HRC705KJ

HRC705KJ Technical Summary

Overview

The HRC705KJ is a high-performance 8-bit microcontroller from the Motorola M68HC05 family. It is designed for embedded control applications requiring robust noise immunity, low power consumption, and flexible I/O capabilities. The microcontroller integrates a Central Processing Unit (CPU), memory, and various peripheral modules into a single chip, making it suitable for cost-sensitive and space-constrained designs.

Key Features

• CPU: 8-bit M68HC05 architecture with 4.0 MHz internal operating frequency at 5.0V
• Memory: 1240 bytes of EPROM/OTPROM (including 8 bytes for user vectors) and 64 bytes of user RAM
• I/O Ports: 10 bidirectional I/O lines with:
  • 10 mA sink capability on all pins
  • Software-programmable pulldowns
  • Keyboard scan with selectable interrupt on 4 pins
  • 5.5 mA source capability on 6 pins
• Peripheral Modules:
  • 15-stage multifunction timer
  • Computer Operating Properly (COP) watchdog
• Interrupts: Selectable sensitivity (edge-and-level or edge-only) on external interrupt
• Oscillator Options: Supports crystal, ceramic resonator, or resistor-capacitor (RC) configurations
• Low Power Modes: Stop and Wait modes for reduced power consumption

Applications

The HRC705KJ is well-suited for a variety of embedded control applications, including:

• Consumer electronics
• Industrial control systems
• Automotive electronics
• Appliance control
• Security systems
• Keyboard interfaces

Electrical Characteristics

Absolute Maximum Ratings

• Supply Voltage (V_DD): -0.3V to +7.0V
• Input Voltage (V_IN): -0.3V to V_DD+0.3V
• Operating Temperature Range: -40°C to +85°C
• Storage Temperature Range: -55°C to +150°C

DC Characteristics (5.0V operation)

• Supply Voltage (V_DD): 4.5V to 5.5V
• Input High Voltage (V_IH): 0.7 × V_DD min
• Input Low Voltage (V_IL): 0.2 × V_DD max
• Output High Voltage (V_OH): V_DD-0.8V min @ 5.5mA
• Output Low Voltage (V_OL): 0.4V max @ 10mA

Power Consumption

• Active Mode (4MHz): 10mA typical
• Wait Mode: 2mA typical
• Stop Mode: 10μA typical

Package Information

The HRC705KJ is available in multiple package options:

• 20-pin Plastic Dual In-line Package (PDIP)
• 20-pin Small Outline Integrated Circuit (SOIC)
• 20-pin Shrink Small Outline Package (SSOP)

Pin Configuration (20-pin PDIP)

• Pin 1: V_DD - Power supply
• Pin 2: OSC1 - Oscillator input
• Pin 3: OSC2 - Oscillator output
• Pin 4: RESET - Reset input
• Pins 5-14: Port A (PA0-PA7) and Port B (PB0-PB1) - General purpose I/O
• Pin 15: IRQ - External interrupt
• Pin 20: V_SS - Ground

Functional Description

Central Processing Unit (CPU)

The 8-bit CPU features:

• Accumulator (A)
• Index Register (X)
• Stack Pointer (SP)
• Program Counter (PC)
• Condition Code Register (CCR)

Memory Organization

• 0000-003F: 64 bytes RAM
• 0040-007F: I/O and control registers
• 0080-07FF: 1240 bytes EPROM/OTPROM
• 07F8-07FF: User vectors

Peripheral Modules

Multifunction Timer

• 15-stage programmable timer
• Input capture/output compare functionality
• Real-time interrupt capability

Computer Operating Properly (COP) Watchdog

• Programmable timeout period
• Reset generation on failure
• Operates in all modes except Stop

Parallel I/O Ports

• Port A: 8-bit bidirectional I/O
• Port B: 2-bit bidirectional I/O
• Programmable pull-down resistors
• High current drive capability

Development Support

The HRC705KJ is supported by:

• In-circuit emulators
• EPROM/OTPROM programmers
• Assemblers and C compilers
• Evaluation boards

Ordering Information

Available variants include:

• MC68HC705KJ1: Standard version
• MC68HRC705KJ1: RC oscillator version
• MC68HLC705KJ1: Low-voltage (3.3V) version