at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 145

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

The Power fail detect monitor the supply generated by the voltage regulator and gener-
ate a reset if this supply falls below a safety threshold as illustrated in the Figure 44
below.
Figure 44. Power Fail Detect
Vcc
t
Reset
Vcc
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 lev-
els 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.
AT89C51RE2
128
7663B–8051–03/07