Rainbow Electronics MAX1698 - Manual

General Description
The MAX1698 is the most efficient driver for white or
color LEDs. The device is ideal for LED backlit displays
in PDAs and digital cameras, and can also be used for
larger displays like those in laptop computers. Its
numerous benefits include greater simplicity, lower
cost, higher efficiency, longer bulb life, and greater reli-
ability when compared to fluorescent (CCFL) and elec-
troluminescent (EL) lamps.
The MAX1698 is a switch-mode boost controller in
which LED current, rather than output voltage, provides
the feedback signal. It can operate with battery inputs
as low as 0.8V. The device drives series-connected
LEDs with a controlled current that is measured at a
sense resistor connected at the feedback pin. The
required sense resistor is typically 15
Ω, not an expen-
sive fractional-ohm value. LED current control and dim-
ming are accomplished with an adjust input (ADJ), not
with lossy current-limiting resistors. For larger light out-
put, multiple LED banks can be connected in parallel
with up to 5W total output power.
The MAX1698 is supplied in a space-saving 10-pin
µMAX package that occupies half the space of an 8-pin
SO. An evaluation kit (MAX1698EVKIT) is available to
speed designs.
Applications
Battery-Powered Backlight Applications
Backlight for LCD Panels
Cell Phones
Handy Terminals
PDAs
Features
♦ Over 90% Efficiency
♦ Lossless, Adjustable LED Brightness
♦ Space-Saving 10-Pin µMAX Package
♦ Simpler, Lower Cost, More Reliable Compared
to CCFL or EL Backlights
♦ Up to 5W Output Power
MAX1698
High-Efficiency Step-Up
Current Regulator for LEDs
________________________________________________________________ Maxim Integrated Products 1
1
2
3
4
5
10
9
8
7
6
EXT
CS
PGND
GND ADJ
REF
V
CC
MAX1698
µMAX
TOP VIEW
FB GND
SHDN
V CC
V
OUT
C OUT
SHDN
FB
GND
ADJ
REF
CS
ON
OFF
PGND
EXT
D1
MAX1698
V CC
V BATT
L
I LED
R FB R N
Typical Operating Circuit
19-1621; Rev 0; 1/00
PART
MAX1698EUB -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
10 µMAX
EVALUATION KIT
AVAILABLE
Pin Configuration
Ordering Information
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.