M27C256B
Table 5. AC Measurement Conditions
High Speed
Input Rise and Fall Times
Input Pulse Voltages
Input and Output Timing Ref. Voltages
≤
10ns
0 to 3V
1.5V
Standard
≤
20ns
0.4V to 2.4V
0.8V and 2V
Figure 3. AC Testing Input Output Waveform
Figure 4. AC Testing Load Circuit
1.3V
High Speed
3V
1.5V
0V
DEVICE
UNDER
TEST
2.0V
0.8V
AI01822
1N914
3.3kΩ
Standard
2.4V
OUT
CL
0.4V
CL = 30pF for High Speed
CL = 100pF for Standard
CL includes JIG capacitance
AI01823B
Table 6. Capacitance
(1)
(T
A
= 25 °C, f = 1 MHz)
Symbol
C
IN
C
OUT
Parameter
Input Capacitance
Output Capacitance
Test Condition
V
IN
= 0V
V
OUT
= 0V
Min
Max
6
12
Unit
pF
pF
Note: 1. Sampled only, not 100% tested.
DEVICE OPERATION
The operating modes of the M27C256B are listed
in the Operating Modes. A single power supply is
required in the read mode. All inputs are TTL lev-
els except for V
PP
and 12V on A9 for Electronic
Signature.
Read Mode
The M27C256B has two control functions, both of
which must be logically active in order to obtain
data at the outputs. Chip Enable (E) is the power
control and should be used for device selection.
Output Enable (G) is the output control and should
be used to gate data to the output pins, indepen-
dent of device selection. Assuming that the ad-
dresses are stable, the address access time
(t
AVQV
) is equal to the delay from E to output
(t
ELQV
). Data is available at the output after delay
of t
GLQV
from the falling edge of G, assuming that
E has been low and the addresses have been sta-
ble for at least t
AVQV
-t
GLQV
.
Standby Mode
The M27C256B has a standby mode which reduc-
es the supply current from 30mA to 100µA. The
M27C256B is placed in the standby mode by ap-
plying a CMOS high signal to the E input. When in
the standby mode, the outputs are in a high imped-
ance state, independent of the G input.
4/16
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