Document
Preliminary Information
X24012 Pin 7 No Connect 1K
X24012
Serial E2PROM
DESCRIPTION
128 x 8 Bit
FEATURES
• • • • • • •
2.7 to 5.5V Power Supply Low Power CMOS —Active Current Less Than 1 mA —Standby Current Less Than 50 µA Internally Organized 128 x 8 Self Timed Write Cycle —Typical Write Cycle Time of 5 ms 2 Wire Serial Interface —Bidirectional Data Transfer Protocol Four Byte Page Write Operation —Minimizes Total Write Time Per Byte High Reliability —Endurance: 100,000 Cycles —Data Retention: 100 Years
The X24012 is a CMOS 1024 bit serial E2PROM, internally organized as one 128 x 8 bank. The X24012 features a serial interface and software protocol allowing operation on a simple two wire bus. Three address inputs allow up to eight devices to share a common two wire bus. Xicor E2PROMs are designed and tested for applications requiring extended endurance. Inherent data retention is greater than 100 years. The X24012 is available in eight pin DIP and SOIC packages.
FUNCTIONAL DIAGRAM
(8) VCC (4) VSS START CYCLE (5) SDA START STOP LOGIC CONTROL LOGIC SLAVE ADDRESS REGISTER +COMPARATOR XDEC E2PROM 32 X 32 H.V. GENERATION TIMING & CONTROL
(6) SCL (3) A2 (2) A1 (1) A0
LOAD
INC
WORD ADDRESS COUNTER R/W YDEC 8 CK PIN DOUT ACK
3847 FHD F01
DATA REGISTER
DOUT
© Xicor, 1991 Patents Pending
3847-1
1
Characteristics subject to change without notice
X24012
PIN DESCRIPTIONS Serial Clock (SCL) The SCL input is used to clock all data into and out of the device. Serial Data (SDA) SDA is a bidirectional pin used to transfer data into and out of the device. It is an open drain output and may be wire-ORed with any number of open drain or open collector outputs. An open drain output requires the use of a pull-up resistor. For selecting typical values, refer to the Guidelines for Calculating Typical Values of Bus Pull-Up Resistors graph. Address (A0, A1, A2) The address inputs are used to set the least significant three bits of the seven bit slave address. These inputs can be static or actively driven. If used statically they must be tied to VSS or VCC as appropriate. If actively driven, they must be driven to VSS or to VCC.
A0 A1 A2 VSS 1 2 3 4 X24012
DIP/SOIC
PIN CONFIGURATION
8 7 6 5
VCC NC SCL SDA
3847 FHD F02
PIN NAMES Symbol A0–A2 SDA SCL NC VSS VCC Description Address Inputs Serial Data Serial Clock No Connect Ground +5V
3847 PGM T01
2
X24012
DEVICE OPERATION The X24012 supports a bidirectional bus oriented protocol. The protocol defines any device that sends data onto the bus as a transmitter, and the receiving device as the receiver. The device controlling the transfer is a master and the device being controlled is the slave. The master will always initiate data transfers and provide the clock for both transmit and receive operations. Therefore, the X24012 will be considered a slave in all applications. Clock and Data Conventions Data states on the SDA line can change only during SCL LOW. SDA state changes during SCL HIGH are reserved for indicating start and stop conditions. Refer to Figures 1 and 2. Start Condition All commands are preceded by the start condition, which is a HIGH to LOW transition of SDA when SCL is HIGH. The X24012 continuously monitors the SDA and SCL lines for the start condition and will not respond to any command until this condition has been met.
Figure 1. Data Validity
SCL
SDA DATA STABLE DATA CHANGE
3847 FHD F05
Figure 2. Definition of Start and Stop
SCL
SDA START BIT STOP BIT
3847 FHD F06
3
X24012
Stop Condition All communications must be terminated by a stop condition, which is a LOW to HIGH transition of SDA when SCL is HIGH. The stop condition is also used by the X24012 to place the device into the standby power mode after a read sequence. A stop condition can only be issued after the transmitting device has released the bus. Acknowledge Acknowledge is a software convention used to indicate successful data transfers. The transmitting device will release the bus after transmitting eight bits. During the ninth clock cycle the receiver will pull the SDA line LOW to acknowledge that it received the eight bits of data. Refer to Figure 3. Figure 3. Acknowledge Response From Receiver
SCL FROM MASTER
The X24012 will respond with an acknowledge after recognition of a start condition and its slave address. If both the device and a write operation have been selected, the X24012 will respond with an acknowledge after the receipt of each subsequent eight bit word. In the read mode the X24012 will transmit eight bits of data, release the SDA line and monitor the line for an acknowledge. If an acknowledge is detected and no stop condition is generated by the master, the X24012 will continue to transmit data. If an acknowledge is not detected, the X24012 will terminate further data transmissions. The master must then issue a stop condition to return the X24012 to the standby power mode and place the device into a known state.
1
8
9
DATA OUTPUT FROM TRANSMITTER
DATA .