The MAX1864/MAX1865 power-supply controllers are cost-effective power management ICs that integrate a current-mode synchronous step-down controller and external PNP pass transistors to generate low-voltage rails directly from the main step-down converter (such as 2.5V or 1.8V from the main 3.3V output) or higher voltages using coupled windings from the step-down converter.
The MAX1864 and MAX1865 are cost‑sensitive power‑supply controllers designed for cable modems, xDSL CPE, set‑top boxes and similar equipment. They operate from a low‑cost unregulated DC source and provide multiple regulated output rails using a synchronous step‑down converter and analog gain blocks.
The document details electrical characteristics, pin descriptions, typical operating curves, and design guidelines such as transistor selection and stability requirements, enabling engineers to integrate these controllers into their designs.
| Operating Input Voltage Range | 4.5 V – 28 V |
|---|---|
| Switching Frequency | 100 kHz / 200 kHz |
| Efficiency | up to 95 % |
| Operating Temperature Range | -40 °C to +85 °C |
The controllers operate from 4.5 V to 28 V input.
The MAX1864 generates three positive output voltages.
The MAX1865 provides four positive outputs and one negative output.
It operates at a fixed frequency of either 100 kHz or 200 kHz.