GENERAL DESCRIPTION
The W541E20X is fully compatible with W741E20X in terms of pin assignment and IC function. It is a high-performance 4-bit microcontroller (µC) that provides an flash EEPROM for the program memory. 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 port for LED driving). There are also seven interrupt sources and 8-level subroutine nesting for interrupt applications. The W541E20X has two power reduction modes, hold mode and stop mode, which help to minimize power dissipation.
The W541E20X is suitable for end product manufacturer engineering testing and earlier samples before mass production.

FEATURES
• Operating voltage: 2.4V−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 × 16 bit program flash EEPROM (including 2K × 4 bit look-up table)
    −128 × 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)
    - Do not be floating when it is as input or output open-drain (NMOS type).
• 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 µS instruction cycle (with 4 MHz operating frequency)
• Packaged in 18-pin, 20-pin, 28-pin PDIP and 20-pin, 28-pin SOP