24LC22A-I/SN Microchip Technology, 24LC22A-I/SN Datasheet - Page 5

• Manufacturer Part Number: 24LC22A-I/SN
• Description: IC EEPROM 2KBIT 400KHZ 8SOIC
• Manufacturer: Microchip Technology

Specifications of 24LC22A-I/SN

• Memory Size: 2K (256 x 8)
• Package / Case: 8-SOIC (3.9mm Width)
• Operating Temperature: -40°C ~ 85°C
• Format - Memory: EEPROMs - Serial
• Memory Type: EEPROM
• Speed: 100kHz, 400kHz
• Interface: I²C, 2-Wire Serial
• Voltage - Supply: 2.5 V ~ 5.5 V
• Organization: 256 K x 8
• Interface Type: 2-Wire
• Maximum Clock Frequency: 0.1 MHz
• Access Time: 10 ms
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 2.5 V
• Maximum Operating Current: 3 mA
• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Operating Supply Voltage: 2.5 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 24LC22A-I/SNG; 24LC22A-I/SNG; 24LC22AI/SN

3.0
Before the 24LC22A can be switched into the Bidirec-
tional mode (Figure 3-1), it must enter the Transition
mode, which is done by applying a valid high-to-low
transition on the Bidirectional mode clock (SCL). As
soon it enters the Transition mode, it looks for a control
byte ‘1010 000X’ on the I
count pulses on VCLK. Any high-to-low transition on
the SCL line will reset the count. If it sees a pulse count
of 128 on VCLK while the SCL line is idle, it will revert
back to the Transmit-Only mode, and transmit its con-
tents starting with the Most Significant bit in address
00h. However, if it detects the control byte on the I
bus, (Figure 3-2) it will switch to the in the Bidirectional
mode. Once the device has made the transition to the
Bidirectional mode, the only way to switch the device
back to the Transmit-Only mode is to remove power
from the device. The mode transition process is shown
in detail in Figure 3-3.
FIGURE 3-1:
FIGURE 3-2:
© 2007 Microchip Technology Inc.
MODE
SCL
SDA
VCLK
SDA
MODE
SCL
VCLK
Transmit-Only
VCLK count =
BIDIRECTIONAL MODE
VCLK count =
Transmit-Only
MODE TRANSITION WITH RECOVERY TO TRANSMIT-ONLY MODE
SUCCESSFUL MODE TRANSITION TO BIDIRECTIONAL MODE
1
2
C™ bus, and starts to
1
T
2
VHZ
Transition mode with possibility to return to Transmit-Only mode
Bidirectional
2
n < 128
n
3
S
0
1
4
2
C
0
127 128
1
Once the device has switched into the Bidirectional
mode, the VCLK input is disregarded, with the excep-
tion that a logic high level is required to enable write
capability. In Bidirectional mode the user has access to
the entire 2K array, whereas in the Transmit-Only mode
the user can only access the first 1K. This mode sup-
ports a two-wire Bidirectional data transmission proto-
col (I
the bus is defined to be the transmitter, and a device
that receives data from the bus is defined to be the
receiver. The bus must be controlled by a master
device that generates the Bidirectional mode clock
(SCL), controls access to the bus and generates the
Start and Stop conditions, while the 24LC22A acts as
the slave. Both master and slave can operate as trans-
mitter or receiver, but the master device determines
which mode is activated. In the Bidirectional mode, the
24LC22A only responds to commands for device
‘1010 000X’.
0
(MSB of data in 00h)
2
Bit 8
C). In this protocol, a device that sends data on
Recovery to Transmit-Only mode
0
0
0
0
24LC22A
ACK
DS21683B-page 5
Bidirectional
permanently