CY14B101Q1
CY14B101Q2
PRELIMINARYCY14B101Q3
Device Operation | SRAM Write |
CY14B101Q1/CY14B101Q2/CY14B101Q3 is 1 Mbit nvSRAM memory with a nonvolatile element in each memory cell. All the reads and writes to nvSRAM happen to the SRAM which gives nvSRAM the unique capability to handle infinite writes to the memory. The data in SRAM is secured by a STORE sequence which transfers the data in parallel to the nonvolatile Quantum Trap cells. A small capacitor (VCAP) is used to AutoStore the SRAM data in nonvolatile cells when power goes down providing power down data security. The Quantum Trap nonvolatile elements built in the reliable SONOS technology make nvSRAM the ideal choice for secure data storage.
The 1 Mbit memory array is organized as 128K words x 8 bits. The memory can be accessed through a standard SPI interface that enables very high clock speeds upto 40 MHz with zero cycle delay read and write cycles. This device supports SPI modes 0 and 3 (CPOL, CPHA = 0, 0 & 1, 1) and operates as SPI slave. The device is enabled using the Chip Select pin (CS) and accessed through Serial Input (SI), Serial Output (SO), and Serial Clock (SCK) pins.
This device provides the feature for hardware and software write protection through WP pin and WRDI instruction respectively along with mechanisms for block write protection (1/4, 1/2, or full array) using BP0 and BP1 pins in the status register. Further, the HOLD pin can be used to suspend any serial communication without resetting the serial sequence.
CY14B101Q1/CY14B101Q2/CY14B101Q3 uses the standard SPI opcodes for memory access. In addition to the general SPI instructions for read and write, it provides four special instructions which enable access to four nvSRAM specific functions: STORE, RECALL, AutoStore Disable (ASDISB), and AutoStore Enable (ASENB).
The major benefit of nvSRAM SPI over serial EEPROMs is that all reads and writes to nvSRAM are performed at the speed of SPI bus with zero delay. Therefore, no wait time is required after any of the memory accesses. The STORE and RECALL operations need finite time to complete and all memory accesses are inhibited during this time. While a STORE or RECALL operation is in progress, the busy status of the device is indicated by the Hardware STORE Busy (HSB) pin and also reflected on the RDY bit of the Status Register.
The Device is available in three different pin configurations that enable the user to choose a part which fits in best in their appli- cation. The Feature summary is given in Table 2.
Table 2. Feature Summary
| Feature | CY14B101Q1 | CY14B101Q2 | CY14B101Q3 | ||
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| Yes | No | Yes |
| WP | |||||
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| VCAP | No | Yes | Yes | ||
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| No | No | Yes |
| HSB | |||||
| AutoStore | No | Yes | Yes | ||
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| Power Up | Yes | Yes | Yes | ||
| RECALL |
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| Hardware | No | No | Yes | ||
| STORE |
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| Software | Yes | Yes | Yes | ||
| STORE |
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All writes to nvSRAM are carried out on the SRAM and do not use up any endurance cycles of the nonvolatile memory. This enables user to perform infinite write operations. A Write cycle is performed through the SPI WRITE instruction. The WRITE instruction is issued through the SI pin of the nvSRAM and consists of the WRITE opcode, three bytes of address, and one byte of data. Write to nvSRAM is done at SPI bus speed with zero cycle delay.
The device allows burst mode writes to be performed through SPI. This enables write operations on consecutive addresses without issuing a new WRITE instruction. When the last address in memory is reached, the address rolls over to 0x0000 and the device continues to write.
The SPI write cycle sequence is defined explicitly in the Memory Access section of SPI Protocol Description.
SRAM Read
A read cycle is performed at the SPI bus speed and the data is read out with zero cycle delay after the READ instruction is performed. The READ instruction is issued through the SI pin of the nvSRAM and consists of the READ opcode and 3 bytes of address. The data is read out on the SO pin.
This device allows burst mode reads to be performed through SPI. This enables reads on consecutive addresses without issuing a new READ instruction. When the last address in memory is reached in burst mode read, the address rolls over to 0x0000 and the device continues to read.
The SPI read cycle sequence is defined explicitly in the Memory Access section of SPI Protocol Description.
STORE Operation
STORE operation transfers the data from the SRAM to the nonvolatile Quantum Trap cells. The device stores data to the nonvolatile cells using one of three STORE operations: AutoStore, activated on device power down; Software STORE, activated by a STORE instruction in the SPI; Hardware STORE, activated by the HSB. During the STORE cycle, an erase of the previous nonvolatile data is first performed, followed by a program of the nonvolatile elements. After a STORE cycle is initiated, further input and output are disabled until the cycle is completed.
The HSB signal or the RDY bit in the Status register can be monitored by the system to detect if a STORE cycle is in progress. The busy status of nvSRAM is indicated by HSB being pulled LOW or RDY bit being set to ‘1’. To avoid unnecessary nonvolatile STOREs, AutoStore and Hardware STORE opera- tions are ignored unless at least one write operation has taken place since the most recent STORE or RECALL cycle. Software initiated STORE cycles are performed regardless of whether a write operation has taken place.
AutoStore Operation
The AutoStore operation is a unique feature of nvSRAM which automatically stores the SRAM data to QuantumTrap during power down. This Store mechanism is implemented using a
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