Maxim MAX16809 Integrated 16-channel led drivers with switch-mode boost and sepic controller Datasheet

19-0656; Rev 1; 3/07
KIT
ATION
EVALU
E
L
B
A
AVAIL
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
Features
The MAX16809/MAX16810 are integrated, high-efficiency white or RGB LED drivers. They are designed for
LCD backlighting and other LED lighting applications
with multiple strings of LEDs. The MAX16809/
MAX16810’s current-mode PWM controller regulates
the necessary voltage to the LED array. Depending on
the input voltage and LED voltage range, it can be
used with boost or buck-boost (SEPIC) topologies.
The MAX16809/MAX16810 LED drivers include 16
open-drain, constant-current-sinking LED driver outputs
rated for 36V continuous operation. The LED currentcontrol circuitry achieves ±3% current matching among
strings and enables paralleling of outputs for LED string
currents higher than 55mA. The output-enable pin is
used for simultaneous PWM dimming of all output channels. Dimming frequency range is 50Hz to 30kHz and
dimming ratio is up to 5000:1. The constant-current outputs are single resistor programmable and the LED current can be adjusted up to 55mA per output channel.
The MAX16809/MAX16810 operate either in stand-alone
mode or with a microcontroller (µC) using an industrystandard, 4-wire serial interface. The MAX16810 includes
a watchdog and circuitry that automatically detects
open-circuit LEDs.
The MAX16809/MAX16810 include overtemperature protection, operate over the full -40°C to +125°C temperature
range, and are available in a 5mm x 7mm thermally
enhanced, 38-pin TQFN exposed paddle package.
o 16 Constant-Current Output Channels (Up to
55mA Each)
o ±3% Current Matching Among Outputs
o Paralleling Channels Allows Higher Current per
LED String
o Outputs Rated for 36V Continuous Voltage
o Output-Enable Pin for PWM Dimming (Up to 30kHz)
o One Resistor Sets LED Current for All Channels
o Wide Dimming Ratio Up to 5000:1
o Low Current-Sense Reference (300mV) for High
Efficiency
o 8V to 26.5V Input Voltage or Higher with External
Biasing Devices
o Open LED Detection and Watchdog Timer
(MAX16810)
o 4-Wire Serial Interface to Control Individual
Output Channels
Pin Configuration appears at end of data sheet.
Applications
LCD White or RGB LED Backlighting:
LCD TVs, Desktop, and Notebook Panels
Automotive Navigation, Heads-Up,
and Infotainment Displays
Industrial and Medical Displays
Ambient, Mood, and Accent Lighting
Ordering Information
TEMP
RANGE
PART
MAX16809ATU+
PINPACKAGE
PKG
CODE
-40°C to +125°C 38 TQFN-EP* T3857-1
MAX16810ATU+ -40°C to +125°C 38 TQFN-EP* T3857-1
+Denotes a lead-free package.
*EP = Exposed paddle.
Typical Operating Circuits
VIN
VOUT
L
COUT
Q1
RCS
CC1
OUT CS AGND
LEDs
R1
CC2
RC1
R2
COMP
VCC
FB
CIN
3V TO 5.5V
OUT0
V+
OUT1
CBYP
OUT2
PGND
OUT3
OUT4
MAX16809
MAX16810
LE
DIN
OUT5
OUT6
CLK
DOUT
OE
OUT7
OUT8
OUT9
OUT10
SET
OUT11
OUT12
OUT13
OUT14
RSET
OUT15
RTCT
REF
STAND-ALONE OPERATION
RT
CREF
CT
Typical Operating Circuits continued at end of data sheet.
________________________________________________________________ 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
MAX16809/MAX16810
General Description
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
ABSOLUTE MAXIMUM RATINGS
VCC to AGND..........................................................-0.3V to +30V
Current into VCC (VCC > 24V) .............................................30mA
V+ to PGND..............................................................-0.3V to +6V
OUT to AGND.............................................-0.3V to (VCC + 0.3V)
OUT Current (10µs duration) .................................................±1A
FB, COMP, CS, RTCT, REF to AGND.......................-0.3V to +6V
COMP Sink Current.............................................................10mA
OUT0–OUT15 to PGND..........................................-0.3V to +40V
DIN, CLK, LE, OE, SET to PGND..................-0.3V to (V+ + 0.3V)
DOUT Current...................................................................±10mA
OUT0–OUT15 Sink Current.................................................60mA
Total PGND Current (1s pulse time) .................................960mA
Continuous Power Dissipation (TA = +70°C)
38-Pin TQFN (derate 35.7mW/°C* above +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
*Per JEDEC51 Standard (Multilayer Board).
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 (PWM CONTROLLER)
(VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT = 10kΩ, CT = 3.3nF, REF = open, COMP = open, CREF = 0.1µF, VFB = 2V,
CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ = TA = -40°C to
+125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
5
5.05
V
0.4
4
mV
50
mV
REFERENCE
Output Voltage
VREF
Line Regulation
∆VLINE
IREF = 1mA, TJ = +25°C
12V< VCC < 25V, IREF = 1mA
Load Regulation
∆VLOAD
1mA < IREF < 20mA
4.95
6
Total Output-Voltage Variation
VREFT
(Note 2)
4.875
Output Noise Voltage
VNOISE
10Hz < f < 10kHz
Output Short-Circuit Current
ISHORT
VREF = 0V
30
Initial Accuracy
TJ = +25°C
51
Voltage Stability
12V < VCC < 25V
5.125
50
V
µV
180
mA
54
57
kHz
0.2
0.5
OSCILLATOR
Temperature Stability
RTCT Ramp Peak-to-Peak
RTCT Ramp Valley
%
1.7
V
1.1
Discharge Current
IDIS
Frequency Range
fOSC
%
1
V
VRTCT = 2V, TJ = +25°C
7.9
8.3
8.7
VRTCT = 2V, -40oC ≤ TJ ≤ +125°C
7.5
8.3
9.0
20
mA
1000
kHz
2.5
2.55
V
-0.01
-0.1
ERROR AMPLIFIER
FB Input Voltage
VFB
FB shorted to COMP
2.45
Input Bias Current
IB(FB)
Open-Loop Gain
AVOL
Unity-Gain Bandwidth
fGBW
Power-Supply Rejection Ratio
PSRR
12V ≤ VCC ≤ 25V
60
80
dB
COMP Sink Current
ISINK
VFB = 2.7V, VCOMP = 1.1V
2
6
mA
0.5
1.2
COMP Source Current
ISOURCE
2V ≤ VCOMP ≤ 4V
VFB = 2.3V, VCOMP = 5V
COMP Output-Voltage High
VOH
VFB = 2.3V, RCOMP = 15kΩ to AGND
COMP Output-Voltage Low
VOL
VFB = 2.7V, RCOMP = 15kΩ to VREF
2
5
µA
100
dB
1
MHz
1.8
5.8
0.1
_______________________________________________________________________________________
mA
V
1.1
V
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
(VCC = +15V, V+ = +3V to +5.5V referenced to PGND, RT = 10kΩ, CT = 3.3nF, REF = open, COMP = open, CREF = 0.1µF, VFB = 2V,
CS = AGND, AGND = PGND = 0V; all voltages are measured with respect to AGND, unless otherwise noted. TJ = TA = -40°C to
+125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
CURRENT-SENSE AMPLIFIER
Current-Sense Gain
ACS
Maximum Current-Sense Signal
VCS_MAX
(Notes 3, 4)
2.85
3
3.40
V/V
(Note 3)
0.275
0.300
0.325
V
12V ≤ VCC ≤ 25V
70
VCOMP = 0V
-1
tPWM
50mV overdrive
60
OUT Low-Side On-Resistance
VRDS_ONL
ISINK = 200mA
OUT High-Side On-Resistance
VRDS_ONH
ISOURCE =
100mA
Power-Supply Rejection Ratio
PSRR
Current-Sense Input Bias Current
ICS
Current Sense to OUT Delay
dB
-2.5
µA
ns
MOSFET DRIVER
Source Current (Peak)
ISOURCE
CLOAD = 10nF
Sink Current (Peak)
TJ = -40°C to +85°C (Note 2)
4.5
10
TJ = -40°C to +125°C
4.5
12
TJ = -40°C to +85°C (Note 2)
3.5
7.5
TJ = -40°C to +125°C
3.5
10
2
Ω
Ω
A
ISINK
CLOAD = 10nF
1
A
Rise Time
tR
CLOAD = 1nF
15
ns
Fall Time
tF
CLOAD = 1nF
22
ns
UNDERVOLTAGE LOCKOUT/STARTUP
Startup Voltage Threshold
VCC_START
7.98
8.4
8.82
V
Minimum Operating Voltage After
Turn-On
VCC_MIN
7.1
7.6
8.0
V
Undervoltage-Lockout Hysteresis
UVLOHYST
0.8
V
PULSE-WIDTH MODULATION (PWM)
Maximum Duty Cycle
DMAX
Minimum Duty Cycle
DMIN
94.5
96
97.5
%
0
%
SUPPLY CURRENT
Startup Supply Current
VCC = 7.5V
32
65
µA
Operating Supply Current
ISTART
ICC
VFB = VCS = 0V
3
5
mA
VCC Zener Voltage
VZ
ICC = 25mA
24
26.5
V
_______________________________________________________________________________________
3
MAX16809/MAX16810
ELECTRICAL CHARACTERISTICS (PWM CONTROLLER) (continued)
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
ELECTRICAL CHARACTERISTICS (LED DRIVER)
(V+ = +3V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ = -40°C
to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
Operating Supply Voltage
Output Voltage
CONDITIONS
V+
MIN
TYP
3.0
VOUT_ _
MAX
UNITS
5.5
V
36
V
Standby Current (Interface Idle, All
Output Ports High Impedance)
RSET = 360Ω, DIN, LE, CLK = PGND or V+,
OE = V+, DOUT unconnected
3.6
4.5
mA
Standby Current
(Interface Active, All Output Ports
High Impedance)
RSET = 360Ω, fCLK = 5MHz, OE = V+,
DIN, LE = PGND or V+, DOUT unconnected
3.8
4.8
mA
RSET = 360Ω, OE = PGND, DIN,
LE = V+, DOUT unconnected
30
52.5
mA
Supply Current
(Interface Idle, All Output Ports
Active Low)
I+
INTERFACE (DIN, CLK, DOUT, LE, OE)
Input-Voltage High
(DIN, CLK, LE, OE)
VIH
Input-Voltage Low
(DIN, CLK, LE, OE)
VIL
Hysteresis Voltage
(DIN, CLK, LE, OE)
VHYST
Input Leakage Current
(DIN, CLK)
ILEAK
0.7
x V+
V
0.3
x V+
0.8
-1
V
V
+1
µA
OE Pullup Current to V+
IOE
V+ = 5.5V, OE = PGND
0.25
1.5
25
µA
LE Pulldown Current to PGND
ILE
V+ = 5.5V, LE = V+
0.25
1.5
25
µA
Output-Voltage High (DOUT)
VOH
Output-Voltage Low (DOUT)
VOL
OUT_ _ Output Current
IOUT_ _
Watchdog Timeout Period
(MAX16810)
4
V
ISINK = 4mA
0°C ≤ TA ≤ +125°C, VOUT = 1V to 2.5V,
RSET = 360Ω
TA = -40°C, VOUT = 1V to 2.5V,
RSET = 360Ω
0.5
43.25
47.5
VOUTTH
tWD
40
51.75
55
1
V+ = 5.5V, OE = V+
V+ = 5.5V
V
mA
OE = V+
OUT_ _ Leakage Current
OUT_ _ Fault Detection Threshold
(MAX16810)
ISOURCE = 4mA
V+
- 0.5V
0.8
0.1
1
_______________________________________________________________________________________
µA
V
2.5
s
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
(V+ = +4.5V to +5.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ =
-40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 5)
PARAMETER
SYMBOL
CONDITION
MIN
TYP
MAX
UNITS
INTERFACE TIMING CHARACTERISTICS
CLK Clock Period
tCP
40
ns
CLK Pulse-Width High
tCH
19
ns
CLK Pulse-Width Low
tCL
19
ns
DIN Setup Time
tDS
4
ns
DIN Hold Time
tDH
8
ns
DOUT Propagation Delay
tDO
50
ns
DOUT Rise Time
tDR
CDOUT = 10pF, 20% to 80%
10
ns
DOUT Fall Time
tDF
CDOUT = 10pF, 80% to 20%
10
ns
LE Pulse-Width High
tLW
20
LE Setup Time
tLS
15
10
ns
ns
LE Rising to OUT_ _ Rising Delay
tLRR
(Note 6)
110
ns
LE Rising to OUT_ _ Falling Delay
tLRF
(Note 6)
340
ns
CLK Rising to OUT_ _ Rising Delay
tCRR
(Note 6)
110
ns
CLK Rising to OUT_ _ Falling Delay
tCRF
(Note 6)
340
ns
OE Rising to OUT_ _ Rising Delay
tOER
(Note 6)
110
ns
OE Falling to OUT_ _ Falling Delay
tOEF
(Note 6)
340
ns
OUT_ _ Turn-On Fall Time
tF
80% to 20% (Note 6)
210
ns
OUT_ _ Turn-Off Rise Time
tR
20% to 80% (Note 6)
130
ns
_______________________________________________________________________________________
5
MAX16809/MAX16810
5V TIMING CHARACTERISTICS
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
3.3V TIMING CHARACTERISTICS
(V+ = +3V to < +4.5V, AGND = PGND = 0V; all voltages are measured with respect to PGND, unless otherwise noted. TA = TJ =
-40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Notes 1, 5)
PARAMETERS
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
INTERFACE TIMING CHARACTERISTICS
CLK Clock Period
tCP
52
ns
CLK Pulse-Width High
tCH
24
ns
CLK Pulse-Width Low
tCL
24
ns
DIN Setup Time
tDS
4
ns
DIN Hold Time
tDH
8
ns
DOUT Propagation Delay
tDO
DOUT Rise Time
tDR
CDOUT = 10pF, 20% to 80%
DOUT Fall Time
tDF
CDOUT = 10pF, 80% to 20%
LE Pulse-Width High
tLW
20
ns
LE Setup Time
tLS
15
ns
12
70
ns
12
ns
12
ns
LE Rising to OUT_ _ Rising Delay
tLRR
(Note 6)
140
ns
LE Rising to OUT_ _ Falling Delay
tLRF
(Note 6)
400
ns
CLK Rising to OUT_ _ Rising Delay
tCRR
(Note 6)
140
ns
CLK Rising to OUT_ _ Falling Delay
tCRF
(Note 6)
400
ns
OE Rising to OUT_ _ Rising Delay
tOER
(Note 6)
140
ns
OE Falling to OUT_ _ Falling Delay
tOEF
(Note 6)
400
ns
OUT_ _ Turn-On Fall Time
tF
80% to 20% (Note 6)
275
ns
OUT_ _ Turn-Off Rise Time
tR
20% to 80% (Note 6)
150
ns
Note 1:
Note 2:
Note 3:
Note 4:
Note 5:
Note 6:
6
All devices are 100% production tested at TJ = +25°C and +125°C. Limits to -40°C are guaranteed by design.
Guaranteed by design, not production tested.
Parameter is measured at trip point of latch with VFB = 0V.
Gain is defined as A = ∆VCOMP / ∆VCS, 0.05V ≤ VCS ≤ 0.25V.
See Figures 3 and 4.
A 65Ω pullup resistor is connected from OUT_ _ to 5.5V. Rising refers to VOUT_ _ when current through OUT_ _ is turned off
and falling refers to VOUT_ _ when current through OUT_ _ is turned on.
_______________________________________________________________________________________
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
VCC FALLING
6
ICC (µA)
VCC (V)
7
VCC = 7.5V
39
5
4
5.1
CT = 560pF
4.9
37
4.7
35
4.5
ICC (mA)
8
41
MAX16809 toc02
VCC RISING
MAX16809 toc01
9
33
MAX16809 toc03
BOOTSTRAP UVLO vs. TEMPERATURE
10
OPERATING SUPPLY CURRENT
vs. TEMPERATURE AFTER STARTUP
(fOSC = fSW = 300kHz)
STARTUP CURRENT
vs. TEMPERATURE
4.3
31
4.1
29
3.9
27
3.7
3
2
HYSTERESIS
1
0
25
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
TEMPERATURE (°C)
REFERENCE VOLTAGE
vs. TEMPERATURE
REFERENCE VOLTAGE
vs. REFERENCE LOAD CURRENT
REFERENCE VOLTAGE
vs. SUPPLY VOLTAGE
5.04
5.00
4.996
IREF = 20mA
4.96
4.994
4.90
VREF (V)
4.98
VREF (V)
IREF = 1mA
5.00
IREF = 1mA
4.998
4.95
5.02
MAX16809 toc06
5.06
5.000
MAX16809 toc05
5.05
MAX16809 toc04
5.08
4.85
4.992
4.990
4.988
4.80
4.986
4.94
4.75
4.92
4.70
4.90
4.65
-40 -25 -10 5 20 35 50 65 80 95 110 125
4.984
4.982
4.980
0
10
TEMPERATURE (°C)
20
30
40
50
60
12
14
530
18
20
22
24
26
520
510
500
490
480
470
8.04
MAX16809 toc08
RT = 3.65kΩ
CT = 560pF
16
VCC (V)
VRT/CT = 2V
RT/CT DISCHARGE CURRENT (mA)
540
10
OSCILLATOR RT/CT DISCHARGE CURRENT
vs. TEMPERATURE
MAX16809 toc07
550
70
IREF (mA)
OSCILLATOR FREQUENCY (fOSC)
vs. TEMPERATURE
OSCILLATOR FREQUENCY (kHz)
VREF (V)
3.5
-40 -25 -10 5 20 35 50 65 80 95 110 125
8.02
8.00
7.98
7.96
7.94
7.92
7.90
460
7.88
450
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
_______________________________________________________________________________________
7
MAX16809/MAX16810
Typical Operating Characteristics
(VCC = +15V, V+ = 3V to 5.5V, RT = 10kΩ, CT = 3.3nF, VREF = COMP = open, CREF = 0.1µF, VFB = 2V, CS = AGND = PGND = 0V.
Typical values are at TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +15V, V+ = 3V to 5.5V, RT = 10kΩ, CT = 3.3nF, VREF = COMP = open, CREF = 0.1µF, VFB = 2V, CS = AGND = PGND = 0V.
Typical values are at TA = +25°C, unless otherwise noted.)
CT = 1nF
100
CT = 560pF
0.34
CT = 100pF
10
0.28
0.26
1
0.24
0.22
0.20
0.1
10k
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40 -25 -10 5 20 35 50 65 80 95 110 125
10M
TEMPERATURE (°C)
OUT IMPEDANCE vs. TEMPERATURE
(RDS_ON NMOS DRIVER)
PROPAGATION DELAY FROM CURRENT-LIMIT
COMPARATOR TO OUT vs. TEMPERATURE
ERROR-AMPLIFIER OPEN-LOOP GAIN
AND PHASE vs. FREQUENCY
5
4
3
80
140
10
120
-15
100
70
60
50
40
30
-115
-140
-165
20
1
10
0
0
0
-20
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
TEMPERATURE (°C)
COMP VOLTAGE LEVEL TO TURN
OFF DEVICE vs. TEMPERATURE
SUPPLY CURRENT
vs. OSCILLATOR FREQUENCY
CT = 100pF
6.0
2.1
ICC (mA)
1.9
5.0
4.5
4.0
1.8
TA = +125°C
TA = -40°C
3.5
1.7
-190
10k 100k 1M 10M 100M
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 720Ω)
5.5
2.0
10 100 1k
FREQUENCY (Hz)
2.00
TA = +125°C
SUPPLY CURRENT (mA)
6.5
0.01 1
MAX16809 toc16
2.2
7.0
MAX16809 toc15
VCC = 15V
-90
40
2
2.3
-65
PHASE
60
20
-40 -25 -10 5 20 35 50 65 80 95 110 125
-40
GAIN
80
MAX16809 toc17
6
90
GAIN (dB)
7
MAX16809 toc14
100
MAX16809 toc13
ISINK = 200mA
8
RDS_ON (Ω)
1M
FREQUENCY (Hz)
PROPAGATION DELAY (ns)
9
100k
TEMPERATURE (°C)
MAX16809 toc12
10
CT = 10nF
CT = 4.7nF
CT = 3.3nF
CT = 2.2nF
ISOURCE = 100mA
TA = +85°C
1.95
TA = +25°C
1.90
TA = -40°C
1.85
3.0
1.6
2.5
1.5
8
1.80
2.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
20 120 220 320 420 520 620 720 820 920 1020
TEMPERATURE (°C)
FREQUENCY (kHz)
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
_______________________________________________________________________________________
5.0
5.5
PHASE (DEGREES)
RT (kΩ)
0.30
RDS_ON (Ω)
CT = 220pF
0.32
5.0
4.8
4.6
4.4
4.2
4.0
3.8
3.6
3.4
3.2
3.0
2.8
2.6
2.4
2.2
2.0
MAX16809 toc11
0.36
MAX16809 toc10
0.38
CS THRESHOLD (V)
1000
MAX16809 toc09
0.40
OUT IMPEDANCE vs. TEMPERATURE
(RDS_ON PMOS DRIVER)
TIMING RESISTANCE
vs. OSCILLATOR FREQUENCY
CURRENT-SENSE TRIP THRESHOLD
vs. TEMPERATURE
VCOMP (V)
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
MAX16809 toc18
45
TA = +125°C
3.65
TA = +85°C
3.60
TA = +25°C
TA =-40°C
3.55
40
SUPPLY CURRENT (mA)
SUPPLY CURRENT (mA)
3.70
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS ON, RSET = 720Ω)
MAX16809 toc19
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS OFF, RSET = 360Ω)
TA = +85°C
TA = +125°C
35
30
25
TA = +25°C
20
TA = -40°C
3.50
15
3.5
4.0
4.5
5.0
5.5
3.0
3.5
4.0
SUPPLY VOLTAGE (V)
TA = -40°C
25
OUT_ _ CURRENT (mA)
30
25
TA = +25°C
20
TA = +25°C
TA = +85°C
15
TA = +125°C
10
5
TA = -40°C
0
15
3.0
3.5
4.0
4.5
5.0
0
5.5
0.5
1.0
1.5
2.0
2.5
OUT_ _ CURRENT vs. OUT_ _ VOLTAGE
(RSET = 720Ω, V+ = 5.0V)
60
30
MAX16809 toc22
OUT_ _ CURRENT vs. OUT_ _ VOLTAGE
(RSET = 360Ω, V+ = 3.3V)
TA = -40°C
TA = +25°C
TA = +85°C
30
TA = +125°C
20
TA = -40°C
25
OUT_ _ CURRENT (mA)
50
40
3.0
OUT_ _ VOLTAGE (V)
SUPPLY VOLTAGE (V)
OUT_ _ CURRENT (mA)
5.5
MAX16809 toc23
SUPPLY CURRENT (mA)
TA = +85°C
35
20
30
MAX16809 toc20
45
TA = +125°C
5.0
OUT_ _ CURRENT vs. OUT_ _ VOLTAGE
(RSET = 720Ω, V+ = 3.3V)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
(INTERFACE IDLE, ALL OUTPUTS ON, RSET = 360Ω)
40
4.5
SUPPLY VOLTAGE (V)
MAX16809 toc21
3.0
20
TA = +25°C
TA = +85°C
15
TA = +125°C
10
5
10
0
0
0
0.5
1.0
1.5
2.0
OUT_ _ VOLTAGE (V)
2.5
3.0
0
0.5
1.0
1.5
2.0
2.5
3.0
OUT_ _ VOLTAGE (V)
_______________________________________________________________________________________
9
MAX16809/MAX16810
Typical Operating Characteristics (continued)
(VCC = +15V, V+ = 3V to 5.5V, RT = 10kΩ, CT = 3.3nF, VREF = COMP = open, CREF = 0.1µF, VFB = 2V, CS = AGND = PGND = 0V.
Typical values are at TA = +25°C, unless otherwise noted.)
Typical Operating Characteristics (continued)
(VCC = +15V, V+ = 3V to 5.5V, RT = 10kΩ, CT = 3.3nF, VREF = COMP = open, CREF = 0.1µF, VFB = 2V, CS = AGND = PGND = 0V.
Typical values are at TA = +25°C, unless otherwise noted.)
OUT_ _ CURRENT vs. V+
(RSET = 720Ω, VOUT = 2V)
OUT_ _ CURRENT vs. OUT_ _ VOLTAGE
(RSET = 360Ω V+ = 5.0V)
OUT_ _ CURRENT (mA)
40
OUT_ _ CURRENT (mA)
TA = +25°C
TA = +85°C
30
TA = +125°C
20
MAX16809 toc25
TA = -40°C
50
25.0
MAX16809 toc24
60
24.5
TA = +85°C
TA = +125°C
24.0
TA = +25°C
TA = -40°C
23.5
10
0
23.0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.0
3.5
OUT_ _ VOLTAGE (V)
TA = +85°C
5.5
MAX16809 toc27
40
30
20
10
TA = +125°C
46
0
3.0
3.5
4.0
4.5
SUPPLY VOLTAGE (V)
10
5.0
50
OUT_ _ CURRENT (mA)
TA = +25°C
TA = -40°C
47
4.5
OUT_ _ CURRENT vs. SET RESISTANCE
(V+ = 5.0V)
MAX16809 toc26
49
48
4.0
SUPPLY VOLTAGE (V)
OUT_ _ CURRENT vs. V+
(RSET = 360Ω, VOUT = 2V)
OUT_ _ CURRENT (mA)
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
5.0
5.5
0
1
2
3
SET RESISTANCE (kΩ)
______________________________________________________________________________________
4
5
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
PIN
NAME
1, 31, 32,
36, 38
N.C.
2
FB
3
COMP
4–11
FUNCTION
No Connection. Not internally connected. Leave unconnected.
Error-Amplifier Inverting Input
Error-Amplifier Output
OUT8–OUT15 LED Driver Outputs. OUT8–OUT15 are open-drain, constant-current-sinking outputs rated for 36V.
Active-Low, Output Enable Input. Drive OE low to PGND to enable the OUT0–OUT15. Drive OE
high to disable OUT0–OUT15.
12
OE
13
DOUT
14
SET
LED Current Setting. Connect RSET from SET to PGND to set the LED current.
LED Driver Positive Supply Voltage. Bypass V+ to PGND with a 0.1µF ceramic capacitor.
15
V+
16, 17
PGND
18
DIN
19
CLK
20
LE
21–28
OUT0–OUT7
29
RTCT
Serial-Data Output. Data is clocked out of the 16-bit internal shift register to DOUT on CLK’s
rising edge.
Power Ground
Serial-Data Input. Data is loaded into the internal 16-bit shift register on CLK’s rising edge.
Serial-Clock Input
Latch-Enable Input. Data is loaded transparently from the internal shift register(s) to the output
latch(es) while LE is high. Data is latched into the output latch(es) on LE’s falling edge, and
retained while LE is low.
LED Driver Outputs. OUT0–OUT7 are open-drain, constant-current-sinking outputs rated for 36V.
PWM Controller Timing Resistor/Capacitor Connection. A resistor RT from RTCT to REF and a
capacitor CT from RTCT to AGND set the oscillator frequency.
30
CS
33
AGND
34
OUT
MOSFET Driver Output OUT. Connects to the gate of the external n-channel MOSFET.
35
VCC
Power-Supply Input. Bypass VCC to AGND with a 0.1µF ceramic capacitor or a parallel
combination of a 0.1µF and a higher value ceramic capacitor.
37
REF
—
EP
PWM Controller Current-Sense Input
Analog Ground
5V Reference Output. Bypass REF to AGND with a 0.1µF ceramic capacitor.
Exposed Paddle. Connect to the ground plane for improved power dissipation. Do not use as the
only ground connection.
Detailed Description
The MAX16809/MAX16810 LED drivers include an
internal switch-mode controller that can be used as
boost or buck-boost (SEPIC) converters to generate the
voltage necessary to drive the multiple strings of LEDs.
These devices incorporate an integrated low-side driver, a programmable oscillator (20kHz to 1MHz), an
error amplifier, a low-voltage (300mV) current sense for
higher efficiency, and a 5V reference to power up
external circuitry (see Figures 1a, 1b, and 1c).
The MAX16809/MAX16810 LED drivers include a 4-wire
serial interface and a current-mode PWM controller to
generate the necessary voltage for driving 16 opendrain, constant-current-sinking output ports. 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
______________________________________________________________________________________
11
MAX16809/MAX16810
Pin Description
automatically shifted out on DOUT when the next data
transmission is shifted in. The MAX16810 also features a
watchdog that monitors activity on the CLK, DIN, and LE
inputs (see the Watchdog (MAX16810) section). The
number of channels can be expanded by using the
MAX6970 and MAX6971 family in conjunction with the
MAX16809 and MAX16810.
cathode of a string of LEDs connected in series. The
constant-current capability is up to 55mA per output,
set for all 16 outputs by an external resistor, RSET. The
devices can operate in a stand-alone mode (see the
Typical Operating Circuits).
The MAX16810 includes circuitry that automatically
detects open-circuit LEDs. Fault status is loaded into the
serial-interface shift register when LE goes high and is
UVLO
REFERENCE
2.5V
VOLTAGEDIVIDER
PREREG
5V
VCC
26.5V
THERMAL
SHUTDOWN
EN_REF
MAX16809
BG
SNS
VDD
REF
5V REG
REG_OK
DELAY
VOLTAGE
DIVIDER
AGND
VCC
300mV
ILIM
S
R
OUT
Q
CS
CPWM
2R
VEA
CLK
FB
COMP
R
OSC
Q
RTCT
CLK
SERIAL-TO-PARALLEL SHIFT REGISTER
DIN
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D9
D10
D11
D12
D13
D14
D15
DOUT
OUTPUT LATCHES
LE
D0
D1
D2
D3
D4
D5
D6
D7
D8
POWER-ON
RESET
V+
OE
V+
CONSTANT-CURRENT SINK
THERMAL
SHUTDOWN
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
CURRENT
REFERENCE
OUT15
OUT14
OUT13
OUT12
OUT11
OUT10
OUT9
OUT8
OUT7
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
PGND
OUT0
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
Figure 1a. Internal Block Diagram (MAX16809)
12
______________________________________________________________________________________
SET
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
REFERENCE
2.5V
MAX16809/MAX16810
UVLO
VOLTAGEDIVIDER
PREREG
5V
VCC
26.5V
THERMAL
SHUTDOWN
EN_REF
BG
SNS
MAX16810
VDD
REF
5V REG
REG_OK
DELAY
VOLTAGE
DIVIDER
AGND
VCC
300mV
ILIM
S
R
OUT
Q
CS
CPWM
2R
VEA
CLK
FB
COMP
R
OSC
Q
RTCT
CLK
SERIAL-TO-PARALLEL SHIFT REGISTER
DIN
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
D9
D10
D11
D12
D13
D14
D15
DOUT
OUTPUT LATCHES
LE
D0
D1
D2
D3
D4
D5
D6
D7
D8
POWER-ON
RESET
V+
OE
WATCHDOG
V+
CONSTANT-CURRENT SINK
THERMAL
SHUTDOWN
D0
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
D13
D14
D15
CURRENT
REFERENCE
SET
FAULT DETECTION (MAX16810 ONLY)
OUT15
OUT14
OUT13
OUT12
OUT11
OUT10
OUT9
OUT8
OUT7
OUT6
OUT5
OUT4
OUT3
OUT2
OUT1
OUT0
PGND
Figure 1b. Internal Block Diagram (MAX16810)
______________________________________________________________________________________
13
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
V+
68W/L
1.23V
W/L
OUT_ _
1.23
REST
945R
R
SET
PGND
Figure 1c. OUT_ _ Driver Internal Diagram
OUT is a push-pull output with the on-resistance of the
pMOS typically 3.5Ω and the on-resistance of the nMOS
typically 4.5Ω. The driver can source 2A and sink 1A typically. This allows for the MAX16809/MAX16810 to quickly
turn on and off high gate-charge MOSFETs. Bypass VCC
with one or more 0.1µF ceramic capacitors to AGND,
placed close to VCC. The average current sourced to
drive the external MOSFET depends on the total gate
charge (QG) and operating frequency of the converter.
The power dissipation in the MAX16809/MAX16810 is a
function of the average output drive current (IDRIVE). Use
the following equation to calculate the power dissipation
in the device due to IDRIVE:
IDRIVE = (QG x fSW)
PD = (IDRIVE + ICC) x VCC
where I CC is the operating supply current. See the
Typical Operating Characteristics for the operating
supply current at a given frequency.
Switch-Mode Controller
Current-Mode Control Loop
The advantages of current-mode control over voltagemode control are twofold. First, there is the feed-forward characteristic brought on by the controller’s ability
to adjust for variations in the input voltage on a cycleby-cycle basis. Second, the stability requirements of
the current-mode controller are reduced to that of a single-pole system unlike the double pole in the voltagemode control scheme. The MAX16809/MAX16810 use
a current-mode control loop where the output of the
error amplifier is compared to the current-sense voltage
(VCS). When the current-sense signal is lower than the
inverting input of the CPWM comparator, the output of
the comparator is low and the switch is turned on at
each clock pulse. When the current-sense signal is
higher than the inverting input of the CPWM comparator, the output is high and the switch is turned off.
Undervoltage Lockout (UVLO)
The turn-on supply voltage for the MAX16809/
MAX16810 is 8.4V (typ). Once VCC reaches 8.4V, the
reference powers up. There is a 0.8V of hysteresis from
the turn-on voltage to the UVLO threshold. Once VCC
reaches 8.4V, the MAX16809/MAX16810 operate with
VCC down to 7.6V. Once VCC goes below 7.6V (typ),
the device is in UVLO. When in UVLO, the quiescent
supply current into VCC falls back to 32µA (typ), and
OUT and REF are pulled low.
MOSFET Driver
OUT drives an external n-channel MOSFET and swings
from AGND to VCC. Ensure that VCC remains below the
absolute maximum VGS rating of the external MOSFET.
14
Error Amplifier
The MAX16809/MAX16810 include an internal error
amplifier. The inverting input is at FB and the noninverting input is internally connected to a 2.5V reference.
Set the output voltage using a resistive divider between
output of the converter VOUT, FB, and AGND. Use the
following formula to set the output voltage:
R1 ⎞
⎛
VOUT = ⎜1 +
⎟ x VFB
⎝
R2 ⎠
where VFB = 2.5V.
Oscillator
The oscillator frequency is programmable using an
external capacitor and a resistor at RTCT (see RT and
CT in the Typical Operating Circuits). RT is connected
from RTCT to the 5V reference (REF), and CT is connected from RTCT to AGND. REF charges CT through
RT until its voltage reaches 2.8V. CT then discharges
through an 8.3mA internal current sink until CT’s voltage
reaches 1.1V, at which time CT is allowed to charge
through RT again. The oscillator’s period is the sum of
the charge and discharge times of CT. Calculate the
charge time as follows:
tC = 0.57 x RT x CT
where t C is in seconds, R T in ohms (Ω), and C T in
Farads (F).
The discharge time is then:
tD = (RT x CT x 1000) / [(4.88 x RT) - (1.8 x 1000)]
where t D is in seconds, R T in ohms (Ω), and C T in
Farads (F).
______________________________________________________________________________________
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
RCS =
1
fOSC =
t
+
( C tD)
Reference Output
REF is a 5V reference output that can source 20mA.
Bypass REF to AGND with a 0.1µF capacitor.
Current Limit
The MAX16809/MAX16810 include a fast current-limit
comparator to terminate the ON cycle during an overload or a fault condition. The current-sense resistor,
RCS, connected between the source of the external
MOSFET and AGND, sets the current limit. The CS
input has a voltage trip level (VCS) of 0.3V. Use the following equation to calculate RCS:
VIN
C1
L1
VCS
IP −P
IP-P is the peak current that flows through the MOSFET.
When the voltage produced by this current (through the
current-sense resistor) exceeds the current-limit comparator threshold, the MOSFET driver (OUT) turns the
switch off within 60ns. In most cases, a small RC filter is
required to filter out the leading-edge spike on the
sense waveform. Set the time constant of the RC filter at
50ns.
Buck-Boost (SEPIC) Operation
Figure 2 shows a buck-boost application circuit using
the MAX16809/MAX16810 in a stand-alone mode of
operation. SEPIC topology is necessary when the total
forward voltage of the LEDs in a string is such that
VOUT can be below or above VIN.
VOUT
D
COUT
L2
Q1
R1
CC2
RCS
CC1
RC1
R2
OUT CS AGND
COMP
VCC
FB
CIN
3V TO 5.5V
OUT0
V+
OUT1
CBYP
OUT2
PGND
OUT3
DIN
LE
EXTERNAL
CLOCK INPUT
EXTERNAL
DIM INPUT
OUT4
MAX16809
MAX16810
OUT5
OUT6
OUT7
OUT8
CLK
DOUT
OUT9
OUT10
OE
OUT11
OUT12
OUT13
OUT14
OUT15
SET
RTCT
REF
RT
RSET
CREF
CT
Figure 2. Buck-Boost (SEPIC) Operation
______________________________________________________________________________________
15
MAX16809/MAX16810
The oscillator frequency is then:
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
LED Driver
CLK is the serial-clock input that shifts data at DIN into
the MAX16809/MAX16810’s 16-bit shift register on its
rising edge.
LE is the latch-enable input of the MAX16809/MAX16810
that transfers data from the 16-bit shift register to its 16bit output latches (transparent latch). The data latches
on the falling edge of LE (Figure 4). The fourth input (OE)
provides output-enable control of the output drivers.
When OE is driven high, the outputs (OUT0–OUT15) are
forced to high impedance without altering the contents of
the output latches. Driving OE low enables the outputs to
follow the state of the output latches. OE is independent
of the serial interface operation. Data can be shifted into
the serial-interface shift register and latched, regardless
of the state of OE. DOUT is the serial-data output that
shifts data out from the MAX16809/MAX16810’s 16-bit
shift register on the rising edge of CLK. Data at DIN
propagates through the shift register and appears at
DOUT 16 clock cycles later. Table 1 shows the 4-wire
serial-interface truth table.
4-Wire Interface
The MAX16809/MAX16810 also operate in a standalone mode (see the Typical Operating Circuits). For
use with a microcontroller, the MAX16809/MAX16810
feature a 4-wire serial interface using DIN, CLK, LE, OE
inputs and DOUT as a data output. This interface is
used to write the LED channels’ data to the MAX16809/
MAX16810. The serial-interface data word length is 16
bits, D0–D15. See Figure 3.
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.
Table 1. 4-Wire Serial-Interface Truth Table
BLANKING
OUTPUT CONTENTS
SERIAL CLOCK SHIFT REGISTER CONTENTS LOAD
LATCH CONTENTS
INPUT
INPUT
CURRENT AT OUT_ _
DATA INPUT
INPUT
CLK D0 D1 D2 … Dn-1 Dn
LE
D0 D1 D2 … Dn-1 Dn
OE
D0 D1 D2 … Dn-1 Dn
DIN
H
H
R0 R1 … Rn-2 Rn-1
L
L
R0 R1 … Rn-2 Rn-1
X
R0
R1 R2 … Rn-1
X
X
X
…
X
P0
P1
P2 … Pn-1
Rn
X
L
R0 R1 R2
… Rn-1 Rn
Pn
H
P0
P1
P2
… Pn-1 Pn
L
P0
X
X
X
…
H
L
X
X
P1 P2
L
L = Low Logic Level
H = High Logic Level
X = Don’t Care
P = Present State (Shift Register)
R = Previous State (Latched)
16
______________________________________________________________________________________
L
…
Pn-1
Pn
…
L
L
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
MAX16809/MAX16810
LE
tLW
tCL
tCH
tLS
tCP
CLK
tDH
tDS
D15
DIN
D14
D1
D0
tDO
D15
DOUT
tOEW
OE
tOEF
tOER
80%
OUT_ _
20%
tf
tr
Figure 3. 4-Wire Serial-Interface Timing Diagram
Watchdog (MAX16810)
LE
tLRF
OUT_ _
LE
tLRR
OUT_ _
CLK
tCRF
OUT_ _
CLK
tCRR
The MAX16810 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 outputlatch data. 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 MAX16810 does not lock up in the watchdog timeout
state. The MAX16810 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 MAX16810. The rise time for CLK,
DIN, and LE should be less than 10µs.
OUT_ _
Figure 4. LE and CLK to OUT_ _ Timing
______________________________________________________________________________________
17
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
LED Fault Detection (MAX16810)
The MAX16810 includes circuitry that detects open-circuit LEDs automatically. An open-circuit fault occurs
when an output is sinking current less than approximately 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 for the first two rising
edges of the clock after the falling edge of LE (see
Figure 5). 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. 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.
OE
The MAX16809/MAX16810 use an external resistor,
RSET, to set the LED current for outputs OUT0–OUT15.
The minimum allowed value of RSET is 311Ω, which
sets the output currents to 55mA. The maximum
allowed value of RSET is 5kΩ (IOUT_ _ = 3.6mA) and
maximum allowed capacitance at SET is 100pF.
Use the following formula to set the output current:
RSET =
17,100V
IOUT _ _
where IOUT_ _ is the desired output current in milliamps
and the value for RSET is in ohms.
Overtemperature Cutoff
The MAX16809/MAX16810 contain an internal temperature sensor that turns off all outputs when the die temperature exceeds +165°C. The outputs are enabled again
when the die temperature drops below +140°C. Register
contents are not affected, so when a driver is overdissipating, the external symptom is the load LEDs cycling on
and off as the driver repeatedly overheats and cools,
alternately turning itself off and then back on again.
Stand-Alone Operation
LE
CLK
DOUT
Selecting External Component
RSET to Set LED Output Current
D15
D14 D13
D12
FAULT STATUS BITS
In stand-alone operation, the MAX16809/MAX16810
does not use the 4-wire interface (see the Typical
Operating Circuits). Connect DIN and LE to V+ and
provide at least 16 external clock pulses to CLK to
enable 16 output ports. This startup pulse sequence
can be provided either using an external clock or the
PWM signal. The external clock can also be generated
using the signal at RTCT and an external comparator.
Figure 5. Fault Timing
18
______________________________________________________________________________________
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
PWM Dimming
All the output channels can be dimmed simultaneously
by applying a PWM signal (50Hz to 30kHz) to OE. This
allows for a wide range of dimming up to a 5000:1 ratio.
Each channel can be independently turned on and off
using a 4-wire serial interface. The dimming is proportional to the PWM duty cycle.
LED Current Amplitude Adjustment
Using an analog or digital potentiometer as RSET allows
for LED current amplitude adjustment and linear dimming.
PCB Layout Guidelines
Careful PCB layout is critical to achieve low switching
losses and clean, stable operation. Use a multilayer
board whenever possible for better noise immunity.
Protect sensitive analog grounds by using a star
ground configuration. Minimize ground noise by connecting AGND, PGND, the input bypass-capacitor
ground lead, and the output-filter ground lead to a single point (star ground configuration). Also, minimize
trace lengths to reduce stray capacitance, trace resistance, and radiated noise. The trace between the output voltage-divider and the FB pin must be kept short,
as well as the trace between AGND and PGND.
Computing Power Dissipation
Use the following equation to estimate the upper limit
power dissipation (PD) for the MAX16809/MAX16810:
i = 15
⎡
⎤
PD = DUTY × ⎢(V + x I+) +
∑ VOUTi x IOUTi⎥
⎢⎣
⎥⎦
i = 0
+ (VCC x ICC)
where:
V+ = supply voltage
I+ = V+ operating supply current
DUTY = PWM duty cycle applied to OE
V OUTi = MAX16809/MAX16810 port output voltage
when driving load LED(s)
IOUTi = LED drive current programmed by RSET
PD = power dissipation
______________________________________________________________________________________
19
MAX16809/MAX16810
LED Dimming
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
Typical Operating Circuits (continued)
VIN
L
VOUT
D
LEDs
COUT
R1
CC2
RCS
CC1
RC1
R2
OUT CS AGND
COMP
VCC
FB
CIN
3V TO 5.5V
OUT0
V+
OUT1
CBYP
OUT2
PGND
OUT3
OUT4
MAX16809
MAX16810
SCLK
µC
MOSI
MISO
LOAD
ENABLE
OUT5
OUT6
OUT7
OUT8
CLK
DIN
DOUT
OUT9
OUT10
LE
OE
OUT11
OUT12
OUT13
OUT14
SET
OPERATION WITH MICROCONTROLER
RT
RSET
CREF
20
OUT15
RTCT
REF
CT
______________________________________________________________________________________
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
Chip Information
LE
OUT0
OUT1
OUT2
OUT3
OUT4
OUT5
OUT6
OUT7
CS
N.C.
RTCT
PROCESS: BiCMOS
TOP VIEW
31 30 29 28 27 26 25 24 23 22 21 20
N.C. 32
19 CLK
AGND 33
18 DIN
OUT 34
17 PGND
VCC 35
16 PGND
MAX16809
MAX16810
N.C. 36
15 V+
REF 37
14 SET
N.C. 38
13 DOUT
9
10 11 12
OE
8
OUT15
OUT9
7
OUT14
OUT8
6
OUT13
5
OUT12
4
OUT11
3
OUT10
2
FB
N.C.
1
COMP
+
TQFN
______________________________________________________________________________________
21
MAX16809/MAX16810
Pin Configuration
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.)
38L THIN QFN.EPS
MAX16809/MAX16810
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
PACKAGE OUTLINE,
38L THIN QFN, 5x7x0.80mm
21-0172
22
______________________________________________________________________________________
B
1
2
Integrated 16-Channel LED Drivers with
Switch-Mode Boost and SEPIC Controller
PACKAGE OUTLINE,
38L THIN QFN, 5x7x0.80mm
21-0172
B
2
2
Revision History
Pages changed at Rev 1: 1, 14, 16, 22, 23
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 23
© 2007 Maxim Integrated Products
Heaney
is a registered trademark of Maxim Integrated Products, Inc.
MAX16809/MAX16810
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.)