RM24C128A-BSNC-T

RM24EP32 | RM24EP64 | RM24EP128 32/64/128-Kbit 2.7V Minimum Sterilization-Tolerant Boot Memory I2C Bus Preliminary Datasheet Features  Gamma Radiation Tolerance: 50 kGy  e-Beam Sterilization Tolerance: 50 kGy  Memory array: 32-Kbit, 64-Kbit, and 128-Kbit EEPROM-compatible boot memory  Single supply voltage: 2.7V - 3.6V  2-wire I2C interface  Compatible with I2C bus modes:      -100kHz -400kHz -1MHz Page size: 32 byte / 64 byte -Byte and Page Write from 1 to 32 or 64 bytes -Byte Write within 50µs -Page Write within 1ms Random and sequential Read modes Write protect of the whole memory array RoHS-compliant and halogen-free packaging Based on Adesto's proprietary CBRAM® technology Description The RM24EP I2C EEPROM-compatible family of gamma-tolerant boot memory is comprised of devices with densities of 32 Kbit, 64 Kbit and 128 Kbit utilizing Adesto's CBRAM resistive memory technology. The memory devices use a single low-voltage supply ranging from 2.7V to 3.6V. 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 up to 32/64 bytes. 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 packages. DS-RM24EP–048C–6/2014 1. Block Diagram Figure 1-1. Block Diagram RM24EP DS-RM24EP–048C–6/2014 2 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 E1 SDA 1 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. 2.1 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 Pin Out Diagram RM24EP DS-RM24EP–048C–6/2014 3 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 3-1). 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. RM24EP DS-RM24EP–048C–6/2014 4 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 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 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 75 µS maximum period. VCC VCCmax Program, Read, Erase and Write Commands Rejected VCCmin VVCCI Device Fully Accessible Device in Reset tPUD TIME RM24EP DS-RM24EP–048C–6/2014 5 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. The control code is “1010” 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 Upon receiving a "1010", 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 5-2. It should be noted that not all the address bits are used. For the 32-Kbit device, only address A0 to A11 are used; the rest are don't cares and must be set to "0". For the 64-Kbit device, only address A0 to A12 are used; the rest are don't cares and must be set to "0". For the 128-Kbit device, only address A0 to A13 are used; the rest are don't cares and must be set to "0". Figure 5-2. 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. RM24EP DS-RM24EP–048C–6/2014 6 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. After the data byte has been written, the internal address pointer will be incremented by one. If, in the RM24EP128, 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 003Fh, the incremented address will be 0000h. 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 7. Page Write Operation Product Density Page Size (byte) RM24EP32 32 Kbit 32 RM24EP64 64 Kbit 32 RM24EP128 128 Kbit 64 During a Page Write cycle, up to a Page 32/64 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. RM24EP DS-RM24EP–048C–6/2014 7 If the master should transmit more than 32/64 bytes prior to generating the STOP command, the internal 32/64-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. For instance, in the RM24EP128, if the address given is 0087Ah and ten data bytes are transmitted by the master before the STOP command occurs, the last data byte received will be written in address location 00843h. 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. 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. 9. 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 Figure 9-1 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. RM24EP DS-RM24EP–048C–6/2014 8 Figure 9-1. Acknowledge Polling Flow 10. 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. 10.1 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. For the 128-Kbit device, if the previous read access was to address 3FFFh, the incremented address will wrap around to 0000h. For the 64-Kbit device the rollover occurs at address 01FFFh and for the 32-Kbit device the rollover occurs at 0FFFh. 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 10-1. Figure 10-1. Current Address Read RM24EP DS-RM24EP–048C–6/2014 9 10.2 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 10-2. After the Random Read operation, the internal address counter will increment to the address location following the one that was just read. Figure 10-2. Random Read 10.3 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 10-3). 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 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 10-3. Sequential Read RM24EP DS-RM24EP–048C–6/2014 10 11. Electrical Specifications 11.1 Absolute Maximum Ratings Table 11-1. Absolute Maximum Ratings* Parameter Specification Temperature under Bias 0°C to +70° C Storage Temperature -20°C to +100°C All Input voltages with respect to GND - 0.3V to +3.6V All Output voltages with respect to GND -0.3V to (VCC + 0.3) ESD protection on all pins (Human Body Model) >2kV Junction temperature 85°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. 11.2 DC Characteristics Symbol Parameter Condition Min Typ Max Units 3.6 V 2.4 V 1 2 mA 1.5 3 mA 5 20 µA +1 µA +1 µA -0.3 VCC x 0.3 V VCC x 0.7 VCC + 0.3 V 0.4 V TA = 0°C to +70° C, 2.7V to 3.6V VCC Supply Range 2.7V to 3.6V 2.7 VVCCI VCC Inhibit ICC1 Supply Current, Read VCC= 3.3V SCL at 1MHz ICC2 Supply Current, Write VCC= 3.3V ICC3 Supply Current, Standby VCC= 3.3V. SCL=SDA=3.3V IIL Input Leakage SCL, SDA, WP, E0, E1, E2 VIN=0V IOL Output Leakage VIL Input Low Voltage VIH Input High Voltage VOL Output Low Voltage to VCC SDA VIN=0V to VCC SCL, SDA, WP, E0, E1, E2 SCL, SDA, WP, E0, E1, E2 SDA IOL = 3.0mA RM24EP DS-RM24EP–048C–6/2014 11 11.3 AC Characteristics Applicable over recommended operating range: TA = 0°C to +70° C, VCC = 2.7V to 3.6V, CL = CB