here'e the latest on MLIN new chip...
Micro Linear Announces Intelligent Chip for Green Switching Power Supplies
PR Newswire - March 22, 1999 13:19
* Chip Automatically Maintains High Efficiency During Light Loads
* Allows Design of Universal Power Supplies that Work Globally
* Key Member of New Family of Innovative PFC/PWM Combos
SAN JOSE, Calif., March 22 /PRNewswire/ -- Micro Linear Corp. (Nasdaq: MLIN) today announced a patented chip for the design of green switching power supplies in systems such as PCs, workstations and servers.
The ML4802 is a low-power BiCMOS device that contains an intelligent "Green Mode" circuit that automatically increases power supply efficiency at light loads. Prior to this chip, power supply efficiency could fall by up to 50 percent when Green systems reduced power loads by turning off unused circuits.
The chip works with a wide range of power line input voltages (85 to 265V) which makes it possible to design universal power supplies that automatically adapt to power outlets in any country. This eliminates the need for power line adapters, and costly and confusing switches, which if set improperly, can destroy a system.
The ML4802, pin compatible with the industry-standard ML4841, also includes a sophisticated power factor correction circuit that reduces supply harmonic radiation, protects systems from line noise and brownouts, with excellent response to load transients. This circuit uses a patented LETE (Leading Edge/Trailing Edge) modulation method that can cut the cost of the PFC high-voltage capacitor in half. The power factor circuit meets the European IEC1000-3-2 regulations for equipment sold on that continent.
According to Thomas Goddard, Product Marketing Manager, "Our device comes at the perfect time because of consumer demand for Green systems, growing interest in Energy Star(TM) programs, and the approaching deadline requiring that electronic systems sold in Europe meet IEC1000-3-2 regulations. Our integrated chip makes life easier for power supply engineers by offering an easy path to meeting the conflicting demands of low power and high efficiency."
Green Mode
When the ML4802 output current sense circuit detects that the power demand has dropped, it automatically activates the green mode of operation. In this mode, the PFC goes into a "Charge and Coast" mode (see diagram) saving power during coasting periods, while the PWM generates fewer, but widely spaced longer pulses, reducing total number of power pulses and the amount of energy that is wasted turning the FET on and off. Although this wasted "on and off" current is not significant when the power supply current is high, it is a significant proportion of total supply energy use when the power supply current is low, causing efficiency to drop over 50 percent in conventional power supplies.
LETE Patent
The patented LETE (Leading Edge Trailing Edge) circuit in the ML4802 reduces the cost of the power capacitor used in power supplies and improves the overall efficiency. The circuit works by synchronizing the PWM FET to turn on precisely when the PFC FET turns off. This allows the bulk of the current to go directly from the PFC stage into the PWM stage without first traveling through the PFC capacitor where energy lost to heating of the capacitor's equivalent series resistance (ESR) would lower efficiency.
Availability and Price
The ML4802 is in production now. The chip is priced at $2.20 for a 16-pin plastic DIP (Dual In-Line Package) in quantities of 1,000. It is also available in a SOIC (Small Outline IC) narrow package.
The ML4800 is used in the design of conventional power factor corrected power supplies that do not use Green mode. It is pin-compatible with the industry-standard ML4824-1. It is in production now. The chip is priced at $1.97 for a 16-pin plastic DIP in quantities of 1,000. It is also available in a SOIC narrow package.
The ML4801 is used in the design of conventional PFC power supplies where the PWM operates at twice the frequency of the PWM for component size savings. It is pin-compatible with the industry-standard ML4841, and is in production now. The chip is priced at $1.97 for a 16-pin plastic DIP (Dual In-Line Package) in quantities of 1,000. It is also available in a SOIC (Small Outline IC) narrow package.
The ML4804 adds a Tri-Fault Detect function to the feature set of the ML4800 to aid in compliance to the UL1950 specification, while saving external active and passive components. It is in production now. The chip is priced at $2.04 for a 16-pin plastic DIP in quantities of 1,000. It is also available in a SOIC narrow package.
The ML4805 is an 18-pin version of the ML4801 for use in the design of voltage-mode PFC/PWM power supplies. It operates the PWM at twice the frequency of the PWM for component size savings. It is pin-compatible with the industry-standard ML4841, and is in production now. The chip is priced at $2.01 for an 18-pin plastic DIP (Dual In-Line Package) in quantities of 1,000. It is also available in a SOIC narrow package.
Reader Contact
Literature Department, Micro Linear Corporation, 2092 Concourse Drive, San Jose, California, 95131. Telephone: 408-433-5200. E-mail: info@ulinear.co Web site: www.microlinear.com
Company Background
Micro Linear Corporation is a public company that designs, manufactures, and markets analog and mixed-signal integrated circuits for a broad range of markets that require high-integration, system-level solutions. These markets include: computers and computer networks, video, and power management. Micro Linear is an ISO 9002 registered company.
SOURCE Micro Linear Corporation
To bad they don't make a vital component for cruise missiles and smart bombs... |
