Overview
The Cypress CY14B256P combines a 256-Kbit nvSRAM [1] with a full-featured real time clock in a monolithic integrated circuit with serial SPI interface. The memory is organized as 32 K words of 8 bits each. The embedded nonvolatile elements incorporate the QuantumTrap technology, creating the world’s most reliable nonvolatile memory. The SRAM provides infinite read and write cycles, while the QuantumTrap cells provide highly reliable nonvolatile storage of data. Data transfers from SRAM to the nonvolatile elements (STORE operation) takes place automatically at power-down. On power-up, data is restored to the SRAM from the nonvolatile memory (RECALL operation). The STORE and RECALL operations can also be initiated by the user through SPI instruction.

FEATUREs
■ 256-Kbit nonvolatile static random access memory (nvSRAM)
   ❐ Internally organized as 32 K × 8
   ❐ STORE to QuantumTrap nonvolatile elements initiated automatically on power-down (AutoStore) or by user using HSB pin (Hardware STORE) or SPI instruction (Software STORE)
   ❐ RECALL to SRAM initiated on power-up (Power-Up RECALL) or by SPI instruction (Software RECALL)
   ❐ Automatic STORE on power-down with a small capacitor
■ High reliability
   ❐ Infinite read, write, and RECALL cycles
   ❐ 1 million STORE cycles to QuantumTrap
   ❐ Data retention: 20 years
■ Real time clock (RTC)
   ❐ Full-featured RTC
   ❐ Watchdog timer
   ❐ Clock alarm with programmable interrupts
   ❐ Capacitor or battery backup for RTC
   ❐ Backup current of 0.35 µA (typical)
■ High-speed serial peripheral interface (SPI)
   ❐ 40-MHz clock rate – SRAM memory access
   ❐ 25-MHz clock rate – RTC memory access
   ❐ Supports SPI mode 0 (0,0) and mode 3 (1,1)
■ Write protection
   ❐ Hardware protection using Write Protect (WP) pin
   ❐ Software protection using Write Disable instruction
   ❐ Software block protection for 1/4, 1/2, or entire array
■ Low power consumption
   ❐ Single 3 V +20%, –10% operation
   ❐ Average active current of 10 mA at 40 MHz operation
■ Industry standard configurations
   ❐ Industrial temperature
   ❐ 16-pin small outline integrated circuit (SOIC) package
   ❐ Restriction of hazardous substances (RoHS) compliant