The LTC1553 is a high power, high efficiency switching regulator controller optimized for 5V or 12V input to 1.8V-3.5V output applications. It features a digitally programmable output voltage, a precision internal reference, and an internal feedback system that provides output accuracy of ±1.5% at room temperature and typically ±2% over-temperature, load current, and line voltage shifts. The LTC1553 uses a synchronous switching architecture with two external N-channel output devices, providing high efficiency and eliminating the need for a high power, high-cost P-channel device. Additionally, it senses the output current across the on-resistance of the upper N-channel FET, providing an adjustable current limit without an external low-value sense resistor.
The LTC1553 is a high‑power, high‑efficiency switching regulator controller optimized for 5 V or 12 V input to 1.8 V‑3.5 V output applications. It features a digitally programmable output voltage, internal reference, and a synchronous architecture that delivers over 95 % efficiency and up to 19 A output current.
The document provides absolute maximum ratings, electrical characteristics, pin functions, typical performance curves, and example application circuits. It also lists package options, ordering information, and related parts for designers integrating the controller into Pentium® II, SPARC, Alpha, or PA‑RISC processor power supplies.
| Output Voltage Range | 1.8 V to 3.5 V |
|---|---|
| Efficiency | >95 % |
| Maximum Output Current | 19 A |
| Oscillator Frequency | 300 kHz |
| Supply Voltage Range | 5 V to 12 V |
The LTC1553 can be programmed to output voltages from 1.8 V up to 3.5 V.
Current limit is set by the voltage drop across an external resistor connected between the drain of Q1 and the Imax pin.
The internal oscillator runs at about 300 kHz, and can be synchronized to a faster external clock if needed.
The digital inputs VIDO, VID1, VID2, VID3, and VID4 are used to set the output voltage.