MAX16838_11 Datasheet, PDF (1/21 Pages) Maxim Integrated Products – Integrated, 2-Channel, High-Brightness LED Driver with High-Voltage Boost and SEPIC Controller

19-4972; Rev 2; 4/11
EVAALVUAAILTAIOBNLEKIT
Integrated, 2-Channel, High-Brightness LED Driver
with High-Voltage Boost and SEPIC Controller
General Description
The MAX16838 is a dual-channel LED driver that inte-
grates 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 volt-
age, connect VIN to VCC. The wide input range allows
powering HB LEDs for small-to-medium-sized LCD dis-
plays in automotive and display backlight applications.
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 protec-
tion, open LED, shorted LED detection and overtempera-
ture 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.
Applications
Automotive Display Backlights
LCD Display Backlights
Automotive Lighting Applications
Typical Operating Circuit and Pin Configurations appear at
end of data sheet.
Features
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
Ordering Information
PART
MAX16838ATP+
MAX16838ATP/V+
MAX16838AUP+
MAX16838AUP/V+
TEMP RANGE
-40NC to +125NC
-40NC to +125NC
-40NC to +125NC
-40NC to +125NC
PIN-PACKAGE
20 TQFN-EP*
20 TQFN-EP*
20 TSSOP-EP*
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
L
D
CIN
R2OV
COUT
CCOMP
RCOMP
IN
EN
CFB
VCC
DRV
DRAIN OV
NDRV
GATE
OUT1
MAX16838 OUT2
ISET
FLT
DIM
CS
COMP
RT
SGND PGND LEDGND
R1OV
RISET
RRT RCS
LED
STRINGS
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