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ST72E91L ST72T91L

1 GENERAL DESCRIPTION

1.1 INTRODUCTION

The ST72E91 and ST72T91 devices form part of

the ST 7 family of Microcontrollers, designed and

produced by SGS-THOMSON Microelectronics

using an n-well proprietary HCMOS process. The

ST72E91 is equipped with internal EPROM mem-

ory and is available in windowed ceramic package,

whereas the ST72T91 OTP version is available in

a plastic package. The EPROM parts are fully

compatible with their ROM versions and the

present Datasheet will thus provide only informa-

tion specifically relating to the EPROM devices.

PLEASE REFER TO THE ST7291 DATASHEET

FOR THE ROM DEVICES FOR FULL DETAILS.

The ST72E91 is a user programmable and erasa-

ble device, best suited for development purposes.

The ST72T91 is a One-Time Programmable de-

vice (OTP) which offers the best cost/flexibility

trade-off for prototyping, pre-production and most

low to medium volume applications.

Both devices are based around an industry stand-

ard 8-bit core and offer an enhanced instruction

set. The processors will run at an 8MHz clock rate

with a 5V supply, and at up to 4MHz with a 3V

supply. Since the design is fully static, operation

down to DC is possible and the devices may be

placed in HALT or WAIT modes under program

control in order to reduce power requirements.

The powerful enhanced instruction set and ad-

dressing modes afford real programming potential.

In addition to standard 8-bit data management, the

ST72E91 and the ST72T91 feature true bit manip-

ulation, 8x8 unsigned multiplication and indirect

addressing modes. The devices include a CPU, an

on-chip oscillator, EPROM, RAM, I/O, and a timer

with output compare system.

Figure 2. ST72E91 Block Diagram

OSCILLATOR

PORT A

PORT B

CARRIER FREQ.

8 BIT CORE

PA0..PA7 (8-bit)

PB0..PB7 (8-bit)

PC0,PC1,PC5,PC6,PC7

PORT C

LOW VOLTAGE

DETECTOR

TIMER

SYSTEM

CONTR OL

Internal

CLOCK

EPROM/OTP

32K

RAM

256/384

GENERATOR

OSCout

OSCin

WKP

RESET