Product category: Power Supply ICs and Controllers
News Release from: Maxim Integrated Products | Subject: MAX1997 and MAX1998
Edited by the Electronicstalk Editorial Team on 31 October 2002
Skinny convertors supply all TFT LCD
voltages
The MAX1997 and MAX1998 power supplies provide the voltages required for active-matrix, thin-film transistor, liquid crystal displays.
The MAX1997 and MAX1998 power supplies 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
This article was originally published on Electronicstalk on 27 Aug 2002 at 8.00am (UK)
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The MAX1997 contains two additional linear-regulator controllers and a VCOM buffer.
The MAX1997/MAX1998 operate from 2.7 to 5.5V input supplies and feature multiple levels of protection circuitry, making a complete power supply system for displays.
The main DC/DC convertor provides the regulated supply voltage for the display's source-driver ICs.
The convertor 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.
Both linear-regulator controllers, as well as the step-up regulator, have supply-sequencing control inputs.
The three outputs can be sequenced in any order by selecting the appropriate external components.
The MAX1997 features a high-current backplane driver (VCOM).
This buffer provides peak currents exceeding 400mA and requires only a 0.47uF 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 fuse by disconnecting the load from the input supply when a fault is detected.
The fault detector monitors all the regulated output voltages as well as 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 QFN package and the MAX1998 is available in a 20-pin QFN package.
Both packages have a maximum 1.0mm thickness suitable for ultra-thin LCD panels.
Prices start at $4.07 for the MAX1997 and $3.38 for the MAX1998 (1000-up, FOB USA).
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