The AT89C51RB2/RC2 retains all features of the 80C52 with 256 Bytes of internal
RAM, a 9-source 4-level interrupt controller and three timer/counters.
In addition, the AT89C51RB2/RC2 has a Programmable Counter Array, an XRAM of
1024 Bytes, a Hardware Watchdog Timer, a Keyboard Interface, an SPI Interface, a
more versatile serial channel that facilitates multiprocessor communication (EUART)
and a speed improvement mechanism (X2 mode).
The Pinout is the standard 40/44 pins of the C52.
The fully static design reduces system power consumption of the AT89C51RB2/RC2 by
allowing it to bring the clock frequency down to any value, even DC, without loss of data.
The AT89C51RB2/RC2 has 2 software-selectable modes of reduced activity and 8-bit
clock prescaler for further reduction in power consumption. In Idle mode, the CPU is fro-
zen while the peripherals and the interrupt system are still operating. In power-down
mode, the RAM is saved and all other functions are inoperative.
The added features of the AT89C51RB2/RC2 make it more powerful for applications
that need pulse width modulation, high speed I/O and counting capabilities such as
alarms, motor control, corded phones, and smart card readers.
Table 1. Memory Size
TOTAL RAM
Part Number
AT89C51RB2
AT89C51RC2
AT89C51IC2
Flash (Bytes)
XRAM (Bytes)
1024
(Bytes)
I/O
32
32
32
16K
32K
32K
1280
1024
1280
1024
1280
2
AT89C51RB2/RC2
4180E–8051–10/06
ATMEL [ ATMEL ]
