AM27C040_99 Datasheet, PDF (6/13 Pages) Advanced Micro Devices – 4 Megabit (512 K x 8-Bit) CMOS EPROM

FINAL
common connection to all devices in the array and con-
nected to the READ line from the system control bus.
This assures that all deselected memory devices are in
their low-power standby mode and that the output pins
are only active when data is desired from a particular
memory device.
System Applications
During the switch between active and standby condi-
tions, transient current peaks are produced on the ris-
ing and falling edges of Chip Enable. The magnitude of
these transient current peaks is dependent on the out-
put capacitance loading of the device. At a minimum, a
0.1 µF ceramic capacitor (high frequency, low inherent
inductance) should be used on each device between
V_CC and V_SS to minimize transient effects. In addition,
to overcome the voltage drop caused by the inductive
effects of the printed circuit board traces on EPROM ar-
rays, a 4.7 µF bulk electrolytic capacitor should be used
between V_CC and V_SS for each eight devices. The loca-
tion of the capacitor should be close to where the
power supply is connected to the array.
MODE SELECT TABLE
Mode
CE#/PGM#
OE#
A0
Read
V_IL
V_IL
X
Output Disable
V_IL
V_IH
X
Standby (TTL)
V_IH
X
X
Standby (CMOS)
V_CC + 0.3 V
X
X
Program
V_IL
V_IH
X
Program Verify
V_IL
V_IL
X
Program Inhibit
V_IH
X
X
Auto Select
Manufacturer Code
V_IL
(Note 3)
Device Code
V_IL
V_IL
V_IL
V_IL
V_IH
A9
V_PP
Outputs
X
X
D_OUT
X
X
HIGH Z
X
X
HIGH Z
X
X
HIGH Z
X
V_PP
D_IN
X
V_PP
D_OUT
X
V_PP
HIGH Z
V_H
X
01h
V_H
X
9Bh
Note:
1. V_H = 12.0 V ± 0.5 V.
2. X = Either V_IH or V_IL
3. A1 – A8 = A10 – A18 = V_IL
4. See DC Programming Characteristics in the EPROM Products Data Book for V_PP voltage during programming
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Am27C040