The MAX1997/MAX1998 provide the voltages required for active-matrix, thin-film transistor liquid-crystal displays (TFT LCDs). Both combine a high-performance step-up regulator with two linear-regulator controllers, input protection switch control, and flexible sequence programming. The MAX1997 contains two additional linear-regulator controllers and a VCOM buffer. The MAX1997/MAX1998 can operate from input supplies of 2.7V to 5.5V and feature multiple levels of protection circuitry, making them complete power-supply systems for displays.
The main DC-to-DC converter provides the regulated supply voltage for the display's source-driver ICs. The converter is a high-frequency (up to 1.5MHz) step-up regulator with an integrated 14V N-channel MOSFET that allows the use of ultra-small inductors and ceramic capacitors while achieving efficiencies over 85%. Its current-mode control architecture provides fast transient response to pulsed loads. Internal soft-start and cycle-by-cycle current limit help prevent input surge currents.
The positive and negative linear-regulator controllers postregulate charge-pump outputs for TFT gate-on and gate-off supplies. The three outputs can be sequenced in any order by selecting the appropriate external components. Both linear-regulator controllers, as well as the step-up regulator, have supply-sequencing control inputs.
The MAX1997 features a high-current backplane driver (VCOM). This buffer provides peak currents exceeding 300mA (typ) and requires only a 0.47µF output filter capacitor. The MAX1997's two additional linear-regulator controllers can be used to build the gamma reference voltage and a logic supply.
The MAX1997/MAX1998 have a unique input switch control that can replace the typical input supply fuse. When a fault is detected, the regulator is disconnected from the input supply. The fault detector monitors all the regulated output voltages and the current from the input supply. In addition, the MAX1997/MAX1998 enter shutdown when the internal overtemperature threshold is reached.
The MAX1997 is available in a 32-pin thin QFN package and the MAX1998 is available in a 20-pin thin QFN package. Both packages have a maximum thickness of 0.8mm suitable for ultra-thin LCD panels.
Key Features
Applications/Uses
2.7V to 5.5V Input Supply Range
Adjustable (Up to +13V) Output Voltage for Source-Driver ICs
Integrated High-Efficiency Power MOSFET
Linear-Regulator Controllers for TFT Gate-On and Gate-Off Supplies
High-Current VCOM Buffer (MAX1997 Only)
Two Additional Linear-Regulator Controllers (MAX1997 Only)
Programmable Power-Up Sequencing
Multiple Overload Protection with Thermal Shutdown
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.
Download
E-Mail