[ Pobierz całość w formacie PDF ]

pin is driven high, the device operates in the word (16-bit) mode. The data is read and programmed at DQ0 to
DQ15. When this pin is driven low, the device operates in byte (8-bit) mode. Under this mode, the DQ15/A-1 pin
becomes the lowest address bit and DQ8 to DQ14 bits are tri-stated. However, the command bus cycle is always
an 8-bit operation and hence commands are written at DQ0 to DQ7 and the DQ8 to DQ15 bits are ignored. Refer
to Figures 13, 14 and 15 for the timing diagram.
Data Protection
The MBM29F800TA/BA are designed to offer protection against accidental erasure or programming caused by
spurious system level signals that may exist during power transitions. During power up the device automatically
resets the internal state machine in the read mode. Also, with its control register architecture, alteration of the
memory contents only occurs after successful completion of specific multi-bus cycle command sequences.
The device also incorporate several features to prevent inadvertent write cycles resulting form VCC power-up and
power-down transitions or system noise.
Low VCC Write Inhibit
To avoid initiation of a write cycle during VCC power-up and power-down, a write cycle is locked out for VCC less
than 3.2 V (typically 3.7 V). If VCC
are disabled. Under this condition the device will reset to the read mode. Subsequent writes will be ignored until
the VCC level is greater than VLKO. It is the users responsibility to ensure that the control pins are logically correct
to prevent unintentional writes when VCC is above 3.2 V.
If Embedded Erase Algorithm is interrupted, there is possibility that the erasing sector(s) cannot be used.
21
MBM29F800TA-55/-70/-90/MBM29F800BA-55/-70/-90
Write Pulse  Glitch Protection
Noise pulses of less than 5 ns (typical) on OE, CE, or WE will not initiate a write cycle.
Logical Inhibit
Writing is inhibited by holding any one of OE = VIL, CE = VIH, or WE = VIH. To initiate a write cycle CE and WE
must be a logical zero while OE is a logical one.
Power-Up Write Inhibit
Power-up of the device with WE = CE = VIL and OE = VIH will not accept commands on the rising edge of WE.
The internal state machine is automatically reset to the read mode on power-up.
22
MBM29F800TA-55/-70/-90/MBM29F800BA-55/-70/-90
ABSOLUTE MAXIMUM RATINGS
Storage Temperature .................................................................................................. 55°C to +125°C
Ambient Temperature with Power Applied .................................................................. 40°C to +85°C
Voltage with respect to Ground All pins except A9, OE, and RESET (Note 1) ............ 2.0 V to +7.0 V
VCC (Note 1) ................................................................................................................ 2.0 V to +7.0 V
A9, OE, and RESET (Note 2) ...................................................................................... 2.0 V to +13.5 V
Notes: 1. Minimum DC voltage on input or I/O pins are  0.5 V. During voltage transitions, inputs may negative
overshoot VSS to  2.0 V for periods of up to 20 ns. Maximum DC voltage on output and I/O pins are
VCC +0.5 V. During voltage transitions, outputs may positive overshoot to VCC +2.0 V for periods of up
to 20 ns.
2. Minimum DC input voltage on A9, OE, and RESET pins are  0.5 V. During voltage transitions, A9, OE,
and RESET pins may negative overshoot VSS to  2.0 V for periods of up to 20 ns. Maximum DC input
voltage on A9, OE, and RESET pins are +13.0 V which may positive overshoot to +14.0 V for periods
of up to 20 ns. Voltage difference between input voltage and power supply. (VIN - VCC) do not exceed 9 V.
WARNING: Semiconductor devices can be permanently damaged by application of stress (voltage, current,
temperature, etc.) in excess of absolute maximum ratings. Do not exceed these ratings.
RECOMMENDED OPERATING RANGES
Ambient Temperature (TA) ............................................................................ 40°C to +85°C
VCC Supply Voltages
MBM29F800TA/BA-55 ..............................................................................+4.75 V to +5.25 V
MBM29F800TA/BA-70/-90 ........................................................................+4.50 V to +5.50 V [ Pobierz całość w formacie PDF ]