Featuring significantly reduced power consumption and shorter propagation delay times, Texas Instruments (TI) today unveiled its latest family of industry standard, Current Mode pulse width modulation (PWM) controllers. Built using a BiCMOS process, the UCC38C42 family features a ten-fold reduction in start-up current (from 500uA down to 50uA), while operating supply current is lowered from 11mA to only 2.3mA. A three-fold reduction in the current sense delay (from 150ns to 50ns) offers superior overload protection at the power switch, making these devices ideal for a variety of telecommunications, data-communications, merchant power, and industrial power supply applications.

This new family of UCC38C42 PWM controllers not only provides significant performance advantages for higher speed and lower power applications, but also offers drop-in- replacements for TI's existing and new UC3842- and UC3842A-based designs with no external part changes required. "The popular architecture of this eight-pin based power management control technology was pioneered and first introduced by TI's Power Supply Control Products group (formerly Unitrode)," said Bill Andreycak, product marketing engineer, TI. "With the UCC38C42 family, TI continues to enable designers of advanced power supply applications to maximize their systems' performance."

For accurate programming of the operating frequency, the UCC38C42 family's oscillator incorporates a trimmed discharge current. Additionally, output dead-time control, hence maximum duty cycle, are both accurate and programmable. The oscillator is useable with switching frequencies to 1 MHz. Rated at +/- 1A peak, the high current, totem-pole gate drive output boasts transitions with 25 nanosecond rise and 20 nanosecond fall times.

A 2.5-V band-gap reference voltage for the error amplifier features a 1 percent initial accuracy for precise programming of the power supply output voltage. The error amplifier has a 1.5 MHz gain-bandwidth product and incorporates 90 dB of gain. The parts also house several protection functions, including under-voltage lockout, pulse-by-pulse over-current limiting and double-pulse suppression.

Family members include the 100 percent maximum duty cycle versions with under-voltage lockout (UVLO) turn-on/turn-off thresholds of 14.5V/9.0V (UCC38C42) for off-line applications and 8.4V/7.6V (UCC38C43) for DC/DC converters. For applications requiring a 50 percent maximum duty cycle, the UCC38C44 contains UVLO thresholds of 14.5V/9.0V while the UCC38C45 uses 8.4V/7.6V thresholds. The UCC38C4x controllers are rated from 0ýC to +70ýC and the UCC28C4x controllers are rated from -40ýC to +85ýC.

Texas Instruments Incorporated Semiconductor Group, SC-01161 Literature Response Center P.O. Box 954 Santa Clarita, CA 91380 1-800-477-8924, ext. 4500

Featuring significantly reduced power consumption and shorter propagation delay times, Texas Instruments (TI) today unveiled its latest family of industry standard, Current Mode pulse width modulation (PWM) controllers. Built using a BiCMOS process, the UCC38C42 family features a ten-fold reduction in start-up current (from 500uA down to 50uA), while operating supply current is lowered from 11mA to only 2.3mA. A three-fold reduction in the current sense delay (from 150ns to 50ns) offers superior overload protection at the power switch, making these devices ideal for a variety of telecommunications, data-communications, merchant power, and industrial power supply applications.

This new family of UCC38C42 PWM controllers not only provides significant performance advantages for higher speed and lower power applications, but also offers drop-in- replacements for TI's existing and new UC3842- and UC3842A-based designs with no external part changes required. "The popular architecture of this eight-pin based power management control technology was pioneered and first introduced by TI's Power Supply Control Products group (formerly Unitrode)," said Bill Andreycak, product marketing engineer, TI. "With the UCC38C42 family, TI continues to enable designers of advanced power supply applications to maximize their systems' performance."

For accurate programming of the operating frequency, the UCC38C42 family's oscillator incorporates a trimmed discharge current. Additionally, output dead-time control, hence maximum duty cycle, are both accurate and programmable. The oscillator is useable with switching frequencies to 1 MHz. Rated at +/- 1A peak, the high current, totem-pole gate drive output boasts transitions with 25 nanosecond rise and 20 nanosecond fall times.

A 2.5-V band-gap reference voltage for the error amplifier features a 1 percent initial accuracy for precise programming of the power supply output voltage. The error amplifier has a 1.5 MHz gain-bandwidth product and incorporates 90 dB of gain. The parts also house several protection functions, including under-voltage lockout, pulse-by-pulse over-current limiting and double-pulse suppression.

Family members include the 100 percent maximum duty cycle versions with under-voltage lockout (UVLO) turn-on/turn-off thresholds of 14.5V/9.0V (UCC38C42) for off-line applications and 8.4V/7.6V (UCC38C43) for DC/DC converters. For applications requiring a 50 percent maximum duty cycle, the UCC38C44 contains UVLO thresholds of 14.5V/9.0V while the UCC38C45 uses 8.4V/7.6V thresholds. The UCC38C4x controllers are rated from 0ýC to +70ýC and the UCC28C4x controllers are rated from -40ýC to +85ýC.

Texas Instruments Incorporated Semiconductor Group, SC-01161 Literature Response Center P.O. Box 954 Santa Clarita, CA 91380 1-800-477-8924, ext. 4500

This is a competitive market but TI has upped the ante to the competition with their 10-fold reduction in start-up current. They lowered it from 500 micro amps to a mere 50 micro amps, when other manufacturers offer a start-up current around the mid-100 micro amp level. The company also managed to reduce the operating current to a competitive 2.3 mA from 11 mA, and also reduce the current sense delay to an aggressive 50 nanoseconds.

TI made sure they covered the most common application needs for duty cycle and turn-on/turn-off voltages. The UCC38C42 offers 100 percent duty cycle at turn-on/turn-off thresholds, 14.5V/9.0V with under-voltage lockout (UVLO) for off-line applications. The UVLO is designed for when the power supply voltage is below the startup voltage. The internal circuitry puts the output into a low impedance state and sets the output to zero. The output will sink the required current and remain below the turn-on threshold voltage. TI also offers 100% duty cycle 8.4V/7.6V (UCC38C43) versions for applications such as DC/DC converters. Two similar versions are available for 50% duty cycle needs.

The UCC38C42 family is available now from TI and its authorized distributors. Packaging options include 8-pin thru-hole PDIP along with the surface mount SOIC. For more space-constrained applications, the 8-pin MSOP package is available, minimizing height and board area. Suggested resale pricing is $0.99 each in quantities of 1,000.