1

PQFP/TQFP

1

2

3

4

5

6

7

8

9

10

11

33

32

31

30

29

28

27

26

25

24

23

P1.5

P1.6

P1.7

RST

(RXD) P3.0

NC

(TXD) P3.1

(INT0) P3.2

(INT1) P3.3

(T0) P3.4

(T1) P3.5

PO.4 (AD4)

P0.5 (AD5)

P0.6 (AD6)

P0.7 (AD7)

EA/VPP

NC

ALE/PROG

PSEN

P2.7 (A15)

P2.6 (A14)

P2.5 (A13)

Features

– Endurance: 1,000 Write/Erase Cycles

Description

The AT89C51 is a low-power, high-performance CMOS 8-bit microcomputer with 4K

bytes of Flash programmable and erasable read only memory (PEROM). The device

is manufactured using Atmel’s high-density nonvolatile memory technology and is

compatible with the industry-standard MCS-51 instruction set and pinout. The on-chip

Flash allows the program memory to be reprogrammed in-system or by a conven-

tional nonvolatile memory programmer. By combining a versatile 8-bit CPU with Flash

on a monolithic chip, the Atmel AT89C51 is a powerful microcomputer which provides

a highly-flexible and cost-effective solution to many embedded control applications.

PDIP

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

40

39

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

P1.0

P1.1

P1.2

P1.3

P1.4

P1.5

P1.6

P1.7

RST

(RXD) P3.0

(TXD) P3.1

(INT0) P3.2

(INT1) P3.3

(T0) P3.4

(T1) P3.5

(WR) P3.6

(RD) P3.7

XTAL2

XTAL1

GND

VCC

P0.0 (AD0)

P0.1 (AD1)

P0.2 (AD2)

P0.3 (AD3)

P0.4 (AD4)

P0.5 (AD5)

P0.6 (AD6)

P0.7 (AD7)

EA/VPP

ALE/PROG

PSEN

P2.7 (A15)

P2.6 (A14)

P2.5 (A13)

P2.4 (A12)

P2.3 (A11)

P2.2 (A10)

P2.1 (A9)

P2.0 (A8)

Rev. 0265G–02/00

8-bit

Microcontroller

with 4K Bytes

Flash

AT89C51

Not Recommended

for New Designs.

Use AT89S51.

Pin Configurations

PLCC

7

8

9

10

11

12

13

14

15

16

17

39

38

37

36

35

34

33

32

31

30

29

P1.5

P1.6

P1.7

RST

(RXD) P3.0

NC

(TXD) P3.1

(INT0) P3.2

(INT1) P3.3

(T0) P3.4

(T1) P3.5

PO.4 (AD4)

P0.5 (AD5)

P0.6 (AD6)

P0.7 (AD7)

EA/VPP

NC

ALE/PROG

PSEN

P2.7 (A15)

P2.6 (A14)

P2.5 (A13)