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DESIGN IDEA
Advanced Technology and New LDO Features for Highly Demanding Applications
Hector F. Arroyo, Sr. Product Marketing Engineer, Power Management
Most designers would agree that linear regulators are one of the most easy-to-use types of regulator available and, for that same reason, usually their most preferred type. But in today's highly demanding applications, it is increasingly difficult to get a high-performance design running by utilizing only linear solutions. This is when the questions arise: What resources can the designer use to his or her favor? What are the trade-offs and the actual limitations for choosing linear technology for DC-DC conversion over other topologies? Which LDOs have better efficiency than others for the same application? Does choosing one manufacturer's linear regulators over another make any difference?
The answers to these questions are not as simple as one might first think. There are several factors and specifications that make a major difference which are often overlooked that system designers need to consider. As power requirements increase, board sizes decrease, and minimum performance needs to be maintained, selecting the right LDO for the application can mean the difference between an effective or unworkable solution.
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NEW PRODUCTS - View National's Complete List of New Products
New Family of Low-Voltage SIMPLE SYNCHRONOUS Buck Regulators
 The LM2852 is the first member of its new, high-efficiency SIMPLE SYNCHRONOUS™ buck regulator family. The SIMPLE SYNCHRONOUS family builds on the extensive system deployment of National’s well-established SIMPLE SWITCHER® portfolio of converters, National’s flagship power management product family. National will expand this family throughout 2005 with additional SIMPLE SYNCHRONOUS regulators with the same input–output voltage range and output currents from 1 to 3 Amps.
The LM2852 is a synchronous, high-frequency step-down switching voltage regulator capable of driving up to a 2 A load with excellent line and load regulation. The LM2852 can accept an input voltage between 2.7 V and 5.5 V and deliver a customizable output voltage that is factory-programmable from 0.8 V to 3.3 V in 100 mV increments. The LM2852 is available with a choice of two switching frequencies, 500 kHz and 1.5 MHz. Soft-start and enable functions permit supply sequencing and reduce in-rush current. It also features internal compensation for low component count and simplified design. The LM2852 is available for simulation on National’s WEBENCH® design tool.
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World’s First LVDS SerDes Chipset for Very High Temperature Analog Interface Applications
Two new high-speed analog interface chips to its industry-leading portfolio of LVDS (low voltage differential signaling) products. The SCAN921025H serializer and SCAN921226H deserializer deliver up to 10 bits of digital data at 20 to 80 MHz over a single point-to-point differential interconnect in backplanes or cable. The SerDes (serializer/deserializer) chipset operates in harsh environments up to 125 degrees Celsius.
- High Temperature Operation to 125°C
- IEEE 1149.1 (JTAG) Compliant and At-Speed BIST test mode.
- Clock recovery from PLL lock to random data patterns.
- Guaranteed transition every data transfer cycle
- Chipset (Tx + Rx) power consumption < 600 mW (typ) @ 80 MHz
- Single differential pair eliminates multi-channel skew
- 800 Mbps serial Bus LVDS data rate (at 80 MHz clock)
- 10-bit parallel interface for 1 byte data plus 2 control bits
- Synchronization mode and LOCK indicator
- Programmable edge trigger on clock
- High impedance on receiver inputs when power is off
- Bus LVDS serial output rated for 27Ω load
- Small 49-lead BGA package
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TFT-LCD Timing Controllers with RSDS Outputs For VGA/SVGA, XGA and Wide XGA Resolutions
The FPD87370 and FPD87346, timing controllers that combine an LVDS single-pixel input interface with National's RSDS™ (Reduced Swing Differential Signaling) output driver interface for VGA/SVGA, XGA and Wide XGA resolutions. The timing controllers reside on the TFT-LCD panel and provide the data buffering and control-signal generation for VGA/SVGA, XGA, and Wide XGA graphic modes. The RSDS™ path to the column driver contributes toward reducing the bus width from the timing controller, lowering the radiated electromagnetic interference (EMI) and reducing system dynamic power consumption.
The single RSDS bus conveys the 8-bit color data for VGA/SVGA, XGA, and Wide XGA panels at 170 Mb/s when using VESA 60 Hz standard timing.
Key Features for the FPD87370 and FPD87346:
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Input clock range from 25 MHz to 85 MHz
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Drives RSDS column drivers at 170 Mb/s with an 85 MHz clock (max.)
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Virtual 8 bit color depth in FRC/dithering mode
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Single narrow 9-bit differential source driver bus minimizes width of Source PCB
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Ability to drive VGA (FPD87370), SVGA (FPD87346), XGA and Wide XGA TFT-LCD Systems
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Failure detect function in DE mode (Bonding Option)
CMOS circuitry operates from a 3.0V-3.6V supply
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