Flash Memory Characteristics
Figure 3-3 shows the definitions of the following signal states:
• Active state, when a bus or signal is driven, and enters a low impedance state
• Tri-stated, when a bus or signal is placed in a high impedance state
• Data Valid state, when a signal level has reached VOL or VOH
• Data Invalid state, when a signal level is in transition between VOL and VOH
Data1 Valid
Data1
Data2 Valid
Data2
Data Invalid State
Data Active
Data
Tri-stated
Figure 3-3 Signal States
3.4 Flash Memory Characteristics
Data3 Valid
Data3
Data Active
Table 3-5 Flash Memory Truth Table
Mode
XE1 YE2 SE3 OE4
Standby
L
L
L
L
Read
H
H
H
H
Word Program
H
H
L
L
Page Erase
H
L
L
L
Mass Erase
H
L
L
L
1. X address enable, all rows are disabled when XE = 0
2. Y address enable, YMUX is disabled when YE = 0
3. Sense amplifier enable
4. Output enable, tri-state Flash data out bus when OE = 0
5. Defines program cycle
6. Defines erase cycle
7. Defines mass erase cycle, erase whole block
8. Defines non-volatile store cycle
PROG5
L
L
H
L
L
ERASE6
L
L
L
H
H
MAS17
L
L
L
L
H
NVSTR8
L
L
H
H
H
56F802 Technical Data, Rev. 7
Freescale Semiconductor
19