Overview
The Cypress CY14X256PA combines a 256-Kbit nvSRAM[1] with a full-featured RTC 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). You can also initiate the STORE and RECALL operations 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 using SPI instruction (Software STORE) or HSB pin (Hardware 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 at 85C
■ Real time clock (RTC)
   ❐ Full-featured RTC
   ❐ Watchdog timer
   ❐ Clock alarm with programmable interrupts
   ❐ Backup power fail indication
   ❐ Square wave output with programmable frequency (1 Hz, 512 Hz, 4096 Hz, 32.768 kHz)
   ❐ Capacitor or battery backup for RTC
   ❐ Backup current of 0.45 µA (typical)
■ 40 MHz and 104 MHz High-speed serial peripheral interface (SPI)
   ❐ 40 MHz clock rate SPI write and read with zero cycle delay
   ❐ 104 MHz clock rate SPI write and read (with special fast read instructions)
   ❐ Supports SPI mode 0 (0,0) and mode 3 (1,1)
■ SPI access to special functions
   ❐ Nonvolatile STORE/RECALL
   ❐ 8-byte serial number
   ❐ Manufacturer ID and Product ID
   ❐ Sleep mode
■ 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
   ❐ Average active current of 3 mA at 40 MHz operation
   ❐ Average standby mode current of 250 A
   ❐ Sleep mode current of 8 A
■ Industry standard configurations
   ❐ Operating voltages:
      • CY14C256PA: VCC = 2.4 V to 2.6 V
      • CY14B256PA: VCC = 2.7 V to 3.6 V
      • CY14E256PA: VCC = 4.5 V to 5.5 V
   ❐ Industrial temperature
   ❐ 16-pin small outline integrated circuit (SOIC) package
   ❐ Restriction of hazardous substances (RoHS) compliant