AT29C432 데이터 시트보기 (PDF) - Atmel Corporation

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AT29C432

4 Megabit 5-volt Flash with 256K E2PROM Memory

Atmel Corporation 

Device Operation (Continued)

Memory Arrays

Concurrent Read While Write

The architecture of the AT29C432 provides concurrent

read while write capability. With other programmable non-

volatile memories internal high voltage operations prevent

the reading of data while a write operation is in process.

However, the AT29C432 is partitioned in a manner to al-

low read operations from the Flash memory array during a

write operation within the E2PROM memory array.

Conceptually the device was designed assuming the

Flash memory array would be utilized for infrequently up-

dated program storage and the E2PROM memory array

would be used for frequently updated data storage. This

simple concept eliminates complicated software and hard-

ware schemes using multiple blocks of memory just to

hold duplicate down-load routines.

Valid Concurrent Read

Reads from the Flash are allowed throughout the

E2PROM write cycle time (tWCE). The E2PROM memory

array must be deselected (CEE HIGH).

Reads from the Flash are allowed during tWPH o f a

E2PROM write so long as tBLC for the E2PROM write is not

violated. The E2PROM memory array must be deselected

(CEE HIGH).

Invalid Concurrent Reads

Attempts to read the Flash memory array during tWCF will

effectively be polling operations.

Attempts to access the Flash memory array while CEE is

low will be ignored. That is, CEE low and CEF low at the

same time is not allowed. Attempts to read the E2PROM

memory array while a write to the Flash memory array is

in progress is not allowed.

Absolute Maximum Ratings*

Temperature Under Bias................. -55°C to +125°C

Storage Temperature...................... -65°C to +150°C

All Input Voltages

(including NC Pins)

with Respect to Ground ................... -0.6V to +6.25V

All Output Voltages

with Respect to Ground .............-0.6V to VCC + 0.6V

Voltage on OE

with Respect to Ground ................... -0.6V to +13.5V

*NOTICE: Stresses beyond those listed under “Absolute Maxi-

mum Ratings” may cause permanent damage to the device.

This is a stress rating only and functional operation of the

device at these or any other conditions beyond those indi-

cated in the operational sections of this specification is not

implied. Exposure to absolute maximum rating conditions

for extended periods may affect device reliability.

Pin Capacitance (f = 1 MHz, T = 25°C) (1)

Parameter

Typ

CIN

Input Capacitance

4

COUT Output Capacitance

8

Note: 1. This parameter is characterized and is not 100% tested.

Max

10

12

4

AT29C432

Units

pF

pF

Conditions

VIN = 0V

VOUT = 0V

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