MX27C1000
To activate this mode, the programming equipment must
force 12.0
±
0.5 V on address line A9 of the device.
Two identifier bytes may then be sequenced from the
device outputs by toggling address line A0 from VIL to
VIH. All other address lines must be held at VIL during
auto identify mode.
Byte 0 ( A0 = VIL) represents the manufacturer code,
and byte 1 (A0 = VIH), the device identifier code. For
the MX27C1000, these two identifier bytes are given in
the Mode Select Table. All identifiers for manufacturer
and device codes will possess odd parity, with the MSB
(DQ7) defined as the parity bit.
the primary device-selecting function, while OE be made
a common connection to all devices in the array and
connected 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 CONSIDERATIONS
During the switch between active and standby
conditions, transient current peaks are produced on the
rising and falling edges of Chip Enable. The magnitude
of these transient current peaks is dependent on the
output capacitance loading of the device. At a minimum,
a 0.1 uF ceramic capacitor (high frequency, low inherent
inductance) should be used on each device between
VCC and GND to minimize transient effects. In addition,
to overcome the voltage drop caused by the inductive
effects of the printed circuit board traces on EPROM
arrays, a 4.7 uF bulk electrolytic capacitor should be
used between VCC and GND for each eight devices.
The location of the capacitor should be close to where
the power supply is connected to the array.
READ MODE
The MX27C1000 has two control functions, both of which
must be logically satisfied in order to obtain data at the
outputs. Chip Enable (CE) is the power control and
should be used for device selection. Output Enable (OE)
is the output control and should be used to gate data
to the output pins, independent of device selection.
Assuming that addresses are stable, address access
time (tACC) is equal to the delay from CE to output (tCE).
Data is available at the outputs tQE after the falling edge
of OE, assuming that CE has been LOW and addresses
have been stable for at least tACC - tQE.
STANDBY MODE
The MX27C1000 has a CMOS standby mode which
reduces the maximum VCC current to 100 uA. It is
placed in CMOS standby when CE is at VCC
±
0.3 V.
The MX27C1000 also has a TTL-standby mode which
reduces the maximum VCC current to 1.5 mA. It is
placed in TTL-standby when CE is at VIH. When in
standby mode, the outputs are in a high-impedance
state, independent of the OE input.
TWO-LINE OUTPUT CONTROL FUNCTION
To accommodate multiple memory connections, a two-
line control function is provided to allow for:
1. Low memory power dissipation,
2. Assurance that output bus contention will not
occur.
It is recommended that CE be decoded and used as
P/N: PM0234
REV. 6.0, AUG. 26, 2003
3
MCNIX [ MACRONIX INTERNATIONAL ]
