The AT27C256R is available in a choice of industry stand-

ard JEDEC-approved one time programmable (OTP)

plastic DIP, PLCC, SOIC, and TSOP packages. All de-

vices feature two-line control (CE, OE) to give designers

the flexibility to prevent bus contention.

With 32K byte storage capability, the AT27C256R allows

firmware to be stored reliably and to be accessed by the

system without the delays of mass storage media.

Atmel’s 27C256R has additional features to ensure high

ming Algorithm reduces the time required to program the

part and guarantees reliable programming. Programming

time is typically only 100

µs/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 program-

ming algorithms and voltages.

Description (Continued)

Switching between active and standby conditions via the

Chip Enable pin may produce transient voltage excur-

sions. Unless accommodated by the system design, these

transients may exceed data sheet limits, resulting in de-

vice non-conformance. At a minimum, a 0.1

µF high fre-

quency, low inherent inductance, ceramic capacitor

should be utilized for each device. This capacitor should

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

µF bulk electrolytic

capacitor should be utilized, again connected between the

tioned as close as possible to the point where the power

supply is connected to the array.

System Considerations

3-126

AT27C256R