MC68HC908LB8_05 Datasheet, PDF (91/234 Pages) Freescale Semiconductor, Inc – M68HC08 Microcontrollers

Chapter 10
High Resolution PWM (HRP)
10.1 Introduction
The High Resolution PWM (HRP) provides two complementary outputs that can be used to control
half-bridge systems in, for example, light ballast applications. It uses a dithering control method to provide
a high step resolution (3.906 ns from an 8 MHz input clock). It also provides a shutdown input that can be
used to disable the outputs when a fault condition is detected in the application.
The pins supporting the HRP can be seen in Figure 10-1, and a block diagram of the HRP module is
shown in Figure 10-3.
10.2 Features
Features of the HRP include:
• One complementary output pair for driving a half bridge
• Dithering between two frequencies or duty cycles, for increased output resolution
• Automatic calculation of second frequency or duty cycle for output dithering
• Variable frequency mode with automatic 50% duty cycle calculation
• Variable duty cycle mode
• Programmable deadtime insertion
• Shutdown input for fast disabling of outputs
10.3 Pin Name Conventions
The HRP shares two output pins with two port B input/output (I/O) pins and one input pin with one port C
input pin.
Table 10-1. Pin Naming Conventions
HRP Generic Pin Name
TOP
BOT
SHTDWN
Full HRP Pin Name
PTB0/TOP
PTB1/BOT
PTC2/SHTDWN/IRQ
MC68HC908LB8 Data Sheet, Rev. 1
Freescale Semiconductor
91