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White Electronic Designs Corporation • (602) 437-1520 • www.wedc.com

White Electronic Designs

WME128K8-XXX

January 2004

Rev. 5

White Electronic Designs Corp. reserves the right to change products or specifications without notice.

DATA POLLING

The WME128K8-XXX offers a data polling feature which

allows a faster method of writing to the device. Figure 6

shows the timing diagram for this function. During a byte

or page write cycle, an attempted read of the last byte

written will result in the complement of the written data on

I/O7. Once the write cycle has been completed, true data

is valid on all outputs and the next cycle may begin. Data

polling may begin at any time during the write cycle.

FIGURE 6 – DATA POLLING WAVEFORMS

DATA POLLING CHARACTERISTICS

Parameter

Symbol

Min

Max

Unit

Data Hold Time

tdh

10

ns

OE# Hold Time

toeh

10

ns

OE# To Output Valid

toe

55

ns

Write Recovery Time

twr

0

ns

WE#

HIGH Z

CS#

OE#

ADDRESS

Symbol

Parameter

Min

Max

Units

tDH

Data Hold Time

10

ns

tOEH

OE Hold Time

10

ns

tOE

OE to Output Delay

ns

tOEHP

OE High Pulse

150

ns

tWR

Write Recovery Time

0

ns

TOGGLE BIT: In addition to DATA# Polling another method

for determining the end of a write cycle is provided . During

the write operation, successive attempts to read data from

the device will result in I/O6 toggling between one and zero.

Once the write has completed, I/O6 will stop toggling and

valid data will be read. Reading the toggle bit may begin

at any time during the write cycle.

NOTE:

1. Toggling either OE# or CS# or both OE# and CS# will operate toggle bit.

2. Beginning and ending state of I/O6 will vary

3. Any address location may be used but the address should not vary.

HIGH Z

WE#

CS#

OE#