SGS Thomson Microelectronics ST25W08, ST25C08, ST24W08, ST24C08 Datasheet

with User-Defined Block Write Protection

1 MILLION ERASE/WRITE CYCLES with
40 YEARS DAT A RE TENTION

SINGLE SUPPLY VOLTAGE:
– 3V to 5.5V for ST24x08 versions
– 2.5V to 5.5V for ST25x08 versions
HARDWARE WRITE CONT ROL VERSIONS:

ST24W08 and ST25W08
PROGRAMMABLE WRITE PROTECTION
TWO WIRE SERIAL INTERFACE, FULLY I2C

BUS COMPATIBLE
BYTE and MULTIBYTE WRITE (up to 8

BYTES)
PAGE WRITE (up to 16 BYTES)
BYTE, RANDOM and SEQUENTIAL READ

MODES
SELF TIMED PROGRAMMING CYCLE
AUTOMATIC ADDRESS INCREME NTING
ENHANCE D ESD/LATCH UP

PERFOR MAN C ES

ST24C08, ST25C08

ST24W08, ST25W08

8 Kbit Serial I2C Bus EEPROM

8

1

PSDIP8 (B)

0.25mm Frame

Figure 1. Logic Diagram

8

1

SO8 (M)

150mil Width

V

CC

DESCRIPTION

2

This specification covers a range of 8 Kbits I

C bus
EEPROM products, the ST24/25C08 and the
ST24/25W08. In the text, products are referred to
as ST24/25x08, where "x" is: "C" for Standard
version and "W" for Hardware Write Control ver­sion.

T ab le 1. Signal Names

PRE Write Protect Enable
E Chip Enable Input
SDA Serial Data Address Input/Output
SCL Serial Clock

MODE
WC Write Control (W version)

V

CC

V

SS

February 1999 1/16

Multibyte/Page Write Mode
(C version)

Supply Voltage
Ground

MODE/WC*

Note:

WC signal is only available for ST24/25W08 products.

E SDA

PRE

SCL

ST24x08
ST25x08

V

SS

AI00860E

ST24/25C08, ST24/25W08

Figure 2A. DIP Pin Connections

ST24x08
ST25x08

1

PRE V

2
3

E

4

SS

Warning:

NC = Not Connected.

T ab le 2. Absolute Maximum Ratings

Symbol Parameter Value Unit

T

T

V

Notes:

T

STG

LEAD

V

V

ESD

Ambient Operating Temperature –40 to 125

A

Storage Temperature –65 to 150
Lead Temperature, Soldering (SO8 package)

Input or Output Voltages –0.6 to 6.5 V

IO

Supply Voltage –0.3 to 6.5 V

CC

Electrostatic Discharge Voltage (Human Body model)
Electrostatic Discharge Voltage (Machine model)

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 rating s 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. MIL-STD-883C, 3015.7 (100pF, 1500 Ω).

3. EIAJ IC-121 (Condition C) (200pF, 0 Ω).

8
7
6
5

AI00861E

CC

MODE/WCNC
SCL
SDAV

(1)

(PSDIP8 package)

Figure 2B. SO Pin Connections

ST24x08
ST25x08

8
7
6
5

AI01073E

215
260

4000 V

500 V

Warning:

(2)

(3)

PRE V

1
2
3

E

SS

NC = Not Connected.

40 sec
10 sec

4

CC

MODE/WCNC
SCL
SDAV

C

°

C

°

C

°

DESCRIPTION (cont’d)
The ST24/25x08 are 8 Kbit electrically erasable

programmable memories (EEPROM), organized
as 4 blocks of 256 x8 bits. They are manufactured
in STMicroelectronics’s Hi-Endurance Advanced
CMOS technology which guarantees an endur­ance of one million erase/write cycles with a data
retention of 40 years.

Both Plastic Dual-in-Line and Plastic Small Out line
packages are available.

2

The memories are compatible with the I

C stand-

ard, two wire serial interface which uses a bi-direc-

2/16

tional data bus and serial clock. The memories
carry a built-in 4 bit, unique device identification
code (1010) corresponding to the I2C bus defini­tion. This is used together with 1 chip enable input
(E) so that up to 2 x 8K devices may be attached

2

to the I
ries behave as a slave device in the I

C bus and selected individually. The memo-

2

C protocol
with all memory operations synchronized by the
serial clock. Read and write operations are initiated
by a STAR T condition generated by the bus master .
The START condition is followed by a stream of 7
bits (identification code 1010), plus one read/write
bit and terminated by an acknowledge bit.

T ab le 3. Device Select Code

ST24/25C08, ST24/25W08

Device Code

Bit b7 b6 b5 b4 b3 b2 b1 b0
Device Select 1 0 1 0 E A9 A8 R

Note:

The MSB b7 is sent first.

T ab le 4. Operating Modes

Mode RW bit MODE Bytes Initial Sequence

Current Address Read ’ 1’ X 1 STAR T, Device Select, R

Random Address Read

Sequential Read ’1’ X 1 to 1024 Similar to Current or Random Mode
Byte Write ’0’ X 1 START, Device Select, R

IH

or V

(2)

IL

Multibyte Write
Page Write ’0’ V

Notes:

1. X = V

2. Multibyte Write not available in ST24/25W08 versions.

(1)

’0’
’1’ reSTART, Device Select, R

’0’ V

X1

IH

IL

8 START, Device Select, RW = ’0’

16 START, Device Select, RW = ’0’

Chip

Enable

START, Device Select, R

Block

Select

W = ’1’
W = ’0’, Address,

W = ’1’

W = ’0’

R

W

W

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 condition.

Power On Reset: V

lock out write protect . In

CC

order to prevent data corruption and inadvertent
write operations during power up, a Power On
Reset (POR) circuit is implemented. Until 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 c ommand.
In the same way, when V

drops down from the

CC

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.

SIGNAL DESCRIPTIONS
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

to act as pull up (see Figure 3).

CC

Chip Enable (E). This chip enable input is used to
set one least significant bit (b3) of the device select
byte code. This input may be driven dynamically or
tied to V

or VSS to establish the device select

CC

code.
Protect Enable (PRE). The PRE input pin, in ad-

dition to the status of the Block Address Pointer bit
(b2, location 3FFh as in Figure 7), sets the PRE
write protection active.

Mode (M ODE). The MO DE input is available on pin
7 (see also
cally. It must be at V
mode, V

WC feature) and may be driven dynami-

or VIH for the Byte Write

for Multibyte Write mode or VIL for Page

IH

IL

Write mode. When unconnected, the MODE input
is internally read as a V

Write Control (

(

WC) feature is offered only for ST24W08 and

WC) . An hardware Write Control

(Multibyte Write mode).

IH

ST25W08 versions on pin 7. This feature is usefull
to protect the contents of the memory from any
erroneous erase/write cycle. The Write Control sig­nal is used to enable (

) the internal write protection. When uncon-

V

IL

nected, the

WC input is internally read as VIL and

WC = VIH) or disable (WC =

the memory area is not write protected.

3/16

ST24/25C08, ST24/25W08

SIGNAL DESCRIPTIONS (cont’d)

The devices with this Write Control feature no
longer support the Multibyte Write mode of opera­tion, however all other write modes are fully sup­ported.

Refer to the AN404 Application Note for more de­tailed information about Write Control feature.

DEVICE O PERATION

2

C Bus Background

I

The ST24/25x08 support the 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 devic e 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 ST24/25x08 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 ST AR T condition must
precede any command for data transfer. Except
during a programming cycle, the ST24/25x08 con­tinuously 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 termi­nates communication between the ST24/25x08
and the bus master. A STOP condition at the end
of a Read command, after and only after a No
Acknowledge, forces the standby state. A STOP
condition at the end of a Write command triggers
the internal EEPROM write cycle.

Acknowledge B it ( ACK). An acknowledge signal
is used to indicate a successfull data transfer. The
bus transmitter, eit her master or s lave, will release
the SDA bus after sending 8 bits of data. During the
9th clock pulse period the receiver pulls t he SDA
bus low to acknowledge the receipt of the 8 bits of
data.

Data Input. During data input the ST24/25x08
sample the SDA bus signal on the rising edge of
the clock SCL. Note that 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.

Memory Addressing. To start communication be­tween the bus master and the slave ST24/25x08,
the master must initiate a ST ART condition. Follow­ing this, the master sends onto the SDA bus line 8
bits (MSB first) corresponding to the device select
code (7 bits) and a READ or WRITE bit.

Figure 3. Maximum RL Value versus Bus Capacitance (C

20

16

12

max (kΩ)

L

R

8

4

0

VCC = 5V

100 200 300 400

C

(pF)

BUS

) for an I2C Bus

BUS

V

CC

MASTER

SDA

SCL

R

R

BUS

L

C

BUS

AI01100

L

C

4/16

ST24/25C08, ST24/25W08

T able 5. Input Parameters

(1)

(TA = 25 °C, f = 100 kHz )

Symbol Parameter Test Condition Min Max Unit

C

IN

C

IN

Z

WCL

Z

WCH

t

LP

Note:

1. Sampled only, not 100% tested.

Input Capacitance (SDA) 8 pF
Input Capacitance (other pins) 6 pF
WC Input Impedance (ST24/25W08) VIN ≤ 0.3 V
WC Input Impedance (ST24/25W08) VIN ≥ 0.7 V
Low-pass filter input time constant

(SDA and SCL)

CC

CC

520k

500 k

100 ns

T ab le 6. DC Characteristics
(T

= 0 to 70°C, –20 to 85°C or –40 to 85°C; VCC = 3V to 5.5V or 2.5V to 5.5V)

A

Symbol Parameter Test Condition Min Max Unit

I

I

V

V

V

I

LI

I

LO

I

CC

CC1

CC2

V

V

OL

IL

IH

IL

IH

Input Leakage Current 0V ≤ VIN ≤ V
Output Leakage Current

Supply Current (ST24 series)
Supply Current (ST25 series) V

Supply Current (Standby)
(ST24 series)

Supply Current (Standby)
(ST25 series)

0V ≤ V

SDA in Hi-Z

V

= 5V, fC = 100kHz

CC

(Rise/Fall time < 10ns)

= 2.5V, fC = 100kHz 1 mA

CC

V

= VSS or VCC,

IN

V

CC

V

= VSS or VCC,

IN

V

= 5V, fC = 100kHz

CC

= VSS or VCC,

V

IN

V

CC

V

= VSS or VCC,

IN

V

= 2.5V, fC = 100kHz

CC

≤ VCC

OUT

= 5V

= 2.5V

CC

Input Low Voltage (SCL, SDA) –0.3 0.3 V
Input High Voltage (SCL, SDA) 0.7 V
Input Low Voltage

(E, PRE, MODE,

WC)

Input High Voltage
(E, PRE, MODE,

WC)

CC

–0.3 0.5 V

V

– 0.5 VCC + 1 V

CC

2

±

2

±

2mA

100

300

5

50

CC

VCC + 1 V

Output Low Voltage (ST24 series) IOL = 3mA, VCC = 5V 0.4 V
Output Low Voltage (ST25 series) I

= 2.1mA, VCC = 2.5V 0.4 V

OL

Ω
Ω

A

µ

A

µ

A

µ

A

µ

A

µ

A

µ

V

5/16