General Description
1.1 Introduction
The MC68HC908LB8 is a member of the low-cost, high-performance M68HC08 Family of 8-bit microcontroller units (MCUs). All MCUs in the family use the enhanced M68HC08 central processor unit (CPU08) and are available with a variety of modules, memory sizes, memory types, and package types. The MC68HC908LB8 has peripherals dedicated to high resolution PWM and power factor correction (PFC).

1.2 Features
For convenience, features have been organized to reflect:
• Standard features of the MC68HC908LB8
• Features of the CPU08

1.2.1 Standard Features of the MC68HC908LB8
Features of the MC68HC908LB8 include:
• 8-MHz internal bus frequency
• Trimmable internal oscillator:
   – 4.0 MHz internal bus operation
   – 8-bit trim capability
   – 25% untrimmed
   – 5% trimmed
• 8 Kbytes of 10 K write/erase cycle typical on-chip in application programmable FLASH memory
   with security option(1)
• 128 bytes of on-chip random-access memory (RAM)
• Dual channel high resolution PWM with dead time insertion and shutdown input. The outputs use
   frequency dithering to achieve a 4 ns output resolution.
• Dual channel pulse-width modulator (PWM) module to provide power factor correction capability
• Seven channel, 8-bit successive approximation analog-to-digital converter (ADC)
• Op amp/comparator for power factor correction capability or general purpose use
• 7-bit keyboard interrupt
• One 16-bit, 2-channel timer interface module with one output available on port pin (PTA6) for
   input capture and PWM
• 17 general-purpose input/output (I/O) pins and one input only pin
   – Three shared with high resolution PWM (HRP)
   – Three shared with PWM module
   – Three shared with op amp/comparator
   – Seven shared with ADC module (AD[0:6])
   – One shared with timer channel 0
   – Two shared with OSC1 and OSC2
   – One shared with reset
   – Seven shared with keyboard interrupt
   – One input-only pin shared with external interrupt (IRQ)
• Available packages:
   – 20-pin small outline integrated chip (SOIC) package
   – 20-pin plastic dual in-line package (PDIP)
• On-chip programming firmware for use with host personal computer which does not require high
   voltage for entry
• System protection features:
   – Optional computer operating properly (COP) reset
   – Low-voltage reset
   – Illegal opcode detection with reset
   – Illegal address detection with reset
• Low-power design; fully static with stop and wait modes
• Standard low-power modes of operation:
   – Wait mode
   – Stop mode
• Master reset pin and power-on reset (POR)
• 674 bytes of FLASH programming routines read-only memory (ROM)
• Break module (BRK) to allow single breakpoint setting during in-circuit debugging
• Internal pullup on RST pin to reduce customer system cost
• Selectable pullups on ports A and C
   – Selection on an individual port bit basis
   – During output mode, pullups are disengaged
• High current 8-mA sink / 10-mA source capability on all port pins

1.2.2 Features of the CPU08
Features of the CPU08 include:
• Enhanced HC05 programming model
• Extensive loop control functions
• 16 addressing modes (eight more than the HC05)
• 16-bit index register and stack pointer
• Memory-to-memory data transfers
• Fast 8 × 8 multiply instruction
• Fast 16/8 divide instruction
• Binary coded decimal (BCD) instructions
• Optimization for controller applications
• Efficient C language support