Datasheet

FLASH EEPROM Characteristics
M68HC12B Family Data Sheet, Rev. 9.1
Freescale Semiconductor 317
NOTE
Figure 19-2 is different from the recommended circuit shown in information
about ST662A from ST Microelectronics, but it is correct. The change is in
the location of the capacitor C4, which is now placed between V
DD
and V
FP
.
This change was implemented with the cooperation of ST Microelectronics
to aid in tracking a rapidly falling V
DD
voltage level, such as in Figure 19-3
and Figure 19-4. This circuit also has been verified with the Maxim
Integrated Products device (MAX662).
Be certain that V
FP
decays with V
DD
, as shown in Figure 19-4, as new capacitance values are tested. The
rate of decay of the V
DD
supply powering down will help define how large the C3 capacitance can be
made.
Figure 19-3. V
FP
Exceeding V
DD
during Power-Down