AT28C17
Features
•
•
•
•
•
•
•
•
•
•
Fast Read Access Time - 150 ns
Fast Byte Write - 200
µs
or 1 ms
Self-Timed Byte Write Cycle
Internal Address and Data Latches
Internal Control Timer
Automatic Clear Before Write
Direct Microprocessor Control
DATA POLLING
READY/BUSY Open Drain Output
Low Power
30 mA Active Current
100
µa
CMOS Standby Current
High Reliability
Endurance: 10
4
or 10
5
Cycles
Data Retention: 10 Years
5V
±
10% Supply
CMOS & TTL Compatible Inputs and Outputs
JEDEC Approved Byte Wide Pinout
Commercial and Industrial Temperature Ranges
16K (2K x 8)
CMOS
E
2
PROM
Description
The AT28C17 is a low-power, high-performance Electrically Erasable and Program-
mable Read Only Memory with easy to use features. The AT28C17 is a 16K memory
organized as 2,048 words by 8 bits. The device is manufactured with Atmel’s reliable
nonvolatile CMOS technology.
(continued)
Pin Configurations
Pin Name
A0 - A10
CE
OE
WE
I/O0 - I/O7
RDY/BUSY
NC
DC
Function
Addresses
Chip Enable
Output Enable
Write Enable
AT28C17
Data Inputs/Outputs
Ready/Busy Output
No Connect
Don’t Connect
PDIP, SOIC
Top View
PLCC
Top View
Note: PLCC package pins 1 and
17 are DON’T CONNECT.
0541A
2-183
Description
(Continued)
The AT28C17 is accessed like a static RAM for the read
or write cycles without the need of external components.
During a byte write, the address and data are latched in-
ternally, freeing the microprocessor address and data bus
for other operations. Following the initiation of a write cy-
cle, the device will go to a busy state and automatically
clear and write the latched data using an internal control
timer. The device includes two methods for detecting the
end of a write cycle, level detection of RDY/BUSY and
DATA POLLING of I/O
7
. Once the end of a write cycle has
been detected, a new access for a read or a write can
begin.
The CMOS technology offers fast access times of 150 ns
at low power dissipation. When the chip is deselected the
standby current is less than 100
µA.
Atmel’s 28C17 has additional features to ensure high
quality and manufacturability. The device utilizes error cor-
rection internally for extended endurance and for im-
proved data retention characteristics. An extra 32-bytes of
E
2
PROM are available for device identification or tracking.
Block Diagram
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 V
CC
+ 0.6V
Voltage on OE and A9
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.
2-184
AT28C17
AT28C17
Device Operation
READ:
The AT28C17 is accessed like a Static RAM.
When CE and OE are low and WE is high, the data stored
at the memory location determined by the address pins is
asserted on the outputs. The outputs are put in a high im-
pedance state whenever CE or OE is high. This dual line
control gives designers increased flexibility in preventing
bus contention.
BYTE WRITE:
Writing data into the AT28C17 is similar to
writing into a Static RAM. A low pulse on the WE or CE
input with OE high and CE or WE low (respectively) initi-
ates a byte write. The address location is latched on the
last falling edge of WE (or CE); the new data is latched on
the first rising edge. Internally, the device performs a self-
clear before write. Once a byte write has been started, it
will automatically time itself to completion. Once a pro-
gramming operation has been initiated and for the dura-
tion of t
WC
, a read operation will effectively be a polling
operation.
FAST BYTE WRITE:
The AT28C17E offers a byte write
time of 200
µs
maximum. This feature allows the entire
device to be rewritten in 0.4 seconds.
READY/BUSY:
Pin 1 is an open drain READY/BUSY
output that can be used to detect the end of a write cycle.
RDY/BUSY is actively pulled low during the write cycle
and is released at the completion of the write. The open
drain connection allows for OR-tying of several devices to
the same RDY/BUSY line.
DATA POLLING:
The AT28C17 provides DATA POLL-
ING to signal the completion of a write cycle. During a
write cycle, an attempted read of the data being written
results in the complement of that data for I/O
7
(the other
outputs are indeterminate). When the write cycle is fin-
ished, true data appears on all outputs.
WRITE PROTECTION:
Inadvertent writes to the device
are protected against in the following ways. (a) V
CC
sense— if V
CC
is below 3.8V (typical) the write function is
inhibited. (b) V
CC
power on delay— once V
CC
h a s
reached 3.8V the device will automatically time out 5 ms
(typical) before allowing a byte write. (c) Write Inhibit—
holding any one of OE low, CE high or WE high inhibits
byte write cycles.
CHIP CLEAR:
The contents of the entire memory of the
AT28C17 may be set to the high state by the CHIP CLEAR
operation. By setting CE low and OE to 12 volts, the chip
is cleared when a 10 msec low pulse is applied to WE.
DEVICE IDENTIFICATION:
A n e x t r a 3 2 - b y t e s o f
E
2
PROM memory are available to the user for device
identification. By raising A9 to 12
±
0.5V and using ad-
dress locations 7E0H to 7FFH the additional bytes may be
written to or read from in the same manner as the regular
memory array.
2-185
DC and AC Operating Range
AT28C17-15
Operating
Temperature (Case)
V
CC
Power Supply
Com.
Ind.
0°C - 70°C
-40°C - 85°C
5V
±
10%
Operating Modes
Mode
Read
Write
(2)
Standby/Write Inhibit
Write Inhibit
Write Inhibit
Output Disable
Chip Erase
CE
V
IL
V
IL
V
IH
X
X
X
V
IL
OE
V
IL
V
IH
X
(1)
X
V
IL
V
IH
V
H (3)
3. V
H
= 12.0V
±
0.5V.
WE
V
IH
V
IL
X
V
IH
X
X
V
IL
I/O
D
OUT
D
IN
High Z
High Z
High Z
Notes: 1. X can be V
IL
or V
IH
.
2. Refer to AC Programming Waveforms.
DC Characteristics
Symbol
I
LI
I
LO
I
SB1
I
SB2
I
CC
V
IL
V
IH
V
OL
V
OH
Parameter
Input Load Current
Output Leakage Current
V
CC
Standby Current CMOS
V
CC
Standby Current TTL
V
CC
Active Current AC
Input Low Voltage
Input High Voltage
Output Low Voltage
Output High Voltage
I
OL
= 2.1 mA
= 4.0 for RDY/BUSY
I
OH
= -400
µA
2.4
2.0
.4
Condition
V
IN
= 0V to V
CC
+ 1V
V
I/O
= 0V to V
CC
CE = V
CC
- 0.3V to V
CC
+ 1.0V
CE = 2.0V to V
CC
+ 1.0V
f = 5 MHz; I
OUT
= 0 mA
CE = V
IL
Com.
Ind.
Com.
Ind.
Min
Max
10
10
100
2
3
30
45
0.8
Units
µA
µA
µA
mA
mA
mA
mA
V
V
V
V
2-186
AT28C17
AT28C17
AC Read Characteristics
AT28C17-15
Symbol
t
ACC
t
CE (1)
t
OE (2)
t
DF (3, 4)
t
OH
Parameter
Address to Output Delay
CE to Output Delay
OE to Output Delay
CE or OE High to Output Float
Output Hold from OE, CE or
Address, whichever occurred first
10
0
0
Min
Max
Units
ns
ns
ns
ns
ns
150
150
70
50
AC Read Waveforms
(1, 2, 3, 4)
Notes: 1. CE may be delayed up to t
ACC
- t
CE
after the address
transition without impact on t
ACC
.
2. OE may be delayed up to t
CE
- t
OE
after the falling
edge of CE without impact on t
CE
or by t
ACC
- t
OE
after an address change without impact on t
ACC
.
3. t
DF
is specified from OE or CE whichever occurs first
(C
L
= 5 pF).
4. This parameter is characterized and is not 100% tested.
Input Test Waveforms and
Measurement Level
Output Test Load
t
R
, t
F
< 20 ns
Pin Capacitance
(f = 1 MHz, T = 25°C)
(1)
Typ
C
IN
C
OUT
Note:
Max
6
12
Units
pF
pF
Conditions
V
IN
= 0V
V
OUT
= 0V
4
8
1. This parameter is characterized and is not 100% tested.
2-187
