GENERAL DESCRIPTION

The W741C20X is a high-performance 4-bit microcontroller (mC) that operates on very low current. The device contains a 4-bit ALU, two 8-bit timers, a divider, a serial port, and five 4-bit I/O ports (including 3 output ports for LED driving). There are also seven interrupt sources and 8-level subroutine nesting for interrupt applications. The W741C20X has two power reduction modes, hold mode and stop mode, which help to minimize power dissipation.

FEATURES

· Operating voltage: 2.2V to 5.5V

· Crystal or RC oscillation circuit can be selected by the code option

  - Crystal/Ceramic oscillator: up to 4 MHz

  - RC oscillator: up to 4 MHz

· Both in crystal or RC oscillator operation mode, high-frequency (400 KHz to 4 MHz) or low frequency (32.768 KHz) oscillation must be determined by the code option

· Memory

  - 2048 x 16 bit program ROM (including 2K x 4 bit look-up table)

  - 128 x 4 bit data RAM (including 16 working registers)

· 21 input/output pins

  - Input/output ports: 4 ports/16 pins

  - Serial input/output port: 1 port /4 pins (high sink current for LED driving)

  - MFP output pin: 1 pin (MFP)

· Power-down mode

  - Hold function: no operation (except for oscillator)

  - Stop function: no operation (including oscillator)

· Seven types of interrupts

  - Five internal interrupts (Divider 0, Timer 0, Timer 1, and Serial I/O)

  - Two external interrupts (Port RC and INT pin)

· MFP output pin

  - Output is software selectable as modulating or nonmodulating frequency

  - Works as frequency output specified by Timer 1

· Built-in 14-bit clock frequency divider circuit

· Two built-in 8-bit programmable countdown timers

  - Timer 0: One of two internal clock frequencies (FOSC/4 or FOSC/1024) can be selected

  - Timer 1: Offers auto-reload function, and one of two internal clock frequencies (FOSC or FOSC/64) can be selected, or falling edge of pin RC.0 can be selected (output through MFP pin)

· Built-in 18/14-bit watchdog timer selectable for system reset

· Powerful instruction set: 118 instructions

· 8-level subroutine (include interrupt) nesting

· One serial transmission/receiver port specified by software

· Up to 1 mS instruction cycle (with 4 MHz operating frequency)

· Packaged in 18-pin, 20-pin, 28-pin PDIP and 20-pin, 28-pin SOP