TelCom Semiconductor, Inc. announced the TC105, a step-down (Buck) switching controller that furnishes output currents of up to 1A (max) while delivering a typical efficiency of 92%. This newest member of TelComıs growing line of power management products is an ideal solution for battery-operated applications where small package, low noise and low power operation are critical.

The TC105 normally operates in pulse width modulation mode (PWM), but automatically switches to pulse frequency modulation (PFM) at low output loads for greater efficiency. Oscillator frequency is 300 KHz, allowing use of a small (22 uH) inductor. Supply current draw is only 102 uA (max), and is reduced to less than 0.5 uA when the device is in shutdown. The TC105 accepts a maximum input voltage of 10V. The combination of PWM and PFM is ideal for applications where low-noise and long battery life are important.

"The recent introduction of the ultra-small negative LDO (TC59), the high efficiency boost regulator (TC115), and the PFM/PWM step-down controller (TC105) demonstrate TelComıs continued commitment to providing customers with innovative solutions. TelComıs product line of switching regulators, LDOs, controllers, and charge pumps provide the performance and flexibility that designers need to meet the requirements of todayıs markets," said Tom Grune, Vice President of Worldwide Sales at TelCom.

TelCom has been busy recently and this is another interesting part being added to its portfolio. While the company seems to have had considerable problems achieving market-penetrating success with good products, its second-source/manufacturing agreements with Motorola put it in a better position than it has been for some considerable time.

The TC105 is another of those parts that is designed to change modulation techniques at lower load currents -- in fact, it is becoming the norm -- to maintain operating efficiency. The output inductor required is not the lowest value that I have seen but it is not a large negative to the part's use. The quiescent current at 102 ıA is terrific and nobody could complain about the 0.5 uA shutdown current. The input range to 10 V is comfortable compared to some parts I have seen, some that top out at 7 V or so. The guaranteed start-up voltage of 0.9 V is extremely good. The 1-A load range covers the largest market for the parts required today for portable products.