MAX16821A Datasheet, PDF (1/25 Pages) Maxim Integrated Products – High-Power Synchronous HBLED Drivers with Rapid Current Pulsing

19-0881; Rev 0; 7/07
High-Power Synchronous HBLED
Drivers with Rapid Current Pulsing
General Description
The MAX16821A/MAX16821B/MAX16821C pulse-
width-modulation (PWM) LED driver controllers provide
high output-current capability in a compact package
with a minimum number of external components. The
MAX16821A/MAX16821B/MAX16821C are suitable for
use in synchronous and nonsynchronous step-down
(buck), boost, buck-boost, SEPIC, and Cuk LED drivers. A
logic input (MODE) allows the devices to switch between
synchronous buck and boost modes of operation. These
devices are the first high-power drivers designed specifi-
cally to accommodate common-anode HBLEDs.
The ICs offer average current-mode control that enable
the use of MOSFETs with optimal charge and on-resis-
tance figure of merit, thus minimizing the need for
external heatsinking even when delivering up to 30A of
LED current.
The differential sensing scheme provides accurate con-
trol of the LED current. The ICs operate from a 4.75V to
5.5V supply range with the internal regulator disabled
(V_CC connected to IN). These devices operate from a
7V to 28V input supply voltage with the internal regula-
tor enabled.
The MAX16821A/MAX16821B/MAX16821C feature a
clock output with 180° phase delay to control a second
out-of-phase LED driver to reduce input and output fil-
ter capacitor size and to minimize ripple currents. The
wide switching frequency range (125kHz to 1.5MHz)
allows the use of small inductors and capacitors.
Additional features include programmable overvoltage
protection and an output enable function.
Applications
Front Projectors/Rear Projection TVs
Portable and Pocket Projectors
Automotive Exterior Lighting
LCD TVs and Display Backlight
Automotive Emergency Lighting and Signage
Features
♦ Up to 30A Output Current
♦ True-Differential Remote Output Sensing
♦ Average Current-Mode Control
♦ 4.75V to 5.5V or 7V to 28V Input-Voltage Range
♦ 0.1V/0.03V LED Current-Sense Options Maximize
Efficiency (MAX16821B/MAX16821C)
♦ Thermal Shutdown
♦ Nonlatching Output Overvoltage Protection
♦ Low-Side Buck Mode with or without
Synchronous Rectification
♦ High-Side Buck and Low-Side Boost Mode with or
without Synchronous Rectification
♦ 125kHz to 1.5MHz Programmable/Synchronizable
Switching Frequency
♦ Integrated 4A Gate Drivers
♦ Clock Output for 180° Out-of-Phase Operation for
Second Driver
♦ -40°C to +125°C Operating Temperature Range
Ordering Information
PART
TEMP RANGE
PIN-
PACKAGE
PKG
CODE
MAX16821AATI+ -40°C to +125°C 28 TQFN-EP* T2855-8
MAX16821BATI+ -40°C to +125°C 28 TQFN-EP* T2855-8
MAX16821CATI+ -40°C to +125°C 28 TQFN-EP* T2855-8
+Denotes a lead-free package.
*EP = Exposed pad.
Simplified Diagram
7V TO 28V
IN
EN
I.C.
Q1
DH
MAX16821
Q2
DL
OVI
CSP
CLP
PGND
C1
V_LED
L1
C2
Q3
R1
Typical Operating Circuit and Selector Guide appear at end
of data sheet.
HIGH-FREQUENC.Y
PULSE TRAIN
NOTE: MAXIM PATENT-PENDING TOPOLOGY
________________________________________________________________ Maxim Integrated Products 1
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