is high. Data is latched into the output latch(es) on LE's falling edge, and retained while LE is
low.
21 OE
Output Enable Input. High forces outputs OUT0 to OUT15 high impedance, without altering the contents
of the output latches. Low enables outputs OUT0 to OUT15 to follow the state of the output latches.
22 DOUT Serial-Data Output. Data is clocked out of the 16-bit internal shift-register to DOUT on CLK’s rising edge.
23 SET LED Current Setting. Connect SET to GND through a resistor (RSET) to set the maximum LED current.
24 V+ Positive Supply Voltage. Bypass V+ to GND with a 0.1µF ceramic capacitor.
CLK
SERIAL-TO-PARALLEL SHIFT REGISTER
DIN
LE
OE
D0 D15
D0 D15
D0 D15
LATCHES
CONSTANT-CURRENT SINKS
MAX6983
POWER-ON
RESET
WATCH-
DOG
V+
CURRENT
REFERENCE
DOUT
V+
OUT0
OUT1
FAULT DETECTION
OUT2
OUT13
OUT14
OUT15
GND
GND
R
SET
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
_______________________________________________________________________________________ 7
Detailed Description
The MAX6983 LED driver comprises a 4-wire serial
interface driving eight constant-current sinking opendrain output ports. The outputs drive LEDs in either static or multiplex applications (Figure 1). The constantcurrent outputs are guaranteed for current accuracy
not only with chip-supply voltage variations (5V ±10%
and 3V to 5.5V), but also over a realistic range of driver
output voltage drop (0.8V to 2.5V). The drivers use current-sensing feedback circuitry (not simple current mirrors) to ensure very small current variations over the full
allowed range of output voltage (see the Typical
Operating Characteristics).
The 4-wire serial interface comprises a 16-bit shift register and a 16-bit transparent latch. The shift register is
written through a clock input CLK and a data input DIN
and the data propagates to a data output DOUT. The
data output allows multiple drivers to be cascaded and
operated together. The contents of the 16-bit shift register are loaded into the transparent latch through a
latch-enable input LE. The latch is transparent to the
shift register outputs when high, and latches the current state on the falling edge of LE.
Each driver output is an open-drain, constant-current
sink that should be connected to the cathode of either
a single LED or a series string of multiple LEDs. The
LED anode can be connected to a supply voltage of up
to 36V, independent of the MAX6983 supply, V+. The
constant-current capability is up to 55mA per output,
set for all 16 outputs by an external resistor, R
SET
.
4-Wire Serial Interface
The serial interface on the MAX6983 is a 4-wire serial
interface using four inputs (DIN, CLK, LE, and OE) and
a data output (DOUT). This interface is used to write
display data to the MAX6983. The serial-interface data
word length is 16 bits, D0–D15. See Figure 2.
The functions of the five interface pins are as follows.
DIN is the serial-data input, and must be stable when it
is sampled on the rising edge of CLK. Data is shifted
in, MSB first. This means that data bit D15 is clocked in
first, followed by 15 more data bits, finishing with the
LSB D0.
CLK is the serial-clock input, which shifts data at DIN
into the MAX6983 16-bit shift register on its rising edge.
LE is the latch load input of the MAX6983, which transfers data from the MAX6983 16-bit shift register to its 16bit latch when LE is high (transparent latch), and latches
the data on the falling edge of LE (Figure 2).
Figure 2. 4-Wire Serial-Interface Timing Diagram
t
LW
t
LS
LF
D15
CLK
DIN
DOUT
LE
t
t
CL
CH
t
DH
t
DS
D15 D14
t
OE
OEW
D1 D0
t
CP
t
DO
t
t
OEL
OUT_
t
OEH
80%
20%
t
f
t
r
.
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
8 _______________________________________________________________________________________
The fourth input provides output-enable control of the output drivers. OE is high to force outputs OUT0–OUT15
high impedance, without altering the contents of the output latches, and low to enable outputs OUT0–OUT15 to
follow the state of the output latches.
OE is independent of the operation of the serial interface. Data can be shifted into the serial-interface shift
register and latched regardless of the state of OE.
DOUT is the serial-data output, which shifts data out
from the MAX6983’s 16-bit shift register on the rising
edge of CLK. Data at DIN is propagated through the
shift register and appears at DOUT 16 clock cycles later.
See Figure 2.
Watchdog
The MAX6983 includes a watchdog circuit that monitors
the CLK, DIN, and LE inputs. If there is no transition on
any one of these inputs for nominally 1s, the output
latches are cleared and outputs OUT0–OUT15 go high
impedance like the initial power-up condition. This turns
off all LEDs connected to the outputs. The shift-register
data does not change, just the output-latch data.
The watchdog is intended to be used as a fail-safe feature for applications that prefer a blank display to an
incorrect display if the serial interface fails. When the
watchdog triggers, the outputs remain off until the driver output latches are updated with data turning them
on. Recovery is therefore automatic if the transmission
failure is temporary because the MAX6983 does not
lock up in the watchdog timeout state. The MAX6983
operates correctly when the serial interface is next activated, and the watchdog circuit is reset and starts
monitoring the serial interface again. The watchdog
function requires no software change to the application
driving the MAX6983.
LED Fault Detection
The MAX6983 includes circuitry that detects open-circuit LEDs automatically. An open-circuit fault occurs
when an output is programmed to sink current but less
than about 50% of the programmed current flows.
Open circuits are checked just after the falling edge of
OE. The fault data is latched on the rising edge of LE and
is shifted out when new LED data is loaded into the output latches from the shift register. If one or more output
ports are detected with an open-circuit fault, the D14 and
D13 bits of DOUT go high. If no open-circuit faults are
detected, D14 and D13 are set to low. The data in the
other 14 bit positions in DOUT are not altered.
Fault status is shifted out on DOUT when the next data
transmission is shifted in after the rising edge of LE. LE
is normally taken high after all 16 bits of new LED data
have been clocked into the shift register(s), and then
DOUT outputs data bit D15. On the next two rising
edges of CLK, the 2 fault status bits, D14 and D13, are
clocked out in that order, followed by the remaining 13
unchanged data bits D12 to D0.
A typical fault-detecting application tests all the shifted
out data. Bits D0–D12 and D15 are checked against
the originally transmitted data to check data-link integrity. Bits D13 and D14 are checked first to see that they
contain the same data (validating the status) and second, whether faults are reported or not by the actual
logic level.
Figure 4 is the LE and CLK to OUT_ timing diagram.
Figure 3. LE and CLK to OUT_ Timing
Figure 4. Fault Timing
LE
OUT_
LE
OUT_
CLK
OUT_
CLK
OUT_
t
LRF
t
LRR
t
CRF
t
CRR
OE
LE
CLK
DOUT
D15
D13
D14
FAULT STATUS BITS
D12
Applications Information
Selecting External Component R
SET
to Set
LED Output Current
The MAX6983 uses an external resistor, R
SET,
to set the
LED current for outputs OUT0–OUT15. The minimum
allowed value of R
SET
is 327.3Ω, which sets the output
currents to 55mA. The maximum allowed value of R
SET
is 5kΩ. The reference value, 360Ω, sets the output currents to 50mA. To set a different output current, use the
formula:
R
SET
= 18,000 / I
OUT
where I
OUT
is the desired output current in mA.
Computing Power Dissipation
The upper limit for power dissipation (PD) for the
MAX6983 is determined by the following equation:
PD= (V+ x I+) + (V
OUT
x DUTY x I
OUT
x N)
where:
V+ = supply voltage
I+ = operating supply current when sinking I
OUT
LED
drive current into N outputs
DUTY = PWM duty cycle applied to OE
N = number of MAX6983 outputs driving LEDs at the
same time (maximum is 16)
V
OUT
= MAX6983 port output voltage when driving load
LED(s)
I
OUT
= LED drive current programmed by R
SET
PD= power dissipation, in mW if currents are in mA
Dissipation example:
I
OUT
= 20mA, N = 16, DUTY = 1,
V
OUT
= 2V, V+ = 5.25V
PD= (5.25V x 25mA) + (2V x 1 x 20mA x 16) = 0.77W
Thus, for a 24-pin TSSOP package (TJA= 1 / 0.0122 =
+82°C/W from the Absolute Maximum Ratings), the
maximum allowed ambient temperature TAis given by:
T
J(MAX)
= TA+ (PDx TJA) = +150°C =
TA+ (0.77 x 82°C/W)
so TA= +85°C.
Overtemperature Cutoff
The MAX6983 contains an internal temperature sensor
that turns off all outputs when the die temperature
exceeds approximately +165°C. The outputs are
enabled again when the die temperature drops below
approximately +140°C. Register contents are not affected, so when a driver is overdissipating, the external
symptom is the load LEDs cycling between on and off as
the driver repeatedly overheats and cools, alternately
turning the LEDs off and then back on again.
Power-Supply Considerations
The MAX6983 operates with a chip supply V+, and one
or more LED supplies. Bypass each supply to GND
with a 0.1µF capacitor as close to the MAX6983 as possible. This is normally adequate for static LED driving.
For multiplex or PWM applications, it is necessary to
add an additional bulk electrolytic capacitor of 4.7µF or
more to each supply for every 4 to 16 MAX6983s. The
necessary capacitance depends on the LED load current, PWM switching frequency, and serial interface
speed. Inadequate V+ decoupling can cause timing
problems, and very noisy LED supplies can affect LED
current regulation.
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
_______________________________________________________________________________________ 9
L = Low-logic level; H = High-logic level; X = Don’t care; P = Present state; R = Previous state.
Z
Table 1. 4-Wire Serial-Interface Truth Table
SERIAL
DATA
INPUT
CLOCK
INPUT
DIN
——
——P1P2P3…P
— — —————— —
CLK
HHR
LLR
XR
SHIFT REGISTER
CONTENTS
D
0D1D2
1R2
1R2
0R1R2
XXX…XX H
…D
…R
…R
…R
n-1Dn
n-2Rn-1
n-2Rn-1
n-1Rn
n-1Pn
LOAD
INPUT
LE
—
—
—
L
D
——————
——————
——————
R
P
XXX…XX
LATCH CONTENTS OUTPUT CONTENTS
0D1D2
0R1R2
0P1P2
…D
n-1Dn
R
n-1Rn
…P
n-1Pn
BLANKING
INPUT
D
OE
— — —————
— — —————
— — —————
— — —————
L P0P1P2… P
H Hi-Z Hi-Z Hi-Z … Hi-Z Hi-
0D1D2
…D
n-1Pn
n-1Dn
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
10 ______________________________________________________________________________________
Selector Guide
Typical Application Circuit
µC
MOSI
OUT0
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
SCLK
DIN
CLK
0V
GND
MISO DOUT
360Ω
OEENABLE
+5V
V+
28V
LATCHLOAD
SET
MAX6983
OUT8
OUT9
OUT10
OUT11
OUT12
OUT13
OUT14
OUT15
Chip Information
PROCESS: BiCMOS
*Future product—contact factory for availability.
PART
NUMBER OF
OUTPUTS
MAX6968 ——
MAX6977 Yes —
8 5.5
MAX6978
MAX6970* ——
MAX6981* Yes —
836
MAX6980*
MAX6969 ——
MAX6979
MAX6971 ——
MAX6983
16 5.5
16 36
MAX OUTPUT
VOLTAGE (V)
MAX OUTPUT
CURRENT
55mA
LED FAULT
DETECTION
Yes Yes
Yes Yes
Yes Yes
Yes Yes
WATCHDOG
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
______________________________________________________________________________________ 11
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages
.)
TSSOP4.40mm.EPS
PACKAGE OUTLINE, TSSOP 4.40mm BODY
21-0066
1
G
1
MAX6983
16-Port, 36V Constant-Current LED Driver with
LED Fault Detection and Watchdog
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.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages
.)
PDIPN.EPS
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