ISSI ® IS24C256 262,144-bit 2-WIRE SERIAL CMOS EEPROM ADVANCED INFORMATION MARCH 2003 DESCRIPTION FEATURES • Organization: – 32K-bit x 8-bit • 64-Byte Page Write Buffer • Two-Wire Serial Interface – Bi-directional data transfer protocol • Low Power CMOS Technology – Active Current less than 3 mA (5V) – Standby Current less than 6 µA (5V) – Standby Current less than 2 µA (2.5V) • Wide Voltage Operation – IS24C256-2: Vcc = 1.8V to 5.5V – IS24C256-3: Vcc = 2.5V to 5.5V • 1 MHz (I2CTM Protocol) Compatibility • Hardware Data Protection – Write Protect pin • Sequential Read Feature The IS24C256 is an electrically erasable PROM device that uses the standard 2-wire interface for communications. The IS24C256 contains a memory array of 256K-bits (32,768 x 8), and is further subdivided into 512 pages of 64 bytes each for PageWrite mode. This EEPROM is offered in wide operating voltages of 1.8V to 5.5V (IS24C256-2) and 2.5V to 5.5V (IS24C256-3) to be compatible with most application voltages. ISSI designed the IS24C256 to be a low-cost and low-power 2-wire EEPROM solution. The devices are packaged in 8-pin PDIP, 8-pin SOIC, and 14-pin TSSOP. The IS24C256 maintains compatibility with the popular 2-wire bus protocol, so it is easy to design into applications implementing this bus type. The simple bus consists of the Serial Clock wire (SCL) and the Serial Data wire (SDA). Using the bus, a Master device such as a microcontroller is usually connected to one or more Slave devices such as the IS24C256. The bit stream over the SDA line includes a series of bytes, which identifies a particular Slave device, an instruction, an address within that Slave device, and a series of data, if appropriate. The IS24C256 has a Write Protect pin (WP) to allow blocking of any write instruction transmitted over the bus. • Filtered Inputs for Noise Suppression • Self time Write cycle with auto clear – 5 ms @ 5.0V • High Reliability – Endurance: 100,000 Cycles – Data Retention: 40 Years • Commercial and Industrial temperature ranges • 8-pin PDIP, 8-pin SOIC, and 14-pin TSSOP Copyright © 2003 Integrated Silicon Solution, Inc. All rights reserved. ISSI reserves the right to make changes to this specification and its products at any time without notice. ISSI assumes no liability arising out of the application or use of any information, products or services described herein. Customers are advised to obtain the latest version of this device specification before relying on any published information and before placing orders for products. Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00B 03/11/03 1 ISSI IS24C256 ® FUNCTIONAL BLOCK DIAGRAM HIGH VOLTAGE GENERATOR, TIMING & CONTROL Vcc SCL CONTROL LOGIC WP SLAVE ADDRESS REGISTER & COMPARATOR A0 X DECODER SDA EEPROM ARRAY WORD ADDRESS COUNTER A1 Y DECODER A2 ACK GND nMOS 2 Clock DI/O > DATA REGISTER Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 ISSI IS24C256 PIN CONFIGURATION 8-Pin DIP and SOIC ® 14-pin TSSOP A0 A0 1 8 VCC A1 2 7 WP A2 A1 A2 3 6 SCL NC GND 4 5 SDA NC NC GND 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VCC WP NC NC NC SCL SDA PIN DESCRIPTIONS A0-A2 SDA SCL WP Vcc NC Address Inputs Serial Address/Data I/O Serial Clock Input Write Protect Input Power Supply No Connect GND Ground SCL This input clock pin is used to synchronize the data transfer to and from the device. SDA The SDA is a Bi-directional pin used to transfer addresses and data into and out of the device. The SDA pin is an open drain output and can be wire Or'ed with other open drain or open collector outputs. The SDA bus requires a pullup resistor to Vcc. A0, A1, A2 The A0, A1, and A2 are the device address inputs that are hardwired or left not connected for hardware compatibility with the IS24C32/64/128. When pins are hardwired, as many as eight 256K devices may be addressed on a single bus system. When the pins are not hardwired, the default A0, A1, and A2 are zero. WP WP is the Write Protect pin. If the WP pin is tied to Vcc the entire array becomes Write Protected (Read only). When WP is tied to GND or left floating, normal read/write operations are allowed to the device. Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 3 ISSI IS24C256 ® DEVICE OPERATION Standby Mode The IS24C256 features a serial communication and supports a bi-directional 2-wire bus transmission protocol. Power consumption in reduced in standby mode. The IS24C256 will enter standby mode: a) At Power-up, and remain in it until SCL or SDA toggles; b) Following the Stop signal if no write operation is initiated; or c) Following any internal write operation 2-WIRE BUS The two-wire bus is defined as a Serial Data line (SDA), and a Serial Clock line (SCL). The protocol defines any device that sends data onto the SDA bus as a transmitter, and the receiving devices as a receiver. The bus is controlled by Master device which generates the SCL, controls the bus access and generates the Stop and Start conditions. The IS24C256 is the Slave device on the bus. DEVICE ADDRESSING The Bus Protocol: The Master begins a transmission by sending a Start condition. The Master then sends the address of the particular Slave devices it is requesting. The Slave (Fig. 5) address is 8 bits. – Data transfer may be initiated only when the bus is not busy The four most significant bits of the address are fixed as 1010 for the IS24C256. – During a data transfer, the data line must remain stable whenever the clock line is high. Any changes in the data line while the clock line is high will be interpreted as a Start or Stop condition. This device has three address bits (A1, A2, and A0), which allows up to eight IS24C256 devices to share the 2-wire bus. Upon receiving the Slave address, the device compares the three address bits with the hardwired A2, A1, and A0 input pins to determine if it is the appropriate Slave. If the A2, A1, and A0 pins are not biased to High nor Low, then internal circuitry defaults the value to Low. The state of the data line represents valid data after a Start condition. The data line must be stable for the duration of the High period of the clock signal. The data on the SDA line may be changed during the Low period of the clock signal. There is one clock pulse per bit of data. Each data transfer is initiated with a Start condition and terminated with a Stop condition. Start Condition The Start condition precedes all commands to the device and is defined as a High to Low transition of SDA when SCL is High. The IS24C256 monitors the SDA and SCL lines and will not respond until the Start condition is met. Stop Condition The Stop condition is defined as a Low to High transition of SDA when SCL is High. All operations must end with a Stop condition. Acknowledge (ACK) After a successful data transfer, each receiving device is required to generate an ACK. The Acknowledging device pulls down the SDA line. Reset The IS24C256 contains a reset function in case the 2wire bus transmission is accidentally interrupted (eg. a power loss), or needs to be terminated mid-stream. The reset is caused when the Master device creates a Start condition. To do this, it may be necessary for the Master device to monitor the SDA line while cycling the SCL up to nine times. (For each clock signal transition to High, the Master checks for a High level on SDA.) 4 The last bit of the Slave address specifies whether a Read or Write operation is to be performed. When this bit is set to 1, a Read operation is selected, and when set to 0, a Write operation is selected. After the Master transmits the Start condition and Slave address byte (Fig. 5), the appropriate 2-wire Slave (eg. IS24C256) will respond with ACK on the SDA line. The Slave will pull down the SDA on the ninth clock cycle, signaling that it received the eight bits of data. The selected IS24C256 then prepares for a Read or Write operation by monitoring the bus. WRITE OPERATION Byte Write In the Byte Write mode, the Master device sends the Start condition and the Slave address information (with the R/W set to Zero) to the Slave device. After the Slave generates an ACK, the Master sends two byte addresses that are to be written into the address pointer of the IS24C256. After receiving another ACK from the Slave, the Master device transmits the data byte to be written into the address memory location. The IS24C256 acknowledges once more and the Master generates the Stop condition, at which time the device begins its internal programming cycle. While this internal cycle is in progress, the device will not respond to any request from the Master device. Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 ISSI IS24C256 ® Page Write Random Address Read The IS24C256 is capable of 64-byte Page-Write operation. A Page-Write is initiated in the same manner as a Byte Write, but instead of terminating the internal Write cycle after the first data word is transferred, the Master device can transmit up to 63 more bytes. After the receipt of each data word, the IS24C256 responds immediately with an ACK on SDA line, and the six lower order data word address bits are internally incremented by one, while the higher order bits of the data word address remain constant. If the Master device should transmit more than 64 words, prior to issuing the Stop condition, the address counter will “roll over,” and the previously written data will be overwritten. Once all 64 bytes are received and the Stop condition has been sent by the Master, the internal programming cycle begins. At this point, all received data is written to the IS24C256 in a single Write cycle. All inputs are disabled until completion of the internal Write cycle. Selective Read operations allow the Master device to select at random any memory location for a Read operation. The Master device first performs a 'dummy' Write operation by sending the Start condition, Slave address and word address of the location it wishes to read. After the IS24C256 acknowledges the word address, the Master device resends the Start condition and the Slave address, this time with the R/W bit set to one. The IS24C256 then responds with its ACK and sends the data requested. The Master device does not send an ACK but will generate a Stop condition. (Refer to Figure 9. Random Address Read Diagram.) Acknowledge (ACK) Polling The disabling of the inputs can be used to take advantage of the typical Write cycle time. Once the Stop condition is issued to indicate the end of the host's Write operation, the IS24C256 initiates the internal Write cycle. ACK polling can be initiated immediately. This involves issuing the Start condition followed by the Slave address for a Write operation. If the IS24C256 is still busy with the Write operation, no ACK will be returned. If the IS24C256 has completed the Write operation, an ACK will be returned and the host can then proceed with the next Read or Write operation. READ OPERATION Read operations are initiated in the same manner as Write operations, except that the (R/W) bit of the Slave address is set to “1”. There are three Read operation options: current address read, random address read, and sequential read. Sequential Read Sequential Reads can be initiated as either a Current Address Read or Random Address Read. After the IS24C256 sends initial byte sequence, the Master device now responds with an ACK indicating it requires additional data from the IS24C256. The IS24C256 continues to output data for each ACK received. The Master device terminates the sequential Read operation by pulling SDA High (no ACK) indicating the last data word to be read, followed by a Stop condition. The data output is sequential, with the data from address n followed by the data from address n+1, ... etc. The address counter increments by one automatically, allowing the entire memory contents to be serially read during sequential Read operation. When the memory address boundary 32767 is reached, the address counter “rolls over” to address 0, and the IS24C256 continues to output data for each ACK received. (Refer to Figure 10. Sequential Read Operation Starting with a Random Address Read Diagram.) Current Address Read The IS24C256 contains an internal address counter which maintains the address of the last byte accessed, incremented by one. For example, if the previous operation is either a Read or Write operation addressed to the address location n, the internal address counter would increment to address location n+1. When the IS24C256 receives the Device Addressing Byte with a Read operation (R/W bit set to “1”), it will respond an ACK and transmit the 8-bit data word stored at address location n+1. The Master should not acknowledge the transfer but should generate a Stop condition so the IS24C256 discontinues transmission. If 'n' is the last byte of the memory, then the data from location '0' will be transmitted. (Refer to Figure 8. Current Address Read Diagram.) Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 5 ISSI IS24C256 ® Figure 1. Typical System Bus Configuration Vcc SDA SCL Master Transmitter/ Receiver IS24C256 Figure 2. Output Acknowledge SCL from Master 1 8 9 Data Output from Transmitter tAA Data Output from Receiver tAA ACK STOP Condition SCL START Condition Figure 3. Start and Stop Conditions SDA 6 Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 ISSI IS24C256 ® Figure 4. Data Validity Protocol Data Change SCL Data Stable Data Stable SDA Figure 5. Slave Address BIT 7 6 5 4 3 2 1 0 1 0 1 0 A2 A1 A0 R/W Figure 6. Byte Write SDA Bus Activity S T A R T Device Address M S B W R I T E Word Address Word Address A A A C * C C K K K L M S * = Don't care bit S B B R/W S T O P Data A C K Figure 7. Page Write SDA Bus Activity S T A R T Device Address M S B W R I T E Word Address (n) Word Address (n) A A A C C * C K K K L S B R/W Data (n) Data (n+63) A C K A C K * = Don't care bit Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 Data (n+1) A C K S T O P 7 ISSI IS24C256 ® Figure 8. Current Address Read S T A R T R E A D Device Address SDA Bus Activity S T O P Data A C K M S B L S B N O A C K R/W Figure 9. Random Address Read S T A R T Device Address W R I T E SDA Bus Activity Word Address (n) A C * K M S B S T A R T Word Address (n) A C K Device Address R E A D Data n A C K A C K L S B R/W S T O P N O A C K * = Don't care bit DUMMY WRITE Figure 10. Sequential Read Device Address SDA Bus Activity R E A D Data Byte n A C K Data Byte n+1 A C K Data Byte n+2 A C K S T O P Data Byte n+X A C K N O R/W 8 A C K Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 ISSI IS24C256 ® ABSOLUTE MAXIMUM RATINGS(1) Symbol VS VP TBIAS TSTG IOUT Parameter Supply Voltage Voltage on Any Pin Temperature Under Bias Storage Temperature Output Current Value +0.5 to +6.25 –0.5 to Vcc +0.5 –40 to +85 –65 to +150 5 Unit V V °C °C mA Notes: 1. Stresses violating the conditions listed under ABSOLUTE MAXIMUM RATINGS may cause permanent damage to the device. This is a stress rating only. Functional operation of the device outside these conditions or those indicated in the operational sections of this specification is not implied. Exposure to these conditions for extended periods may affect reliability. OPERATING RANGE (IS24C256-2) Range Commercial Industrial Ambient Temperature 0°C to +70°C –40°C to +85°C VCC 1.8V to 5.5V 1.8V to 5.5V OPERATING RANGE (IS24C256-3) Range Commercial Industrial Ambient Temperature 0°C to +70°C –40°C to +85°C VCC 2.5V to 5.5V 2.5V to 5.5V CAPACITANCE(1,2) Symbol CIN COUT Parameter Input Capacitance Output Capacitance Conditions VIN = 0V VOUT = 0V Max. 6 8 Unit pF pF Notes: 1. Tested initially and after any design or process changes that may affect these parameters. 2. Test conditions: TA = 25°C, f = 1 MHz, Vcc = 5.0V. Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 9 ISSI IS24C256 ® DC ELECTRICAL CHARACTERISTICS Commercial (TA = 0oC to +70oC) Industrial (TA = -40oC to +85oC) Symbol Parameter Test Conditions Min. Max. Unit VOL1 Output Low Voltage VCC = 1.8V, IOL = 0.15 mA — 0.2 V VOL2 Output Low Voltage VCC = 2.5V, IOL = 2.1 mA — 0.4 V VIH Input High Voltage V IL Input Low Voltage I LI Input Leakage Current ILO Output Leakage Current VCC X 0.7 VCC + 0.5 –1.0 VIN = VCC max. VCC X 0.3 V V — 3 µA — 3 µA Min. Max. Unit Notes: VIL min and VIH max are reference only and are not tested. POWER SUPPLY CHARACTERISTICS Commercial (TA = 0oC to +70oC) Industrial (TA = -40oC to +85oC) Symbol Parameter Test Conditions ICC1 Vcc Operating Current Read at 400 KHz (Vcc = 5V) — 2.0 mA ICC2 Vcc Operating Current Write at 400 KHz (Vcc = 5V) — 3.0 mA ISB1 Standby Current Vcc = 1.8V — 1 µA ISB2 Standby Current Vcc = 2.5V — 2 µA ISB3 Standby Current Vcc = 5.0 V — 6 µA AC ELECTRICAL CHARACTERISTICS Commercial (TA = 0oC to +70oC) Industrial (TA = -40oC to +85oC) Symbol Parameter 1.8V-5.5V 2.5V-5.5V 4.5V-5.5V Min. Max. Min. Max. Min. Max. Unit fSCL SCL Clock Frequency 0 100 0 400 0 1000 KHz T Noise Suppression Time(1) — 100 — 50 — 50 ns tLow Clock Low Period 4.7 — 1.2 — 0.6 — µs tHigh Clock High Period 4 — 0.6 — 0.4 — µs Transmission(1) tBUF Bus Free Time Before New 4.7 — 1.2 — 0.5 — µs tSU:STA Start Condition Setup Time 4 — 0.6 — 0.25 — µs tSU:STO Stop Condition Setup Time 4 — 0.6 — 0.25 — µs tHD:STA Start Condition Hold Time 4 — 0.6 — 0.25 — µs tHD:STO Stop Condition Hold Time tSU:DAT Data In Setup Time tHD:DAT 4 — 0.6 — 0.25 — µs 100 — 100 — 100 — ns Data In Hold Time 0 — 0 — 0 — ns tSU:WP WP pin Setup Time 4 — 0.6 — 0.6 — µs tHD:WP WP pin Hold Time 4.7 — 1.2 — 1.2 — µs tDH Data Out Hold Time (SCL Low to SDA Data Out Change) 100 — 50 — 50 — ns tAA Clock to Output (SCL Low to SDA Data Out Valid) 100 3500 50 900 50 400 ns — 1000 — 300 — 300 ns — 300 — 300 — 100 ns — 10 — 10 — 5 ms tR SCL and SDA Rise tF SCL and SDA Fall tWR Write Cycle Time 10 Time(1) Time(1) Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 ISSI IS24C256 ® AC WAVEFORMS Figure 11. Bus Timing tR tF tHIGH tLOW tSU:STO SCL tSU:STA tBUF tHD:DAT tHD:STA tSU:DAT SDAIN tAA tDH SDAOUT tSU:WP tHD:WP WP Figure 12. Write Cycle Timing SCL 8th BIT SDA ACK tWR WORD n STOP Condition Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03 START Condition 11 ISSI IS24C256 ® ORDERING INFORMATION Commercial Range: 0°C to +70°C Frequency Voltage Range Part Number Package 100 KHz 1.8V to 5.5V IS24C256-2P IS24C256-2G IS24C256-2Z 300-mil Plastic DIP (8-pin) Small Outline (JEDEC STD) (8-pin) TSSOP (14-pin) 400 KHz 2.5V to 5.5V IS24C256-3P IS24C256-3G IS24C256-3Z 300-mil Plastic DIP (8-pin) Small Outline (JEDEC STD) (8-pin) TSSOP (14-pin) Part Number Package Industrial Range: –40°C to +85°C Frequency Voltage Range 100 KHz 1.8V to 5.5V IS24C256-2PI IS24C256-2GI IS24C256-2ZI 300-mil Plastic DIP (8-pin) Small Outline (JEDEC STD) (8-pin) TSSOP (14-pin) 400 KHz 2.5V to 5.5V IS24C256-3PI IS24C256-3GI IS24C256-3ZI 300-mil Plastic DIP (8-pin) Small Outline (JEDEC STD) (8-pin) TSSOP (14-pin) ISSI Integrated Silicon Solution, Inc. 2231 Lawson Lane Santa Clara, CA 95054 12 ® Tel: 1-800-379-4774 Fax: (408) 588-0806 E-mail: [email protected] www.issi.com Integrated Silicon Solution, Inc. — www.issi.com — 1-800-379-4774 ADVANCED INFORMATION Rev. 00A 03/11/03