W921E840A Datasheet, PDF (3/58 Pages) Winbond – 4-BIT MICROCONTROLLER

W921E840A/W921C840
1. GENERAL DESCRIPTION
The W921E840A/W921C840 is single-chip CMOS 4-bit microcontroller that is subset of
W921E880A/W921C880. They features four multi-function timers, one channel DTMF generator, an
8-bit D/A converter circuit, ten interrupt sources, 48-level subroutine nesting, and built in four by one
channel comparator circuit. Two power down modes, hold and stop mode, reduce power dissipation.
The excellent memory structure, 8K super EPROM in W921E840A and 8K mask ROM in W921C840
for program code and 512 x 4 bit RAM minimize the need for external memory devices.
The W921E840A/W921C840 are powerful microcontroller for wide range consuming applications,
requiring few external components, which is especially suited for telecommunication design.
2. FEATURES
Operating Voltage
• 2.8 to 5.5V operating voltage for W921E840A EPROM Type
• 2.4 to 5.5V operating voltage for W921C840 Mask ROM Type
Operating Frequency
• Crystal or RC for main system clock
− Crystal for 400 K, 800 K, 2 M, 3.58 M, 4 MHz
− RC up to 4 MHz
Memory
• 8K × 10-bit ROM (super EPROM)
• 512 × 4-bit RAM
− 64 × 4-bit special registers
− 16 × 4-bit working registers
− 128 × 4-bit general registers
− 304 × 4-bit multi-purpose registers
Stack
• 8-bit stack pointer
I/O Pins
• 20 bidirectional and individually controllable I/O lines
− P2 Port: P2.0 to P2.3 large sink current pins and open drain option
− P3 Port: P3.0 to P3.3 multi-function I/O
− P4 Port: P4.0 to P4.3 open drain and pull high resistor option, multi-function I/O
− P5 Port: P5.0 to P5.3 multi-function I/O
− P6 Port: P6.0 to P6.3 open drain and pull high resistor option, multi-function I/O
• 14 bidirectional I/O lines
− PA Port: PA.0 to PA.3 open drain and pull high resistor option
Publication Release Date: July 1999
-3-
Revision A3