37C957FR Datasheet, PDF (145/328 Pages) SMSC Corporation – ULTRA I/O CONTROLLER FOR PORTABLE APPLICATIONS

No power to System
[VCC0, VCC1, VCC2 OFF
VCC0,VCC1 ON : VCC2 OFF
VCC1 powered registers
are reset to their VCC1
POR values. IRESET_OUT
bit forced high and latched
by orion hardware.
ring oscillator is started
Once the ring osc has
stabilized, the 8051is held in
reset for the required number
of clock cycles and then
released.
N
nEA = 0 ?
the 8051 begins executing
from program address 00h.
Y
8051, begins executing code
at address 8000h.
FIGURE 3 - SYSTEM POWER UP SEQUENCE
139