1999 Microchip Technology Inc.
DS21100F-page 1
FEATURES
Single supply with operation down to 1.8V
Low power CMOS technology
- 1 mA active current typical
- 10
A standby current typical at 5.5V
- 5
A standby current typical at 3.0V
Organized as 8 blocks of 256 bytes (8 x 256 x 8)
2-wire serial interface bus, I
2
C
TM
compatible
Functional address inputs for cascading up to 8
devices
Schmitt trigger, filtered inputs for noise suppres-
sion
Output slope control to eliminate ground bounce
100 kHz (1.8V) and 400 kHz (5V) compatibility
Self-timed write cycle (including auto-erase)
Page-write buffer for up to 16 bytes
2 ms typical write cycle time for page-write
Hardware write protect for entire memory
Can be operated as a serial ROM
Factory programming (QTP) available
ESD protection > 4,000V
1,000,000 Erase/Write cycles guaranteed
Data retention > 200 years
8-pin DIP, 8-lead SOIC packages
Available for commercial temperature range
DESCRIPTION
The Microchip Technology Inc. 24AA164 is a cascad-
able 16K bit Electrically Erasable PROM. The device is
organized as eight blocks of 256 x 8-bit memory with a
2-wire serial interface. Low voltage design permits
operation down to 1.8 volts (end-of-life voltage for most
popular battery technologies) with standby and active
currents of only 5
A and 1 mA respectively. The
24AA164 also has a page-write capability for up to 16
bytes of data. The 24AA164 is available in the standard
8-pin DIP and 8-lead surface mount SOIC packages.
The three select pins, A0, A1, and A2, function as chip
select inputs and allow up to eight devices to share a
common bus, for up to 128K bits total system
EEPROM.
- Commercial (C):
0C to +70C
PACKAGE TYPES
BLOCK DIAGRAM
24AA164
A0
A1
A2
V
SS
1
2
3
4
8
7
6
5
V
CC
WP
SCL
SDA
24AA164
A0
A1
A2
V
SS
1
2
3
4
8
7
6
5
V
CC
WP
SCL
SDA
PDIP
8-lead
SOIC
HV GENERATOR
EEPROM ARRAY
(8 x 256 x 8)
PAGE LATCHES
YDEC
XDEC
SENSE AMP
R/W CONTROL
MEMORY
CONTROL
LOGIC
I/O
CONTROL
LOGIC
WP
SDA
SCL
V
CC
V
SS
A0
A2
A1
24AA164
16K 1.8V Cascadable I
2
C
TM
Serial EEPROM
I
2
C is a trademark of Philips Corporation.
24AA164
DS21100F-page 2
1999 Microchip Technology Inc.
1.0
ELECTRICAL CHARACTERISTICS
1.1
Maximum Ratings*
V
CC
...................................................................................7.0V
All inputs and outputs w.r.t. V
SS ..................
-0.3V to V
CC
+1.0V
Storage temperature ..................................... -65C to +150C
Ambient temp. with power applied................. -65C to +125C
Soldering temperature of leads (10 seconds) ............. +300C
ESD protection on all pins
..................................................
4 kV
*Notice:
Stresses above those listed under "Maximum ratings"
may cause permanent damage to the device. This is a stress rat-
ing only and functional operation of the device at those or any
other conditions above those indicated in the operational listings
of this specification is not implied. Exposure to maximum rating
conditions for extended periods may affect device reliability.
TABLE 1-1:
PIN FUNCTION TABLE
Name
Function
V
SS
Ground
SDA
Serial Address/Data I/O
SCL
Serial Clock
WP
Write Protect Input
V
CC
1.8V to 6.0V Power Supply
A0, A1, A2
Chip Address Inputs
TABLE 1-2:
DC CHARACTERISTICS
FIGURE 1-1:
BUS TIMING START/STOP
V
CC
= 1.8V to +6.0
Commercial (C): Tamb = 0C to +70C
Parameter
Symbol
Min
Typ
Max
Units
Conditions
WP, SCL and SDA pins:
High level input voltage
V
IH
.7 V
CC
--
V
Low level input voltage
V
IL
--
.3 V
CC
V
Hysteresis of Schmitt trigger inputs
V
HYS
.05 V
CC
--
V
(Note)
Low level output voltage
V
OL
--
.40
V
I
OL
= 3.0 mA, V
CC
= 1.8V
Input leakage current
I
LI
-10
10
A
V
IN
= .1V to V
CC
Output leakage current
I
LO
-10
10
A
V
OUT
= .1V to V
CC
Pin capacitance
(all inputs/outputs
C
IN
,
C
OUT
--
10
pF
V
CC
= 5.0V (Note 1)
Tamb = 25C, F
CLK
= 1 MHz
Operating current
I
CC
Write
I
CC
Read
--
--
--
--
--
0.5
--
0.05
3
--
1
--
mA
mA
mA
mA
V
CC
= 5.5V, SCL = 400 kHz
V
CC
= 1.8V, SCL = 100 kHz
V
CC
= 5.5V, SCL = 400 kHz
V
CC
= 1.8V, SCL = 100 kHz
Standby current
I
CCS
--
--
--
--
--
3
100
30
--
A
A
A
V
CC
= 5.5V, SDA = SCL=V
CC
V
CC
= 3.0V, SDA = SCL=V
CC
V
CC
= 1.8V, SDA = SCL=V
CC
WP = V
SS
Note:
This parameter is periodically sampled and not 100% tested.
T
SU
:
STA
T
HD
:
STA
V
HYS
T
SU
:
STO
START
STOP
SCL
SDA
1999 Microchip Technology Inc.
DS21100F-page 3
24AA164
TABLE 1-3:
AC CHARACTERISTICS
FIGURE 1-2:
BUS TIMING DATA
Parameter
Symbol
STANDARD
MODE
V
CC
= 4.5-5.5V
FAST MODE
Units
Remarks
Min
Max
Min
Max
Clock frequency
F
CLK
--
100
--
400
kHz
Clock high time
T
HIGH
4000
--
600
--
ns
Clock low time
T
LOW
4700
--
1300
--
ns
SDA and SCL rise time
T
R
--
1000
--
300
ns
(Note 1)
SDA and SCL fall time
T
F
--
300
--
300
ns
(Note 1)
START condition hold
time
T
HD
:
STA
4000
--
600
--
ns
After this period the first
clock pulse is generated
START condition setup
time
T
SU
:
STA
4700
--
600
--
ns
Only relevant for repeated
START condition
Data input hold time
T
HD
:
DAT
0
--
0
--
ns
Data input setup time
T
SU
:
DAT
250
--
100
--
ns
STOP condition setup
time
T
SU
:
STO
4000
--
600
--
ns
Output valid from clock
T
AA
--
3500
--
900
ns
(Note 2)
Bus free time
T
BUF
4700
--
1300
--
ns
Time the bus must be free
before a new transmission
can start
Output fall time from V
IH
min to V
IL
max
T
OF
--
250
20 + 0.1
C
B
250
ns
(Note 1), C
B
100 pF
Input filter spike suppres-
sion (SDA and SCL pins)
T
SP
--
50
--
50
ns
(Note 3)
Write cycle time
T
WR
--
10
--
10
ms
Byte or Page mode
Endurance
--
1M
--
1M
--
cycles
25C, Vcc = 5.0V, Block
Mode ((Note 4)
Note 1: Not 100% tested. C
B
= total capacitance of one bus line in pF.
2: As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region
(minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions.
3: The combined T
SP
and V
HYS
=specifications are due to new Schmitt trigger inputs which provide improved
noise and spike suppression. This eliminates the need for a T
I
specification for standard operation.
4: This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific appli-
cation, please consult the Total Endurance Model which can be obtained on our website.
SCL
SDA
IN
SDA
OUT
T
SU
:
STA
T
SP
T
AA
T
F
T
LOW
T
HIGH
T
HD
:
STA
T
HD
:
DAT
T
SU
:
DAT
T
SU
:
STO
T
BUF
T
AA
T
R
24AA164
DS21100F-page 4
1999 Microchip Technology Inc.
2.0
FUNCTIONAL DESCRIPTION
The 24AA164 supports aBi-directional two wire bus
and data transmission protocol. A device that sends
data onto the bus is defined as transmitter, and a
device receiving data as receiver. The bus has to be
controlled by a master device which generates the
serial clock (SCL), controls the bus access, and gener-
ates the START and STOP conditions, while the
24AA164 works as slave. Both, master and slave can
operate as transmitter or receiver but the master device
determines which mode is activated.
3.0
BUS CHARACTERISTICS
The following bus protocol has been defined:
Data transfer may be initiated only when the bus
is not busy.
During data transfer, the data line must remain
stable whenever the clock line is HIGH. Changes
in the data line while the clock line is HIGH will be
interpreted as a START or STOP condition.
Accordingly, the following bus conditions have been
defined (Figure 3-1).
3.1
Bus not Busy (A)
Both data and clock lines remain HIGH.
3.2
Start Data Transfer (B)
A HIGH to LOW transition of the SDA line while the
clock (SCL) is HIGH determines a START condition. All
commands must be preceded by a START condition.
3.3
Stop Data Transfer (C)
A LOW to HIGH transition of the SDA line while the
clock (SCL) is HIGH determines a STOP condition. All
operations must be ended with a STOP condition.
3.4
Data Valid (D)
The state of the data line represents valid data when,
after a START condition, the data line is stable for the
duration of the HIGH period of the clock signal.
The data on the line must be changed during the LOW
period of the clock signal. There is one clock pulse per
bit of data.
Each data transfer is initiated with a START condition
and terminated with a STOP condition. The number of
the data bytes transferred between the START and
STOP conditions is determined by the master device
and is theoretically unlimited, although only the last 16
will be stored when doing a write operation. When an
overwrite does occur it will replace data in a first in first
out fashion.
3.5
Acknowledge
Each receiving device, when addressed, is obliged to
generate an acknowledge after the reception of each
byte. The master device must generate an extra clock
pulse which is associated with this acknowledge bit.
The device that acknowledges, has to pull down the
SDA line during the acknowledge clock pulse in such a
way that the SDA line is stable LOW during the HIGH
period of the acknowledge related clock pulse. Of
course, setup and hold times must be taken into
account. During reads, a master must signal an end of
data to the slave by not generating an acknowledge bit
on the last byte that has been clocked out of the slave.
In this case, the slave (24AA164) will leave the data line
HIGH to enable the master to generate the STOP con-
dition.
Note:
The 24AA164 does not generate any
acknowledge bits if an internal program-
ming cycle is in progress.
FIGURE 3-1:
DATA TRANSFER SEQUENCE ON THE SERIAL BUS
SCL
SDA
(A)
(B)
(D)
(D)
(A)
(C)
START
CONDITION
ADDRESS OR
ACKNOWLEDGE
VALID
DATA
ALLOWED
TO CHANGE
STOP
CONDITION
1999 Microchip Technology Inc.
DS21100F-page 5
24AA164
3.6
Device Addressing
A control byte is the first byte received following the
start condition from the master device. The first bit is
always a one. The next three bits of the control byte are
the device select bits (A2, A1, A0). They are used to
select which of the eight devices are to be accessed.
The A1 bit must be the inverse of the A1 device select
pin.
The next three bits of the control byte are the block
select bits (B2, B1, B0). They are used by the master
device to select which of the eight 256 word blocks of
memory are to be accessed. These bits are in effect
the three most significant bits of the word address.
The last bit of the control byte defines the operation to
be performed. When set to one a read operation is
selected, when set to zero a write operation is selected.
Following the start condition, the 24AA164 looks for the
slave address for the device selected. Depending on
the state of the R/W bit, the 24AA164 will select a read
or write operation.
FIGURE 3-2:
CONTROL BYTE
ALLOCATION
Operation
Control Code
Block Select
R/W
Read
1
A2 A1 A0
Block Address
1
Write
1
A2 A1 A0
Block Address
0
SLAVE ADDRESS
1
A2
A1
A0
B2
B1
B0
R/W A
START
READ/WRITE
MSB
LSB
4.0
WRITE OPERATION
4.1
Byte Write
Following the start condition from the master, the
device code (4 bits), the block address (3 bits), and the
R/W bit which is a logic low is placed onto the bus by
the master transmitter. This indicates to the addressed
slave receiver that a byte with a word address will follow
after it has generated an acknowledge bit during the
ninth clock cycle. Therefore the next byte transmitted
by the master is the word address and will be written
into the address pointer of the 24AA164. After receiv-
ing another acknowledge signal from the 24AA164 the
master device will transmit the data word to be written
into the addressed memory location. The 24AA164
acknowledges again and the master generates a stop
condition. This initiates the internal write cycle, and
during this time the 24AA164 will not generate
acknowledge signals (Figure 4-1).
4.2
Page Write
The write control byte, word address and the first data
byte are transmitted to the 24AA164 in the same way
as in a byte write. But instead of generating a stop con-
dition the master transmits up to 16 data bytes to the
24AA164 which are temporarily stored in the on-chip
page buffer and will be written into the memory after the
master has transmitted a stop condition. After the
receipt of each word, the four lower order address
pointer bits are internally incremented by one. The
higher order seven bits of the word address remains
constant. If the master should transmit more than 16
words prior to generating the stop condition, the
address counter will roll over and the previously
received data will be overwritten. As with the byte write
operation, once the stop condition is received an inter-
nal write cycle will begin (Figure 4-2).
Note:
Page write operations are limited to writing
bytes within a single physical page,
regardless of the number of bytes actually
being written. Physical page boundaries
start at addresses that are integer multiples
of the page buffer size (or page size) and
end at addresses that are integer multiples
of [page size - 1]. If a page write command
attempts to write across a physical page
boundary, the result is that the data wraps
around to the beginning of the current page
(overwriting data previously stored there),
instead of being written to the next page as
might be expected. It is therefore neces-
sary for the application software to prevent
page write operations that would attempt to
cross a page boundary.
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