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September 1993

INTEL CORPORATION 1995

Order Number 270961-003

87C51FA 87C51FB 87C51FC 87C51FC-20

CHMOS SINGLE-CHIP 8-BIT MICROCONTROLLER

Automotive

FX Core Architecture Device

Extended Automotive Temperature
Range (

40 C to

125 C Ambient)

Available in 12 MHz 16 MHz and
20 MHz Versions

High Performance CHMOS EPROM

Three 16-Bit Timer Counters

Timer 2 (Up Down Counter)

Programmable Counter Array with

High Speed Output
Compare Capture
Pulse Width Modulator
Watchdog Timer Capabilities

One-to-Three Level Program Lock
System on EPROM

8K On-Chip User Programmable
EPROM in 87C51FA

16K On-Chip User Programmable
EPROM in 87C51FB

32K On-Chip User Programmable
EPROM in 87C51FC

256 Bytes of On-Chip Data RAM

Quick Pulse Programming Algorithm

Boolean Processor

32 Programmable I O Lines

7 Interrupt Sources

Four Level Interrupt Priority

Programmable Serial Channel with

Framing Error Detection
Automatic Address Recognition

TTL and CMOS Compatible Logic
Levels

64K External Program Memory Space

64K External Data Memory Space

MCS -51 Fully Compatible Instruction
Set

Power Saving Idle and Power Down
Modes

ONCE (On-Circuit Emulation) Mode

RFI Reduction Mode

Available in PLCC and PDIP Packages

MEMORY ORGANIZATION

PROGRAM MEMORY Up to 8 Kbytes of the program memory can reside in the 87C51FA On-Chip EPROM
Up to 16 Kbytes of the program memory can reside in the 87C51FB on-chip EPROM Up to 32 Kbytes of the
program memory can reside in the 87C51FC on-chip EPROM In addition the device can address up to 64K of
program memory external to the chip

DATA MEMORY This microcontroller has a 256 x 8 on-chip RAM In addition it can address up to 64 Kbytes of
external data memory

The Intel 87C51FA 87C51FB 87C51FC is a single-chip control-oriented microcontroller which is fabricated on
Intel's reliable CHMOS EPROM technology Being a member of the MCS-51 family the 87C51FB 87C51FC
uses the same powerful instruction set has the same architecture and is pin-for-pin compatible with the
existing MCS-51 family of products The 87C51FA is an enhanced version of the 87C51 The 87C51FB is an
enhanced version of the 87C51FA The 87C51FC is an enhanced version of the 87C51FB With 8 Kbytes of
program memory in the 87C51FA and 16 Kbytes of program memory in the 87C51FB and 32 Kbytes of
program memory in the 87C51FC it is an even more powerful microcontroller for applications that require
Pulse Width Modulation High Speed I O and up down counting capabilities such as brake and traction
control

For the remainder of this document the 87F51FA 87C51FB and 87C51FC will be referred to as the
87C51FA FB FC

AUTOMOTIVE 87C51FA FB FC FC-20

range of b40 C to a85 C ambient For the automo-
tive temperature range option operational charac-
teristics are guaranteed over the temperature range
of b40 C to a125 C ambient The automotive ex-
tended and commercial temperature versions of the
MCS-51 product families are available with or with-
out burn-in options

As shown in Figure 2 temperature burn-in and
package options are identified by a one- or two-letter
prefix to the part number

PIN DESCRIPTIONS

Supply voltage

Circuit ground

SS1

Secondary ground (in PLCC only) Provided to

reduce ground bounce and improve power supply
by-passing

NOTE

This pin is NOT a substitute for V

pin (pin 22)

Port 0

Port 0 is an 8-bit open drain bidirectional

I O port As an output port each pin can sink several
LS TTL inputs Port 0 pins that have 1's written to
them float and in that state can be used as high-im-
pedance inputs

270961 2

Example

AN87C51FA FB FC indicates an automotive temperature range version of the 87C51FA FB FC in a PLCC package
with 16 Kbyte 32 Kbyte EPROM program memory

Figure 2 Package Options

Table 1 Temperature Options

Temperature

Operating

Burn-In

Classification

Designation

Temperature

Options

C Ambient

Extended

40 to a85

Standard

40 to a85

Extended

Automotive

40 to a125

Standard

40 to a125

Extended

AUTOMOTIVE 87C51FA FB FC FC-20

Port 0 is also the multiplexed low-order address and
data bus during accesses to external Program and
Data Memory In this application it uses strong inter-
nal pullups when emitting 1's and can source and
sink several LS TTL inputs

Port 0 also receives the code bytes during EPROM
programming and outputs the code bytes during
program verification External pullup resistors are re-
quired during program verification

Port 1

Port 1 is an 8-bit bidirectional I O port with

internal pullups The Port 1 output buffers can drive
LS TTL inputs Port 1 pins that have 1's written to
them are pulled high by the internal pullups and in
that state can be used as inputs As inputs Port 1
pins that are externally pulled low will source current
(I

on the data sheet) because of the internal pull-

ups

In addition Port 1 serves the functions of the follow-
ing special features of the 87C51FB FC

Port Pin

Alternate Function

P1 0

T2 (External Count Input to
Timer Counter 2)

P1 1

T2EX (Timer Counter 2 Capture
Reload Trigger and Direction Control)

P1 2

ECI (External Count Input to the PCA)

P1 3

CEX0 (External I O for Compare
Capture Module 0)

P1 4

CEX1 (External I O for Compare
Capture Module 1)

P1 5

CEX2 (External I O for Compare
Capture Module 2)

P1 6

CEX3 (External I O for Compare
Capture Module 3)

P1 7

CEX4 (External I O for Compare
Capture Module 4)

Port 1 receives the low-order address bytes during
EPROM programming and verifying

Port 2

Port 2 is an 8-bit bidirectional I O port with

internal pullups The Port 2 output buffers can drive
LS TTL inputs Port 2 pins that have 1's written to
them are pulled high by the internal pullups and in
that state can be used as inputs As inputs Port 2
pins that are externally pulled low will source current
(I

on the data sheet) because of the internal pull-

ups

PACKAGES

Part

Prefix

Package Type

87C51FA FB FC

40-Pin Plastic DIP

44-Pin PLCC

DIP

270961 3

PAD (PLCC)

270961 4

EPROM only

Do not connect reserved pins

Diagrams are for pin reference only Package sizes are
not to scale

Figure 3 Pin Connections (Top View)

AUTOMOTIVE 87C51FA FB FC FC-20

Port 2 emits the high-order address byte during
fetches from external Program Memory and during
accesses to external Data Memory that use 16-bit
addresses (MOVX

DPTR) In this application it

uses strong internal pullups when emitting 1's Dur-
ing accesses to external Data Memory that use 8-bit
addresses (MOVX

Ri) Port 2 emits the contents

of the P2 Special Function Register

Some Port 2 pins receive the high-order address bits
during EPROM programming and program verifica-
tion

Port 3

Port 3 is an 8-bit bidirectional I O port with

internal pullups The Port 3 output buffers can drive
LS TTL inputs Port 3 pins that have 1's written to
them are pulled high by the internal pullups and in
that state can be used as inputs As inputs Port 3
pins that are externally pulled low will source current
(I

on the data sheet) because of the pullups

Port 3 also serves the functions of various special
features of the MCS-51 Family as listed below

Port Pin

Alternate Function

P3 0

RXD (serial input port)

P3 1

TXD (serial output port)

P3 2

INT0 (external interrupt 0)

P3 3

INT1 (external interrupt 1)

P3 4

T0 (Timer 0 external input)

P3 5

T1 (Timer 1 external input)

P3 6

WR (external data memory write strobe)

P3 7

RD (external data memory read strobe)

RST

Reset input A high on this pin for two machine

cycles while the oscillator is running resets the de-
vice The port pins will be driven to their reset condi-
tion when a minimum V

IH1

is applied whether the

oscillator is running or not An internal pulldown re-
sistor permits a power-on reset with only a capacitor
connected to V

ALE PROG

Address Latch Enable output pulse for

latching the low byte of the address during accesses
to external memory This pin (ALE PROG) is also
the program pulse input during EPROM program-
ming for the 87C51FA FB FC

In normal operation ALE is emitted at a constant
rate of

the oscillator frequency and may be used

for external timing or clocking purposes Note how-
ever that one ALE pulse is skipped during each ac-
cess to external Data Memory

Throughout the remainder of this data sheet ALE
will refer to the signal coming out of the ALE PROG
pin and the pin will be referred to as the ALE PROG
pin

PSEN

Program Store Enable is the read strobe to

external Program Memory

When the 87C51FA FB FC is executing code from
external Program Memory PSEN is activated twice
each machine cycle except that two PSEN activa-
tions are skipped during each access to external
Data Memory

EA V

External Access enable

EA must be

strapped to V

in order to enable the device to

fetch code from external Program Memory locations
0000H to 0FFFFH Note however that if either of
the Program Lock bits are programmed EA will be
internally latched on reset

EA should be strapped to V

for internal program

executions

This pin also receives the programming supply volt-
age (V

) during EPROM programming

XTAL1

Input to the inverting oscillator amplifier

XTAL2

Output from the inverting oscillator amplifier

OSCILLATOR CHARACTERISTICS

XTAL1 and XTAL2 are the input and output respec-
tively of an inverting amplifier which can be config-
ured for use as an on-chip oscillator as shown in
Figure 4 Either a quartz crystal or ceramic resonator
may be used More detailed information concerning
the use of the on-chip oscillator is available in Appli-
cation Note AP-155 ``Oscillators for Microcontrol-
lers'' and in Application Note AP-486

``Oscillator

Design for Microcontrollers''

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