AT89C5122D-RDRUM Atmel, AT89C5122D-RDRUM Datasheet - Page 170

• Manufacturer Part Number: AT89C5122D-RDRUM
• Description: IC 8051 MCU 32K CRAM USB 64-VQFP
• Manufacturer: Atmel
• Series: 89Cr

Specifications of AT89C5122D-RDRUM

• Core Processor: 8051
• Core Size: 8-Bit
• Speed: 48MHz
• Connectivity: SmartCard, SPI, UART/USART, USB
• Peripherals: LED, POR, WDT
• Number Of I /o: 46
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 768 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-TQFP, 64-VQFP
• For Use With: AT89OCD-01 - USB EMULATOR FOR AT8XC51 MCUAT89STK-10 - KIT EVAL APPL MASS STORAGEAT89STK-03 - KIT STARTER FOR MCU AT8XC5122/23
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Data Converters: -
• Other names: AT89C5122D-RDRUMTR

Microcontroller Reset
Introduction
170
AT83R5122, AT8xC5122/23
The internal reset is used to start up (cold reset) or to re-start (warm reset) the micro-
controller activity. When the reset is applied (active state), all internal registers are
initialized so that the microcontroller starts from a known and clean state for the program
always runs as expected.
The reset is released (inactive state) when the following conditions are internally met :
If one of the above conditions is not met the microcontroller is not correctly reset and
might not work properly.
The internal reset comes from four different sources :
Figure 100. Reset bock diagram
RST
Vcc
–
–
–
–
–
–
–
The power supply has reatched a minimum level which garantees that the
microcontroller works properly
The on-chip oscillator has reached a minimum oscillation level which
ensures a good noise to signal ratio and a correct internal duty cycle
the active state duration is at least two machine cycles.
Reset pin
Power On Reset (POR)
Power Fail Detector (PFD)
Hardware Watch-Dog Timer (WDT)
3.3V Internal
Digital Regulator
POR
Watch Dog
Timer
PFD
Core
C51
Microcontroller
4202F–SCR–07/2008
Internal Reset
VCore