MAX1889 Datasheet, PDF (1/32 Pages) Maxim Integrated Products – Triple-Output TFT LCD Power Supply with Fault Protection

19-2485; Rev 1; 10/02
Triple-Output TFT LCD Power Supply
with Fault Protection
General Description
The MAX1889 provides the three regulated output volt-
ages required for active matrix, thin-film transistor liquid
crystal displays (TFT LCDs). It combines a high-perfor-
mance step-up regulator with two linear-regulator con-
trollers and multiple levels of protection circuitry for a
complete power-supply system.
The main DC-DC converter is a high-frequency
(500kHz/1MHz), current-mode step-up regulator with
an integrated N-channel power MOSFET that allows the
use of ultra-small inductors and ceramic capacitors.
With its high closed-loop bandwidth performance, the
MAX1889 provides fast transient response to pulsed
loads while operating with efficiencies over 85%. The
positive and negative linear-regulator controllers post-
regulate charge-pump outputs for TFT gate-on and
gate-off supplies.
The MAX1889 has a unique input switch control that
can replace the typical input fuse by disconnecting the
load from the input supply when a fault is detected.
The fault detector monitors all three regulated output
voltages and can monitor current from the input supply
as well. Additionally, the MAX1889 enters thermal shut-
down when its overtemperature threshold is reached.
The MAX1889 undervoltage lockout is set at 2.5V (max)
to allow the input supply to droop under pulsed load
conditions while avoiding any unexpected behavior
when its input voltage dips momentarily. Also, the built-
in soft-start and cycle-by-cycle current limiting prevent
input surge currents during power-up.
The MAX1889 is available in a 16-pin thin QFN pack-
age with a maximum thickness of 0.8mm for ultra-thin
LCD panel design.
Applications
Notebook Computer Displays
LCD Monitors
Car Navigation Displays
Features
o High-Performance Step-Up Regulator
Fast Transient Response
Current-Mode Control Architecture
Built-In High-Efficiency N-Channel Power
MOSFET
Current-Limit Comparator
>85% Efficiency
Selectable Switching Frequency
(500kHz/1MHz)
Internal Soft-Start
o Positive Linear-Regulator Controller
o Negative Linear-Regulator Controller
o Triple-Level Protection Against Smoke or Fire
Input Switch Replaces Input Fuse
Output Overload Detection with Timer Latch
Thermal Shutdown
o 2.7V to 5.5V Input Operating Range
o Ultra-Small External Components
o 1µA Shutdown Current (max)
o 1mA Quiescent Current (max)
o Ultra-Thin 16-Pin QFN Package
(0.8mm Maximum Thickness)
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1889ETE -40°C to +85°C 16 Thin QFN (5mm ✕ 5mm)
MAX1889EGE* -40°C to +85°C 16 QFN (5mm ✕ 5mm)
* Future product—Contact factory for availability.
Pin Configuration
TOP VIEW
16 15 14 13
SHDN 1
PGND 2
GND 3
REF 4
MAX1889
5
6
7
8
12 TGND
11 LX
10 FREQ
9 FBP
THIN QFN
(5mm x 5mm)
________________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.