DS18B20+

Designers need open-drain logic to run at 1.8V at the 1-Wire master IO. Most 1-Wire slave devices cannot run at 1.8V. This application note presents an RD (reference design) of a circuit that translates from a 1.8V 1-Wire master to a 5V 1-Wire slave device. The RD is used for driving typical 1-Wire slave devices. The MAX3394E voltage-level translator is featured in the design.

This document describes a microcontroller-based 1-Wire® master interface for reliable operation of small, medium, and large 1-Wire networks. This is accomplished using careful impedance matching, intelligent (software-controlled) active pullup, and slew-rate control. Software flow charts are included to assist the user in generating the correct 1-Wire timing for reset pulse, presence detect, write one, write zero, and read time slots using any suitable microcontroller. Scope traces illustrate the timing performance of the driver as well as transmission line effects as they appear with long cables.