ST24E16
ST25E16
16 Kbit Serial I
2
C EEPROM with Extended Addressing
February 1999
1/16
AI01102B
3
E0-E2
SDA
VCC
ST24E16
ST25E16
WC
SCL
VSS
Figure 1. Logic Diagram
COMPATIBLE with I
2
C EXTENDED
ADDRESSING
TWO WIRE SERIAL INTERFACE,
SUPPORTS 400kHz PROTOCOL
1 MILLION ERASE/WRITE CYCLES, OVER
the FULL SUPPLY VOLTAGE RANGE
40 YEARS DATA RETENTION
SINGLE SUPPLY VOLTAGE
4.5V to 5.5V for ST24E16 version
2.5V to 5.5V for ST25E16 version
WRITE CONTROL FEATURE
BYTE and PAGE WRITE (up to 16 BYTES)
BYTE, RANDOM and SEQUENTIAL READ
MODES
SELF TIMED PROGRAMING CYCLE
AUTOMATIC ADDRESS INCREMENTING
ENHANCED ESD/LATCH UP
PERFORMANCES
DESCRIPTION
The ST24/25E16 are 16 Kbit electrically erasable
programmable memories (EEPROM), organized
as 8 blocks of 256 x8 bits. It is manufactured in
STMicroelectronics's Hi-Endurance Advanced
CMOS technology which guarantees an endur-
ance of one million erase/write cycles over the full
supply voltage range, and a data retention of over
40 years. The ST25E16 operates with a power
supply value as low as 2.5V.
E0 - E2
Chip Enable Inputs
SDA
Serial Data Address Input/Output
SCL
Serial Clock
WC
Write Control
V
CC
Supply Voltage
V
SS
Ground
Table 1. Signal Names
8
1
SO8 (M)
150mil Width
8
1
PSDIP8 (B)
0.25mm Frame
SDA
VSS
SCL
WC
E1
E0
VCC
E2
AI01103B
ST24E16
ST25E16
1
2
3
4
8
7
6
5
Figure 2A. DIP Pin Connections
1
AI01104C
2
3
4
8
7
6
5
SDA
VSS
SCL
WC
E1
E0
VCC
E2
ST24E16
ST25E16
Figure 2B. SO Pin Connections
Both Plastic Dual-in-Line and Plastic Small Outline
packages are available.
Each memory is compatible with the I
2
C extended
addressing standard, two wire serial interface
which uses a bi-directional data bus and serial
clock. The ST24/25E16 carry a built-in 4 bit, unique
device identification code (1010) corresponding to
DESCRIPTION (cont'd)
the I
2
C bus definition. The ST24/25E16 behave as
slave devices in the I
2
C protocol with all memory
operations synchronized by the serial clock. Read
and write operations are initiated by a START
condition generated by the bus master. The START
condition is followed by a stream of 4 bits (identifi-
cation code 1010), 3 bit Chip Enable input to form
a 7 bit Device Select, plus one read/write bit and
terminated by an acknowledge bit.
Symbol
Parameter
Value
Unit
T
A
Ambient Operating Temperature
40 to 125
C
T
STG
Storage Temperature
65 to 150
C
T
LEAD
Lead Temperature, Soldering
(SO8)
(PSDIP8)
40 sec
10 sec
215
260
C
V
IO
Input or Output Voltages
0.6 to 6.5
V
V
CC
Supply Voltage
0.3 to 6.5
V
V
ESD
Electrostatic Discharge Voltage (Human Body model)
(2)
4000
V
Electrostatic Discharge Voltage (Machine model)
(3)
500
V
Notes: 1. Except for the rating "Operating Temperature Range", stresses above those listed in the Table "Absolute Maximum Ratings"
may cause permanent damage to the device. These are stress ratings only and operation of the device at these or any other
conditions above those indicated in the Operating sections of this specification is not implied. Exposure to Absolute Maximum
Rating conditions for extended periods may affect device reliability. Refer also to the STMicroelectronics SURE Program and
other relevant quality documents.
2. 100pF through 1500
; MIL-STD-883C, 3015.7
3. 200pF through 0
; EIAJ IC-121 (condition C)
Table 2. Absolute Maximum Ratings
(1)
2/16
ST24E16, ST25E16
Mode
RW bit
Bytes
Initial Sequence
Current Address Read
'1'
1
START, Device Select, RW = '1'
Random Address Read
'0'
1
START, Device Select, RW = '0', Address,
'1'
reSTART, Device Select, RW = '1'
Sequential Read
'1'
1 to 2048
As CURRENT or RANDOM Mode
Byte Write
'0'
1
START, Device Select, RW = '0'
Page Write
'0'
16
START, Device Select, RW = '0'
Table 4. Operating Modes
Device Code
Chip Enable
RW
Bit
b7
b6
b5
b4
b3
b2
b1
b0
Device Select
1
0
1
0
E2
E1
E0
RW
Note: The MSB b7 is sent first.
Table 3. Device Select Code
When writing data to the memory it responds to the
8 bits received by asserting an acknowledge bit
during the 9th bit time. When data is read by the
bus master, it acknowledges the receipt of the data
bytes in the same way.
Data transfers are terminated with a STOP condi-
tion. In this way, up to 8 ST24/25E16 may be
connected to the same I
2
C bus and selected indi-
vidually, allowing a total addressing field of 128
Kbit.
Power On Reset: V
CC
lock out write protect. In
order to prevent data corruption and inadvertent
write operations during power up, a Power On
Reset (POR) circuit is implemented. Untill the V
CC
voltage has reached the POR threshold value, the
internal reset is active: all operations are disabled
and the device will not respond to any command.
In the same way, when V
CC
drops down from the
operating voltage to below the POR threshold
value, all operations are disabled and the device
will not respond to any command. A stable V
CC
must be applied before applying any logic signal.
SIGNALS DESCRIPTION
Serial Clock (SCL). The SCL input pin is used to
synchronize all data in and out of the memory. A
resistor can be connected from the SCL line to V
CC
to act as a pull up (see Figure 3)
Serial Data (SDA). The SDA pin is bi-directional
and is used to transfer data in or out of the memory.
It is an open drain output that may be wire-OR'ed
with other open drain or open collector signals on
the bus. A resistor must be connected from the SDA
bus line to V
CC
to act as pull up (see Figure 3).
Chip Enable (E0 - E2). These chip enable inputs
are used to set the 3 least significant bits of the 7
bit device select code. They may be driven dynami-
cally or tied to V
CC
or V
SS
to establish the device
select code. Note that the V
IL
and V
IH
levels for the
inputs are CMOS, not TTL compatible.
Write Control (WC). The Write Control feature
WC is useful to protect the contents of the memory
from any erroneous erase/write cycle. The Write
Control signal is used to enable (WC at V
IH
) or
disable (WC at V
IL
) the internal write protection.
The devices with this Write Control feature no
longer supports the multibyte mode of operation.
When unconnected, the WC input is internally read
as V
IL
(see Table 5).
When WC = '1', Device Select and Address bytes
are acknowledged; Data bytes are not acnowl-
edged.
Refer to the AN404 Application Note for more de-
tailed information about Write Control feature.
3/16
ST24E16, ST25E16
AI01115
VCC
CBUS
SDA
RL
MASTER
RL
SCL
CBUS
25
50
75
100
0
4
8
12
16
20
CBUS (pF)
R
L
max (k
)
VCC = 5V
Figure 3. Maximum R
L
Value versus Bus Capacitance (C
BUS
) for an I
2
C Bus, f
C
= 400kHz
DEVICE OPERATION
I
2
C Bus Background
The ST24/25E16 support the extended addressing
I
2
C protocol. This protocol defines any device that
sends data onto the bus as a transmitter and any
device that reads the data as a receiver.The device
that controls the data transfer is known as the
master and the other as the slave. The master will
always initiate a data transfer and will provide the
serial clock for synchronisation. The ST24/25E16
are always slave devices in all communications.
Start Condition. START is identified by a high to
low transition of the SDA line while the clock SCL
is stable in the high state. A START condition must
precede any command for data transfer. Except
during a programming cycle, the ST24/25E16 con-
tinuously monitor the SDA and SCL signals for a
START condition and will not respond unless one
is given.
Stop Condition. STOP is identified by a low to high
transition of the SDA line while the clock SCL is
stable in the high state. A STOP condition termi-
nates communication between the ST24/25E16
and the bus master. A STOP condition at the end
of a Read command forces the standby state. A
STOP condition at the end of a Write command
triggers the internal EEPROM write cycle.
Acknowledge Bit (ACK). An acknowledge signal
is used to indicate a successful data transfer. The
bus transmitter, either master or slave, will release
the SDA bus after sending 8 bits of data. During the
9th clock pulse the receiver pulls the SDA bus low
to acknowledge the receipt of the 8 bits of data.
Data Input. During data input the ST24/25E16
sample the SDA bus signal on the rising edge of
the clock SCL. For correct device operation the
SDA signal must be stable during the clock low to
high transition and the data must change ONLY
when the SCL line is low.
Device Selection. To start communication be-
tween the bus master and the slave ST24/25E16,
the master must initiate a START condition. The 8
bits sent after a START condition are made up of a
device select of 4 bits that identifies the device type,
3 Chip Enable bits and one bit for a READ (RW =
1) or WRITE (RW = 0) operation. There are two
modes both for read and write. These are summa-
rised in Table 4 and described hereafter. A commu-
nication between the master and the slave is ended
with a STOP condition.
4/16
ST24E16, ST25E16
Symbol
Parameter
Test Condition
Min
Max
Unit
C
IN
Input Capacitance (SDA)
8
pF
C
IN
Input Capacitance (other pins)
6
pF
Z
WCL
WC Input Impedance
V
IN
0.3 V
CC
5
20
k
Z
WCH
WC Input Impedance
V
IN
0.7 V
CC
500
k
t
LP
Low-pass filter input time constant
(SDA and SCL)
100
ns
Note: 1. Sampled only, not 100% tested.
Table 5. Input Parameters
(1)
(T
A
= 25
C, f = 400 kHz )
Symbol
Parameter
Test Condition
Min
Max
Unit
I
LI
Input Leakage Current
(SCL, SDA, E0-E2)
0V
V
IN
V
CC
2
A
I
LO
Output Leakage Current
0V
V
OUT
V
CC
SDA in Hi-Z
2
A
I
CC
Supply Current (ST24 series)
f
C
= 400kHz
(Rise/Fall time < 30ns)
2
mA
Supply Current (ST25 series)
1
mA
I
CC1
Supply Current (Standby)
(ST24 series)
V
IN
= V
SS
or V
CC
,
V
CC
= 5V
100
A
V
IN
= V
SS
or V
CC
,
V
CC
= 5V, f
C
= 400kHz
300
A
I
CC2
Supply Current (Standby)
(ST25 series)
V
IN
= V
SS
or V
CC
,
V
CC
= 2.5V
5
A
V
IN
= V
SS
or V
CC
,
V
CC
= 2.5V, f
C
= 400kHz
50
A
V
IL
Input Low Voltage (SCL, SDA)
0.3
0.3 V
CC
V
V
IH
Input High Voltage (SCL, SDA)
0.7 V
CC
V
CC
+ 1
V
V
IL
Input Low Voltage (E0-E2, WC)
0.3
0.5
V
V
IH
Input High Voltage (E0-E2, WC)
V
CC
0.5
V
CC
+ 1
V
V
OL
Output Low Voltage (ST24 series)
I
OL
= 3mA, V
CC
= 5V
0.4
V
Output Low Voltage (ST25 series)
I
OL
= 2.1mA, V
CC
= 2.5V
0.4
V
Table 6. DC Characteristics
(T
A
= 0 to 70
or 40 to 85
C; V
CC
= 4.5V to 5.5V or 2.5V to 5.5V)
5/16
ST24E16, ST25E16
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