The MAX1889 provides the three regulated output voltages required for active matrix, thin-film transistor liquid crystal displays (TFT LCDs). It combines a high-performance step-up regulator with two linear-regulator controllers 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 shutdown 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 package with a maximum thickness of 0.8mm for ultra-thin LCD panel design.
Key Features
Applications/Uses
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
Positive Linear-Regulator Controller
Negative Linear-Regulator Controller
Triple-Level Protection Against Smoke or Fire
Input Switch Replaces Input Fuse
Output Overload Detection with Timer Latch
Thermal Shutdown
2.7V to 5.5V Input Operating Range
Ultra-Small External Components
1µA Shutdown Current (max)
1mA Quiescent Current (max)
Ultra-Thin 16-Pin QFN Package
(0.8mm Maximum Thickness)
Notes: **This pricing is BUDGETARY, for comparing similar parts. Prices are in
U.S. dollars and subject to change. Quantity pricing may vary
substantially and international prices may differ due to local
duties, taxes, fees, and exchange rates. For volume-specific prices
and delivery, please see the price and availability page
or contact an authorized distributor.
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