TI Develops Interleaved PWM Controllers on Single Chip

10/1/2003 - Texas Instruments Incorporated (TI) (NYSE: TXN) announced the industry´s first single-chip, interleaved pulse-width modulation (PWM) controllers for 50-A to 100-A high current power supplies in off-line and DC/DC converters used in computer servers, telecom, datacomm and consumer systems such as plasma display products.

TI's new UCC28220 and UCC28221 peak current-mode controllers use advanced interleaving techniques to control two isolated power stages to maximize power density, reduce output current ripple and improve transient response. The devices, available in either interleaved forward or interleaved fly-back isolated topologies, integrate two PWM channels operating at 180 degrees out of phase to control one high current output. In addition, the controllers provide programmable internal slope compensation with an internal circuit to precisely match currents between the two channels.

Enabling higher power density than competing two- or three-chip solutions, the UCC28220 and UCC28221 PWM controllers provide an accurate maximum duty clamp, which can be programmed between 60 percent to 90 percent duty cycles per channel. The controllers also include programmable soft start and highly accurate (within one percent) input line under-voltage (UV) and over-voltage (OV) thresholds with programmable hysteresis for each threshold. Additionally, the UCC28221 has a 110-V start-up device that removes the need for an external trickle charge boot strap resistor to help save cost.

Key Features of UCC28220 and UCC28221:

Availability, Packaging and Pricing
The UCC28220 and UCC28221 are available in volume from TI and its authorized distributors. The UCC28220 is available in both 16-pin SOIC package and low-profile TSSOP packages. The UCC28221 with the high voltage startup circuit comes in a 16-pin SOIC and a slightly larger 20-pin TSSOP package to allow for higher voltage pin spacing that meets UL1950 "creepage clearance" safety requirements. Suggested resale pricing is $1.49 and $1.57 in quantities of 1,000 units for UCC28220 and UCC28221 respectively. Half-brick evaluation modules that include a 200-W 48-V to 12-V converter are available in less than 24 hours through power.ti.com.

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