Introduction
The MC68HC05CT4 is a 44-pin member of the MC68HC05 Family of microcontrollers (MCUs), which supports cordless telephone applications. The memory map includes 5376 bytes of on-chip ROM and 256 bytes of RAM. The microcontroller unit has three 8-bit input/output (I/O) ports: A, B, and C; and one 7-bit I/O port: D. Port C has pullup options and keyscan capability. The MC68HC05CT4 includes a bird core, a bird timer, a synchronous serial interface (SSI), 16-bit timer, a dual 60-MHz phase-locked loop (PLL), pulse width modulator (PWM), and an on-chip computer operating properly (COP) watchdog circuit.

Features of the MC68HC05CT4 include:
• Low Cost
• HC05 Core
• 44-Pin Plastic Leaded Chip Carrier (PLCC) Package
• 10.24-MHz On-Chip Crystal Oscillator
• 2.048-MHz Internal CPU Speed
• 5136 Bytes of User ROM
• 240 Bytes of Self-Check ROM
• 256 Bytes of On-Chip RAM
• 16-Bit Timer
• 31 Bidirectional I/O Lines
• Power-Saving Stop and Wait Modes
• Core Timer
• Dual 60-MHz PLL
• Simple Serial with Bidirectional Data (SSI)
• Keyscan Interrupt with Pullups on Port C
• Mask Selectable Options:
   – COP Watchdog Timer
   – Edge-Sensitive or Edge- and Level-Sensitive Interrupt Trigger
   – Port C Pullups for Keyscan
   – 1-Channel, 6-Bit Pulse Width Modulator (PWM)
• Three Comparators
• ROM Security Feature