AT27C020

2

The AT27C020 is available in a choice of industry standard

JEDEC-approved one-time programmable (OTP) plastic

PDIP, PLCC, and TSOP packages. All devices feature two-

line control (CE, OE) to give designers the flexibility to pre-

vent bus contention.

With 256K byte storage capability, the AT27C020 allows

firmware to be stored reliably and to be accessed by the

system without the delays of mass storage media.

Atmel’s 27C020 have additional features to ensure high

quality and efficient production use. The Rapid

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 programming

algorithms and voltages.

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

µF high frequency,

low inherent inductance, ceramic capacitor should be uti-

lized for each device. This capacitor should be connected

between the V

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 V

terminals. This capacitor should be positioned as close as

possible to the point where the power supply is connected

to the array.

Block Diagram