TelCom Semi Intros TC1142 DC/DC Converter

The TC1142 from TelCom Semiconductor Inc. (Mountain View, CA) is a 20mA regulated dc/dc converter. Designed to be connected directly to a 3.6V single-cell lithium-ion battery, the TC1142 requires no inductors, thereby saving space and cost, and reducing the effects of EMI, according to TelCom. The TC1142's "boost/buck" operation maintains a fixed output voltage (-3V to -5V in 1.0V increments) over an input voltage range of 2.5V to 5.5V, making it suitable for regulated negative dc bias applications. The device generates a regulated negative dc voltage using only three extenal capacitors and requires no external resistors. Active feedback circuitry maintains a 2 ohm (typical) output impedance while in regulation. The TC1142 can be clocked from its on-board 200kHz oscillator or from an external oscillator ranging from 3kHz to 500kHz. When placed in shutdown, the TC1142 halts conversion and reduces supply current to less than 1uA. Applications include cellular phones, palm tops and other portable battery-powered equipment. Available in an MSOP, the TC1142 is priced from $1.96 in 1,000-piece quantities.