TelCom Semiconductor, Inc. announced the TC115, a high-efficiency step-up DC/DC converter for small, low input voltage or battery powered systems. Packaged in a tiny SOT-89 package, the TC115 is a space-saving solution optimized for low-power 1-cell and 2-cell battery operated systems.

The TC115 has a guaranteed start-up voltage of 0.9V and a typical supply current of 80 uA. Phase compensation and soft-start circuitry are included on-chip. Unlike conventional pulse width modulation (PWM) step-up converters, the TC115 automatically shifts to pulse frequency modulation (PFM) at low loads, resulting in reduced supply current and improved efficiency. The combination of PWM and PFM is ideal for applications where low-noise and long battery life are important.

The TC115 requires only an external diode, an inductor, and a capacitor, and supports typical output currents of 140 mA. Supply current is reduced to less than 0.5 uA, max when the shutdown input is low.

We now have to think that with their agreements every product announcement from TelCom is really a product announcement for the analog group at Motorola; that is not a negative -- per se -- as it will maximize the marketing for the parts, but we do now have the situation where TelCom has effectively become a design center for Motorola.

This step-up converter has a lot going for it: I like the start-up voltage of 0.9 V and the switching between PWM and PFM -- which is not unique -- at different loads to maintain efficiency; I also like the ratio between supply current and the available output current, which itself is good for more than half of portable applications in current use. The circuit area required is also small with the SOT-89 package and the few external components required; a negative, of course, is the need for the inductor. I also think that the pricing includes a premium for the package which will not survive market pressure.