AN1836 Motorola / Freescale Semiconductor, AN1836 Datasheet - Page 23

• Manufacturer Part Number: AN1836
• Description: FLASH Programming for Motorola MC68HC912 Microcontrollers
• Manufacturer: Motorola / Freescale Semiconductor

AN1836
MOTOROLA
NOTE:
corruption in the FLASH array. (Refer to
dc-dc converter stores charge to supply V
supply must be able to source approximately 30 mA of current for at least
20 s (based on programming cycle requirements) and 4 mA of current
for at least 10 ms (based on erase cycle requirements).
A certain degree of experimentation might be required when selecting
C4 and C3. When trying different capacitor values, always monitor the
effects on V
pin.
R1 must be no larger than 10 k , to make certain that the SHDN pin on
the dc-dc converter is never allowed to fall below V
pin of the microcontroller is driven low. The external pullup ensures this
behavior, no matter what port pin is used on the microcontroller or what
the internal structure of that pin looks like. Without a strong enough
pullup resistor on R1, the voltage on the SHDN pin might drop during a
reset event, causing the dc-dc converter to activate and begin driving the
voltage on V
corruption in the FLASH.
Figure 10
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
cooperation of ST Microelectronics to aid in tracking a rapidly falling V
voltage level, such as in
been verified with the Maxim Integrated Products device (MAX662).
is different from the recommended circuit shown in
DD
FP
Out
and V
decay during power-down and current supplied to the V
to begin to rise to 12 volts. This would result in data
FP
. This change was implemented with the
Figure 11
Programming Voltage Supply Considerations
and
Figure
Figure
Out
to the target device. The
12. This circuit also has
11.) C4 is where the
DD
unless the output
Application Note
DD
FP
23