AT89C51RE2-SLSUM Atmel, AT89C51RE2-SLSUM Datasheet - Page 126

• Manufacturer Part Number: AT89C51RE2-SLSUM
• Description: MCU 8BIT FLASH 2.7-5.5V 44-PLCC
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C51RE2-SLSUM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 60MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: POR, PWM, WDT
• Number Of I /o: 34
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 44-PLCC
• Package: 44PLCC
• Device Core: 8051
• Family Name: 89C
• Maximum Speed: 40 MHz
• Operating Supply Voltage: 3.3|5 V
• Data Bus Width: 8 Bit
• Number Of Programmable I/os: 34
• Interface Type: SPI/TWI/UART
• Number Of Timers: 3
• Processor Series: AT89x
• Core: 8051
• Data Ram Size: 8 KB
• Maximum Clock Frequency: 40 MHz
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• 3rd Party Development Tools: PK51, CA51, A51, ULINK2
• Development Tools By Supplier: AT89OCD-01
• Minimum Operating Temperature: - 40 C
• Cpu Family: 89C
• Device Core Size: 8b
• Frequency (max): 40MHz
• Total Internal Ram Size: 8KB
• # I/os (max): 34
• Number Of Timers - General Purpose: 3
• Operating Supply Voltage (typ): 3.3/5V
• Operating Supply Voltage (max): 5.5V
• Operating Supply Voltage (min): 2.7V
• Instruction Set Architecture: CISC
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 44
• Package Type: PLCC
• For Use With: AT89OCD-01 - USB EMULATOR FOR AT8XC51 MCUAT89STK-11 - KIT STARTER FOR AT89C51RX2
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Reduced EMI
Mode
126
AT89C51RE2
The ALE signal is used to demultiplex address and data buses on port 0 when used with exter-
nal program or data memory. Nevertheless, during internal code execution, ALE signal is still
generated. In order to reduce EMI, ALE signal can be disabled by setting AO bit.
The AO bit is located in AUXR register at bit location 0. As soon as AO is set, ALE is no longer
output but remains active during MOVX and MOVC instructions and external fetches. During
ALE disabling, ALE pin is weakly pulled high.
Table 94. AUXR Register
AUXR - Auxiliary Register (8Eh)
Reset Value = XX00 10’HSB. XRAM’0b
Not bit addressable
Number
Bit
7
-
7
6
5
4
3
2
1
0
Mnemonic
EXTRAM
XRS2
XRS1
XRS0
Bit
M0
AO
6
-
-
-
Description
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Reserved
The value read from this bit is indeterminate. Do not set this bit.
Pulse length
Cleared to stretch MOVX control: the RD/ and the WR/ pulse length is 6 clock periods
(default).
Set to stretch MOVX control: the RD/ and the WR/ pulse length is 30 clock periods.
XRAM Size
XRS2
0
0
0
0
1
EXTRAM bit
Cleared to access internal XRAM using movx @ Ri/ @ DPTR.
Set to access external memory.
Programmed by hardware after Power-up regarding Hardware Security Byte (HSB),
default setting, XRAM selected.
ALE Output bit
Cleared, ALE is emitted at a constant rate of 1/6 the oscillator frequency (or 1/3 if X2
mode is used). (default) Set, ALE is active only during a MOVX or MOVC instruction is
used.
M0
5
XRS1
0
0
1
1
0
XRS2
XRS0 XRAM size
0
1
0
0
1
4
256 bytes
768 bytes(default)
1024 bytes
1792 bytes
512 bytes
XRS1
3
XRS0
2
EXTRAM
1
7663E–8051–10/08
AO
0