P87C51RB2BBD datasheet(8/67 Pages) PHILIPS

8 / 67 page

Philips Semiconductors

Product data

P87C51RA2/RB2/RC2/RD2

80C51 8-bit microcontroller family 8KB/16KB/32KB/64KB OTP

with 512B/1KB RAM, low voltage (2.7 to 5.5 V), low power, high

speed (30/33 MHz)

2003 Jan 24

MNEMONIC

NAME AND FUNCTION

TYPE

PIN NUMBER

MNEMONIC

NAME AND FUNCTION

TYPE

LQFP

PLCC

PDIP

PSEN

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

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

held low to enable the device to fetch code from external program memory

locations. If EA is held high, the device executes from internal program memory.

The value on the EA pin is latched when RST is released and any subsequent

changes have no effect. This pin also receives the programming supply voltage

(VPP) during programming.

XTAL1

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

generator circuits.

XTAL2

Crystal 2: Output from the inverting oscillator amplifier.

NOTE:

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

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