MPC555
/
MPC556
CDR MoneT FLASH EEPROM
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
19-39
bias drop across D1. Capacitor C1 filters transients, while R2 provides a discharge
bleed path for C1. Allow for RC charge and discharge time constants when applying
and removing power. When using this circuit, keep leakage from external devices con-
nected to the VPP pin low, to minimize diode voltage drop.
Figure 19-10 VPP Conditioning Circuit
19.10 Reset Operation
19.10.1 Master Reset
The MPC555 / MPC556 signals a master reset (both PORESET or HRESET) to the
CMF EEPROM when a full reset is required. A master reset is the highest priority op-
eration for the CMF EEPROM and will terminate all other operations. The CMF EE-
PROM module uses master reset to initialize all register bits to their reset values. If the
CMF EEPROM is in program or erase operation (EHV = 1) and a master reset is gen-
erated, the module will perform the needed interlocks to disable the high voltage with-
out damage to the high voltage circuits. Master reset will terminate any other mode of
operation and force the CMF EEPROM BIU to a state ready to receive U-bus accesses
within 10 clocks of the end of master reset.
If the HC bit of the reset configuration word = 0 and the SIU requests internal configu-
ration during reset, the CMF EEPROM will provide the reset configuration word to the
device from CMFRC.
19.10.2 Soft Reset
A soft reset forces the BIU into a state ready to receive U-bus accesses and clear the
EHV bit. All other register bits remain unaltered by a soft reset.
D
1
C
1
0.1
µ
F
R
2
22K
Ω
D
2
VDDL
V
PP
Pin
PROGRAMMING VOLTAGE
POWER SUPPLY*
*The VPP voltage specification is the voltage at the VPP pin,
not the input to diode D1.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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