Rainbow Electronics MAX16834 - Manual

General Description
The MAX16834 is a current-mode high-brightness LED
(HB LED) driver for boost, buck-boost, SEPIC, and high-
side buck topologies. In addition to driving an n-channel
power MOSFET switch controlled by the switching con-
troller, it also drives an n-channel PWM dimming switch to
achieve LED PWM dimming. The MAX16834 integrates
all the building blocks necessary to implement a fixed-fre-
quency HB LED driver with wide-range dimming control.
The MAX16834 features constant-frequency peak cur-
rent-mode control with programmable slope compensa-
tion to control the duty cycle of the PWM controller.
A dimming driver designed to drive an external n-chan-
nel MOSFET in series with the LED string provides
wide-range dimming control up to 20kHz. In addition to
PWM dimming, the MAX16834 provides analog dim-
ming using a DC input at REFI. The programmable
switching frequency (100kHz to 1MHz) allows design
optimization for efficiency and board space reduction.
A single resistor from RT/SYNC to ground sets the
switching frequency from 100kHz to 1MHz while an
external clock signal at RT/SYNC disables the internal
oscillator and allows the MAX16834 to synchronize to
an external clock. The MAX16834’s integrated high-
side current-sense amplifier eliminates the need for a
separate high-side LED current-sense amplifier in
buck-boost applications.
The MAX16834 operates over a wide supply range of
4.75V to 28V and includes a 3A sink/source gate driver
for driving a power MOSFET in high-power LED driver
applications. The MAX16834 is also suitable for DC-DC
converter applications such as boost or buck-boost.
Additional features include external enable/disable
input, an on-chip oscillator, fault indicator output (FLT)
for LED open/short or overtemperature conditions, and
an overvoltage protection sense input (OVP+) for true
overvoltage protection.
The MAX16834 is available in a thermally enhanced
4mm x 4mm, 20-pin TQFN-EP package and is specified
over the automotive -40°C to +125°C temperature range.
Applications
Single-String LED LCD Backlighting
Automotive Rear and Front Lighting
Projection System RGB LED Light Sources
Architectural and Decorative Lighting (MR16, M111)
Spot and Ambient Lights
DC-DC Boost/Buck-Boost Converters
Features
♦ Wide Input Operating Voltage Range (4.75V to
28V)
♦ 3000:1 PWM Dimming
♦ Analog Dimming
♦ Integrated PWM Dimming MOSFET Driver
♦ Integrated High-Side Current-Sense Amplifier for
LED Current Sense in Buck-Boost Converter
♦ 100kHz to 1MHz Programmable High-Frequency
Operation
♦ External Clock Synchronization Input
♦ Programmable UVLO
♦ Internal 7V Low-Dropout Regulator
♦ Fault Output (FLT) for Overvoltage, Overcurrent,
and Thermal Warning Faults
♦ Programmable True Differential Overvoltage
Protection
♦ 20-Pin TQFN-EP Package
MAX16834
High-Power LED Driver with Integrated High-Side LED
Current Sense and PWM Dimming MOSFET Driver
________________________________________________________________ Maxim Integrated Products 1
V IN
BOOST LED DRIVER
IN
ON
NDRV
CS
ANALOG
DIM
OFF
DIMOUT
SENSE+
PWMDIM
PGND
LED+
LEDs
LED-
MAX16834
REFI
Simplified Application Circuit
Ordering Information
19-4235; Rev 0; 8/08
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.
EVALUATION KIT
AVAILABLE
+ Denotes a lead-free/RoHS-compliant package.
* EP = Exposed pad.
PART TEMP RANGE PIN-PACKAGE
MAX16834ATP+ -40°C to +125°C 20 TQFN-EP*
Pin Configuration appears at end of data sheet.