Electrical Specifications
FLASH Memory Characteristics
MC68HC908MR16/MC68HC908MR32 — Rev. 4.0 Advance Information
MOTOROLA Electrical Specifications 371
22.7 FLASH Memory CharacteristicsCharacteristic Symbol/
Description Min Max Units
RAM data retention voltage VRDR 1.3 — V
FLASH program bus clock frequency — 1 — MHz
FLASH read bus clock frequency fRead(1)
1. fRead is defined as the frequency range for which the FLASH memory can be read.
32 k 8.4 M Hz
FLASH page erase time tErase(2)
2. If the page erase time is longer than tErase (min), there is no erase-disturb, but it reduces the endurance of the FLASH
memory.
1—ms
FLASH mass erase time tMErase(3)
3. If the mass erase time is longer than tMErase (min), there is no erase-disturb, but it reduces the endurance of the FLASH
memory.
4—ms
FLASH PGM/Erase to HVEN set up time tNVS 10 — µs
FLASH high-voltage hold time tNVH 5—µs
FLASH high-voltage hold time (mass erase) tNVHL 100 — µs
FLASH program hold time tPGS 5—µs
FLASH program time tPROG 30 40 µs
FLASH return to read time tRCV(4)
4. tRCV is defined as the time it needs before the FLASH can be read after turning off the high voltage charge pump, by
clearing HVEN to logic 0.
1—µs
FLASH cumulative program HV period tHV(5)
5. tHV is defined as the cumulative high voltage pro gramming time to the same row before next erase.
tHV must satisfy this condition: tNVS + t NVH + tPGS + (tPROG × 64) ≤ tHV max.
—4ms
FLASH row erase endurance(6)
6. The minimum row endurance value specifies each row o f the FLASH memory is guaranteed to work for at least
this many erase/program cycles.
—10 k—Cycles
FLASH row program endurance(7)
7. The minimum row endurance value specifies each row o f the FLASH memory is guaranteed to work for at least
this many erase/program cycles.
—10 k—Cycles
FLASH data retention time(8)
8. The FLASH is guaranteed to retain data over the entire operating temperatur e range for at least the minimum
time specified.
—10—Years