RM24C256DS-LSNI-B

RM24C256DS 256-Kbit 1.65V Minimum Non-volatile Serial EEPROM I 2 C Bus Advance Datasheet  Features  Memory array: 256Kbit non-volatile serial EEPROM memory  Single supply voltage: 1.65V - 3.6V  2-wire I2C interface  Compatible with I2C bus modes:                -100kHz -400kHz -1MHz Page size: 64 bytes -Byte and Page Write from 1 to 64 bytes 128-byte, One-Time Programmable (OTP) Security Register - 64 bytes factory programmed with a unique identifier - 64 bytes user programmable Low Energy Byte Write -Byte Write consuming 50 nJ Low power consumption -0.25 mA active Read current -1.0 mA active Write current -1.0 µA Standby current Fast Write -Page Write in 1.5 ms (64 byte page)  -Byte Write within 60 µs Random and sequential Read modes Industry’s lowest read cycle latency Unlimited read cycles Write protect of the whole memory array 8-lead SOIC, 8-lead TSSOP, 8-pad UDFN and WLCSP packages RoHS-compliant and halogen-free packaging Data Retention: >40 years at 125°C Endurance: 100,000 write cycles (for both byte and page write cycles) - No degradation across temperature range No data loss under UV exposure on bare die or WLCSP Based on Adesto's proprietary CBRAM® technology Description The Adesto® RM24C256DS is a 256Kbit, serial EEPROM memory device that utilizes Adesto's CBRAM® resistive technology. The memory devices use a single lowvoltage supply ranging from 1.65V to 3.6V. DS-RM24C256DS–085B–11/2016 The Adesto® I2C device is accessed through a 2-wire I2C compatible interface consisting of a Serial Data (SDA) and Serial Clock (SCL). The maximum clock (SCL) frequency is 1MHz. The devices have both byte write and page write capability. Page write is 64 bytes. The Byte Write operation of CBRAM consumes only 10% of the energy consumed by a Byte Write operation of EEPROM devices of similar size. Adesto's EEPROM endurance can be as much as 40X higher than industry standard EEPROM devices operating in byte write mode at 85°C. Unlike EEPROMs based on floating gate technology (which require read-modify-write on a whole page for every write operation) CBRAM write endurance is based on the capability to write each byte individually, irrespective of whether the user writes single bytes or an entire page. Additionally, unlike floating gate technology, CBRAM does not experience any degradation of endurance across the full temperature range. By contrast, in order to modify a single byte, most EEPROMs modify and write full pages of 32, 64 or 128 bytes. This provides significantly less endurance for floating gate devices used in byte write mode when compared to page write mode. The Page Write operation of CBRAM is 4-6 times faster than the Page Write operation of similar EEPROM devices. Both random and sequential reads are available. Sequential reads are capable of reading the entire memory in one operation. External address pins permit up to eight devices on the same data bus. The devices are available in standard 8-pin SOIC, TSSOP and 8-pad UDFN. RM24C256DS DS-RM24C256DS–085B–11/2016 2 Block Diagram Figure 1-1. Block Diagram I/O Buffers and Data Latches VCC SCL SDA I/O Control Logic Page Buffer E0 E1 E2 Y-Decoder Memory Control Logic WP GND Address Latch & Counter X-Decoder 1. 256 Kb Resistive Memory RM24C256DS DS-RM24C256DS–085B–11/2016 3 2. Pin/Signal Descriptions Table 2-1. Symbol Pin/Signal Descriptions Pin # Name/Function Description LSB - Least Significant Bit, External Enable LSB of the three external enable bits (E0, E1 and E2). The levels of the external enable bits are compared with three enable bits in the received control byte to provide device selection. The device is selected if the comparison is true. Up to eight devices may be connected to the same bus by using different E0, E1, E2 combinations. 2 External Enable The middle of the three external enable bits (E0, E1 and E2). The levels of the enable bits are compared with three enable bits in the received control byte to provide device selection. Also see the E0, E2 pin. E2 3 MSB - Most Significant Bit, External Enable MSB of the three external enable bits (E0, E1 and E2). The levels of the enable bits are compared with three enable bits in the received control byte to provide device selection. Also see the E0, E1 pin. GND 4 Ground E0 1 E1 SDA 5 Serial Data Bidirectional pin used to transfer addresses and data into and data out of the device. It is an open-drain terminal, and therefore requires a pull-up resistor to VCC. Typical pull-up resistors are: 10KΩ for 100KHz, and 2KΩ for 400KHz and 1MHz. 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. SCL 6 Serial Clock This input is used to synchronize the data transfer from and to the device. SCL is an input only, since it is a slave-only device. WP 7 Write Protect Connect to either VCC or GND. If pulled low, write operations are enabled. If pulled high, write operations are inhibited, but read operations are not affected. Vcc 8 Power Power supply pin 2.1 Pin Out Diagram 2.1.1 Pinouts 8-Lead SOIC, TSSOP and 8-pad UDFN (Top View) WLCSP (Contact Adesto) RM24C256DS DS-RM24C256DS–085B–11/2016 4 3. I2C Bus Protocol I2C is a 2-wire serial bus architecture with a clock pin (SCL) for synchronization, and a data pin (SDA) for data transfer. On the device the SDA pin is bi-directional. The SCL pin is an input only, because the device is slave-only. The SCL and SDA pins are both externally connected to a positive supply voltage via a current source or pull-up resistor. When the bus is free, both lines are high. The output stages of devices connected to the bus must have an open drain or open collector to perform a wired-AND function. Data on the I2C bus can be transferred at rates of up to 1 Mbit/s. The number of interfaces that may be connected to the bus is solely dependent on the bus capacitance limit of 400pF. The data on the SDA line must be stable during the high period of the clock. The high or low state of the data line can only change when the clock signal on the SCL line is low (see Figure 1-1). Figure 3-1. Bit Transfer on the I2C bus A high-to-low transition on the SDA line while SCL is high indicates a START condition. A low-to-high transition on the SDA line while SCL is high defines a STOP condition. START and STOP conditions are always generated by the master. The bus is considered to be busy after the START condition. The bus is considered to be free again a certain time after the STOP condition (see Figure 3-2). Figure 3-2. START and STOP conditions Every byte put on the SDA line must be 8 bits long. The number of bytes that can be transmitted per transfer is unrestricted. Each byte must be followed by an acknowledge bit; therefore, the number of clock cycles to transfer one byte is nine. Data is transferred with the most significant bit (MSB) first. RM24C256DS DS-RM24C256DS–085B–11/2016 5 3.1 I2C Master and Slave Configuration The device has a two-pin industry-standard I2C interface. It is configured as a slave-only device and therefore does not generate a clock. By connecting the E0, E1 and E2 enable pins in the configuration shown in Figure 3-3, up to eight devices can be connected onto an I2C Interface bus controlled by an I2C master device, such as a microcontroller. Figure 3-3. Connection between I2C Master and Slaves 4. Device Timing Figure 4-1. Bus Timing Data Figure 4-2. Power-up Timing VCC VCCmax Program, Read, Erase and Write Commands Rejected VCCmin VVCCI Device Fully Accessible Device in Reset tPUD TIME Power up delay tPUD is based on VCCi which is the voltage level at which the internal reset circuit releases and signals the controller to initiate the power-on reset condition for a 75µS maximum period. RM24C256DS DS-RM24C256DS–085B–11/2016 6 5. Device Addressing The first byte sent from the master device to the EEPROM following the START condition is the control byte (See Figure 5-1). The first four bits of the control byte is the Control Code. When accessing the EEPROM memory area, the Control Code is “1010” both for read and for write operations. When accessing the OTP Security Registers, the Control Code is “1011” both for read and for write operations. The next three bits of the control byte are the enable bits (E2, E1 and E0), which are compared to the levels set on the E0, E1 and E2 pins. The E0, E1 and E2 bits sent in the control byte must correspond to the logic levels set on the corresponding E0, E1 and E2 pins for a device to be selected. In effect, the E0, E1 and E2 bits in the control register act as the three MSB bits of a word address. These three bits allow the use of up to eight devices on the same bus. The last bit of the control byte (R/W) defines the operation to be performed, read or write: if set to a one, a read operation is selected; if set to a zero, a write operation is selected. Figure 5-1. Control Byte, EEPROM access Figure 5-2. Control Byte, OTP Security Register Access Upon receiving the correct Control Code, the chip enable bits, and the R/W bit, the device performs an acknowledge by pulling the SDA line low during the 9th clock pulse. As stated above, the device will now be set for either a read or a write operation by the R/W bit. After the device acknowledges the control byte, two additional bytes are sent by the master to the slave. These define the target address of the byte in the device to be written. The bit assignment for the address is shown in Figure 5-3.  It should be noted that not all the address bits are used. For the 256-Kbit device, only address A0 to A14 are used; the rest are don't cares and must be set to "0". RM24C256DS DS-RM24C256DS–085B–11/2016 7 Figure 5-3. Address sequence bit assignment The device will acknowledge each byte of data that is received by pulling the SDA line low during the 9th clock pulse. If the device does not provide an acknowledge, it has not received the data; consequently the entire sequence, starting with the control byte, must be resent. 6. Byte Write Operation If the R/W bit in the control byte is set to zero, the device will be in write mode. Once the control byte is received, the device will perform an acknowledge; it will then be ready to receive the Address High Byte (see Figure 6-1). After receiving the Address High Byte, the device acknowledges and then is ready to receive the Address Low Byte. After receiving the Address Low Byte, the device will acknowledge and then write the address (expressed by the high and low address bytes) into its address pointer. The device is then ready to receive a byte of data to be written into the addressed memory location. After the device receives the data, it performs an acknowledge. After the master has received the last acknowledge (after the data byte) the master should send a STOP condition. The STOP condition initiates the internal write cycle in the device. If the master does not send a STOP, the device will not write the data into the addressed memory location. While the device is in the write cycle it will not generate an acknowledge signal. Meanwhile, the master can poll the device to determine when the write cycle is complete by sending it a control byte and looking for an acknowledge. Once the write cycle has completed, the device will acknowledge a control byte sent to it. If, in the RM24C256DS, the byte written is the last byte in a 64-byte page, the address will wrap around to the beginning of the same page. For instance, if the byte is written to address 007Fh, the incremented address will be 0040h. If the byte is written to address 07FFh, the incremented address will be 07C0h. If a write cycle is attempted with the WP (write protect) pin held high, the device will acknowledge the command, address, and data, but no write cycle will occur following the STOP command. The data will not be written, and the device will immediately be available to accept a new command. However, the internal address pointer will be written; so after the data byte is transmitted to the device and the STOP command issued by the master, the internal address pointer will again be incremented by one. Figure 6-1. Byte Write Cycle RM24C256DS DS-RM24C256DS–085B–11/2016 8 7. Page Write Operation Table 7-1. Density and Page Size Product Density Page Size (byte) RM24C256DS 256 Kbit 64 During a Page Write cycle, a page with up to 64 bytes of data can be written in one continuous write command. The Page Write starts in the same manner as the Byte Write. In a Page Write, after the acknowledge following the first data byte, the master does not send a STOP, but continues to send additional data bytes. (See Figure 7-1.) At the end of the number of bytes to be written, the master sends a STOP command. Once the STOP command is sent, the device will write all the data bytes into memory, starting at the address location given in the address bytes. If the master should transmit more than 64 bytes prior to generating the STOP command, the internal 64-byte data buffer in the device will wrap around and the first data bytes transmitted will be overwritten. The internal address pointer will not increment beyond a page boundary but will instead wrap around to the first byte of the addressed page. As with the Byte Write cycle, once the STOP command is received the device enters a write cycle. During the write cycle, the device will not generate an acknowledge signal. Meanwhile, the master can poll the device to determine when the write cycle is complete by sending it a control byte and looking for an acknowledge. Once the write cycle has completed, the device will acknowledge a control byte sent to it. During the Page Write cycle, the first byte in the data byte buffer will be written in the address location indicated by the address bytes transmitted to the device. Each successive data byte will be written in the successive address locations. If a Page Write cycle is attempted with the WP pin held high, the device will acknowledge the command, address and data bytes, but will not enter a write cycle after the STOP command is issued. No data will be written, and the device will immediately be available to accept a new command. However, the internal address pointer will be written; so after the Page Write data bytes are transmitted to the device and the STOP command issued by the master, the internal address pointer will be incremented by the number of data bytes sent (but only within the page addressed). Note that the Page Write operation is internally executed by sequentially writing the words in the Page Buffer. Therefore the Page Write time can be estimated as Byte Write time multiplied by the Number of Words to be written. Figure 7-1. Page Write Cycle 8. OTP Security Register Write Operation Table 8-1. OTP Security Register Security Register Byte Number 0 Data Type 1 ··· One-Time User Programmable 63 64 65 ··· 127 Factory Programmed by Adesto RM24C256DS DS-RM24C256DS–085B–11/2016 9 The OTP Security Register Write Operation allows to user to write the 64 bytes of user programmable OTP data. Be aware that the OTP Security Registers can only be written once, even if only a few bytes are written. Once the OTP Security Register Write Operation is executed, the OTP Security Registers are locked from further updates. The OTP Security Register Write Operation is similar to the Page Write Operation, except that the Control Code (the first four bits of the Command Byte) is “1011” instead of “1010”. During a Security Register Write cycle, a page with up to 64 bytes of data can be written in one continuous write command. The Security Register Write starts in the same manner as the Byte Write. In a Security Register Write, after the acknowledge following the first data byte, the master does not send a STOP, but continues to send additional data bytes. (See Figure 8-1.) At the end of the number of bytes to be written, the master sends a STOP command. Once the STOP command is sent, the device will write all the data bytes into memory, starting at the address location given in the address bytes. Note that only the lower 6 bits of the address will be considered by the OTP Security Register Write Operation. The upper 12 bits will be masked out and considered to be 0. An attempt to write to address 128, for instance, will become a write to address 0. If the master should transmit more than 64 bytes prior to generating the STOP command, the internal 64-byte data buffer in the device will wrap around and the first data bytes transmitted will be overwritten. The internal address pointer will not increment beyond a page boundary but will instead wrap around to the first byte of the OTP Security Registers. As with the Byte Write cycle, once the STOP command is received the device enters a write cycle. During the write cycle, the device will not generate an acknowledge signal. Meanwhile, the master can poll the device to determine when the write cycle is complete by sending it a control byte and looking for an acknowledge. Once the write cycle has completed, the device will acknowledge a control byte sent to it. During the Security Register Write cycle, the first byte in the data byte buffer will be written in the address location indicated by the address bytes transmitted to the device. Each successive data byte will be written in the successive address locations. If a Security Register Write cycle is attempted with the WP pin held high, the device will acknowledge the command, address and data bytes, but will not enter a write cycle after the STOP command is issued. This operation will not be considered a write, and the OTP Security Registers can still be written by a later command if they have not been written already. No data will be written, and the device will immediately be available to accept a new command. However, the internal address pointer will be written; so after the Security Register Write data bytes are transmitted to the device and the STOP command issued by the master, the internal address pointer will be incremented by the number of data bytes sent (but only within the page addressed). Note that the Security Register Write operation is internally executed by sequentially writing the words in the Page Buffer. Therefore the Security Register Write time can be estimated as Byte Write time multiplied by the Number of Words to be written. Figure 8-1. OTP Security Register Write Cycle RM24C256DS DS-RM24C256DS–085B–11/2016 10 9. Write Protection The WP pin allows the user to write-protect the entire memory array when the pin is tied to VCC. If the WP pin is tied to GND, write protection is disabled. The WP pin is sampled at the STOP command for every Write command. Toggling the WP pin after the STOP command will have no effect on the execution of the write cycle. 10. Polling The fact that the device will not acknowledge during a write cycle can be used to determine when the write cycle is complete. By polling the device during the write cycle, bus throughput can be maximized. Once the STOP command for the write cycle is sent by the master, the device initiates the internally timed write cycle. Acknowledge polling, by the master, can be initiated immediately. Acknowledge polling involves the master sending a START command, followed by the control byte for a write command (R/W=0). If the device is still busy with the write cycle, no acknowledge is returned. If no acknowledge is returned, the START command and control byte can be retransmitted. If the write cycle is complete, the device will return an acknowledge. The master can then proceed with the next read or write command. See for a flow diagram. NOTE: Care must be taken when polling the device. The control byte that was used to initiate the write must match the control byte used for polling. Figure 10-1. Acknowledge Polling Flow 11. Read Operation Read operations are initiated in the same way as the write operations, except that the R/W bit of the control byte is set to one. There are three types of read operations: Current Address Read, Random Read, and Sequential Read. RM24C256DS DS-RM24C256DS–085B–11/2016 11 Note that the same address pointer is used for accessing both the EEPROM array and the OTP Security registers. Changes done to the address register as a result of access to one of the arrays will affect the access of the other unless the address pointer gets updated again. 11.1 Current Address Read The device internal address pointer maintains the address of the last word accessed, internally incremented by one. Therefore, if the previous read access was to address n (any legal address), the next Current Address Read operation would access data from address n+1. After the last memory address, the address counter “rolls-over”, and the device continues to output data from memory address 00h. If a Current Address Read is performed after a Byte Write or Page Write, care must be taken to understand that during the page/byte write command, the address can wrap around within the same page. Upon receipt of the control byte with the R/W bit set to one, the device issues an acknowledge and transmits the 8-bit data word located at the address of the internal address pointer. The master will not acknowledge the transfer, but does generate a STOP condition and the device discontinues transmission. See Figure 11-1. Figure 11-1. Current Address Read 11.2 Random Read Random read operations allow the master to access any memory location in a random manner. To perform a Random Read, first the address to be accessed must be set. This is done by sending the address to the device as part of a write operation (R/W = 0). After the address is sent and acknowledged by the device, the master generates a START. This terminates the write operation, but the address pointer will be set to the address sent. The master then issues the same control byte as the write operation, but with the R/W bit set to 1. The device will acknowledge and transmit the 8-bit data byte located at the address location written. The master will not acknowledge the transfer of the data byte, but will instead generate a STOP condition, which causes the device to discontinue transmission. See Figure 11-2. After the Random Read operation, the internal address counter will increment to the address location following the one that was just read. Figure 11-2. Random Read 11.3 Sequential Read Sequential read allows the whole memory contents to be serially read during one operation. Sequential Read is initiated in the same way as a Random Read except that after the device transmits the first data byte, the master issues an acknowledge instead of a STOP condition. This acknowledge from the master directs the device to transmit the next sequentially addressed byte (See Figure 11-3). Following the final byte transmitted to the master, the master will not generate an acknowledge, but will generate a STOP condition which causes the device to discontinue transmission. RM24C256DS DS-RM24C256DS–085B–11/2016 12 To provide the Sequential Read, the device contains an internal address pointer which is incremented by one at each acknowledge received by the master, and by the STOP condition. Figure 11-3. Sequential Read 12. OTP Security Register Read Operation OTP Security Register Read operations are initiated in the same way as the write operations, except that the R/W bit of the control byte is set to one. There are three types of OTP Security Register Read operations: OTP Security Register Current Address Read, OTP Security Register Random Read, and OTP Security Register Sequential Read. Note that the same address pointer is used for accessing both the EEPROM array and the OTP Security registers. Changes done to the address register as a result of access to one of the arrays will affect the access of the other unless the address pointer gets updated again. The OTP Security Register Read operations will mask off the upper 9 bits of the address pointer and only consider the lower 7, but all bits of the address pointer will be updated by these read operations. Reading address 0-63 provides access to the user programmable section of the OTP Security Registers, while reading address 64-127 provides access to the registers that are factory programmed by Adesto. See Table 8-1 for details. 12.1 OTP Security Register Current Address Read The device internal address pointer maintains the address of the last word accessed, internally incremented by one. Therefore, if the previous read access was to address n (any legal address), the next Current Address Read operation would access data from address n+1. Upon receipt of the control byte with the R/W bit set to one, the device issues an acknowledge and transmits the 8-bit data word located at the address of the internal address pointer. The master will not acknowledge the transfer, but does generate a STOP condition and the device discontinues transmission. See Figure 121. Figure 12-1. OTP Security Register Current Address Read RM24C256DS DS-RM24C256DS–085B–11/2016 13 12.2 OTP Security Register Random Read Random read operations allow the master to access any OTP Security Register location in a random manner. To perform a OTP Security Register Random Read, first the address to be accessed must be set. This is done by sending the address to the device as part of a write operation (R/W = 0). After the address is sent and acknowledged by the device, the master generates a START. This terminates the write operation, but the address pointer will be set to the address sent. The master then issues the same control byte as the write operation, but with the R/W bit set to 1. The device will acknowledge and transmit the 8-bit data byte located at the address location written. The master will not acknowledge the transfer of the data byte, but will instead generate a STOP condition, which causes the device to discontinue transmission. See Figure 12-2. After the OTP Security Register Random Read operation, the internal address counter will increment to the address location following the one that was just read. Figure 12-2. OTP Security Register Random Read 12.3 OTP Security Register Sequential Read Sequential read allows the whole OTP Security Register contents to be serially read during one operation. Sequential Read is initiated in the same way as a Random Read except that after the device transmits the first data byte, the master issues an acknowledge instead of a STOP condition. This acknowledge from the master directs the device to transmit the next sequentially addressed byte (See Figure 12-3). Following the final byte transmitted to the master, the master will not generate an acknowledge, but will generate a STOP condition which causes the device to discontinue transmission. To provide the OTP Security Register Sequential Read, the device contains an internal address pointer which is incremented by one at each acknowledge received by the master, and by the STOP condition. Figure 12-3. OTP Security Register Sequential Read RM24C256DS DS-RM24C256DS–085B–11/2016 14 13. Electrical Specifications 13.1 Absolute Maximum Ratings Table 13-1. Absolute Maximum Ratings* Parameter Specification Operating ambient temp range -40°C to +85°C Storage temperature range -65°C to +150°C Input supply voltage, VCC to GND - 0.3V to 3.6V Voltage on any pin with respect to GND -0.5V to (VCC + 0.5V) ESD protection on all pins (Human Body Model) >2kV Junction temperature 125°C *NOTICE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these, or any other conditions beyond those indicated in the operational sections of this specification, is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 13.2 DC Characteristics Symbol Parameter Condition Max Units 3.6 V 1.55 V 0.25 0.5 mA 1 3 mA @25C 1 3 @85C 6 11 @25C 2.2 3 @85C 11 17 Min Typ TA = ‐40°C to +85° C, VCC = 1.65V to 3.6V VCC Supply Range 1.65V to 3.6V VVCCI VCC Inhibit   VCC= 3.3V SCL at 1MHz ICC2  VCC= 3.3V VCC= 1.65V. SCL=SDA=1.65V ICC3 Supply Current, Standby (1) VCC= 3.3V. SCL=SDA=3.3V 1. 1.65 µA IIL Input Leakage SCL, SDA, WP, E0, E1, E2, VIN=0V or +1 µA IOL Output Leakage SDA VIN=0V to VCC +1 µA VIL Input Low Voltage SCL, SDA, WP, E0, E1, E2 -0.3 VCC x V VIH Input High Voltage SCL, SDA, WP, E0, E1, E2 VCC x 0.7 VCC + V VOL Output Low Voltage SDA IOL = 3.0mA 0.4 V Values are based on device characterization, not 100% tested in production. RM24C256DS DS-RM24C256DS–085B–11/2016 15 13.3 AC Characteristics Applicable over recommended operating range:  TA = -40°C to +85° C, VCC = 1.65V to 3.6V, CL = CB