P89V51RB2BBC View Datasheet(PDF) - NXP Semiconductors.

Part Name

Description

Manufacturer

P89V51RB2BBC

8-bit 80C51 5 V low power 16/32/64 kB flash microcontroller with 1 kB RAM

NXP Semiconductors. 

NXP Semiconductors

P89V51RB2/RC2/RD2

8-bit microcontrollers with 80C51 core

Table 3. P89V51RB2/RC2/RD2 pin description …continued

Symbol

Pin

Type

Description

DIP40 TQFP44 PLCC44

RST

9

4

10

I

Reset: While the oscillator is running, a HIGH logic state

on this pin for two machine cycles will reset the device. If

the PSEN pin is driven by a HIGH-to-LOW input transition

while the RST input pin is held HIGH, the device will enter

the external host mode, otherwise the device will enter the

normal operation mode.

EA

31

29

35

I

External Access Enable: EA must be connected to VSS in

order to enable the device to fetch code from the external

program memory. EA must be strapped to VDD for internal

program execution. The EA pin can tolerate a high voltage

of 12 V.

ALE/PROG 30

27

33

I/O

Address Latch Enable: ALE is the output signal for

latching the low byte of the address during an access to

external memory. This pin is also the programming pulse

input (PROG) for flash programming. Normally the ALE[1]

is emitted at a constant rate of 1⁄6 the crystal frequency[2]

and can be used for external timing and clocking. One ALE

pulse is skipped during each access to external data

memory. However, if AO is set to ‘1’, ALE is disabled.

n.c.

-

6, 17, 28, 1, 12, 23, I/O

not connected

39

34

XTAL1

19

15

21

I

Crystal 1: Input to the inverting oscillator amplifier and

input to the internal clock generator circuits.

XTAL2

18

14

20

O

Crystal 2: Output from the inverting oscillator amplifier.

VDD

40

38

44

I

Power supply

VSS

20

16

22

I

Ground

[1] ALE loading issue: When ALE pin experiences higher loading (>30 pF) during the reset, the microcontroller may accidentally enter into

modes other than normal working mode. The solution is to add a pull-up resistor of 3 kΩ to 50 kΩ to VDD, e.g., for ALE pin.

[2] For 6-clock mode, ALE is emitted at 1⁄3 of crystal frequency.

P89V51RB2_RC2_RD2_5

Product data sheet

Rev. 05 — 12 November 2009

© NXP B.V. 2009. All rights reserved.

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