下载
Maxim > Design Support > Technical Documents > Application Notes > Digital Potentiometers > APP 163
Maxim > Design Support > Technical Documents > Application Notes > Display Drivers > APP 163
Maxim > Design Support > Technical Documents > Application Notes > Power-Supply Circuits > APP 163
Keywords: fan control, fan speed, brightness control, contrast control, 2 wire bus, 2wire devices, PWM,
pulse width modulator, dc motor, LCD LED backlight
APPLICATION NOTE 163
Using DS1050 Programmable PWMs to Control a
DC Motor and an LCD LED Backlight
Dec 17, 2001
Abstract: The DS1050 is a 5-bit pulse-width modulator (PWM) controlled by a 2-wire bus. This allows a
single master device to control up to 8 slave (DS1050 and other 2-wire devices) on a single 2-wire bus.
In this application note, an interface to a 2-wire bus via a PC serial interface is demonstrated. The
hardware and software requirements are given and available for download from the Dallas
Semiconductor FTP site.
Introduction
The DS1050 is a 5-bit programmable Pulse Width Modulator (PWM) that allows you to vary the duty
cycle "on-the-fly" from 0 to 100% in 3.125% increments. It is controlled by a 2-wire serial interface that
can address up to eight DS1050s on a single 2-wire bus. It is available in both an 8-pin SOIC and an 8-
pin µSOP package in the following frequencies: 1kHz, 5kHz, 10kHz, and 25kHz.
This application note shows examples using a DS1050 as a DC fan controller and as a backlight
brightness controller for an LED backlit LCD. In addition, this application note will show how to interface
multiple DS1050s on a single 2-wire bus. Firmware for an 8051 based system is included in Appendix A.
System Overview
The reference schematic in Figure 1 is divided into two subsystems, the DC fan motor controller block
and the LCD LED backlight controller block. In addition, it shows a microcontroller as the 2-wire master
and how it interfaces to the 2-wire slaves, the DS1050s.
Page 1 of 18
