EVALUATION KIT AVAILABLE
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
General Description
Features
The MAX16838 is a dual-channel LED driver that integrates both the DC-DC switching boost regulator and
two 150mA current sinks. A current-mode switching
DC-DC controller provides the necessary voltage to
both strings of HB LEDs. The MAX16838 accepts a wide
4.75V to 40V input voltage range and directly withstands
automotive load-dump events. For a 5V Q10% input voltage, connect VIN to VCC. The wide input range allows
powering HB LEDs for small-to-medium-sized LCD displays in automotive and display backlight applications.
S Integrated, 2-Channel, 20mA to 150mA Linear LED
Current Sinks
S Boost or SEPIC Power Topologies for Maximum
Flexibility
S Adaptive Voltage Optimization to Minimize Power
Dissipation in Linear Current Sinks
S 4.75V to 40V or 5V ±10% Input Operating Voltage
Range
S 5000:1 PWM Dimming at 200Hz
S Open-Drain Fault Indicator Output
S LED Open/Short Detection and Protection
S Output Overvoltage and Overtemperature
Protection
S Programmable LED Current Foldback at Lower
Input Voltages
S 200kHz to 2MHz Resistor Programmable
Switching Frequency with External
Synchronization
S Current-Mode Control Switching Stage with
Internal Slope Compensation
S Enable Input
S Thermally Enhanced, 20-Pin TQFN (4mm x 4mm)
and 20-Pin TSSOP Packages
An internal current-mode switching DC-DC controller
supports the boost or SEPIC topologies and operates
in an adjustable frequency range between 200kHz and
2MHz. The current-mode control provides fast response
and simplifies loop compensation. The MAX16838 also
features an adaptive output-voltage adjustment scheme
that minimizes the power dissipation in the LED current
sink paths. The MAX16838 can be combined with the
MAX15054 to achieve a buck-boost LED driver with two
integrated current sinks.
The channel current is adjustable from 20mA to 150mA
using an external resistor. The external resistor sets both
channel currents to the same value. The device allows
connecting both strings in parallel to achieve a maximum
current of 300mA in a single channel. The MAX16838
also features pulsed dimming control with minimum
pulse widths as low as 1Fs, on both channels through a
logic input (DIM).
The MAX16838 includes an output overvoltage protection, open LED, shorted LED detection and overtemperature protection. The device operates over the -40NC to
+125NC automotive temperature range. The MAX16838
is available in the 20-pin TSSOP and 4mm x 4mm, 20-pin
TQFN packages.
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX16838ATP+
-40NC to +125NC
20 TQFN-EP*
MAX16838ATP/V+
-40NC to +125NC
20 TQFN-EP*
MAX16838AUP+
-40NC to +125NC
20 TSSOP-EP*
MAX16838AUP/V+
-40NC to +125NC
20 TSSOP-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
/V denotes an automotive qualified part.
Simplified Schematic
4.75V TO 40V
Applications
L
D
CIN
R2OV
Automotive Display Backlights
LCD Display Backlights
IN
Automotive Lighting Applications
DRAIN
EN
OV
R1OV
NDRV
CFB
GATE
VCC
OUT1
OUT2
DRV
MAX16838
COUT
LED
STRINGS
RISET
ISET
FLT
DIM
CS
RT
COMP
CCOMP
RCOMP
SGND
PGND
LEDGND
RRT
RCS
Typical Operating Circuit and Pin Configurations appear at
end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-4972; Rev 4; 3/16
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
ABSOLUTE MAXIMUM RATINGS
IN, OUT_, DRAIN to SGND....................................-0.3V to +45V
EN to SGND................................................-0.3V to (VIN + 0.3V)
PGND to SGND.....................................................-0.3V to +0.3V
LEDGND to SGND................................................-0.3V to +0.3V
DRV to PGND........... -0.3V to the lower of (VIN + 0.3V) and +6V
GATE to PGND.........................................................-0.3V to +6V
NDRV to PGND........................................-0.3V to (VDRV + 0.3V)
VCC, FLT, DIM, CS, OV, CFB, to SGND..................-0.3V to +6V
RT, COMP, ISET to SGND..........................-0.3V to (VCC + 0.3V)
DRAIN and CS Continuous Current................................... Q2.5A
OUT_ Continuous Current.................................................175mA
VDRV Short-Circuit Duration ......................................Continuous
Continuous Power Dissipation (TA = +70NC)
20-Pin TQFN (derate 25.6mW/NC above +70NC).............2051mW
20-Pin TSSOP (derate 26.5mW/NC above +70NC).......2122mW
Operating Temperature Range......................... -40NC to +125NC
Junction Temperature......................................................+150NC
Storage Temperature Range............................. -65NC to +150NC
Soldering Temperature (reflow).......................................+260NC
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.
PACKAGE THERMAL CHARACTERISTICS (Note 1)
20 TQFN
Juction-to-Ambient Thermal Resistance (BJA)........... +39NC/W
Junction-to-Case Thermal Resistance (BJC)................ +6NC/W
20 TSSOP
Junction-to-Ambient Thermal Resistance (BJA)...... +37.7NC/W
Junction-to-Case Thermal Resistance (BJC)................ +2NC/W
Note 1: Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer
board. For detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial.
ELECTRICAL CHARACTERISTICS
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
V
Input Voltage Range
VIN
Internal LDO on
4.75
40
Input Voltage Range
VIN
VIN = VCC
4.55
5.5
V
Quiescent Supply Current
IQ
VDIM = 5V
3.1
5
mA
Standby Supply Current
ISH
VEN = SGND (Note 3)
15.5
40
FA
UVLOIN
VIN rising, VDIM = 5V
4.3
4.55
Undervoltage Lockout
4
Undervoltage Lockout Hysteresis
177
V
mV
DRV REGULATOR
Output Voltage
Dropout Voltage
VDRV
VCC (UVLO) Hysteresis
2
6.5V < VIN < 40V, 0.1mA < ILOAD < 3mA
4.75
VDO
VIN = 4.75V, IOUT = 30mA
(VIN - VDRV)
Short-Circuit Current Limit
VCC Undervoltage Lockout
Threshold
5.75V < VIN < 10V, 0.1mA < ILOAD < 30mA
DRV shorted to GND
UVLOVCC
VCC rising
5
5.25
V
0.11
0.5
V
97
3.4
4.0
123
mA
4.4
V
mV
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
RT OSCILLATOR
Switching Frequency Range
Duty Cycle
fSW
DMAX
2000
kHz
fSW = 200kHz
200
87
90
95
%
fSW = 2000kHz
83
85
91
%
Oscillator Frequency Accuracy
fSW = 200kHz to 2MHz
-7.5
+7.5
%
Synchronization Logic-High
VRT rising
1.8
3.6
V
Synchronization Logic-Low
VRT falling
Logic-Level Before SYNC
Capacitor
3.1
Synchronization Pulse Width
SYNC Frequency Range
2.5
V
3.8
50
ns
1.1 x
fSW
fSYNC
V
1.5 x
fSW
Hz
PWM COMPARATOR
Leading-Edge Blanking
Propagation Delay to NDRV
66
ns
Including leading-edge blanking time
100
ns
Voltage ramp added to CS
0.12
V
SLOPE COMPENSATION
Slope Compensation Peak
Voltage per Cycle
CS LIMIT COMPARATOR
CS Threshold Voltage
VCS_MAX
CS Limit Comparator Propagation
Delay to NDRV
CS Input Current
VCOMP = 3V
285
10mV overdrive (including leading-edge
blanking time)
ICS
300
315
100
0 P VCS P 0.35V
-1.3
VDIM = 5V
0.9
340
mV
ns
+0.5
FA
1
1.1
V
600
880
ERROR AMPLIFIER
OUT_ Regulation Voltage
Transconductance
No-Load Gain
Gm
FS
(Note 4)
50
ISINK
VDIM = VOUT_ = 5V, VCOMP = 3V
400
800
FA
ISOURCE
VDIM = 5V, VOUT_ = VCOMP = 0V
400
800
FA
ISINK = 100mA, VIN > 5.5V
1.5
4
I
ISOURCE = 100mA, VIN > 5.5V
1.5
4
I
Peak Sink Current
VNDRV = 5V
0.8
A
Peak Source Current
VNDRV = 0V
0.8
A
COMP Sink Current
COMP Source Current
A
dB
MOSFET DRIVER
NDRV On-Resistance
POWER MOSFET
Power Switch On-Resistance
ISWITCH = 0.5A, VGS = 5V
0.15
0.35
I
Switch Leakage Current
VDRAIN = 40V, VGATE = 0V
0.003
1.2
FA
Switch Gate Charge
VDRAIN = 40V, VGS = 4.5V
3.1
Maxim Integrated
nC
3
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
150
mA
Q2
%
0.3
0.5
V
LED CURRENT SINKS
OUT_ Current Range
IOUT_
VDIM = 5V, VOUT_ = 1.0V
LED Strings Current Matching
IOUT_ = 100mA, RISET = 15kI
Maximum Peak-to-Peak Boost
Ripple
1% IOUT variation, IOUT = 100mA,
RISET = 15kI
IOUT_ = 100mA,
RISET = 15kI
Output Current Accuracy
TA = +25NC
97
100
103
mA
TA = -40NC to +125NC
95
100
105
mA
18.7
20
21.3
mA
1
300
nA
IOUT_ = 20mA, RISET
TA = -40NC to +125NC
= 75kI
VDIM = 0V, VOUT_ = 40V
OUT_ Leakage Current
20
Current Foldback Threshold
Voltage
1.23
CFB Input Bias Current
0 P VCFB P 1.3V
-0.3
VEN rising
1.1
V
+0.3
FA
ENABLE COMPARATOR (EN)
Enable Threshold
Enable Threshold Hysteresis
VENHI
VEN_HYS
Enable Input Current
1.24
1.34
71
VEN = 40V
-500
+50
V
mV
+700
nA
DIM LOGIC
DIM Input Logic-High
VIH
DIM Input Logic-Low
VIL
Hysteresis
DIM Input Current
2.1
VDIM_HYS
IDIM
V
0.8
110
VDIM = 5V or 0
-600
V
mV
+100
nA
DIM to LED Turn-On Time
VDIM rising edge to 90% of set current
50
290
1000
ns
DIM to LED Turn-Off Time
VDIM falling edge to 10% of set current
10
121
700
ns
IOUT_ Rise Time
tR
Rise time measured from 10% to 90%
120
600
ns
IOUT_ Fall Time
tF
Fall time measured from 90% to 10%
50
500
ns
LED FAULT DETECTION
LED Shorted Fault Indicator
Threshold
TA = +125NC
LED String Shorted Shutoff
Threshold
TA = +125NC
Shorted LED Detection FLAG
Delay
4
3.1
3.55
6
6.8
4.2
7.7
6
5.5
4.85
9.5
8.6
V
V
Fs
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, DRAIN, COMP, OUT_, FLT = unconnected, VOV
= VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = TJ = -40NC to +125NC, unless otherwise noted. Typical
values are at TA = 25NC.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
FLT LOGIC
Output-Voltage Low
VOL
Output Leakage Current
VIN = 4.75V and ISINK = 5mA
VFILT = 5.5V
-300
VOV rising
1.19
0.4
V
+300
nA
OVERVOLTAGE PROTECTION
OV Trip Threshold
1.23
OV Hysteresis
1.265
70
OV Input Bias Current
0 P VOV P 1.3V
V
mV
-100
+100
nA
THERMAL SHUTDOWN
Thermal Shutdown
165
oC
Thermal Shutdown Hysteresis
15
oC
Note 2: All devices are 100% tested at TA = +125NC. Limits over temperature are guaranteed by design, not production tested.
Note 3: The shutdown current does not include currents in the OV and CFB resistive dividers.
Note 4: Gain = DVCOMP/DVCS, 0.05V < VCS < 0.15V.
Typical Operating Characteristics
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
SWITCHING WAVEFORM AT 200Hz
(50% DUTY CYCLE)
IIN vs. SUPPLY VOLTAGE
MAX16838 toc02
5.0
MAX16838 toc01
4.5
10V/div
0V
100mA/div
ILED
0A
20V/div
0V
VOUT
4.0
IIIN (mA)
VLX
TA = +125°C
TA = +25°C
3.5
3.0
TA = -40°C
2.5
VIN = 12V
2.0
1ms/div
4
8
12
16
20
24
28
32
36
40
SUPPLY VOLTAGE (V)
Maxim Integrated
5
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
SWITCHING FREQUENCY
vs. TEMPERATURE
IIN vs. FREQUENCY
8
IIN (mA)
7
6
5
4
3
2
1
360
MAX16838 toc04
9
359
SWITCHING FREQUENCY (kHz)
MAX16838 toc03
10
358
357
356
355
354
353
352
VIN = 12V
351
VIN = 12V
0
350
0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2
-40 -25 -10 5 20 35 50 65 80 95 110 125
FREQUENCY (MHz)
TEMPERATURE (°C)
VISET vs. ILED
VISET vs. TEMPERATURE
1.222
1.220
VIN = 12V
1.230
1.230
VISET (V)
1.219
1.229
1.218
1.217
1.229
VIN = 12V
VDIM = 0V
1.216
1.229
1.215
20
-40 -25 -10 5 20 35 50 65 80 95 110 125
80
100
120
VEN_TH vs. TEMPERATURE
EN LEAKAGE CURRENT
vs. TEMPERATURE
MAX16838 toc07
VEN RISING
VEN FALLING
1.15
140
300
250
EN LEAKAGE CURRENT (nA)
VEN_TH (V)
1.20
60
ILED (mA)
1.30
1.25
40
TEMPERATURE (°C)
200
160
MAX16838 toc08
VISET (V)
1.221
1.230
MAX16838 toc06
MAX16838 toc05
1.223
VEN = 40V
150
100
VEN = 12V
50
1.10
6
0
-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)
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
DRV LINE REGULATION
DRV LOAD REGULATION
5.000
TA = +125°C
5.000
TA = +25°C
4.995
VDRV (V)
4.990
TA = +25°C
4.990
4.985
TA = -40°C
4.980
TA = -40°C
4.975
4.980
4.970
4.975
VIN = 12V
4.965
10
20
30
40
50
0
5
10
15
20
25
INPUT VOLTAGE (V)
LOAD (mA)
FREQUENCY vs. RRT
LODIM MODE RESPONSE
30
MAX16838 toc12
2.5
VIN = 12V
2.0
MAX16838 toc11
0
FREQUENCY(MHz)
TA = +125°C
5.005
4.995
4.985
MAX16838 toc10
5.005
DRV VOLTAGE (V)
5.010
MAX16838 toc09
5.010
10V/div
VIN
0V
5V/div
VDIM
1.5
0V
100mA/div
1.0
IOUT_
0A
20V/div
0.5
VLED_
DIM ON-TIME < 5 x fSW
0V
0
0
4
8
20ms/div
12 16 20 24 28 32 36 40
RRT (kI)
LED SWITCHING WITH DIM AT 200Hz
(50% DUTY CYCLE)
10mA/div
IOUT1
100mA/div
IOUT2
0A
5V/div
0V
VDIM
2ms/div
ILED (mA)
0A
150
140
130
120
110
100
90
80
70
60
50
40
30
20
10
0
VIN = 12V
MAX16838 toc14
ILED vs. RISET
MAX16838 toc13
10 15 20 25 30 35 40 45 50 55 60 65 70 75
RISET (kI)
Maxim Integrated
7
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Typical Operating Characteristics (continued)
(VIN = VEN = 12V, RRT = 12.2kI, RISET = 15kI, CVCC = 1FF, VCC = VDRV = VCFB, VDRAIN = VCOMP = VOUT_, FLT = unconnected,
VOV = VCS = VLEDGND = VDIM = VPGND = VSGND = 0V, VGATE = VNDRV, TA = +25NC, unless otherwise noted.)
40
VOUT = 40V
MAX16838 toc16
45
VOUT = 12V
35
30
25
20
15
10
5
0
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
OV LEAKAGE CURRENT
vs. TEMPERATURE
POWER MOSFET RDSON
vs. TEMPERATURE
VIN = 12V
VEN = HIGH
1.0
0.5
0
-0.5
-1.0
0.50
0.45
MAX16838 toc18
MAX16838 toc17
OV LEAKAGE CURRENT (nA)
VIN = 12V
VEN = HIGH
TEMPERATURE (°C)
VIN = 12V
0.40
0.35
0.30
0.25
0.20
0.15
0.10
-1.5
0.05
0
-2.0
8
55
50
-40 -25 -10 5 20 35 50 65 80 95 110 125
2.0
1.5
60
OUT_ LEAKAGE CURRENT (nA)
VIN = 12V
VEN = HIGH
VCOMP = 2V
VDIM = LOW
POWER MOSFET RDSON (I)
3.0
2.8
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0
OUT_ LEAKAGE CURRENT
vs. TEMPERATURE
MAX16838 toc15
COMP LEAKAGE CURRENT (nA)
COMP LEAKAGE CURRENT
vs. TEMPERATURE
-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)
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Pin Description
PIN
NAME
FUNCTION
4
NDRV
Gate Drive for Switching MOSFET. Connect NDRV to GATE directly or through a resistor
to control the rise and fall times of the gate drive.
2
5
DRV
5V Regulator Output. MOSFET gate-driver supply input. Bypass DRV to PGND with a
minimum of 1FF ceramic capacitor. Place the capacitor as close as possible to DRV
and PGND.
3
6
VCC
Internal Circuitry Supply Voltage. Bypass VCC to SGND with a minimum of 0.1FF
ceramic capacitor. Place the capacitor as close as possible to VCC and SGND.
4
7
IN
Supply Input. Connect a 4.75V to 40V supply to IN. Bypass IN to PGND with a minimum
of 1FF ceramic capacitor. For a 5V Q10% supply voltage, connect VIN to VCC.
5
8
EN
Enable/Undervoltage Lockout (UVLO) Threshold Input. EN is a dual-function input.
Connect EN to VIN through a resistor-divider to program the UVLO threshold.
6
9
SGND
Signal Ground. SGND is the current return path connection for the low-noise analog
signals. Connect SGND, LEDGND, and PGND at a single point.
TQFN
TSSOP
1
7
10
CFB
Current Foldback Reference Input. Connect a resistor-divider between IN, CFB, and
ground to set the current foldback threshold. When the voltage at CFB goes below
1.23V, the LED current starts reducing linearly. Connect to VCC to disable the current
foldback feature.
8
11
OV
Overvoltage Threshold Adjust Input. Connect a resistor-divider from the switching
converter output to OV and SGND. The OV comparator reference is internally set to 1.23V.
9
12
ISET
LED Current Adjust Input. Connect a resistor RISET from ISET to SGND to set the
current through each LED string (ILED) according to the formula ILED = 1512V/RISET.
10
13
FLT
Open-Drain, Active-Low Flag Output. FLT asserts when there is an open/short-LED
condition at the output or when there is a thermal shutdown event.
11
14
OUT2
12
15
LEDGND
13
16
OUT1
14
17
RT
Oscillator Timing Resistor Connection. Connect a timing resistor (RRT) from RT to SGND
to program the switching frequency. Apply an AC-coupled external clock at RT to
synchronize the switching frequency with an external clock source.
15
18
COMP
Switching Converter Compensation Input. Connect an RC network from COMP to SGND
(see the Feedback Compensation section).
Maxim Integrated
LED String Cathode Connection 2. OUT2 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT2. OUT2 sinks
up to 150mA.
LED Ground. LEDGND is the return path connection for the linear current sinks.
Connect SGND, LEDGND, and PGND at a single point.
LED String Cathode Connection 1. OUT1 is the open-drain output of the linear current
sink that controls the current through the LED string connected to OUT1. OUT1 sinks
up to 150mA.
9
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Pin Description (continued)
PIN
NAME
FUNCTION
TQFN
TSSOP
16
19
DIM
Digital PWM Dimming Input
17
20
CS
Current-Sense Input. CS is the current-sense input for the switching regulator and is
also connected to the source of the internal power MOSFET. Connect a sense resistor
from CS to PGND to set the switching current limit.
18
1
DRAIN
Internal Switching MOSFET Drain Output
19
2
GATE
Internal Switching MOSFET Gate Input. Connect GATE to NDRV directly or through a
resistor to control the rise and fall times of the gate drive.
20
3
PGND
Power Ground. PGND is the high-switching current return path connection. Connect
SGND, LEDGND, and PGND at a single point.
—
—
EP
10
Exposed Pad. EP is internally connected to SGND. Connect EP to a large-area
contiguous ground plane for effective power dissipation. Connect EP to SGND.
Do not use as the only ground connection.
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Simplified Functional Diagram
FLT
DRAIN
POK SHDN
DRV
DIM
SHORT-LED
DETECTOR
FLAG LOGIC
CS
DRIVER
GATE
PWM
LOGIC
NDRV
OPEN-LED
DETECTOR
PWM
COMP
PGND
1.8V
COMP
RT
MINIMUM
STRING
VOLTAGE
RT OSCILLATOR
GM
120mV
ARRAY = 2
0
ILIM
1
1
0.3V
0
SLOPE
COMPENSATION
CS
OUT_
OV
SOFTSTART
DAC
CS BLANKING
LOGIC
DIM DUTY
TOO LOW
1.0V
1.17V
OV
COMPARATOR
IN
DIM
UVLO
DRV
5V LDO
BANDGAP
VBG
VCC
VCC
1
THERMAL
SHUTDOWN
UVLO
POK
IN
EN
0
SHDN
MAX16838
VBG
VBG
SGND
Maxim Integrated
LEDGND
OV
CFB
ISET
11
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Detailed Description
The MAX16838 high-efficiency, HB LED driver integrates all the necessary features to implement a highperformance backlight driver to power LEDs in small-tomedium-sized displays for automotive as well as general
applications. The device provides load-dump voltage
protection up to 40V in automotive applications. The
MAX16838 incorporates a DC-DC controller with peak
current-mode control to implement a boost, coupled
inductor boost-buck, or SEPIC-type switched-mode
power supply and a 2-channel LED driver with 20mA
to 150mA constant-current-sink capability per channel.
The MAX16838 can be combined with the MAX15054 to
achieve boost-buck topology without a coupled inductor
(see Figure 5).
The MAX16838 features a constant-frequency peak
current-mode control with internal slope compensation
to control the duty cycle of the PWM controller. The
DC-DC converter generates the required supply voltage for the LED strings from a wide input supply range.
Connect LED strings from the DC-DC converter output
to the 2-channel constant current sinks that control the
current through the LED strings. A single resistor
connected from ISET to ground sets the forward current
through both LED strings.
The MAX16838 features adaptive LED voltage control
that adjusts the converter output voltage depending
on the forward voltage of the LED strings. This feature
minimizes the voltage drops across the constant-current
sinks and reduces power dissipation in the device. The
MAX16838 provides a very wide PWM dimming range
where a dimming pulse as narrow as 1Fs is possible at
a 200Hz dimming frequency.
A logic input (EN) shuts down the device when pulled low.
The device includes an internal 5V LDO to power up the
internal circuitry and drive the internal switching MOSFET.
The MAX16838 includes output overvoltage protection that limits the converter output voltage to the programmed OV threshold in the event of an open-LED
condition. The device also features an overtemperature
protection that shuts down the controller if the die temperature exceeds +165°C. In addition, the MAX16838
has a shorted LED string detection and an open-drain
FLT signal to indicate open LED, shorted LED, and overtemperature conditions.
12
Current-Mode DC-DC Controller
The MAX16838 uses current-mode control to provide
the required supply voltage for the LED strings. The
internal MOSFET is turned on at the beginning of every
switching cycle. The inductor current ramps up linearly
until it is turned off at the peak current level set by the
feedback loop. The peak inductor current is sensedfrom
the voltage across the current-sense resistor (RCS)
connected from the source of the internal MOSFET to
PGND. A PWM comparator compares the current-sense
voltage plus the internal slope compensation signal with
the output of the transconductance error amplifier. The
controller turns off the internal MOSFET when the voltage
at CS exceeds the error amplifier’s output voltage. This
process repeats every switching cycle to achieve peak
current-mode control.
Error Amplifier
The internal error amplifier compares an internal feedback (FB) signal with an internal reference voltage
(VREF) and regulates its output to adjust the inductor
current. An internal minimum string detector measures
the minimum LED string cathode voltage with respect
to SGND. During normal operation, this minimum VOUT_
voltage is regulated to 1V through feedback. The resulting DC-DC converter output voltage is 1V above the
maximum required total LED voltage.
The converter stops switching when LED strings are
turned off during PWM dimming. The error amplifier is
disconnected from the COMP output to retain the compensation capacitor charge. This allows the converter to
settle to a steady-state level immediately when the LED
strings are turned on again. This unique feature provides
fast dimming response without having to use large output capacitors. If the PWM dimming on-pulse is less than
five switching cycles, the feedback controls the voltage
on OV such that the converter output voltage is regulated at 95% of the OV threshold. This mode ensures
that narrow PWM dimming pulses are not affected by
the response time of the converter. During this mode,
the error amplifier remains continuously connected to
the COMP output.
Adaptive LED Voltage Control
The MAX16838 reduces power dissipation using an
adaptive LED voltage control scheme. The adaptive LED
voltage control regulates the DC-DC converter output
based on the operating voltage of the LED strings.
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
The voltage at each of the current-sink outputs (OUT_)
is the difference between the DC-DC regulator output
voltage (VLED) and the total forward voltage of the LED
string connected to the output (OUT_). The DC-DC converter then adjusts VLED until the output channel with
the lowest voltage at OUT_ is 1V relative to LEDGND. As
a result, the device minimizes power dissipation in the
current sinks and still maintains LED current regulation.
For efficient adaptive control functionality, use an equal
number of HB LEDs of the same forward voltage rating
in each string.
Current Limit
The MAX16838 includes 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 internal MOSFET and ground
sets the current limit. The CS input has a 0.3V voltage
trip level (VCS). Use the following equation to calculate
RCS:
as the oscillator frequency. The oscillator frequency is
determined using the following formula:
fSW = (7.342X109/RRT)(Hz)
where RRT is in ω.
Synchronize the oscillator with an external clock by
AC-coupling the external clock to the RRT input. The
capacitor used for the AC-coupling should satisfy the
following relation:
9.862
CSYNC ≤
− 0.144 × 10−3 (µF)
R
T
where RRT is in I.
The pulse width for the synchronization signal should
satisfy the following relations:
tPW
VS < 0.8
tCLK
RCS = (VCS)/IPEAK
tPW
VS + VS > 3.4
0.8 −
tCLK
where IPEAK is the peak current that flows through the
MOSFET.
Undervoltage Lockout
The MAX16838 features two undervoltage lockouts:
UVLOIN and UVLOVCC. The undervoltage lockout
threshold for VIN is 4.3V (typ) and the undervoltage
lockout threshold for VCC is 4V (typ).
Soft-Start
The MAX16838 features a soft-start that activates during
power-up. The soft-start ramps up the output of the converter in 64 steps in a period of 100ms (typ), unless both
strings reach regulation point, in which case the soft-start
would terminate to resume normal operation immediately.
Once the soft-start is over, the internal soft-start circuitry
is disabled and the normal operation begins.
Oscillator Frequency/External Synchronization
The MAX16838 oscillator frequency is programmable
between 200kHz and 2MHz using one external resistor (RRT) connected between RT and SGND. The PWM
MOSFET driver output switching frequency is the same
where tPW is the synchronization source pulse width,
tCLK is the synchronization clock time period, and VS
is the synchronization pulse voltage level. See Figure 1.
5V LDO Regulator (DRV)
The internal LDO regulator converts the input voltage
at IN to a 5V output voltage at DRV. The LDO regulator
output supports up to 30mA current, enough to provide
power to the internal control circuitry and the gate driver.
VS
tPW
tCLK
Figure 1. Synchronizing External Clock Signal
Maxim Integrated
13
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Connect a 4.7I resistor from VCC to DRV to power the
rest of the chip from the VCC pin with the 5V internal
regulator. Bypass DRV to PGND with a minimum of 1FF
ceramic capacitor as close as possible to the device. For
input voltage range of 4.5V to 5.5V, connect IN to VCC.
LED Current Control (ISET)
The MAX16838 features two identical constant-current
sources used to drive multiple HB LED strings. The
current through each of the channels is adjustable
between 20mA and 150mA using an external resistor
(RISET) connected between ISET and SGND. Select
RISET using the following formula:
R ISET
=
1512
I OUT _
(Ω)
where IOUT_ is the desired output current for both
channels in amps.
For single-channel operation, connect channel 1 and
channel 2 together. See Figure 2.
LED Dimming Control
The MAX16838 features LED brightness control using an
external PWM signal applied at DIM. The device accepts
a minimum pulse width of 1Fs. Therefore, a 5000:1 dimming ratio is achieved when using a PWM frequency of
200Hz. Drive DIM high to enable both LED current sinks
and drive DIM low to disable both LED current sinks.
The duty cycle of the PWM signal applied to DIM also
controls the DC-DC converter’s output voltage. If the
turn-on duration of the PWM signal is less than five
oscillator clock cycles, then the boost converter regulates its output based on feedback from the OV input.
During this mode, the converter output voltage is regulated to 95% of the OV threshold voltage. If the turn-on
duration of the PWM signal is greater than or equal to
six oscillator clock cycles, then the converter regulates
its output such that the minimum voltage at OUT_ is 1V.
When the DIM signal crosses the 5 or 6 oscillator clock
cycle boundary, the control loop of the MAX16838 experiences a discontinuity due to an internal mode transition that can cause flickering (the boost output voltage
changes as described in the previous paragraph). To
avoid flicker, the following is recommended:
S Avoid crossing the 5 or 6 oscillator clock cycle
boundary. Furthermore, DIM duty cycles that close to
the 5 or 6 cycle boundary should not be used.
S Do not set the OVP level higher than 3V above the
maximum LED operating voltage.
S Optimize the compensation components so that
recovery is as fast as possible, If the loop phase
margin is less than 45°, the output voltage can ring
during the 5 or 6 oscillator clock cycle boundary
crossing, which can contribute to flicker.
Fault Protections
The MAX16838 fault protections include cycle-by-cycle
current limiting, DC-DC converter output overvoltage
protection, open-LED detection, short-LED detection,
and overtemperature detection. An open-drain LED fault
flag output (FLT) goes low when an open-LED/short-LED
or overtemperature condition is detected.
BOOST
CONVERTER
OUTPUT
40mA TO 300mA
OUT1
MAX16838
OUT2
Open-LED Management and Overvoltage Protection
The MAX16838 monitors the drains of the current sinks
(OUT_) to detect any open string. If the voltage at
any output falls below 300mV and the OV threshold is
triggered (i.e., even with OUT_ at the OV voltage the
string is not able to regulate above 300mV), then the
MAX16838 interprets that string to be open, asserts FLT,
and disconnects that string from the operation loop. The
MAX16838 features an adjustable overvoltage threshold
input (OV). Connect a resistor-divider from the switching
converter output to OV and SGND to set the overvoltage
threshold level.
Figure 2. Configuration for Higher LED String Current
14
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Use the following formula to program the overvoltage
threshold:
R2
VOV
= 1.23V × 1 + OV
R1
OV
R1EN
EN
Open-LED detection is disabled when PWM pulse width
is less than five switching clock cycles.
Short-LED Detection
The MAX16838 features a two-level short-LED detection
circuitry. If a level 1 short is detected on any one of the
strings, FLT is asserted. A level 1 short is detected if
the difference between the total forward LED voltages
of the two strings exceeds 4.2V (typ). If a level 2 short
is detected on any one of the strings, the particular LED
string with the short is turned off after 6Fs and FLT is
asserted. A level 2 short is detected if the difference
between the total forward LED voltages of the two strings
exceeds 7.8V (typ). The strings are reevaluated on each
DIM rising edge and FLT is deasserted if the short is
removed. Short-LED detection is disabled when PWM
pulse width is less than five switching clock cycles.
Enable (EN)
EN is a logic input that completely shuts down the
device when connected to logic-low, reducing the
current consumption of the device to less than 15FA
(typ). The logic threshold at EN is 1.24V (typ). The voltage at EN must exceed 1.24V before any operation can
commence. There is a 71mV hysteresis on EN. The EN
input also allows programming the supply input UVLO
threshold using an external voltage-divider to sense the
input voltage, as shown in Figure 3. Use the following
equation to calculate the value of R1EN and R2EN in
Figure 3:
=
R1EN
VON
− 1 × R2 EN
VUVLOIN
where VUVLOIN is the EN rising threshold (1.24V) and
VON is the desired input startup voltage. Choose an
R2EN between 10kI and 50kI. Connect EN to IN if not
used.
Maxim Integrated
VIN
MAX16838
R2EN
1.24V
Figure 3. Setting the MAX16838 Undervoltage Lockout
Threshold
Current Foldback
The MAX16838 includes a current-foldback feature to
limit the input current at low VIN. Connect a resistordivider between IN, CFB, and SGND to set the currentfoldback threshold. When the voltage at CFB goes below
1.23V, then the LED current starts reducing proportionally to VCFB.
This feature can also be used for analog dimming of the
LEDs. Connect CFB to VCC to disable this feature.
Applications Information
Boost-Circuit Design
First, determine the required input supply voltage range,
the maximum voltage needed to drive the LED strings
including the minimum 1V across the constant LED
current sink (VLED), and the total output current needed
to drive the LED strings (ILED).
Calculate the maximum duty cycle (DMAX) using the
following equation:
DMAX = (VLED + VD – VIN_MIN)/(VLED + VD)
where VD is the forward drop of the rectifier diode,
VIN_MIN is the minimum input supply voltage, and
VLED is the output voltage. Select the switching
frequency (fSW) depending on the space, noise, dynamic response, and efficiency constraints.
15
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Inductor Selection in Boost Configuration
Select the maximum peak-to-peak ripple on the inductor
current (ILP-P). Use the following equations to calculate
the maximum average inductor current (ILAVG) and
peak inductor current (ILPEAK):
ILAVG = ILED/(1 - DMAX)
Assuming ILP-P is 40% of the average inductor current:
ILP-P = ILAVG x 0.4
ILPEAK = ILAVG + ILP-P/2
Calculate the minimum inductance value LMIN with the
inductor current ripple set to the maximum value:
LMIN = VIN_MIN x DMAX/(fSW x ILP-P)
Choose an inductor that has a minimum inductance
greater than the calculated LMIN and current rating
greater than ILPEAK. The recommended saturation
current limit of the selected inductor is 10% higher than
the inductor peak current. The ILP-P can be chosen
to have a higher ripple than 40%. Adjust the minimum
value of the inductance according to the chosen ripple.
One fact that must be noted is that the slope compensation is fixed and has a 120mV peak per switching cycle.
The dv/dt of the slope compensation ramp is 120fSWV/
Fs, where fSW is in kHz. After selecting the inductance
it is necessary to verify that the slope compensation is
adequate to prevent subharmonic oscillations. In the
case of the boost, the following criteria must be satisfied:
120fSW > RCS (VLED - 2VIN_MIN)/2L
where L is the inductance value in FH, RCS is the
current-sense resistor value in ω, VIN_MIN is the minimum input voltage in V, VLED is the output voltage, and
fSW is the switching frequency in kHz.
If the inductance value is chosen to keep the inductor
in discontinuous conduction mode, the equation above
does not need to be satisfied.
Output Capacitor Selection in
Boost Configuration
For the boost converter, the output capacitor
supplies the load current when the main switch is on.
The required output capacitance is high, especially at
higher duty cycles.
Calculate the output capacitor (COUT) using the following equation:
COUT > (DMAX x ILED)/(VLED_P-P x fSW)
where VLED_P-P is the peak-to-peak ripple in the LED
supply voltage. Use a combination of low-ESR and high-
16
capacitance ceramic capacitors for lower output ripple
and noise.
Input Capacitor Selection in Boost Configuration
The input current for the boost converter is continuous
and the RMS ripple current at the input capacitor is low.
Calculate the minimum input capacitor CIN using the following equation:
CIN = ILP-P/(8 x fSW x VIN_P-P)
where VIN_P-P is the peak-to-peak input ripple voltage.
This equation assumes that input capacitors supply
most of the input ripple current.
Rectifier Diode Selection
Using a Schottky rectifier diode produces less forward drop
and puts the least burden on the MOSFET during reverse
recovery. A diode with considerable reverse-recovery time
increases the MOSFET switching loss. Select a Schottky
diode with a voltage rating 20% higher than the maximum
boost-converter output voltage and current rating greater
than that calculated in the following equation:
ID = IL AVG (1 - D MAX ) ( A )
Feedback Compensation
The voltage feedback loop needs proper compensation for stable operation. This is done by connecting
a resistor (RCOMP) and capacitor (CCOMP) in series
from COMP to SGND. RCOMP is chosen to set the highfrequency integrator gain for fast transient response,
while CCOMP is chosen to set the integrator zero to maintain loop stability. For optimum performance, choose the
components using the following equations:
R COMP =
fZRHP × R CS × ILED
5 × FP1× GM COMP × VLED × (1 − D MAX )
where:
fZRHP =
VLED (1 − D MAX ) 2
2π × L × ILED
is the right-half plane zero for the boost regulator.
RCS is the current-sense resistor in series with the
source of the internal switching MOSFET. ILED is the total
LED current that is the sum of the LED currents in both
the channels. VLED is the output voltage of the boost
regulator. DMAX is the maximum duty cycle that occurs
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
4.75V TO 40V
L1
Cs
D
CIN
COUT
L2
R2OV
LED
STRINGS
R1OV
R2EN
IN
EN
R1EN
CVCC
DRAIN
OV
NDRV
CFB
GATE
VCC
OUT1
OUT2
RDRV
RISET
MAX16838
DRV
ISET
CDRV
FLT
RCOMP
DIM
CS
COMP
RT
CCOMP
SGND
PGND
LEDGND
RRT
RCS
Figure 4. SEPIC Configuration
at minimum input voltage. GMCOMP is the transconductance of the error amplifier.
FP1 =
ILED
2 × π × VLED × C OUT
is the output pole formed by the boost regulator.
Set the zero formed by RCOMP and CCOMP a decade
below the crossover frequency. Using the value of
RCOMP from above, the crossover frequency is at
fZRHP/5.
50
C COMP =
2π × R COMP × fZRHP
SEPIC Operation
Figure 4 shows a SEPIC application circuit using the
MAX16838. The SEPIC topology is necessary to keep
the output voltage of the DC-DC converter regulated
Maxim Integrated
when the input voltage can rise above and drop below
the output voltage.
Boost-Buck Configuration
Figure 5 shows a boost-buck configuration with the
MAX16838 and MAX15054.
PCB Layout Considerations
LED driver circuits based on the MAX16838 device use
a high-frequency switching converter to generate the
voltage for LED strings. Take proper care while laying
out the circuit to ensure proper operation. The switchingconverter part of the circuit has nodes with very fast voltage changes that could lead to undesirable effects on
the sensitive parts of the circuit. Follow these guidelines
to reduce noise as much as possible:
1) Connect the bypass capacitor on VCC and DRV as
close as possible to the device, and connect the
capacitor ground to the analog ground plane using
vias close to the capacitor terminal. Connect SGND
17
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
of the device to the analog ground plane using a via
close to SGND. Lay the analog ground plane on the
inner layer, preferably next to the top layer. Use the
analog ground plane to cover the entire area under
critical signal components for the power converter.
internal MOSFET, and the current-sense resistor, to
the input capacitor negative terminal. The other loop
is when the MOSFET is off—from the input capacitor
positive terminal, through the inductor, the rectifier
diode, output filter capacitor, to the input capacitor negative terminal. Analyze these two loops and
make the loop areas as small as possible. Wherever
possible, have a return path on the power ground
plane for the switching currents on the top layer
copper traces, or through power components. This
reduces the loop area considerably and provides
a low-inductance path for the switching currents.
Reducing the loop area also reduces radiation during switching.
2) Have a power ground plane for the switchingconverter power circuit under the power components (input filter capacitor, output filter capacitor,
inductor, MOSFET, rectifier diode, and currentsense resistor). Connect PGND to the power ground
plane as close to PGND as possible. Connect all
other ground connections to the power ground
plane using vias close to the terminals.
3) There are two loops in the power circuit that carry
high-frequency switching currents. One loop is
when the MOSFET is on—from the input filter
capacitor positive terminal, through the inductor, the
4) Connect the power ground plane for the constantcurrent LED driver part of the circuit to LEDGND as
close as possible to the device. Connect SGND to
PGND at the same point.
D1
VDD
VIN
BST
C1
CBST
MAX15054
Q1
HDRV
GND
HI
LX
L
D3
D2
COUT
R1OV
CIN
LED
STRINGS
R1EN
IN
GATE
NDRV
R2EN
CVCC
R2OV
DRAIN
EN
CFB
OV
VCC
OUT1
OUT2
RDRV
RISET
MAX16838
DRV
ISET
CDRV
FLT
CS
RT
DIM
COMP
RCOMP
SGND
PGND
LEDGND
RRT
RCS
CCOMP
Figure 5. Boost-Buck Configuration
18
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
GATE
DRAIN
CS
DIM
TOP VIEW
PGND
Pin Configurations
20
19
18
17
16
+
+
DRAIN 1
20 CS
GATE 2
19 DIM
NDRV
1
15
COMP
DRV
2
14
RT
VCC
3
13
OUT1
DRV 5
16 OUT1
IN
4
12
LEDGND
VCC 6
15 LEDGND
MAX16838
5
11
*EP
9
NDRV 4
OUT2
18 COMP
MAX16838
17 RT
IN 7
14 OUT2
EN 8
13 FLT
SGND 9
10
12 ISET
CFB 10
FLT
8
ISET
7
OV
SGND
6
CFB
EN
PGND 3
*EP
11 OV
TSSOP
TQFN
*EXPOSED PAD
Typical Operating Circuit
4.75V TO 40V
L
D
CIN
R2OV
COUT
LED
STRINGS
R1OV
R2EN
IN
R1EN
DRAIN
OV
EN
NDRV
CFB
GATE
VCC
CVCC
OUT1
OUT2
RDRV
MAX16838
RISET
DRV
ISET
CDRV
FLT
RCOMP
CCOMP
Maxim Integrated
DIM
CS
COMP
RT
SGND
PGND
LEDGND
RRT
RCS
19
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Package Information
Chip Information
PROCESS: BiCMOS DMOS
20
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
OUTLINE
NO.
LAND
PATTERN NO.
20 TQFN-EP
T2044+3
21-0139
90-0037
20 TSSOP-EP
U20E+1
21-0108
90-0114
Maxim Integrated
MAX16838
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
Revision History
REVISION
NUMBER
REVISION
DATE
DESCRIPTION
0
9/02
Initial release
1
12/09
Added /V part number, updated soldering temperature
2
4/11
Corrected formulas for CSYNC and OVP
3
6/13
Updated Open-LED Management and Overvoltage Protection and Short-LED
Detection sections and corrected equation in Rectifier Diode Selection section
4
3/16
Updated LED Dimming Control section
PAGES
CHANGED
—
1, 2
2, 13, 14
14, 16
14
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 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2016
Maxim Integrated Products, Inc.
21
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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