Rainbow Electronics AT27BV256 - Manual (Page 2)

AT27BV256
2
Atmel’s innovative design techniques provide fast speeds
that rival 5V parts while keeping the low power consump-
tion of a 3V supply. At V
CC
= 2.7V, any word can be
accessed in less than 70 ns. With a typical power dissipa-
tion of only 18 mW at 5 MHz and V
CC
= 3V, the AT27BV256
consumes less than one fifth the power of a standard 5V
EPROM.
Standby mode supply current is typically less than 1
µ
A at
3V. The AT27BV25 6 simplifies syste m d esign an d
stretches battery lifetime even further by eliminating the
need for power supply regulation.
The AT27BV256 is available in industry standard JEDEC-
approved one-time programmable (OTP) plastic PLCC,
SOIC and TSOP packages. All devices feature two-line
control (CE, OE) to give designers the flexibility to prevent
bus contention.
The AT27BV256 operating with V
CC
at 3.0V produces TTL
level outputs that are compatible with standard TTL logic
devices operating at V
CC
= 5.0V. At V
CC
= 2.7V, the part is
compatible with JEDEC approved low voltage battery oper-
ation (LVBO) interface specifications. The device is also
capable of standard 5-volt operation making it ideally suited
for dual supply range systems or card products that are
pluggable in both 3-volt and 5-volt hosts.
Atmel’s AT27BV256 has additional features to ensure high
quality and efficient production use. The Rapid™ Program-
ming Algorithm reduces the time required to program the
part and guarantees reliable programming. Programming
time is typically only 100
µ
s/byte. The Integrated Product
Identification Code electronically identifies the device and
manufacturer. This feature is used by industry standard
programming equipment to select the proper programming
algorithms and voltages. The AT27BV256 programs
exactly the same way as a standard 5V AT27C256R and
uses the same programming equipment.
System Considerations
Switching between active and standby conditions via the
Chip Enable pin may produce transient voltage excursions.
Unless accommodated by the system design, these tran-
sients may exceed data sheet limits, resulting in device
non-conformance. At a minimum, a 0.1
µ
F high frequency,
low inherent inductance, ceramic capacitor should be uti-
lized for each device. This capacitor should be connected
between the V
CC
and Ground terminals of the device, as
close to the device as possible. Additionally, to stabilize the
supply voltage level on printed circuit boards with large
EPROM arrays, a 4.7
µ
F bulk electrolytic capacitor should
be utilized, again connected between the V
CC
and Ground
terminals. This capacitor should be positioned as close as
possible to the point where the power supply is connected
to the array.
Block Diagram