P87C54UFBB Просмотр технического описания (PDF) - Philips Electronics

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P87C54UFBB

80C51 8-bit microcontroller family 8K–64K/256–1K OTP/ROM/ROMless, low voltage (2.7V–5.5V), low power, high speed (33 MHz)

Philips Electronics 

Philips Semiconductors

80C51 8-bit microcontroller family

8K–64K/256–1K OTP/ROM/ROMless, low voltage (2.7V–5.5V),

low power, high speed (33 MHz)

Product specification

8XC52/54/58/80C32

8XC51FA/FB/FC/80C51FA

8XC51RA+/RB+/RC+/RD+/80C51RA+

PIN DESCRIPTIONS (Continued)

PIN NUMBER

MNEMONIC DIP LCC QFP TYPE NAME AND FUNCTION

PSEN

29

32

26

O Program Store Enable: The read strobe to external program memory. When executing

code from the external program memory, PSEN is activated twice each machine cycle,

except that two PSEN activations are skipped during each access to external data memory.

PSEN is not activated during fetches from internal program memory.

EA/VPP

31

35

29

I External Access Enable/Programming Supply Voltage: EA must be externally held low

to enable the device to fetch code from external program memory locations starting with

0000H. If EA is held high, the device executes from internal program memory unless the

program counter contains an address greater than 8k Devices (IFFFH), 16k Devices

(3FFFH) or 32k Devices (7FFFH). Since the RD+ has 64k Internal Memory, the RD+ will

execute only from internal memory when EA is held high. This pin also receives the 12.75V

programming supply voltage (VPP) during EPROM programming. If security bit 1 is

programmed, EA will be internally latched on Reset.

XTAL1

19

21

15

I Crystal 1: Input to the inverting oscillator amplifier and input to the internal clock generator

circuits.

XTAL2

18

20

14

O Crystal 2: Output from the inverting oscillator amplifier.

NOTE:

To avoid “latch-up” effect at power-on, the voltage on any pin at any time must not be higher than VCC + 0.5V or VSS – 0.5V, respectively.

1999 Apr 01

6

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