The LTC1433/LTC1434 are monolithic pulse width modulated step-down DC/DC converters. By utilizing current mode switching techniques, they provide excellent AC and DC load and line regulation. Both devices operate at a fixed frequency with the LTC1434 phase-lockable to an external clock signal.

Both devices incorporate two internal P-channel power MOSFETs with a parallel combined resistance of 0.6Ω (at a supply of 10V). The Adaptive Power output stage selectively drives one or both of the switches at frequencies up to 700kHz to reduce switching losses and maintain high efficiencies at low output currents.

The LTC1433/LTC1434 are capable of supplying up to 450mA of output current and boasts a ±2.4% output voltage accuracy. An internal low-battery detector has the same level of accuracy as the output voltage. A power-on reset timer (POR) is included which generates a signal delayed by 65536/f_CLK (300ms typ) after the output is within 5% of the regulated output voltage.

Ideal for current sensitive applications, the devices draw only 470µA of quiescent current. In shutdown the devices draw a mere 15µA. To further maximize the life of the battery source, the internal P-channel MOSFET switch is turned on continuously in dropout.

Applications

• Cellular Telephones
• Portable Instruments
• Wireless Modems
• RF Communications
• Distributed Power Systems
• Scanners
• Battery-Powered Equipment