FM33256-G

Preliminary FM33256/FM3316 3V Integrated Processor Companion with Memory Features High Integration Device Replaces Multiple Parts • Serial Nonvolatile Memory • Real-time Clock (RTC) with Alarm • Low VDD Detection Drives Reset • Watchdog Window Timer • Early Power-Fail Warning/NMI • 16-bit Nonvolatile Event Counter • Serial Number with Write-lock for Security Ferroelectric Nonvolatile RAM • 256Kb and 16Kb versions • Unlimited Read/Write Endurance • 10 year Data Retention • NoDelay™ Writes Real-time Clock/Calendar • Backup Current under 1 µA • Seconds through Centuries in BCD format • Tracks Leap Years through 2099 • Uses Standard 32.768 kHz Crystal • Software Calibration • Supports Battery or Capacitor Backup Processor Companion • Active-low Reset Output for VDD and Watchdog • Programmable Low-VDD Reset Thresholds • Manual Reset Filtered and Debounced • Programmable Watchdog Window Timer • Nonvolatile Event Counter Tracks System Intrusions or other Events • Comparator for Power-Fail Interrupt or Other Use • 64-bit Programmable Serial Number with Lock Fast SPI Interface • Up to 16 MHz Maximum Bus Frequency • RTC, Supervisor Controlled via SPI Interface • SPI Mode 0 & 3 (CPOL, CPHA=0,0 & 1,1) Easy to Use Configurations • Operates from 2.7 to 3.6V • Small Footprint “Green” 14-pin SOIC (-G) • Low Operating Current, 50µA Standby Current • -40°C to +85°C Operation Description The FM33256 and FM3316 are devices that integrate FRAM memory with the most commonly needed functions for processor-based systems. Major features include nonvolatile memory, real-time clock, low-VDD reset, watchdog timer, nonvolatile event counter, lockable 64-bit serial number area, and general purpose comparator that can be used for a power-fail (NMI) interrupt or other purpose. The devices operate from 2.7 to 3.6V. Each FM33xx provides nonvolatile RAM available in memory capacity of 16Kb and 256Kb. Fast write speed and unlimited endurance allow the memory to serve as extra RAM or conventional nonvolatile storage. This memory is truly nonvolatile rather than battery backed. The real-time clock (RTC) provides time and date information in BCD format. It can be permanently powered from external backup voltage source, either a battery or a capacitor. The timekeeper uses a common external 32.768 kHz crystal and provides a calibration mode that allows software adjustment of timekeeping accuracy. The processor companion includes commonly needed CPU support functions. Supervisory functions include a reset output signal controlled by either a low VDD condition or a watchdog timeout. /RST goes active when VDD drops below a programmable threshold and remains active for 100 ms (max.) after VDD rises above the trip point. A programmable watchdog timer runs from 60 ms to 1.8 seconds. The timer may also be programmed for a delayed start, which functions as a window timer. The watchdog timer is optional, but if enabled it will assert the reset signal for 100 ms if not restarted by the host within the time window. A flag-bit indicates the source of the reset. A comparator on PFI compares an external input pin to the onboard 1.5V reference. This is useful for generating a power-fail interrupt (NMI) but can be used for any purpose. The family also includes a programmable 64-bit serial number that can be locked making it unalterable. Additionally it offers an event counter that tracks the number of rising or falling edges detected on a dedicated input pin. The counter can be programmed to be non-volatile under VDD power or battery-backed using only VBAK. If VBAK is connected to a battery or capacitor, then events will be counted even in the absence of VDD. Ramtron International Corporation 1850 Ramtron Drive, Colorado Springs, CO 80921 (800) 545-FRAM, (719) 481-7000 http://www.ramtron.com Page 1 of 28 This is a product that has fixed target specifications but are subject to change pending characterization results. Rev. 1.0 Dec. 2006 FM33256/FM3316 SPI Companion w/ FRAM Pin Configuration CS SO CNT VBAK X2 X1 VSS 1 2 3 4 5 6 7 14 13 12 11 10 9 8 VDD ACS SCK SI PFO RST PFI Pin Name /CS SCK SI SO PFI PFO CNT ACS /RST X1, X2 VDD VBAK VSS Function Chip Select Serial Clock Serial Data Input Serial Data Output Power Fail Input Power Fail Output (NMI) Event Counter Input Alarm/Calibration/SqWave Reset Input/Output Crystal Connections Supply Voltage Battery-Backup Supply Ground Pin Descriptions Pin Name /CS Type Input Pin Description Chip Select: This active low input activates the device. When high, the device enters lowpower standby mode, ignores the SCK and SI inputs, and the SO output is tri-stated. When low, the device internally activates the SCK signal. A falling edge on /CS must occur prior to every op-code. Serial Clock: All I/O activity is synchronized to the serial clock. Inputs are latched on the rising edge and outputs occur on the falling edge. Since the device is static, the clock frequency may be any value between 0 and 16 MHz and may be interrupted at any time. Serial Input: All data is input to the device on this pin. The pin is sampled on the rising edge of SCK and is ignored at other times. It should always be driven to a valid logic level to meet IDD specifications. The SI pin may be connected to SO for a single pin data interface. Serial Output: This is the data output pin. It is driven during a read and remains tri-stated at all other times. Data transitions are driven on the falling edge of the serial clock. The SO pin may be connected to SI for a single pin data interface. Event Counter Input: This input increments the counter when an edge is detected on this pin. The polarity is programmable and the counter value is nonvolatile or battery-backed, depending on the mode. This pin should be tied to ground if unused. Alarm/Calibration/SquareWave: This is an open-drain output that requires an external pullup resistor. In normal operation, this pin acts as the active-low alarm output. In Calibration mode, a 512 Hz square-wave is driven out. In SquareWave mode, the user may select a frequency of 1, 512, 4096, or 32768 Hz to be used as a continuous output. The SquareWave mode is entered by clearing the AL/SW and CAL bits in register 18h. 32.768 kHz crystal connection. When using an external oscillator, apply the clock to X1 and a DC mid-level to X2 (see Crystal Type section for suggestions). Reset: This active-low output is open drain with weak pull-up. It is also an input when used as a manual reset. This pin should be left floating if unused. Early Power-fail Input: Typically connected to an unregulated power supply to detect an early power failure. This pin must be tied to ground if unused. Early Power-fail Output: This pin is the early power-fail output and is typically used to drive a microcontroller NMI pin. PFO drives low when the PFI voltage is