24AA256/24LC256/24FC256 256K Bit I2C™CMOS Serial EEPROM DEVICE SELECTION TABLE PACKAGE TYPE PDIP Part Number VCC Range Max Clock Frequency 24AA256 1.8-5.5V 400 kHz C 24LC256 2.5-5.5V 400 kHz‡ I, E 24FC256 2.5-5.5V 1 MHz I †100 ‡100 kHz for VCC < 2.5V. kHz for E temperature range. FEATURES A0 1 A1 2 A2 3 Vss 4 SOIC A0 8 1 A1 2 A2 3 VSS 4 24XX256 • Low power CMOS technology - Maximum write current 3 mA at 5.5V - Maximum read current 400 µA at 5.5V - Standby current 100 nA typical at 5.5V • 2-wire serial interface bus, I2C compatible • Cascadable for up to eight devices • Self-timed ERASE/WRITE cycle • 64-byte page-write mode available • 5 ms max write-cycle time • Hardware write protect for entire array • Output slope control to eliminate ground bounce • Schmitt trigger inputs for noise suppression • 100,000 erase/write cycles guaranteed • Electrostatic discharge protection > 4000V • Data retention > 200 years • 8-pin PDIP and SOIC (208 mil) packages • Temperature ranges: - Commercial (C): 0°C to +70°C - Industrial (I): -40°C to +85°C - Automotive (E): -40°C to +125°C 24XX256 † Temp Ranges 8 Vcc 7 WP 6 SCL 5 SDA VCC 7 WP 6 SCL 5 SDA BLOCK DIAGRAM A0 A1 A2 WP I/O CONTROL LOGIC MEMORY CONTROL LOGIC HV GENERATOR XDEC EEPROM ARRAY PAGE LATCHES I/O SCL YDEC SDA DESCRIPTION The Microchip Technology Inc. 24AA256/24LC256/ 24FC256 (24XX256*) is a 32K x 8 (256K bit) Serial Electrically Erasable PROM, capable of operation across a broad voltage range (1.8V to 5.5V). It has been developed for advanced, low power applications such as personal communications or data acquisition. This device also has a page-write capability of up to 64 bytes of data. This device is capable of both random and sequential reads up to the 256K boundary. Functional address lines allow up to eight devices on the same bus, for up to 2M bit address space. This device is available in the standard 8-pin plastic DIP and 8-pin SOIC (208 mil) packages. VCC VSS SENSE AMP R/W CONTROL I2C is a trademark of Philips Corporation. *24XX256 is used in this document as a generic part number for the 24AA256/24LC256/24FC256 devices. 1999 Microchip Technology Inc. Preliminary DS21203F-page 1 24AA256/24LC256/24FC256 1.0 1.1 ELECTRICAL CHARACTERISTICS TABLE 1-1 Name Maximum Ratings* Function A0, A1, A2 User Configurable Chip Selects VCC.................................................................................................7.0V All inputs and outputs w.r.t. VSS ............................. -0.6V to VCC +1.0V Storage temperature ...................................................-65°C to +150°C Ambient temp. with power applied ..............................-65°C to +125°C Soldering temperature of leads (10 seconds) ........................... +300°C ESD protection on all pins...........................................................Š 4 kV *Notice: Stresses above those listed under “Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at those or any other conditions above those indicated in the operational listings of this specification is not implied. Exposure to maximum rating conditions for extended periods may affect device reliability. TABLE 1-2 PIN FUNCTION TABLE VSS Ground SDA Serial Data SCL Serial Clock WP Write Protect Input VCC +1.8 to 5.5V (24AA256) +2.5 to 5.5V (24LC256,24FC256) DC CHARACTERISTICS All parameters apply across the specified operating ranges, unless otherwise noted. Commercial (C): Industrial (I): Automotive (E): VCC = +1.8V to 5.5V VCC = +2.5V to 5.5V VCC = +4.5V to 5.5V Tamb = 0°C to +70°C Tamb = -40°C to +85°C Tamb = -40°C to 125°C Parameter Symbol Min Max Units A0, A1, A2, SCL, SDA, and WP pins: High level input voltage Low level input voltage VIH VIL 0.7 VCC — Hysteresis of Schmitt Trigger inputs (SDA, SCL pins) Low level output voltage VHYS 0.05 VCC — 0.3 VCC 0.2 VCC — V V V V VOL — 0.40 V Input leakage current ILI -10 10 µA Output leakage current Pin capacitance (all inputs/outputs) Operating current ILO CIN, COUT -10 — 10 10 µA pF ICC Read ICC Write ICCS — — — 400 3 1 µA mA µA Standby current Conditions VCC 2.5V VCC < 2.5V VCC 2.5V (Note) IOL = 3.0 mA @ VCC = 4.5V IOL = 2.1 mA @ VCC = 2.5V VIN = VSS or VCC, WP = VSS VIN = VSS or VCC, WP = VCC VOUT = VSS or VCC VCC = 5.0V (Note) Tamb = 25°C, fc= 1 MHz VCC = 5.5V, SCL = 400 kHz VCC = 5.5V SCL = SDA = VCC = 5.5V A0, A1, A2, WP = VSS Note: This parameter is periodically sampled and not 100% tested. FIGURE 1-1: BUS TIMING DATA THIGH TF SCL SDA OUT WP THD:DAT TSU:DAT TSU:STO THD:STA TSP TBUF TAA (protected) (unprotected) DS21203F-page 2 TR TSU:STA TLOW SDA IN VHYS Preliminary TSU:WP THD:WP 1999 Microchip Technology Inc. 24AA256/24LC256/24FC256 TABLE 1-3 AC CHARACTERISTICS All parameters apply across the spec- Commercial (C): VCC = +1.8V to 5.5V ified operating ranges unless otherIndustrial (I): VCC = +2.5V to 5.5V wise noted. Automotive (E): VCC = +4.5V to 5.5V Tamb = 0°C to +70°C Tamb = -40°C to +85°C Tamb = -40°C to 125°C Symbol Min Max Units Clock frequency FCLK — — — — 100 100 400 1000 kHz 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) Clock high time THIGH 4000 4000 600 500 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) Clock low time TLOW 4700 4700 1300 500 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) SDA and SCL rise time (Note 1) TR — — — — 1000 1000 300 300 ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) SDA and SCL fall time (Note 1) TF — — 300 100 ns All except 24FC256 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) START condition hold time THD:STA 4000 4000 600 250 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) START condition setup time TSU:STA 4700 4700 600 250 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) Data input hold time THD:DAT 0 — ns (Note 2) Data input setup time TSU:DAT 250 250 100 100 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) STOP condition setup time TSU:STO 4000 4000 600 250 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) WP setup time TSU:WP 4000 4000 600 600 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) WP hold time THD:WP 4700 4700 1300 1300 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) TAA — — — — 3500 3500 900 400 ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) TBUF 4700 4700 1300 500 — — — — ns 4.5V ≤ VCC ≤ 5.5V (E Temp range) 1.8V ≤ VCC ≤ 2.5V 2.5V ≤ VCC ≤ 5.5V 24FC256 (2.5 V ≤ Vcc ≤ 5.5 V) TOF 10 + 0.1CB 250 250 ns All except 24FC256 (Note 1) 24FC256 (Note 1) Output valid from clock (Note 2) Bus free time: Time the bus must be free before a new transmission can start Output fall time from VIH minimum to VIL maximum CB ≤ 100 pF 1999 Microchip Technology Inc. Preliminary Conditions DS21203F-page 3 24AA256/24LC256/24FC256 TABLE 1-3 AC CHARACTERISTICS All parameters apply across the spec- Commercial (C): VCC = +1.8V to 5.5V ified operating ranges unless otherIndustrial (I): VCC = +2.5V to 5.5V wise noted. Automotive (E): VCC = +4.5V to 5.5V Symbol Min Max Units Input filter spike suppression (SDA and SCL pins) TSP — 50 ns Write cycle time (byte or page) TWC Endurance Note 1: 2: 3: 4: — 5 ms 100K — cycles Tamb = 0°C to +70°C Tamb = -40°C to +85°C Tamb = -40°C to 125°C Conditions All except 24FC256 (Notes 1 and 3) 25°C, VCC = 5.0V, Block Mode (Note 4) Not 100% tested. C B = total capacitance of one bus line in pF. As a transmitter, the device must provide an internal minimum delay time to bridge the undefined region (minimum 300 ns) of the falling edge of SCL to avoid unintended generation of START or STOP conditions. The combined TSP and VHYS specifications are due to new Schmitt trigger inputs which provide improved noise spike suppression. This eliminates the need for a TI specification for standard operation. This parameter is not tested but guaranteed by characterization. For endurance estimates in a specific application, please consult the Total Endurance Model which can be obtained on Microchip’s website @www.microchip.com. DS21203F-page 4 Preliminary 1999 Microchip Technology Inc. 24AA256/24LC256/24FC256 2.0 PIN DESCRIPTIONS 4.0 2.1 A0, A1, A2 Chip Address Inputs The following bus protocol has been defined: The A0, A1, A2 inputs are used by the 24XX256 for multiple device operations. The levels on these inputs are compared with the corresponding bits in the slave address. The chip is selected if the compare is true. Up to eight devices may be connected to the same bus by using different chip select bit combinations. If left unconnected, these inputs will be pulled down internally to VSS. 2.2 • Data transfer may be initiated only when the bus is not busy. • During data transfer, the data line must remain stable whenever the clock line is HIGH. Changes in the data line while the clock line is HIGH will be interpreted as a START or STOP condition. Accordingly, the following bus conditions have been defined (Figure 4-1). 4.1 SDA Serial Data BUS CHARACTERISTICS Bus not Busy (A) Both data and clock lines remain HIGH. This is a bi-directional pin used to transfer addresses and data into and data out of the device. It is an opendrain terminal, therefore, the SDA bus requires a pullup resistor to VCC (typical 10 kΩ for 100 kHz, 2 kΩ for 400 kHz and 1 MHz). For normal data transfer SDA is allowed to change only during SCL low. Changes during SCL high are reserved for indicating the START and STOP conditions. 2.3 SCL Serial Clock This input is used to synchronize the data transfer from and to the device. 2.4 WP This pin can be connected to either VSS, VCC or left floating. An internal pull-down resistor on this pin will keep the device in the unprotected state if left floating. If tied to VSS or left floating, normal memory operation is enabled (read/write the entire memory 0000-7FFF). If tied to VCC, WRITE operations are inhibited. Read operations are not affected. 3.0 The 24XX256 supports a bi-directional 2-wire bus and data transmission protocol. A device that sends data onto the bus is defined as a transmitter, and a device receiving data as a receiver. The bus must be controlled by a master device which generates the serial clock (SCL), controls the bus access, and generates the START and STOP conditions while the 24XX256 works as a slave. Both master and slave can operate as a transmitter or receiver, but the master device determines which mode is activated. Start Data Transfer (B) A HIGH to LOW transition of the SDA line while the clock (SCL) is HIGH determines a START condition. All commands must be preceded by a START condition. 4.3 Stop Data Transfer (C) A LOW to HIGH transition of the SDA line while the clock (SCL) is HIGH determines a STOP condition. All operations must end with a STOP condition. 4.4 Data Valid (D) The state of the data line represents valid data when, after a START condition, the data line is stable for the duration of the HIGH period of the clock signal. The data on the line must be changed during the LOW period of the clock signal. There is one bit of data per clock pulse. Each data transfer is initiated with a START condition and terminated with a STOP condition. The number of the data bytes transferred between the START and STOP conditions is determined by the master device. 4.5 FUNCTIONAL DESCRIPTION 1999 Microchip Technology Inc. 4.2 Acknowledge Each receiving device, when addressed, is obliged to generate an acknowledge signal after the reception of each byte. The master device must generate an extra clock pulse which is associated with this acknowledge bit. Note: The 24XX256 does not generate any acknowledge bits if an internal programming cycle is in progress. A device that acknowledges must pull down the SDA line during the acknowledge clock pulse in such a way that the SDA line is stable LOW during the HIGH period of the acknowledge related clock pulse. Of course, setup and hold times must be taken into account. During reads, a master must signal an end of data to the slave by NOT generating an acknowledge bit on the last byte that has been clocked out of the slave. In this case, the slave (24XX256) will leave the data line HIGH to enable the master to generate the STOP condition. Preliminary DS21203F-page 5 24AA256/24LC256/24FC256 FIGURE 4-1: (A) DATA TRANSFER SEQUENCE ON THE SERIAL BUS (B) (D) (D) (C) (A) SCL SDA START CONDITION FIGURE 4-2: ADDRESS OR DATA ACKNOWLEDGE ALLOWED VALID TO CHANGE STOP CONDITION ACKNOWLEDGE TIMING Acknowledge Bit SCL SDA 1 2 3 4 5 6 7 8 1 2 3 Data from transmitter Data from transmitter Transmitter must release the SDA line at this point allowing the Receiver to pull the SDA line low to acknowledge the previous eight bits of data. DS21203F-page 6 9 Preliminary Receiver must release the SDA line at this point so the Transmitter can continue sending data. 1999 Microchip Technology Inc. 24AA256/24LC256/24FC256 5.0 DEVICE ADDRESSING FIGURE 5-1: A control byte is the first byte received following the start condition from the master device (Figure 5-1). The control byte consists of a 4-bit control code; for the 24XX256 this is set as 1010 binary for read and write operations. The next three bits of the control byte are the chip select bits (A2, A1, A0). The chip select bits allow the use of up to eight 24XX256 devices on the same bus and are used to select which device is accessed. The chip select bits in the control byte must correspond to the logic levels on the corresponding A2, A1, and A0 pins for the device to respond. These bits are in effect the three most significant bits of the word address. The last bit of the control byte defines the operation to be performed. When set to a one a read operation is selected, and when set to a zero a write operation is selected. The next two bytes received define the address of the first data byte (Figure 5-2). Because only A14…A0 are used, the upper address bits is a don’t care. The upper address bits are transferred first, followed by the less significant bits. Following the start condition, the 24XX256 monitors the SDA bus checking the device type identifier being transmitted. Upon receiving a 1010 code and appropriate device select bits, the slave device outputs an acknowledge signal on the SDA line. Depending on the state of the R/W bit, the 24XX256 will select a read or write operation. FIGURE 5-2: 0 Read/Write Bit Chip Select Bits Control Code S 1 0 1 0 A2 A1 A0 R/W ACK Slave Address Start Bit 5.1 Acknowledge Bit Contiguous Addressing Across Multiple Devices The chip select bits A2, A1, A0 can be used to expand the contiguous address space for up to 2 Mbit by adding up to eight 24XX256's on the same bus. In this case, software can use A0 of the control byte as address bit A15; A1, as address bit A16; and A2, as address bit A17. It is not possible to sequentially read across device boundaries. ADDRESS SEQUENCE BIT ASSIGNMENTS CONTROL BYTE 1 CONTROL BYTE FORMAT 1 CONTROL CODE 0 A 2 A 1 ADDRESS HIGH BYTE A 0 R/W X A A A A A 14 13 12 11 10 CHIP SELECT BITS 1999 Microchip Technology Inc. A 9 ADDRESS LOW BYTE A 8 A 7 • • • • • • A 0 X = Don’t Care Bit Preliminary DS21203F-page 7 24AA256/24LC256/24FC256 6.0 WRITE OPERATIONS 6.1 Byte Write than 64 bytes prior to generating the stop condition, the address counter will roll over and the previously received data will be overwritten. As with the byte write operation, once the stop condition is received, an internal write cycle will begin (Figure 6-2). If an attempt is made to write to the array with the WP pin held high, the device will acknowledge the command but no write cycle will occur, no data will be written, and the device will immediately accept a new command. Following the start condition from the master, the control code (four bits), the chip select (three bits), and the R/W bit (which is a logic low) are clocked onto the bus by the master transmitter. This indicates to the addressed slave receiver that the address high byte will follow after it has generated an acknowledge bit during the ninth clock cycle. Therefore, the next byte transmitted by the master is the high-order byte of the word address and will be written into the address pointer of the 24XX256. The next byte is the least significant address byte. After receiving another acknowledge signal from the 24XX256, the master device will transmit the data word to be written into the addressed memory location. The 24XX256 acknowledges again and the master generates a stop condition. This initiates the internal write cycle, and, during this time, the 24XX256 will not generate acknowledge signals (Figure 6-1). If an attempt is made to write to the array with the WP pin held high, the device will acknowledge the command but no write cycle will occur, no data will be written, and the device will immediately accept a new command. After a byte write command, the internal address counter will point to the address location following the one that was just written. 6.2 6.3 Write Protection The WP pin allows the user to write-protect the entire array (0000-7FFF) when the pin is tied to VCC. If tied to VSS or left floating, the write protection is disabled. The WP pin is sampled at the STOP bit for every write command (Figure 1-1) Toggling the WP pin after the STOP bit will have no effect on the execution of the write cycle. Note: Page write operations are limited to writing bytes within a single physical page, regardless of the number of bytes actually being written. Physical page boundaries start at addresses that are integer multiples of the page buffer size (or ‘page size’) and end at addresses that are integer multiples of [page size - 1]. If a page write command attempts to write across a physical page boundary, the result is that the data wraps around to the beginning of the current page (overwriting data previously stored there), instead of being written to the next page as might be expected. It is therefore necessary for the application software to prevent page write operations that would attempt to cross a page boundary. Page Write The write control byte, word address, and the first data byte are transmitted to the 24XX256 in the same way as in a byte write. But instead of generating a stop condition, the master transmits up to 63 additional bytes, which are temporarily stored in the on-chip page buffer and will be written into memory after the master has transmitted a stop condition. After receipt of each word, the six lower address pointer bits are internally incremented by one. If the master should transmit more FIGURE 6-1: BYTE WRITE BUS ACTIVITY MASTER S T A R T CONTROL BYTE ADDRESS HIGH BYTE A A S 1 0 1 0 A 2 1 0 0 SDA LINE S T O P DATA X P A C K BUS ACTIVITY ADDRESS LOW BYTE A C K A C K A C K X = don’t care bit FIGURE 6-2: PAGE WRITE BUS ACTIVITY MASTER S T A R T SDA LINE S10 1 0 2 1 0 0 BUS ACTIVITY CONTROL BYTE ADDRESS HIGH BYTE A A A ADDRESS LOW BYTE DATA BYTE 0 S T O P DATA BYTE 63 X A C K P A C K A C K A C K A C K X = don’t care bit DS21203F-page 8 Preliminary 1999 Microchip Technology Inc. 24AA256/24LC256/24FC256 7.0 ACKNOWLEDGE POLLING FIGURE 7-1: Since the device will not acknowledge during a write cycle, this can be used to determine when the cycle is complete (This feature can be used to maximize bus throughput.) Once the stop condition for a write command has been issued from the master, the device initiates the internally timed write cycle. ACK polling can be initiated immediately. This involves the master sending a start condition, followed by the control byte for a write command (R/W = 0). If the device is still busy with the write cycle, then no ACK will be returned. If no ACK is returned, then the start bit and control byte must be resent. If the cycle is complete, then the device will return the ACK, and the master can then proceed with the next read or write command. See Figure 7-1 for flow diagram. ACKNOWLEDGE POLLING FLOW Send Write Command Send Stop Condition to Initiate Write Cycle Send Start Send Control Byte with R/W = 0 Did Device Acknowledge (ACK = 0)? NO YES Next Operation 1999 Microchip Technology Inc. Preliminary DS21203F-page 9 24AA256/24LC256/24FC256 8.0 READ OPERATION 8.2 Read operations are initiated in the same way as write operations with the exception that the R/W bit of the control byte is set to one. There are three basic types of read operations: current address read, random read, and sequential read. 8.1 Random read operations allow the master to access any memory location in a random manner. To perform this type of read operation, first the word address must be set. This is done by sending the word address to the 24XX256 as part of a write operation (R/W bit set to 0). After the word address is sent, the master generates a start condition following the acknowledge. This terminates the write operation, but not before the internal address pointer is set. Then, the master issues the control byte again but with the R/W bit set to a one. The 24XX256 will then issue an acknowledge and transmit the 8-bit data word. The master will not acknowledge the transfer but does generate a stop condition which causes the 24XX256 to discontinue transmission (Figure 8-2). After a random read command, the internal address counter will point to the address location following the one that was just read. Current Address Read The 24XX256 contains an address counter that maintains the address of the last word accessed, internally incremented by one. Therefore, if the previous read access was to address n (n is any legal address), the next current address read operation would access data from address n + 1. Upon receipt of the control byte with R/W bit set to one, the 24XX256 issues an acknowledge and transmits the 8-bit data word. The master will not acknowledge the transfer but does generate a stop condition and the 24XX256 discontinues transmission (Figure 8-1). FIGURE 8-1: 8.3 S T A R T SDA LINE S 1 0 1 0 A AA 1 2 1 0 P A C K BUS ACTIVITY FIGURE 8-2: S T O P DATA BYTE CONTROL BYTE Sequential Read Sequential reads are initiated in the same way as a random read except that after the 24XX256 transmits the first data byte, the master issues an acknowledge as opposed to the stop condition used in a random read. This acknowledge directs the 24XX256 to transmit the next sequentially addressed 8-bit word (Figure 8-3). Following the final byte transmitted to the master, the master will NOT generate an acknowledge but will generate a stop condition. To provide sequential reads, the 24XX256 contains an internal address pointer which is incremented by one at the completion of each operation. This address pointer allows the entire memory contents to be serially read during one operation. The internal address pointer will automatically roll over from address 7FFF to address 0000 if the master acknowledges the byte received from the array address 7FFF. CURRENT ADDRESS READ BUS ACTIVITY MASTER Random Read N O A C K RANDOM READ S T A R T BUS ACTIVITY MASTER CONTROL BYTE ADDRESS HIGH BYTE S1 0 1 0 AAA0 2 1 0 SDA LINE ADDRESS LOW BYTE CONTROL BYTE S T O P DATA BYTE S 1 0 1 0 A A A1 2 1 0 X A C K BUS ACTIVITY S T A R T A C K A C K DATA n + 1 DATA n + 2 P N O A C K A C K X = Don’t Care Bit FIGURE 8-3: SEQUENTIAL READ BUS ACTIVITY MASTER CONTROL BYTE DATA n P SDA LINE BUS ACTIVITY DS21203F-page 10 S T O P DATA n + X A C K A C K Preliminary A C K A C K N O A C K 1999 Microchip Technology Inc. 24AA256/24LC256/24FC256 24XX256 PRODUCT IDENTIFICATION SYSTEM To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. 24XX256 — /P Package: Temperature Range: Device: P = Plastic DIP (300 mil Body), 8-lead SM = Plastic SOIC (208 mil Body, EIAJ standard), 8-lead Blank = 0°C to +70°C I = -40°C to +85°C E = -40°C to +125°C 24AA256 24AA256T 24LC256 24LC256T 24FC256 24FC256T 256K bit 1.8V I2C Serial EEPROM 256K bit 1.8V I2C Serial EEPROM (Tape and Reel) 256K bit 2.5V I2C Serial EEPROM 256K bit 2.5V I2C Serial EEPROM (Tape and Reel) 256K bit 1MHz I2C Serial EEPROM 256K bit 1MHz I2C Serial EEPROM (Tape and Reel) Sales and Support Data Sheets Products supported by a preliminary Data Sheet may have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. Your local Microchip sales office 2. The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277 3. The Microchip Worldwide Site (www.microchip.com) Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. New Customer Notification System Register on our web site (www.microchip.com/cn) to receive the most current information on our products. 1999 Microchip Technology Inc. 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Le Colleoni 1 20041 Agrate Brianza Milan, Italy Tel: 39-39-6899939 Fax: 39-39-6899883 Microchip Technology Inc. 18201 Von Karman, Suite 1090 Irvine, CA 92612 Tel: 949-263-1888 Fax: 949-263-1338 New York Microchip Technology Inc. 150 Motor Parkway, Suite 202 Hauppauge, NY 11788 Tel: 516-273-5305 Fax: 516-273-5335 San Jose Microchip Technology Inc. 2107 North First Street, Suite 590 San Jose, CA 95131 Tel: 408-436-7950 Fax: 408-436-7955 All rights reserved. © 1999 Microchip Technology Incorporated. Printed in the USA. 3/99 Arizona Microchip Technology GmbH Gustav-Heinemann-Ring 125 D-81739 München, Germany Tel: 49-89-627-144 0 Fax: 49-89-627-144-44 03/15/99 Microchip received ISO 9001 Quality System certification for its worldwide headquarters, design, and wafer fabrication facilities in January, 1997. Our field-programmable PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs, related specialty memory products and development systems conform to the stringent quality standards of the International Standard Organization (ISO). Printed on recycled paper. Information contained in this publication regarding device applications and the like is intended for suggestion only and may be superseded by updates. No representation or warranty is given and no liability is assumed by Microchip Technology Incorporated with respect to the accuracy or use of such information, or infringement of patents or other intellectual property rights arising from such use or otherwise. Use of Microchip’s products as critical components in life support systems is not authorized except with express written approval by Microchip. No licenses are conveyed, implicitly or otherwise, under any intellectual property rights. The Microchip logo and name are registered trademarks of Microchip Technology Inc. in the U.S.A. and other countries. All rights reserved. All other trademarks mentioned herein are the property of their respective companies. DS21203F-page 12 1999 Microchip Technology Inc.