MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
General Description
The MAX16804 current regulator operates from a 5.5V
to 40V input voltage range and delivers 35mA to 350mA
to one or more strings of high-brightness LEDs (HB
LEDs). The output current of the MAX16804 is set by
using an external current-sense resistor in series with the
LEDs. A dual-mode DIM pin and on-board 200Hz ramp
generator allow PWM dimming with an analog or PWM
input signal. The analog control signal at dimming input
DIM allows for a theater-dimming effect to be implemented.
Fast turn-on and turn-off times ensure a wide-range PWM
operation, while wave-shaping circuitry minimizes EMI. The
differential current-sense input increases LED current
accuracy and noise immunity. The MAX16804 is well suited for
applications requiring high-voltage input and is able to
withstand load-dump events up to 45V. An on-board pass
element minimizes external components while providing
3% output-current accuracy. Additional features include a
5V regulated output and short-circuit and thermal protection.
The MAX16804 is available in a thermally enhanced,
5mm x 5mm, 20-pin TQFN package and is specified over
the automotive -40°C to +125°C temperature range.
Applications
●● Warning Lights for Emergency Vehicles
●● Navigation and Marine Indicators
●● Signage, Canopies, and Beacons
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX16804ATP+
-40°C to +125°C
Benefits and Features
●● Flexible Dimming Control Simplifies Lighting System
Design
• Analog or PWM Control Signal for PWM and
Theater Dimming
• 200Hz On-Board Ramp Generator
• High-Voltage (Up to 40V) DIM Pin
• Additional +5V On-Board Regulator with 2mA
Capability
●● External Synchronization and Pulse Shaping Reduce
Radio Interference
• Wave-Shaped Edges Minimize EMI During PWM
Dimming
• Syncs to External PWM Signal (Up to 2kHz)
●● Powers High-Power, High-Brightness LEDs
• 35mA to 350mA Adjustable LED Current
• 3% LED Current Accuracy
• Differential LED Current Sense
●● Enables High-Efficiency Designs to Minimize Heat
Dissipation
• Integrated Pass Element with Low-Dropout Voltage
(0.5V typ)
• 200mV Current-Sense Reference Reduces Power
Losses
●● Thermal Shutdown and Output Short-Circuit
Protection Provide Additional Safety
• 5.5V to 40V Operating Range
• -40°C to +125°C Operating Temperature Range
Pin Configuration appears at end of data sheet.
20 TQFN-EP*
+Denotes lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
Simplified Diagrams
+5.5V TO +40V
ILED
IN
OUT
0.1µF
V5
0.1µF
MAX16804
V5
EN
+5.5V TO +40V
+5V REG
0.1µF
CS-
ANALOG CONTROL PWM DIMMING
19-0589; Rev 3; 4/15
V5
EN
RSENSE
GND
OUT
LEDs
CS+
DIM
ILED
IN
MAX16804
+5V REG
0.1µF
LEDs
CS+
RSENSE
PWM DIMMING
DIM
GND
CS-
PWM CONTROL DIMMING
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Absolute Maximum Ratings
IN to GND...............................................................-0.3V to +45V
DIM, OUT, EN to GND.................................-0.3V to (VIN + 0.3V)
IN Slew Rate (20V < VIN < 45V)...................................250mV/μs
CS+, V5 to GND.......................................................-0.3V to +6V
CS- to GND............................................................-0.3V to +0.3V
OUT Short Circuited to GND Duration
(at VIN < +16V)...............................................................1hour
Maximum Current Into Any Pin (except IN and OUT).........±20mA
Continuous Power Dissipation (TA = +70°C)
20-Pin TQFN (derate 34.5mW/°C above +70°C)....2758.6mW
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
(VIN = VEN = 12V, CV5 = 0.1μF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω (see the Typical Operating Circuit), VDIM = 4V, TA = TJ = -40°C
to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
Ground Current
Shutdown Supply Current
Guaranteed Output Current
SYMBOL
CONDITIONS
VIN
(Note 2)
IG
ILOAD = 350mA
IOUT
RSENSE = 0.55Ω
ISHDN
MIN
TYP
MAX
UNITS
40.0
V
2.5
4.5
mA
12
40
5.5
VEN ≤ 0.3V
350
35mA < IOUT < 350mA, not including
RSENSE tolerance
Output Current Accuracy
3
IOUT = 350mA, 12V < VIN < 40V
0.4
1.2
IOUT = 350mA, 6.5V < VIN < 12V
0.5
1.5
Output Current Slew Rate
(External PWM Signal at DIM)
Current rising, DIM rising to 4V
17
Current falling, DIM falling to 0.6V
17
Short-Circuit Current
VOUT = 0V
600
Dropout Voltage (Note 3)
∆VDO
µA
mA
%
V
mA/µs
mA
ENABLE INPUT
EN Input Current
IEN
EN Input-Voltage High
VIH
EN Input-Voltage Low
VIL
Enable Turn–On Time
tON
100
2.8
V
0.6
EN rising edge to 90% of OUT
nA
250
V
µs
CURRENT SENSE (Note 4)
Regulated RSENSE Voltage
VRSENSE
VSENSE = VCS+ - VCS-
Input Current (CS+)
VCS+ = 220mV
Input Current (CS-)
VCS+ = 220mV
192
198
204
mV
+14
µA
-75
µA
INTERNAL RAMP GENERATOR
Internal Ramp Frequency
External Sync Frequency Range
fRAMP
180
fDIM
80
200
External Sync Voltage Low
External Sync Voltage High
220
Hz
2000
Hz
0.4
V
2.8
V
EXTERNAL PWM DIMMING INPUT
DIM Input Current
1
µA
Turn-On Time
tON
After DIM rising to 4V (Note 5)
28
52
µs
Turn-Off Time
tOFF
After DIM falling to 0.6V (Note 5)
19
38
µs
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Maxim Integrated │ 2
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Electrical Characteristics (continued)
(VIN = VEN = 12V, CV5 = 0.1μF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω (see the Typical Operating Circuit), VDIM = 4V, TA = TJ = -40°C
to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
THERMAL PROTECTION
Thermal-Shutdown Temperature
TJ(SHDN)
Thermal-Shutdown Hysteresis
+155
°C
23
°C
+5V REGULATOR
Output Voltage Regulation
V5
0 ≤ IV5 ≤ 2mA
V5 Short-Circuit Current
4.8
5.1
V5 = 0V (Note 6)
5.4
V
12
mA
Note 1: All devices are 100% production tested at TA = +25°C. Limits over the operating temperature range are guaranteed by design.
Note 2: Resistors were added from OUT to CS+ to aid with the power dissipation during testing.
Note 3: Dropout is measured as follows:
Connect a resistor from OUT to CS+. Connect RSENSE = 0.56Ω from CS+ to CS-. Set VIN = VOUT +3V (record VOUT as
VOUT1). Reduce VIN until VOUT = 0.97 x VOUT1 (record as VIN2 and VOUT2). ΔVDO = VIN2 - VOUT2.
Note 4:IV5 = 0mA.
Note 5:tON time includes the delay and the rise time needed for IOUT to reach 90% of its final value. tOFF time is the time needed
for IOUT to drop below 10%. See the Typical Operating Characteristics. tON and tOFF are tested with 13Ω from OUT to CS+.
Note 6: Thermal shutdown does not function if the output of the 5V reference is shorted to ground. Shorting V5 to GND disables the
output.
Typical Operating Characteristics
(VIN = 12V, VEN = VIN, CV5 = 0.1μF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless
otherwise noted.)
0.200
300
250
200
150
100
0.199
ILOAD = 200mA
0.198
0.197
ILOAD = 100mA
ILOAD = 35mA
50
0
0.201
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
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0.196
0.195
400
350
IOUT = 350mA
300
250
200
150
100
IOUT = 100mA
50
0.194
0.193
OUTPUT CURRENT
vs. INPUT VOLTAGE
20 50 80 110 140 170 200 230 260 290 320 350
OUTPUT CURRENT (mA)
MAX16804 toc03
ILOAD = 350mA
VIN = 12V
0.202
OUTPUT CURRENT (mA)
350
0.203
(VCS+ - VCS-) (V)
OUTPUT CURRENT (mA)
400
(VCS+ - VCS-) vs. OUTPUT CURRENT
MAX16804 toc02
450
MAX16804 toc01
OUTPUT CURRENT
vs. TEMPERATURE
0
0
2
4
6
8
10
12
14
16
INPUT VOLTAGE (V)
Maxim Integrated │ 3
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Typical Operating Characteristics (continued)
(VIN = 12V, VEN = VIN, CV5 = 0.1μF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless
otherwise noted.)
0.6
0.5
0.4
0.3
0.2
VIN = 20V
20
15
VIN = 12V
10
5
0
0
VIN = 6.5V
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
MAX16804 toc07
5.10
ILOAD = 2mA
5.05
0.1988
5.00
VIN = 12V
-40 -25 -10 5 20 35 50 65 80 95 110 125
200Hz DIMMED OPERATION
MAX16804 toc09
VDIM
2V/div
0.1987
0.1986
0V
ILOAD = 350mA
VIN = 12V
DIM PULSED AT
200Hz (1% DUTY
CYCLE)
0.1985
0.1984
0.1983
ILOAD = 1mA
MAX16804 toc06
ILOAD = 2mA
5.05
TEMPERATURE (°C)
ILOAD = 350mA
VIN = 12V
0.1989
(VCS+ - VCS-) (V)
+5V REGULATOR OUTPUT (V)
NO LOAD
5.15
5.10
(VCS+ - VCS-) vs. IV5
0.1990
NO LOAD
ILOAD = 1mA
5.15
TEMPERATURE (°C)
+5V REGULATOR OUTPUT vs. VIN
5.20
MAX16804 toc05
25
0.1
-40 -25 -10 5 20 35 50 65 80 95 110 125
VIN = 40V
30
5.20
+5V REGULATOR OUTPUT (V)
0.7
35
+5V REGULATOR OUTPUT
vs. TEMPERATURE
MAX16804 toc08
0.8
40
SHUTDOWN CURRENT (µA)
VIN = 12V
ILOAD = 350mA
0.9
MAX16804 toc04
1.0
DROPOUT VOLTAGE (V)
SHUTDOWN CURRENT
vs. TEMPERATURE
DROPOUT VOLTAGE
vs. TEMPERATURE
ILOAD
200mA/div
0A
0.1982
0.1981
5.00
5
10
15
20
25
30
35
40
0.1980
0
LED CURRENT FALL TIME (EXPANDED)
20µs/div
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2
3
4
5
6
7
8
9
10
20µs/div
LED CURRENT RISE TIME (EXPANDED)
MAX16804 toc10
DIM PULSED AT
200Hz
1
IV5 (mA)
VIN (V)
MAX16804 toc11
VDIM
2V/div
DIM PULSED AT
200Hz
VDIM
2V/div
0V
0V
ILED
200mA/div
ILED
200mA/div
0A
0A
20µs/div
Maxim Integrated │ 4
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Typical Operating Characteristics (continued)
(VIN = 12V, VEN = VIN, CV5 = 0.1μF, IV5 = 0, CS- = GND, RSENSE = 0.56Ω, connect OUT to CS+, VDIM = 4V, TA = +25°C, unless
otherwise noted.)
VIN = 12V
100
VIN = 16V
250
200
IDIM (µA)
80
60
150
40
100
20
50
0
IDIM vs. VDIM
300
MAX16804 toc12
OUTPUT CURRENT DUTY CYCLE (%)
120
MAX16804 toc13
OUTPUT CURRENT DUTY CYCLE
vs. ANALOG DIM VOLTAGE
1
0
2
3
4
0
0
2
4
6
8
10
12
14
16
VDIM (V)
ANALOG DIM VOLTAGE (V)
Pin Description
PIN
NAME
1, 20
OUT
2, 3
IN
FUNCTION
Current-Regulated Output. Connect pin 1 to pin 20.
Input Supply. Bypass IN with a 0.1µF (min) capacitor to GND. Connect pin 2 to pin 3.
4, 9, 11, 18
N.C.
No Connection. Leave unconnected (internal connection).
5–8, 10, 16
GND
Ground
12, 15
V5
13
CS+
Positive Input of the Internal Differential Amplifier. Connect the current-sense resistor between CS+
and CS- to program the output current level.
14
CS-
Negative Input of the Internal Differential Amplifier. Connect the current-sense resistor between CSand CS+ to program the output current level.
17
DIM
Dimming Input. See the Dimming Input (DIM) section.
19
EN
Enable Input. Drive EN high to enable the output and the 5V LDO.
—
EP
Exposed Pad. Connect to the ground plane for effective power dissipation. Do not use as the only
ground connection.
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+5V Regulated Output. Connect a 0.1µF capacitor from V5 to GND.
Maxim Integrated │ 5
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Functional Diagram
V5
IN
IN
REGULATOR
TRIMMED
BANDGAP
EN
1.25V
I_REG
OUT
GND
DIFFERENTIAL
SENSE
AMPLIFIER
MAX16804
CS+
CS-
THERMAL
SHUTDOWN
210mV
200Hz RAMP
GENERATOR
MUX
DIM
POR
PULSE
DETECTOR
Detailed Description
The MAX16804 is a high-current regulator that
operates from a wide input voltage range of 5.5V to 40V
and is capable of providing up to 350mA of current to
one or more strings of HB LEDs. A +5V regulated output
provides up to 2mA of current to power external circuitry.
In addition, the MAX16804 features thermal and output
short-circuit protection. The wide operating voltage range
helps protect the MAX16804 against large transients such
as those found in load-dump situations up to 45V.
The MAX16804 uses a feedback loop to control the
output current. The differential voltage across the sense
resistor is compared to a fixed reference voltage, and the
error is amplified to serve as the drive to the internal pass
device (see the Functional Diagram). The regulation point
is factory-set at (VCS+ - VCS-) = 198 ±6mV. The regulated
current is user-defined by the value of RSENSE.
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The MAX16804 is a current controller internally optimized
for driving the impedance range expected from one to ten
or more HB LEDs.
Dimming Input (DIM)
The MAX16804’s dimming input functions with either an
analog or PWM control signal. If the pulse detector detects
three edges of a PWM signal with a frequency range
between 80Hz and 2kHz, the MAX16804 synchronizes to
external PWM input signal and pulse-width modulates the
LED current. If an analog control signal is applied to DIM, the
MAX16804 compares the DC input to an internally generated 200Hz ramp to pulse-width modulate the LED current.
The output current duty cycle is adjustable from 0% to
100% (0.21V < VDIM < 3.1V).
Use the following formula to calculate the output current
duty cycle:
Duty cycle = (VDIM - 0.21V)/(2.895V) (1)
Maxim Integrated │ 6
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
The dimming feature can be used for LED brightness
adjustment (see the Simplified Diagrams) and theater
dimming. If an external PWM signal is used, the theaterdimming effect can be achieved by varying the PWM duty
cycle. Figure 1 shows a simple circuit that implements
theater dimming with a DC input signal.
+5V Regulator
The MAX16804 includes a fixed +5V output regulator that
delivers up to 2mA of load current throughout the 6.5V to
40V input voltage range. Connect a 0.1μF compensation
capacitor from V5 to ground. Shorting V5 to ground disables the thermal shutdown. When EN is low, V5 is off. V5
stays on during PWM dimming.
Thermal Protection
The MAX16804 enters a thermal-shutdown mode in the
event of overheating. This typically occurs in overload
or short-circuit conditions on the output. If the junction
temperature exceeds TJ = +155°C (typ), the internal
thermal-protection circuitry turns off the series pass
device. The MAX16804 recovers from thermal-shutdown
mode once the junction temperature drops by 23°C (typ).
The part therefore protects itself by thermally cycling in
the event of a short-circuit or overload condition.
VIN
IN
V5
Programming the LED Current
The MAX16804 uses a sense resistor across CS+
and CS- to set the LED current. The differential sense
amplifier connected across RSENSE provides groundloop immunity and low-frequency noise rejection. The
LED current is given by:
ILED = VSENSE/RSENSE (2)
Input-Voltage Considerations
For proper operation, the minimum input voltage must
always be:
VIN(MIN) ≥ VRSENSE(MAX) + VFT(MAX) + ΔVDO(MAX) (3)
where VFT(MAX) is the maximum forward voltage of all
series connected LEDs and ΔVDO(MAX) is the maximum
drop output voltage. The minimum operating voltage of
the device is +5.5V.
Two Brightness Levels for TAIL/STOP Lights
Figure 2 shows two-level brightness adjustment using the
MAX16804 with minimum external components. Set the
dimming level with a resistive divider connected to DIM.
See Equation 1 for details.
D1
STOP
OUT
EN
Applications Information
+5V REG
TAIL
D2
LEDs
IN
OUT
0.1µF
MAX16804
THEATER
DIMMING
SIGNAL
EN
D3
CS+
R1
RSENSE
DIM
GND
CS-
D4
V5
MAX16804
DIM
CS+
R2
RSENSE
GND
Figure 1. Theater Dimming
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LEDs
CS-
Figure 2. Two-Level Brightness Operation
Maxim Integrated │ 7
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
LED Current Thermal Foldback
With a minimum number of external components, the
MAX16804 provides LED current thermal foldback using
a negative temperature coefficient (NTC) thermistor.
Figure 3 shows a thermistor connected to V5 and the
CS+ of the MAX16804. As the temperature increases, the
voltage drop across R2 increases causing the LED current
to decrease.
Other Applications
Figure 4 shows an application circuit with the MAX16804
using a single BJT to provide high output current. For
proper operation:
VIN(MIN) > VCESAT(MAX) + VFT(MAX) + VRSENSE (5)
where VCESAT(MAX) is the maximum saturation voltage
of the external BJT.
ILED = [VSENSE - [R2/(R2 + RT)] x V5]/R1 (4)
VIN
IN
OUT
C1
EN
LEDs
V5
C2
MAX16804
PWM DIMMING
RT
R2
DIM
CS+
R1
CS-
GND
Figure 3. LED Current Thermal Foldback Operation with an NTC Thermistor
LEDs
VIN
IN
Q1
OUT
C1
EN
V5
C2
MAX16804
PWM DIMMING
DIM
CS+
RSENSE
GND
CS-
Figure 4. Increased Output Current (Ampere Range) with a Single BJT
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Maxim Integrated │ 8
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Typical Operating Circuit
ANALOG OR PWM
CONTROL SIGNAL
20
OUT
1 OUT
VIN
19
18
17
EN
N.C.
DIM
16
3
MAX16804
IN
5 GND
GND
6
Pin Configuration
V5 12
GND
GND
N.C.
7
8
9
C2
N.C. 11
GND
10
Chip Information
PROCESS: BiCMOS
V5
CS-
CS+
V5
N.C.
TOP VIEW
15
14
13
12
11
Package Information
GND 16
10
GND
DIM 17
9
N.C.
8
GND
7
GND
6
GND
MAX16804
EN 19
1
2
3
4
5
IN
IN
N.C.
GND
+
OUT
OUT 20
RSENSE
CS+ 13
4 N.C.
N.C. 18
LEDs
CS- 14
2 IN
C1
GND
V5 15
For the latest package outline information and land patterns
(footprints), go to www.maximintegrated.com/packages. Note
that a “+”, “#”, or “-” in the package code indicates RoHS status
only. Package drawings may show a different suffix character, but
the drawing pertains to the package regardless of RoHS status.
PACKAGE TYPE
PACKAGE CODE
DOCUMENT NO.
20 TQFN
T2055MN-5
21-0140
THIN QFN
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Maxim Integrated │ 9
MAX16804
High-Voltage, 350mA LED Driver with
Analog and PWM Dimming Control
Revision History
REVISION
NUMBER
REVISION
DATE
0
7/06
Initial release
—
1
5/08
Corrected Figure 2.
7
2
1/15
Updated Benefits and Features section
1
4/15
Deleted automotive references in General Description, Applications, and
Detailed Description sections
3
PAGES
CHANGED
DESCRIPTION
1, 6
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent licenses
are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits)
shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2015 Maxim Integrated Products, Inc. │ 10