AT89C51RE2 Atmel Corporation, AT89C51RE2 Datasheet - Page 162

• Manufacturer Part Number: AT89C51RE2
• Manufacturer: Atmel Corporation

Specifications of AT89C51RE2

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 60 MHz
• Cpu: 8051-12C
• Max I/o Pins: 34
• Spi: 1
• Uart: 2
• Sram (kbytes): 8.25
• Self Program Memory: API
• Operating Voltage (vcc): 2.7 to 5.5
• Timers: 4
• Isp: UART/OCD
• Watchdog: Yes

Figure 67. Power Fail Detect
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Vcc
AT89C51RE2
Vcc
Reset
The Power fail detect monitor the supply generated by the voltage regulator and generate a
reset if this supply falls below a safety threshold as illustrated in the Figure 67 below.
When the power is applied, the Power Monitor immediately asserts a reset. Once the internal
supply after the voltage regulator reach a safety level, the power monitor then looks at the XTAL
clock input. The internal reset will remain asserted until the Xtal1 levels are above and below
VIH and VIL. Further more. An internal counter will count 1024 clock periods before the reset is
de-asserted.
If the internal power supply falls below a safety level, a reset is immediately asserted.
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