Unitrode Introduces UCC35701

12 April 1999

Unitrode Introduces UCC35701; Advanced Voltage Mode PWM Controller Tackles Tough Telecom Requirements

    MERRIMACK, N.H.--April 12, 1999--Unitrode Corporation announced the introduction of a new, advanced low-power voltage mode PWM (pulse width modulator) that features an integrated oscillator and input-voltage, feed-forward circuit designed to yield instantaneous rejection of input supply-voltage changes. The UCC35701 enhances the overall system performance of isolated switching power supplies using primary-side control, offering robust features for demanding single-ended flyback or forward converters. Applicable to a wide variety of applications, the UCC35701 is especially well-suited for telecommunications applications, as well as industrial control and instrumentation applications.
    Commenting on the product, Rich Valley, Business Line Director for Unitrode's Power Supply Control Products, said, "The advanced features of the UCC 35701 address the high-performance and reliability needs of the telecom market. Full utilization of transformer volume is a primary objective in high-density modules and is directly impacted by tighter tolerances on operating extremes."
    Voltage-mode control with input-feed-forward compensation provides noise-free operation with fast and accurate response to input-line-voltage changes over a 4:1 range. The UCC35701 device will operate over a 5:1 input range, allowing power supply operation during over-voltage conditions. A programmable, accurate maximum volt-second clamp prevents transformer saturation, and facilitates precise endpoints of operation.
    The UCC35701's high-frequency oscillator is usable up to 700kHz for high-density converters. Separately programmable oscillator timing resistor and capacitor circuits provide a high degree of design versatility to enhance system performance. The device features a low startup current (130uA), allowing for efficient off-line starting, and a low operating current (0.75mA) for simplified IC power circuitry, yet has sufficient output drive to switch power MOSFETs at high frequencies. A synchronization pin also permits simplified synchronization to the main system or other power supplies.
    The device includes a number of protection features. In addition to the volt-second clamp, the device also features over-current protection and a programmable soft start function to control initial and post-fault power-up sequence. An innovative fault counting function is also incorporated as a mechanism to ride through temporary load transients and changes.
    The device is available in a choice of DIL-14, SOIC-14, TSSOP-14 or LCC-20 packages. The UCC35701N is priced at $2.22 in quantities of 1,000. More information on the UCC35701 is available at http://www.unitrode.com or by calling Unitrode at (603) 424-2410.
    Unitrode Corporation designs and manufactures analog/linear and mixed-signal integrated circuits, modules, and non-volatile products, principally to perform power management, portable power, and interface functions. Its products, branded under Unitrode and Benchmarq, are sold throughout the world for a variety of computer, tele- and data-communications, space communications, industrial, and consumer applications.