ST24FC21M6TR STMicroelectronics, ST24FC21M6TR Datasheet - Page 5

• Manufacturer Part Number: ST24FC21M6TR
• Description: EEPROM Serial-I2C 1K-Bit 128 x 8 3.3V/5V 8-Pin SO N T/R
• Manufacturer: STMicroelectronics

Specifications of ST24FC21M6TR

• Package: 8SO N
• Interface Type: Serial-I2C
• Density: 1 Kb
• Maximum Operating Frequency: 0.1|0.4 MHz
• Maximum Random Access Time: 3500|900 ns
• Typical Operating Supply Voltage: 3.3|5 V
• Organization: 128x8
• Data Retention: 40 Year
• Hardware Data Protection: Yes
• Operating Temperature: -40 to 85 °C

Figure 4. Transition from Transmit Only (DDC1) to Bi-directional (DDC2B) Mode Waveforms
A byte is clocked out (on SDA pin) with nine clock
pulses on VCLK: 8 clock pulses for the data byte
and one extra clock pulse for a Don’t Care bit.
As long as the SCL pin is held high, each byte of
the memory array is transmitted serially on the SDA
pin with an automatic address increment.
When the last byte is transmitted, the address
counter will roll-over to location 00h.
I
The ST24xy21 can be switched from Transmit Only
mode to I
high to low transition on the SCL pin (see Figure 4).
– When the ST24LC21B (or the ST24FC21 or
– When the ST24LW21 (or the ST24FW21) is in
The ST24xy21 is compatible with the I
two wire serial interface which uses a bidirectional
data bus and serial clock. The ST24xy21 carries a
built-in 4 bit, unique device identification code
(1010) named Device Select code corresponding
to the I
unique device identification code (1010.0000 RW)
2
C Bidirectional Mode
the ST24FC21B) is in the I
mode, the VCLK input (pin 7) enables (or inhib-
its) the execution of any write instruction: if
VCLK = 1, write instructions are executed; if
VCLK = 0, write instructions are not executed.
the I
(WC on pin 3) input enables (or inhibits) the
execution of any write instruction: if WC = 1,
write instructions are executed;if WC = 0,
write instructions are not executed.
SCL
SDA
VCLK
2
2
C bus definition. The ST24LC21B carries a
C Bidirectional mode, the Write Control
2
C Bidirectional mode by applying a valid
Transmit Only Mode
2
C Bidirectional
ST24LC21B, ST24LW21, ST24FC21, ST24FC21B, ST24FW21
2
C standard,
- Temporary Bi-Directional Mode
- Locked Bi-Directional Mode
(ST24FC21 and ST24FW21)
(ST24LC21B and ST24LW21)
START
CONDITION
MSB
1
named Device Select code corresponding to the
I
The ST24xy21 behaves as a slave device in the
I
nized by the serial clock SCL. Read and write
operations are initiated by a START condition gen-
erated by the bus master. The START condition is
followed by a stream of 7 bits, plus one read/write
bit and terminated by an acknowledge bit.
When data is written into the memory, the
ST24xy21 responds to the 8 bits received by as-
serting an acknowledge bit during the 9th bit time.
When data is read by the bus master, it must
acknowledge the receipt of the data bytes in the
same way. Data transfers are terminated with a
STOP condition (see READ and WRITE descrip-
tions in the following pages).
Power On Reset: V
In order to prevent data corruption and inadvertent
write operations during power up, a Power On
Reset (POR) circuit is implemented. Until the V
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
operating voltage to below the POR threshold
value, all operations are disabled and the device
will not respond to any command. A stable V
must be applied before applying any logic signal.
Error Recovery Modes available in the
ST24FC21, ST24FC21B and the ST24FW21
2
2
C bus definition.
C protocol with all memory operations synchro-
2
8
CC
ACK
lock out write protect
9
CC
drops down from the
- Locked Bi-Directional
Mode (ST24FC21
and ST24FW21)
AI01892
5/22
CC
CC