GENERAL DESCRIPTION

The W741L250 is a high-performance 4-bit microcontroller (mC) that provides an LCD driver. The device contains a 4-bit ALU, two 8-bit timers, a divider, a 24 ′ 4 LCD driver, and five 4-bit I/O ports (including 1 output port for high sink current). There are also five interrupt sources and 8-level subroutine nesting for interrupt applications. The W741L250 operates on very low voltage and very low current and has two power reduction modes, hold mode and stop mode, which help to minimize power dissipation.

FEATURES

? Operating voltage: 1.2V to 1.8V (LCD drive voltage: 3.0V or 4.5V)

? Operating frequency up to 1 MHz

? Crystal/RC oscillation circuit selectable by code option for system clock

? Only low-frequency clock (32.768 KHz) for crystal mode

? Memory

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

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

- 24 ′ 4 LCD data RAM

? 21 input/output pins

- Ports for input only: 2 ports/8 pins

- Input/output ports: 2 ports/8 pins

- Port for output only: 1 port /4 pins (high sink current)

- MFP output pin: 1 pin (MFP)

? Power-down mode

- Hold function: no operation (except for oscillator)

- Stop function: no operation (including oscillator)

? Five types of interrupts

- Three internal interrupts (Divider 0, Timer 0, Timer 1)

- Two external interrupts (Port RC and INT pin)

? LCD driver output

- 24 segment ′ 4 common

- Static, 1/2 duty (1/2 bias), 1/3 duty (1/2 or 1/3 bias),

1/4 duty (1/3 bias) driving mode can be

selected

- LCD driver output pins can be used as DC output port by code option

? 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: 116 instructions

? 8-level subroutine (include interrupt) nesting

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

? Packaged in 64-pin QFP