STK15C88-SF45

STK15C88 256 Kbit (32K x 8) PowerStore nvSRAM Functional Description ■ 25 ns and 45 ns Access Times ■ Pin compatible with Industry Standard SRAMs ■ Automatic Nonvolatile STORE on power loss ■ Nonvolatile STORE under Software Control ■ Automatic RECALL to SRAM on Power Up ■ Unlimited Read/Write Endurance ■ Unlimited RECALL Cycles ■ 1,000,000 STORE Cycles The Cypress STK15C88 is a 256Kb fast static RAM with a nonvolatile element in each memory cell. The embedded nonvolatile elements incorporate QuantumTrap™ technology producing the world’s most reliable nonvolatile memory. The SRAM provides unlimited read and write cycles, while independent, nonvolatile data resides in the highly reliable QuantumTrap cell. Data transfers from the SRAM to the nonvolatile elements (the STORE operation) takes place automatically at power down. On power up, data is restored to the SRAM (the RECALL operation) from the nonvolatile memory. Both the STORE and RECALL operations are also available under software control. ■ 100 year Data Retention ■ Single 5V+10% Power Supply ■ Commercial and Industrial Temperatures ■ 28-pin (300 mil and 330 mil) SOIC packages ■ RoHS Compliance ra m s on l y. Features N In ot r pr ec od om uc m tio en n de to d su fo pp r n or ew to d ng es oi ig ng ns pr . od uc tio n pr og PowerStore nvSRAM products depend on the intrinsic system capacitance to maintain system power long enough for an automatic store on power loss. If the power ramp from 5 volts to 3.6 volts is faster than 10 ms, consider our 14C88 or 16C88 for more reliable operation. Logic Block Diagram Cypress Semiconductor Corporation Document Number: 001-50593 Rev. *A • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600 Revised December 11, 2009 [+] Feedback STK15C88 Contents pr og ra m s on l y. Data Retention and Endurance ......................................... 8 Capacitance ........................................................................ 8 Thermal Resistance ............................................................ 8 AC Test Conditions ............................................................ 8 AC Switching Characteristics ........................................... 9 SRAM Read Cycle ........................................................ 9 Switching Waveforms ........................................................ 9 Switching Waveforms ......................................................10 AutoStore or Power Up RECALL ....................................11 Switching Waveforms ......................................................11 Software Controlled STORE/RECALL Cycle ..................12 Part Numbering Nomenclature ........................................13 Ordering Information ........................................................13 Package Diagrams ............................................................14 Sales, Solutions and Legal Information .........................16 Worldwide Sales and Design Support......................... 16 Products ...................................................................... 16 N In ot r pr ec od om uc m tio en n de to d su fo pp r n or ew to d ng es oi ig ng ns pr . od uc tio n Features ...............................................................................1 Functional Description .......................................................1 Logic Block Diagram ..........................................................1 Contents ..............................................................................2 Pin Configurations .............................................................3 Device Operation ................................................................4 SRAM Read .........................................................................4 SRAM Write .........................................................................4 AutoStore Operation ..........................................................4 Hardware RECALL (Power Up) ..........................................4 Software STORE .................................................................4 Software RECALL ...............................................................4 Hardware Protect ................................................................5 Noise Considerations .........................................................5 Low Average Active Power ................................................5 Best Practices .....................................................................5 Maximum Ratings ...............................................................7 DC Electrical Characteristics ............................................7 Document Number: 001-50593 Rev. *A Page 2 of 16 [+] Feedback STK15C88 Pin Configurations Figure 1. Pin Diagram - 28-Pin SOIC $   9&& $ $     :( $ $  $ $ $      $   &( $   '4 '4   '4 '4 '4     '4 '4 966   '4 y. on l m 2( $ ra   og  $ N In ot r pr ec od om uc m tio en n de to d su fo pp r n or ew to d ng es oi ig ng ns pr . od uc tio n  s $ $ pr 723 $ Table 1. Pin Definitions - 28-Pin SOIC Pin Name Alt I/O Type A0–A14 Input DQ0-DQ7 Input or Output WE CE OE VSS VCC Description Address Inputs. Used to select one of the 32,768 bytes of the nvSRAM. Bidirectional Data I/O lines. Used as input or output lines depending on operation. W Input Write Enable Input, Active LOW. When the chip is enabled and WE is LOW, data on the I/O pins is written to the specific address location. E Input Chip Enable Input, Active LOW. When LOW, selects the chip. When HIGH, deselects the chip. G Input Output Enable, Active LOW. The active LOW OE input enables the data output buffers during read cycles. Deasserting OE HIGH causes the I/O pins to tristate. Ground Ground for the Device. The device is connected to ground of the system. Power Supply Power Supply Inputs to the Device. Document Number: 001-50593 Rev. *A Page 3 of 16 [+] Feedback STK15C88 Device Operation Software STORE The STK15C88 is a versatile memory chip that provides several modes of operation. The STK15C88 can operate as a standard 32K x 8 SRAM. It has a 32K x 8 nonvolatile element shadow to which the SRAM information can be copied, or from which the SRAM can be updated in nonvolatile mode. Data is transferred from the SRAM to the nonvolatile memory by a software address sequence. The STK15C88 software STORE cycle is initiated by executing sequential CE controlled READ cycles from six specific address locations in exact order. During the STORE cycle, an erase of the previous nonvolatile data is first performed, followed by a program of the nonvolatile elements. When a STORE cycle is initiated, input and output are disabled until the cycle is completed. SRAM Write on l y. Because a sequence of READs from specific addresses is used for STORE initiation, it is important that no other READ or WRITE accesses intervene in the sequence. If they intervene, the sequence is aborted and no STORE or RECALL takes place. ra m s To initiate the software STORE cycle, the following READ sequence is performed: 1. Read address 0x0E38, Valid READ 2. Read address 0x31C7, Valid READ 3. Read address 0x03E0, Valid READ 4. Read address 0x3C1F, Valid READ 5. Read address 0x303F, Valid READ 6. Read address 0x0FC0, Initiate STORE cycle og The STK15C88 performs a READ cycle whenever CE and OE are LOW while WE is HIGH. The address specified on pins A0–14 determines the 32,768 data bytes accessed. When the READ is initiated by an address transition, the outputs are valid after a delay of tAA (READ cycle 1). If the READ is initiated by CE or OE, the outputs are valid at tACE or at tDOE, whichever is later (READ cycle 2). The data outputs repeatedly respond to address changes within the tAA access time without the need for transitions on any control input pins, and remains valid until another address change or until CE or OE is brought HIGH. pr SRAM Read The software sequence is clocked with CE controlled READs. When the sixth address in the sequence is entered, the STORE cycle commences and the chip is disabled. It is important that READ cycles and not WRITE cycles are used in the sequence. It is not necessary that OE is LOW for a valid sequence. After the tSTORE cycle time is fulfilled, the SRAM is again activated for READ and WRITE operation. AutoStore Operation Software RECALL The STK15C88 uses the intrinsic system capacitance to perform an automatic STORE on power down. As long as the system power supply takes at least tSTORE to decay from VSWITCH down to 3.6V, the STK15C88 will safely and automatically store the SRAM data in nonvolatile elements on power down. Data is transferred from the nonvolatile memory to the SRAM by a software address sequence. A software RECALL cycle is initiated with a sequence of READ operations in a manner similar to the software STORE initiation. To initiate the RECALL cycle, the following sequence of CE controlled READ operations is performed: 1. Read address 0x0E38, Valid READ 2. Read address 0x31C7, Valid READ 3. Read address 0x03E0, Valid READ 4. Read address 0x3C1F, Valid READ 5. Read address 0x303F, Valid READ 6. Read address 0x0C63, Initiate RECALL cycle N In ot r pr ec od om uc m tio en n de to d su fo pp r n or ew to d ng es oi ig ng ns pr . od uc tio n A WRITE cycle is performed whenever CE and WE are LOW. The address inputs must be stable prior to entering the WRITE cycle and must remain stable until either CE or WE goes HIGH at the end of the cycle. The data on the common I/O pins DQ0–7 are written into the memory if it has valid tSD, before the end of a WE controlled WRITE or before the end of an CE controlled WRITE. Keep OE HIGH during the entire WRITE cycle to avoid data bus contention on common I/O lines. If OE is left LOW, internal circuitry turns off the output buffers tHZWE after WE goes LOW. In order to prevent unneeded STORE operations, automatic STOREs will be 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. Hardware RECALL (Power Up) During power up or after any low power condition (VCC < VRESET), an internal RECALL request is latched. When VCC once again exceeds the sense voltage of VSWITCH, a RECALL cycle is automatically initiated and takes tHRECALL to complete. If the STK15C88 is in a WRITE state at the end of power up RECALL, the SRAM data is corrupted. To help avoid this situation, a 10 Kohm resistor is connected either between WE and system VCC or between CE and system VCC. Document Number: 001-50593 Rev. *A Internally, RECALL is a two step procedure. First, the SRAM data is cleared, and then the nonvolatile information is transferred into the SRAM cells. After the tRECALL cycle time, the SRAM is once again ready for READ and WRITE operations. The RECALL operation does not alter the data in the nonvolatile elements. The nonvolatile data can be recalled an unlimited number of times. Page 4 of 16 [+] Feedback STK15C88 Hardware Protect Figure 3. Current Versus Cycle Time (READ) The STK15C88 offers hardware protection against inadvertent STORE operation and SRAM WRITEs during low voltage conditions. When VCAP (VCC – 0.2V). All other inputs cycling. at tRC= 200 ns, 5V, Dependent on output loading and cycle rate. Values obtained without output loads. 25°C Typical Average Current during AutoStore Cycle All Inputs Do Not Care, VCC = Max Average current for duration tSTORE Average VCC Current tRC=25ns, CE > VIH tRC=45ns, CE > VIH (Standby, Cycling TTL Input Levels) VCC Standby Current CE > (VCC – 0.2V). All others VIN < 0.2V or > (VCC – 0.2V). (Standby, Stable CMOS Input Levels) Input Leakage Current VCC = Max, VSS < VIN < VCC -1 +1 μA Off State Output Leakage Current VCC = Max, VSS < VIN < VCC, CE or OE > VIH or WE < VIL -5 +5 μA Input HIGH Voltage 2.2 VCC + 0.5 V Input LOW Voltage VSS – 0.5 0.8 V Output HIGH Voltage IOUT = –4 mA Output LOW Voltage IOUT = 8 mA 2.4 V 0.4 V Note 3. CE > VIH will not produce standby current levels until any nonvolatile cycle in progress has timed out. Document Number: 001-50593 Rev. *A Page 7 of 16 [+] Feedback STK15C88 Data Retention and Endurance Parameter Description DATAR Data Retention NVC Nonvolatile STORE Operations Min Unit 100 Years 1,000 K Capacitance In the following table, the capacitance parameters are listed.[4] CIN Input Capacitance COUT Output Capacitance Test Conditions Max TA = 25°C, f = 1 MHz, VCC = 0 to 3.0 V 5 7 pF Thermal Resistance (Junction to Case) m 28-SOIC (300 mil) 28-SOIC (330 mil) Unit TBD TBD °C/W TBD TBD °C/W og Test conditions follow standard test methods and procedures for measuring thermal impedance, per EIA / JESD51. N In ot r pr ec od om uc m tio en n de to d su fo pp r n or ew to d ng es oi ig ng ns pr . od uc tio n ΘJC Thermal Resistance (Junction to Ambient) Test Conditions pr ΘJA Description ra In the following table, the thermal resistance parameters are listed.[4] Parameter pF s Thermal Resistance Unit y. Description on l Parameter Figure 4. AC Test Loads R1 480Ω 5.0V Output 30 pF R2 255Ω AC Test Conditions Input Pulse Levels .................................................. 0 V to 3 V Input Rise and Fall Times (10% - 90%)........................