AT27C400

2

Description (Continued)

The AT27C400 can be organized as either word-wide or

organization is selected and the O15/A-1 pin is used for

byte-wide organization is selected and the O15/A-1 pin is

used for the address pin A-1. When the AT27C400 is logi-

cally regarded as x16 (word-wide), but read in the byte-

16-bit word are selected.

In read mode, the AT27C400 typically consumes 15 mA.

Standby mode supply current is typically less than 10

µA.

The A T 2 7 C4 00 i s a v ai la bl e i n i ndu s t r y s t and ar d

JEDEC-approved one-time programmable (OTP) PDIP,

SOIC (SOP), and TSOP packages. The device features

two-line control (CE, OE) to eliminate bus contention in

high-speed systems.

With high density 256K word or 512K byte storage capabil-

ity, the AT27C400 allows firmware to be stored reliably and

to be accessed by the system without the delays of mass

storage media.

Atmel’s AT27C400 has additional features that ensure high

ming Algorithm reduces the time required to program the

part and guarantees reliable programming. Programming

time is typically only 50

µs/word. 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

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

terminals. This capacitor should be positioned as close as

possible to the point where the power supply is connected

to the array.