AT89C51RB2-3CSUM データシートの表示（PDF） - Atmel Corporation

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AT89C51RB2-3CSUM

8-bit Microcontroller with 16K/32K Bytes Flash

Atmel Corporation 

Table 12. Pin Description for 40 - 44 Pin Packages (Continued)

Pin Number

Mnemonic

DIL

LCC VQFP44 1.4 Type Name and Function

PSEN

29

32

26

O Program Strobe 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

31

35

29

I

External Access Enable: EA must be externally held low to enable the device to

fetch code from external program memory locations 0000H to FFFFH (RD). If

security level 1 is programmed, EA will be internally latched on Reset.

12 AT89C51RB2/RC2

4180E–8051–10/06

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