AN1836 Motorola / Freescale Semiconductor, AN1836 Datasheet - Page 25

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

AN1836
MOTOROLA
When checking to ensure that the reservoir capacitance value of C4 is
not too low, the voltage level of V
erase and a write pulse. Remember that the largest current draw on
erasing is when all of the bits of the FLASH are programmed to 0.
Conversely, the highest programming current is seen when
programming all the bits to 0 from the erased state of 1. The user should
look at this on an oscilloscope, due to the brevity of the pulses. Using a
port pin or the SHDN signal may be useful to trigger the scope when the
pulses are fired. If the voltage dips below 11.4 volts, the capacitance
used can be increased, but be sure to verify that decay rates of V
V
inserting some delays between each pulse to allow the charge pump to
recharge.
FP
are still the same. If V
Figure 12. V
FP
Tracking V
FP
is declining with each successive pulse, try
FP
Programming Voltage Supply Considerations
can be monitored during an initial
DD
during Power-Down
Application Note
DD
and
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