w29c020-12b Winbond Electronics Corp America, w29c020-12b Datasheet - Page 5

• Manufacturer Part Number: w29c020-12b
• Description: 256k X 8 Cmos Flash Memory
• Manufacturer: Winbond Electronics Corp America

Toggle Bit (DQ6)- Write Status Detection
In addition to data polling, the W29C020 provides another method for determining the end of a write
cycle. During the internal write cycle, any consecutive attempts to read DQ6 will produce alternating
0's and 1's. When the write cycle is completed, this toggling between 0's and 1's will stop. The device
is then ready for the next operation. See Toggle Bit Timing Diagram.
Product Identification
The product ID operation outputs the manufacturer code and device code. The programming
equipment automatically matches the device with its proper erase and programming algorithms.
The manufacturer and device codes can be accessed through software or by hardware operation. In
the software access mode, a six-byte command sequence can be used to access the product ID. A
read from address "00000 hex" outputs the manufacturer code "DA hex." A read from address "00001
hex" outputs the device code "45 hex." The product ID operation can be terminated by a three-byte
command sequence.
In the hardware access mode, access to the product ID is activated by forcing CE and OE low, WE
high, and raising A9 to 12 volts.
TABLE OF OPERATING MODES
Operating Mode Selection
Operating Range: 0 to 70 C (Ambient Temperature), V
Read
Write
Standby
Write Inhibit
Output Disable
5-Volt Software Chip Erase
Product ID
MODE
V
CE
V
V
V
V
V
X
X
X
IH
IL
IL
IL
IL
IL
OE
V
V
V
V
V
V
V
X
X
IH
IH
IH
IL
IL
IL
IL
DD
WE
V
V
V
V
V
V
X
X
X
IH
IH
IH
IH
IL
IL
= 5V 10%, V
A
A
X
X
X
X
A
A0 = V
A9 = V
A0 = V
A9 = V
- 5 -
IN
IN
IN
IL
HH
IH
HH
SS
ADDRESS
; A1 A17 = V
; A1 A17 = V
= 0V, V
PINS
Publication Release Date: February 1998
HH
= 12V
IL
IL
;
;
Dout
Din
High Z
High Z/D
High Z/D
High Z
D
Manufacturer Code DA
(Hex)
Device Code
45 (Hex)
IN
W29C020
OUT
OUT
DQ.
Revision A3