CY14E256LA 256-Kbit (32 K × 8) Nonvolatile SRAM 256-Kbit (32 K × 8) Nonvolatile SRAM Features Functional Description ■ 25 ns and 45 ns access times ■ Internally organized as 32 K × 8 (CY14E256LA) ■ Hands-off automatic STORE on power-down with only a small capacitor ■ STORE to QuantumTrap nonvolatile elements initiated by software, device pin, or autostore on power-down ■ RECALL to SRAM initiated by software or power-up ■ Infinite read, write, and RECALL cycles ■ 1 million STORE cycles to QuantumTrap ■ 20-year data retention ■ Single 5 V +10% operation ■ Industrial temperature ■ 44-pin thin small-outline package (TSOP II) and 32-pin small-outline integrated circuit (SOIC) package ■ Pb-free and restriction of hazardous substances (RoHS) compliant The Cypress CY14E256LA is a fast static RAM, with a nonvolatile element in each memory cell. The memory is organized as 32 KB. The embedded nonvolatile elements incorporate QuantumTrap technology, producing the world’s most reliable nonvolatile memory. The SRAM provides infinite 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. Logic Block Diagram Cypress Semiconductor Corporation Document Number: 001-54952 Rev. *F • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600 Revised January 17, 2011 [+] Feedback CY14E256LA Contents Pinouts .............................................................................. 3 Pin Definitions .................................................................. 3 Device Operation .............................................................. 4 SRAM Read ....................................................................... 4 SRAM Write ....................................................................... 4 AutoStore Operation ........................................................ 4 Hardware STORE Operation ............................................ 4 Hardware RECALL (Power-up) ........................................ 5 Software STORE ............................................................... 5 Software RECALL ............................................................. 5 Preventing AutoStore ....................................................... 6 Data Protection ................................................................. 6 Noise Considerations ....................................................... 6 Best Practices ................................................................... 7 Maximum Ratings ............................................................. 8 Operating Range ............................................................... 8 DC Electrical Characteristics .......................................... 8 Data Retention and Endurance ....................................... 9 Capacitance ...................................................................... 9 Thermal Resistance .......................................................... 9 Document Number: 001-54952 Rev. *F AC Test Conditions .......................................................... 9 AC Switching Characteristics ....................................... 10 SRAM Read Cycle .................................................... 10 SRAM Write Cycle ..................................................... 10 AutoStore/Power-up RECALL ....................................... 12 Software Controlled STORE/RECALL Cycle ................ 13 Hardware STORE Cycle ................................................. 14 Truth Table For SRAM Operations ................................ 15 Ordering Information ...................................................... 15 Ordering Code Definition ........................................... 15 Package Diagrams .......................................................... 16 Acronyms ........................................................................ 17 Acronyms Used ......................................................... 17 Document Conventions ................................................. 17 Units of Measure ....................................................... 17 Document History Page ................................................. 18 Sales, Solutions, and Legal Information ...................... 19 Worldwide Sales and Design Support ....................... 19 Products .................................................................... 19 PSoC Solutions ......................................................... 19 Page 2 of 19 [+] Feedback CY14E256LA Pinouts Figure 1. Pin Diagram – 44-Pin TSOP II / 32-Pin SOIC NC [5] NC A0 A1 A2 A3 A4 CE DQ0 DQ1 VCC VSS DQ2 DQ3 WE A5 A6 A7 A8 A9 NC NC 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 44 – TSOP II (x8) Top View (not to scale) 44 43 42 41 40 39 38 37 36 35 34 33 32 31 HSB NC [4] NC [3] NC [2] NC NC [1] [1] NC OE DQ7 DQ6 VSS VCC DQ5 DQ4 30 29 28 27 26 25 24 23 VCAP A14 A13 32 – SOIC (x8) Top View (not to scale) A12 A11 A10 NC NC Pin Definitions Pin Name I/O Type A0 – A14 Input Description Address inputs. Used to select one of the 32,768 bytes of the nvSRAM. DQ0 – DQ7 Input/Output Bidirectional data I/O Lines. Used as input or output lines depending on operation. WE 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. CE Input Chip Enable input, Active LOW. When LOW, selects the chip. When HIGH, deselects the chip. OE Input Output Enable, Active LOW. The active LOW OE input enables the data output buffers during read cycles. I/O pins are tri-stated on deasserting OE HIGH. VSS Ground Ground for the device. Must be connected to the ground of the system. VCC Power supply Power supply inputs to the device. HSB VCAP NC Input/Output Hardware STORE Busy (HSB). When LOW, this output indicates that a Hardware STORE is in progress. When pulled LOW, external to the chip, it initiates a nonvolatile STORE operation. After each Hardware and Software STORE operation HSB is driven HIGH for a short time (tHHHD) with standard output high current and then a weak internal pull-up resistor keeps this pin HIGH (external pull-up resistor connection is optional). Power supply AutoStore capacitor. Supplies power to the nvSRAM during power loss to store data from SRAM to nonvolatile elements. No connect No connect. This pin is not connected to the die. Notes 1. Address expansion for 1 Mbit. NC pin not connected to die. 2. Address expansion for 2 Mbit. NC pin not connected to die. 3. Address expansion for 4 Mbit. NC pin not connected to die. 4. Address expansion for 8 Mbit. NC pin not connected to die. 5. Address expansion for 16 Mbit. NC pin not connected to die. Document Number: 001-54952 Rev. *F Page 3 of 19 [+] Feedback CY14E256LA The CY14E256LA nvSRAM is made up of two functional components paired in the same physical cell. They are an SRAM memory cell and a nonvolatile QuantumTrap cell. The SRAM memory cell operates as a standard fast static RAM. Data in the SRAM is transferred to the nonvolatile cell (the STORE operation), or from the nonvolatile cell to the SRAM (the RECALL operation). Using this unique architecture, all cells are stored and recalled in parallel. During the STORE and RECALL operations, SRAM read and write operations are inhibited. The CY14E256LA supports infinite reads and writes similar to a typical SRAM. In addition, it provides infinite RECALL operations from the nonvolatile cells and up to 1 million STORE operations. Refer to the Truth Table For SRAM Operations on page 15 for a complete description of read and write modes. SRAM Read The CY14E256LA performs a read cycle when CE and OE are LOW and WE and HSB are HIGH. The address specified on pins A0-14 determines which of the 32,768 data bytes each are 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 output repeatedly responds to address changes within the tAA access time without the need for transitions on any control input pins. This remains valid until another address change or until CE or OE is brought HIGH, or WE or HSB is brought LOW. SRAM Write A write cycle is performed when CE and WE are LOW and HSB is HIGH. The address inputs must be stable before entering the write cycle and must remain stable until 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 the data is valid tSD before the end of a WE-controlled write or before the end of a 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. Note If the capacitor is not connected to VCAP pin, AutoStore must be disabled using the soft sequence specified in Preventing AutoStore on page 6. In case AutoStore is enabled without a capacitor on VCAP pin, the device attempts an AutoStore operation without sufficient charge to complete the Store. This corrupts the data stored in nvSRAM. Figure 2 shows the proper connection of the storage capacitor (VCAP) for automatic STORE operation. Refer to DC Electrical Characteristics on page 8 for the size of VCAP. The voltage on the VCAP pin is driven to VCC by a regulator on the chip. Place a pull-up on WE to hold it inactive during power-up. This pull-up is only effective if the WE signal is tristate during power-up. Many MPUs tristate their controls on power-up. This must be verified when using the pull-up. When the nvSRAM comes out of power-on-RECALL, the MPU must be active or the WE held inactive until the MPU comes out of reset. To reduce unnecessary nonvolatile stores, AutoStore and Hardware STORE operations 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. The HSB signal is monitored by the system to detect if an AutoStore cycle is in progress. Figure 2. AutoStore Mode VCC 0.1 uF 10 kOhm Device Operation VCC WE VCAP VSS VCAP AutoStore Operation The CY14E256LA stores data to the nvSRAM using one of the following three storage operations: Hardware STORE activated by HSB; Software STORE activated by an address sequence; AutoStore on device power-down. The AutoStore operation is a unique feature of QuantumTrap technology and is enabled by default on the CY14E256LA. During a normal operation, the device draws current from VCC to charge a capacitor connected to the VCAP pin. This stored charge is used by the chip to perform a single STORE operation. If the voltage on the VCC pin drops below VSWITCH, the part automatically disconnects the VCAP pin from VCC. A STORE operation is initiated with power provided by the VCAP capacitor. Hardware STORE Operation The CY14E256LA provides the HSB pin to control and acknowledge the STORE operations. Use the HSB pin to request a Hardware STORE cycle. When the HSB pin is driven LOW, the CY14E256LA conditionally initiates a STORE operation after tDELAY. An actual STORE cycle only begins if a write to the SRAM has taken place since the last STORE or RECALL cycle. The HSB pin also acts as an open drain driver (internal 100 kΩ weak pull-up resistor) that is internally driven LOW to indicate a busy condition when the STORE (initiated by any means) is in progress. Note After each Hardware and Software STORE operation HSB is driven HIGH for a short time (tHHHD) with standard output high current and then remains HIGH by internal 100 kΩ pull-up resistor. Document Number: 001-54952 Rev. *F Page 4 of 19 [+] Feedback CY14E256LA To initiate the Software STORE cycle, the following read sequence must be 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 SRAM write operations that are in progress when HSB is driven LOW by any means are given time (tDELAY) to complete before the STORE operation is initiated. However, any SRAM write cycles requested after HSB goes LOW are inhibited until HSB returns HIGH. In case the write latch is not set, HSB is not driven LOW by the CY14E256LA. But any SRAM read and write cycles are inhibited until HSB is returned HIGH by MPU or other external source. During any STORE operation, regardless of how it is initiated, the CY14E256LA continues to drive the HSB pin LOW, releasing it only when the STORE is complete. Upon completion of the STORE operation, the nvSRAM memory access is inhibited for tLZHSB time after HSB pin returns HIGH. Leave the HSB unconnected if it is not used. The software sequence may be clocked with CE controlled reads or OE controlled reads, with WE kept HIGH for all the six READ sequences. After the sixth address in the sequence is entered, the STORE cycle commences and the chip is disabled. HSB is driven LOW. After the tSTORE cycle time is fulfilled, the SRAM is activated again for the read and write operation. Hardware RECALL (Power-up) During power-up or after any low power condition (VCC< VSWITCH), an internal RECALL request is latched. When VCC again exceeds the sense voltage of VSWITCH, a RECALL cycle is automatically initiated and takes tHRECALL to complete. During this time, HSB is driven low by the HSB driver. Software RECALL Data is transferred from 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 or OE controlled read operations must be 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 Software STORE Data is transferred from SRAM to the nonvolatile memory by a software address sequence. The CY14E256LA Software STORE cycle is initiated by executing sequential CE or OE 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. After a STORE cycle is initiated, further input and output are disabled until the cycle is completed. 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, or the sequence is aborted and no STORE or RECALL takes place. Internally, RECALL is a two step procedure. First, the SRAM data is cleared. Next, the nonvolatile information is transferred into the SRAM cells. After the tRECALL cycle time, the SRAM is again ready for read and write operations. The RECALL operation does not alter the data in the nonvolatile elements. Table 1. Mode Selection CE WE OE A14 - A0[6] Mode I/O Power H X X X Not selected Output high Z Standby L H L X Read SRAM Output data Active L L X X Write SRAM Input data Active L H L 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0B45 Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM AutoStore disable Output data Output data Output data Output data Output data Output data Active[7] Notes 6. While there are 15 address lines on the CY14E256LA, only the lower 14 are used to control software modes. 7. The six consecutive address locations must be in the order listed. WE must be HIGH during all six cycles to enable a nonvolatile cycle. Document Number: 001-54952 Rev. *F Page 5 of 19 [+] Feedback CY14E256LA Table 1. Mode Selection (continued) CE WE OE A14 - A0[6] Mode I/O Power L H L 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0B46 Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM AutoStore enable Output data Output data Output data Output data Output data Output data Active[7] L H L 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0FC0 Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM Nonvolatile STORE Output data Output data Output data Output data Output data Output high Z Active ICC2[7] L H L 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0C63 Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM Nonvolatile RECALL Output data Output data Output data Output data Output data Output high Z Active[7] Preventing AutoStore The AutoStore function is disabled by initiating an AutoStore disable sequence. A sequence of read operations is performed in a manner similar to the Software STORE initiation. To initiate the AutoStore disable sequence, the following sequence of CE or OE controlled read operations must be 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 0x0B45 AutoStore Disable The AutoStore is reenabled by initiating an AutoStore enable sequence. A sequence of read operations is performed in a manner similar to the Software RECALL initiation. To initiate the AutoStore enable sequence, the following sequence of CE or OE controlled read operations must be 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 0x0B46 AutoStore Enable Document Number: 001-54952 Rev. *F If the AutoStore function is disabled or reenabled, a manual STORE operation (Hardware or Software) must be issued to save the AutoStore state through subsequent power-down cycles. The part comes from the factory with AutoStore enabled. Data Protection The CY14E256LA protects data from corruption during low voltage conditions by inhibiting all externally initiated STORE and write operations. The low voltage condition is detected when VCC is less than VSWITCH. If the CY14E256LA is in a write mode (both CE and WE are LOW) at power-up, after a RECALL or STORE, the write is inhibited until the SRAM is enabled after tLZHSB (HSB to output active). This protects against inadvertent writes during power-up or brown out conditions. Noise Considerations Refer to CY application note AN1064. Page 6 of 19 [+] Feedback CY14E256LA Best Practices nvSRAM products have been used effectively for over 27 years. While ease-of-use is one of the product’s main system values, experience gained working with hundreds of applications has resulted in the following suggestions as best practices: ■ The nonvolatile cells in this nvSRAM product are delivered from Cypress with 0x00 written in all cells. Incoming inspection routines at customer or contract manufacturer’s sites sometimes reprogram these values. Final NV patterns are typically repeating patterns of AA, 55, 00, FF, A5, or 5A. End product’s firmware should not assume an NV array is in a set programmed state. Routines that check memory content values to determine first time system configuration, cold or warm boot status, and so on should always program a unique NV pattern (that is, complex 4-byte pattern of 46 E6 49 53 hex or more random bytes) as part of the final system manufacturing test to ensure these system routines work consistently. Document Number: 001-54952 Rev. *F ■ Power-up boot firmware routines should rewrite the nvSRAM into the desired state (for example, AutoStore enabled). While the nvSRAM is shipped in a preset state, best practice is to again rewrite the nvSRAM into the desired state as a safeguard against events that might flip the bit inadvertently such as program bugs and incoming inspection routines. ■ The VCAP value specified in this data sheet includes a minimum and a maximum value size. Best practice is to meet this requirement and not exceed the maximum VCAP value because the nvSRAM internal algorithm calculates VCAP charge and discharge time based on this maximum VCAP value. Customers that want to use a larger VCAP value to make sure there is extra store charge and store time should discuss their VCAP size selection with Cypress to understand any impact on the VCAP voltage level at the end of a tRECALL period. Page 7 of 19 [+] Feedback CY14E256LA Maximum Ratings Exceeding maximum ratings may shorten the useful life of the device. These user guidelines are not tested. Storage temperature ................................–65 °C to +150 °C Maximum accumulated storage time: Transient voltage (<20 ns) on any pin to ground potential.................. –2.0 V to VCC + 2.0 V Package power dissipation capability (TA = 25 °C)...................................................1.0 W Surface mount Pb soldering temperature (3 seconds) ...........................................+260 °C At 150 °C ambient temperature........................ 1000 h DC output current (1 output at a time, 1 s duration).....15 mA At 85 °C ambient temperature...................... 20 Years Static discharge voltage ......................................... > 2001 V (per MIL-STD-883, Method 3015) Ambient temperature with power applied..–55 °C to +150 °C Supply voltage on VCC relative to VSS ........... –0.5 V to 7.0 V Voltage applied to outputs in high Z state ..........................–0.5 V to VCC + 0.5 V Input voltage........................................... –0.5 V to Vcc+0.5 V Latch up current .................................................... > 200 mA Operating Range Range Ambient Temperature VCC –40 °C to +85 °C 4.5 V to 5.5 V Industrial DC Electrical Characteristics Over the operating range (VCC = 4.5 V to 5.5 V) Parameter Description Test Conditions Min Typ[8] Max Unit 4.5 5.0 5.5 V VCC Power supply ICC1 Average VCC current tRC = 25 ns tRC = 45 ns Values obtained without output loads (IOUT = 0 mA) – – 70 52 mA mA ICC2 Average VCC current during STORE All inputs don’t care, VCC = Max Average current for duration tSTORE – – 10 mA ICC3 Average VCC current at All inputs cycling at CMOS levels. Values obtained without output loads (IOUT = 0 mA). tRC= 200 ns, VCC (Typ), 25 °C – 35 – mA ICC4 Average VCAP current All inputs don’t care. Average current for duration tSTORE during AutoStore cycle – – 8 mA ISB VCC standby current CE > (VCC – 0.2 V). VIN < 0.2 V or > (VCC – 0.2 V). Standby current level after nonvolatile cycle is complete. Inputs are static. f = 0 MHz. – – 8 mA IIX[9] Input leakage current (except HSB) VCC = Max, VSS < VIN < VCC –1 – +1 μA Input leakage current (for HSB) VCC = Max, VSS < VIN < VCC –100 – +1 μA IOZ Off-state output leakage current VCC = Max, VSS < VOUT < VCC, CE or OE > VIH or WE < VIL –1 – +1 μA VIH Input HIGH voltage 2.0 – VCC + 0.5 V VIL Input LOW voltage VSS – 0.5 – 0.8 V VOH Output HIGH voltage IOUT = –2 mA 2.4 – – V VOL Output LOW voltage IOUT = 4 mA – – 0.4 V VCAP Storage capacitor Between VCAP pin and VSS, 6 V rated 61 68 180 μF Notes 8. Typical values are at 25 °C, VCC= VCC (Typ). Not 100% tested. 9. The HSB pin has IOUT = –2 uA for VOH of 2.4 V when both active high and low drivers are disabled. When they are enabled standard VOH and VOL are valid. This parameter is characterized but not tested. Document Number: 001-54952 Rev. *F Page 8 of 19 [+] Feedback CY14E256LA Data Retention and Endurance Parameter Description DATAR Data retention NVC Nonvolatile STORE operations Min Unit 20 Years 1,000 K Max Unit 7 pF 7 pF Capacitance Parameter[10] Description CIN Input capacitance COUT Output capacitance Test Conditions TA = 25 °C, f = 1 MHz, VCC = VCC (Typ) Thermal Resistance Parameter[10] Description ΘJA Thermal resistance (Junction to ambient) ΘJC Thermal resistance (Junction to case) Test Conditions Test conditions follow standard test methods and procedures for measuring thermal impedance, in accordance with EIA/JESD51. 44-TSOP II 32-SOIC Unit 41.74 41.55 °C/W 11.90 24.43 °C/W Figure 3. AC Test Loads 963 Ω 5.0 V 963 Ω 5.0 V R1 for tri-state specs R1 OUTPUT OUTPUT 30 pF R2 512 Ω 5 pF R2 512 Ω AC Test Conditions Input Pulse Levels ..................................................0 V to 3 V Input Rise and Fall Times (10% to 90%) ...................... <3 ns Input and Output Timing Reference Levels ................... 1.5 V Note 10. These parameters are guaranteed by design and are not tested. Document Number: 001-54952 Rev. *F Page 9 of 19 [+] Feedback CY14E256LA AC Switching Characteristics Parameters Cypress Alt Parameter Parameter 25 ns Description 45 ns Min Max Min Max Unit SRAM Read Cycle tRC[11] tACE tACS tRC Chip enable access time Read cycle time – 25 25 – – 45 45 – ns ns tAA[12] tAA Address access time – 25 – 45 ns tDOE tOE Output enable to data valid – 12 – 20 ns tOHA[12] tLZCE[13, 14] tHZCE[13, 14] tLZOE[13, 14] tHZOE[13, 14] tPU[13] tPD[13] tOH Output hold after address change 3 – 3 – ns tLZ Chip enable to output active 3 – 3 – ns tHZ Chip disable to output inactive – 10 – 15 ns tOLZ Output enable to output active 0 – 0 – ns tOHZ Output disable to output inactive – 10 – 15 ns tPA Chip enable to power active 0 – 0 – ns tPS Chip disable to power standby – 25 – 45 ns tHZWE[13, 14,15] tWC tWP tCW tDW tDH tAW tAS tWR tWZ Write cycle time Write pulse width Chip enable to end of write Data setup to end of write Data hold after end of write Address setup to end of write Address setup to start of write Address hold after end of write Write enable to output disable 25 20 20 10 0 20 0 0 – – – – – – – – – 10 45 30 30 15 0 30 0 0 – – – – – – – – – 15 ns ns ns ns ns ns ns ns ns tLZWE[13, 14] tOW Output active after end of write 3 – 3 – ns SRAM Write Cycle tWC tPWE tSCE tSD tHD tAW tSA tHA Switching Waveforms Figure 4. SRAM Read Cycle #1: Address Controlled [11, 12, 16] tRC Address Address Valid tAA Data Output Previous Data Valid Output Data Valid tOHA Notes 11. WE must be HIGH during SRAM read cycles. 12. Device is continuously selected with CE and OE LOW. 13. These parameters are guaranteed by design and are not tested. 14. Measured ±200 mV from steady state output voltage. 15. If WE is low when CE goes low, the outputs remain in the high impedance state. 16. HSB must remain HIGH during READ and WRITE cycles. Document Number: 001-54952 Rev. *F Page 10 of 19 [+] Feedback CY14E256LA Figure 5. SRAM Read Cycle #2: CE and OE Controlled[17, 18] Address Address Valid tRC tHZCE tACE CE tAA tLZCE tHZOE tDOE OE tLZOE High Impedance Data Output Output Data Valid tPU ICC tPD Active Standby Figure 6. SRAM Write Cycle #1: WE Controlled[18, 19, 20] tWC Address Address Valid tSCE tHA CE tAW tPWE WE tSA tHD tSD Data Input Input Data Valid tLZWE tHZWE Data Output High Impedance Previous Data Figure 7. SRAM Write Cycle #2: CE Controlled[18, 19, 20] tWC Address Valid Address tSA tSCE tHA CE tPWE WE tSD Input Data Valid Data Input Data Output tHD High Impedance Note 17. WE must be HIGH during SRAM read cycles. 18. HSB must remain HIGH during READ and WRITE cycles. 19. If WE is low when CE goes low, the outputs remain in the high impedance state. 20. CE or WE must be > VIH during address transitions. Document Number: 001-54952 Rev. *F Page 11 of 19 [+] Feedback CY14E256LA AutoStore/Power-up RECALL Parameter CY14E256LA Min Max – 20 Description Unit tHRECALL[21] Power-up RECALL duration tSTORE[22] tDELAY[23] STORE cycle duration – 8 ms Time allowed to complete SRAM write cycle – 25 ns VSWITCH Low voltage trigger level – 4.4 V tVCCRISE VCC rise time [24] VHDIS[24] tLZHSB[24] tHHHD[24] ms 150 – µs HSB output disable voltage – 1.9 V HSB to output active time HSB high active time – – 5 500 µs ns Switching Waveforms Figure 8. AutoStore or Power-up RECALL[25] VCC VSWITCH VHDIS t VCCRISE 22 tHHHD Note Note 22 tSTORE tHHHD Note26 HSB OUT tSTORE 26 Note tDELAY tLZHSB AutoStore tLZHSB tDELAY POWERUP RECALL Read & Write Inhibited (RWI) tHRECALL POWER-UP RECALL Read & Write tHRECALL BROWN OUT AutoStore POWER-UP RECALL Read & Write POWER DOWN AutoStore Notes 21. tHRECALL starts from the time VCC rises above VSWITCH. 22. If an SRAM write has not taken place since the last nonvolatile cycle, no AutoStore or Hardware STORE takes place. 23. On a Hardware STORE and AutoStore initiation, SRAM write operation continues to be enabled for time tDELAY. 24. These parameters are guaranteed by design and are not tested. 25. Read and Write cycles are ignored during STORE, RECALL, and while VCC is less than VSWITCH. 26. During power-up and power-down, HSB glitches when HSB pin is pulled up through an external resistor. Document Number: 001-54952 Rev. *F Page 12 of 19 [+] Feedback CY14E256LA Software Controlled STORE/RECALL Cycle Parameter[27, 28] 25 ns Description 45 ns Min 25 Max – Min 45 Max – Unit tRC STORE/RECALL initiation cycle time tSA Address setup time 0 – 0 – ns tCW Clock pulse width 20 – 30 – ns tHA Address hold time 0 – 0 – ns tRECALL RECALL duration – 200 – 200 µs ns Switching Waveforms Figure 9. CE and OE Controlled Software STORE/RECALL Cycle[28] tRC Address tRC Address #1 tSA Address #6 tCW tCW CE tHA tSA tHA tHA tHA OE tHHHD HSB (STORE only) tHZCE tLZCE t DELAY 29 Note tLZHSB High Impedance tSTORE/tRECALL DQ (DATA) RWI Figure 10. AutoStore Enable / Disable Cycle Address tRC tRC Address #1 Address #6 tSA CE tCW tCW tHA tSA tHA tHA tHA OE tLZCE tHZCE tSS 29 Note t DELAY DQ (DATA) Notes 27. The software sequence is clocked with CE controlled or OE controlled reads. 28. The six consecutive addresses must be read in the order listed in Table 1 on page 5. WE must be HIGH during all six consecutive cycles. 29. DQ output data at the sixth read may be invalid since the output is disabled at tDELAY time. Document Number: 001-54952 Rev. *F Page 13 of 19 [+] Feedback CY14E256LA Hardware STORE Cycle Parameter CY14E256LA Description Min Max Unit tDHSB HSB to output active time when write latch not set – 25 ns tPHSB Hardware STORE pulse width 15 – ns Soft sequence processing time – 100 μs tSS [30, 31] Switching Waveforms Figure 11. Hardware STORE Cycle[32] Write Latch set ~ ~ tPHSB HSB (IN) tSTORE tHHHD ~ ~ ~ ~ tDELAY HSB (OUT) SO tLZHSB RWI Write Latch not set tDELAY HSB pin is driven high to VCCQ only by Internal 100 K: resistor, HSB driver is disabled SRAM is disabled as long as HSB (IN) is driven LOW. tDHSB tDHSB ~ ~ HSB (OUT) tPHSB ~ ~ HSB (IN) RWI Figure 12. Soft Sequence Processing[30, 31] Soft Sequence Command Address Address #1 tSA Address #6 tCW tSS Soft Sequence Command Address #1 tSS Address #6 tCW CE VCC Notes 30. This is the amount of time it takes to take action on a soft sequence command. Vcc power must remain HIGH to effectively register command. 31. Commands such as STORE and RECALL lock out I/O until operation is complete which further increases this time. See the specific command. 32. If an SRAM write has not taken place since the last nonvolatile cycle, no AutoStore or Hardware STORE takes place. Document Number: 001-54952 Rev. *F Page 14 of 19 [+] Feedback CY14E256LA Truth Table For SRAM Operations HSB must remain HIGH for SRAM operations. Table 2. Truth Table CE WE OE Inputs/Outputs Mode Power H X X High Z Deselect/power-down Standby L H L Data out (DQ0–DQ7) Read Active L H H High Z Output disabled Active L L X Data in (DQ0–DQ7) Write Active Ordering Information Speed (ns) 25 Ordering Code CY14E256LA-SZ25XIT Package Diagram 51-85127 Operating Range Package Type 32-pin SOIC Industrial CY14E256LA-SZ25XI 45 CY14E256LA-SZ45XIT CY14E256LA-SZ45XI All the mentioned parts are Pb-free. Ordering Code Definition CY 14 E 256 L A-ZS 25 X I T Option: T – Tape and Reel Blank – Std. Pb-Free Die revision: Blank – No rev A – 1st Rev Voltage: E – 5.0 V Temperature: I – Industrial (–40 to 85 oC) Speed: 25 to 25 ns 45 to 45 ns Package: ZS – 44 TSOP II SZ – 32 SOIC Data Bus: L – x8 Density: 256 – 256 Kb 14 – nvSRAM Cypress Document Number: 001-54952 Rev. *F Page 15 of 19 [+] Feedback CY14E256LA Package Diagrams M Figure 13. 44-Pin TSOP II (51-85087) 51-85087 *C Figure 14. 32-Pin SOIC (51-85127) PIN 1 ID 16 1 DIMENSIONS IN INCHES[MM] 0.292[7.416] 0.299[7.594] REFERENCE JEDEC MO-119 0.405[10.287] 0.419[10.642] 17 MIN. MAX. PART # S32.3 STANDARD PKG. SZ32.3 LEAD FREE PKG. 32 SEATING PLANE 0.810[20.574] 0.822[20.878] 0.090[2.286] 0.100[2.540] 0.004[0.101] 0.050[1.270] TYP. 0.026[0.660] 0.032[0.812] 0.014[0.355] 0.020[0.508] Document Number: 001-54952 Rev. *F 0.004[0.101] 0.0100[0.254] 0.021[0.533] 0.041[1.041] 0.006[0.152] 0.012[0.304] 51-85127 *B Page 16 of 19 [+] Feedback CY14E256LA Acronyms Document Conventions Acronyms Used Units of Measure Acronym Description Symbol Unit of Measure CMOS complementary metal oxide semiconductor Kbit 1024 bits EIA electronic industries alliance °C degrees celsius I/O input/output KΩ kilo ohms JEDEC joint electron devices engineering council MHz megahertz nvSRAM nonvolatile static random access memory μA microamperes RoHS restriction of hazardous substances μf microfarads RWI read and write inhibited μs microseconds SOIC small-outline integrated circuit mA milliampere TSOP II thin small outline package ms millisecond ns nanoseconds Ω ohms pF picofarads ps picoseconds V volts W watts Document Number: 001-54952 Rev. *F Page 17 of 19 [+] Feedback CY14E256LA Document History Page Document Title: CY14E256LA 256-Kbit (32 K × 8) Nonvolatile SRAM Document Number: 001-54952 Revision ECN Orig. of Change Submission Date ** 2748216 GVCH/PYRS 08/04/09 New Datasheet *A 2772059 GVCH 09/30/09 Updated Software STORE, RECALL and Autostore Enable, Disable soft sequence *B 2829117 GVCH 12/16/09 Updated STORE cycles to QuantumTrap from 200K to 1 Million Added Contents. Moved to external web. *C 2891356 GVCH 03/12/10 Removed inactive parts from Ordering Information table. Updated links in Sales, Solutions, and Legal Information. *D 2922858 GVCH 04/26/10 Table 1: Added more clarity on HSB pin operation Hardware STORE Operation: Added more clarity on HSB pin operation Updated HSB pin operation in Figure 8 and updated footnote 21 Updated package diagram 51-85087 *E 3030490 GVCH 09/15/10 Change: ISB and ICC4 max value from 5 mA to 8 mA. Areas affected: DC Electrical Characteristics on page 8. Change: Template and styles update. Areas affected: Entire datasheet *F 3143330 GVCH 01/17/2011 Document Number: 001-54952 Rev. *F Description of Change Fixed typo in Figure 8. Page 18 of 19 [+] Feedback CY14E256LA Sales, Solutions, and Legal Information Worldwide Sales and Design Support Cypress maintains a worldwide network of offices, solution centers, manufacturer’s representatives, and distributors. To find the office closest to you, visit us at Cypress Locations. Products Automotive Clocks & Buffers Interface Lighting & Power Control PSoC Solutions cypress.com/go/automotive psoc.cypress.com/solutions cypress.com/go/clocks PSoC 1 | PSoC 3 | PSoC 5 cypress.com/go/interface cypress.com/go/powerpsoc cypress.com/go/plc Memory Optical & Image Sensing PSoC Touch Sensing USB Controllers Wireless/RF cypress.com/go/memory cypress.com/go/image cypress.com/go/psoc cypress.com/go/touch cypress.com/go/USB cypress.com/go/wireless © Cypress Semiconductor Corporation, 2009-2011. The information contained herein is subject to change without notice. Cypress Semiconductor Corporation assumes no responsibility for the use of any circuitry other than circuitry embodied in a Cypress product. Nor does it convey or imply any license under patent or other rights. Cypress products are not warranted nor intended to be used for medical, life support, life saving, critical control or safety applications, unless pursuant to an express written agreement with Cypress. Furthermore, Cypress does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress products in life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges. Any Source Code (software and/or firmware) is owned by Cypress Semiconductor Corporation (Cypress) and is protected by and subject to worldwide patent protection (United States and foreign), United States copyright laws and international treaty provisions. Cypress hereby grants to licensee a personal, non-exclusive, non-transferable license to copy, use, modify, create derivative works of, and compile the Cypress Source Code and derivative works for the sole purpose of creating custom software and or firmware in support of licensee product to be used only in conjunction with a Cypress integrated circuit as specified in the applicable agreement. Any reproduction, modification, translation, compilation, or representation of this Source Code except as specified above is prohibited without the express written permission of Cypress. Disclaimer: CYPRESS MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARD TO THIS MATERIAL, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. Cypress reserves the right to make changes without further notice to the materials described herein. Cypress does not assume any liability arising out of the application or use of any product or circuit described herein. Cypress does not authorize its products for use as critical components in life-support systems where a malfunction or failure may reasonably be expected to result in significant injury to the user. The inclusion of Cypress’ product in a life-support systems application implies that the manufacturer assumes all risk of such use and in doing so indemnifies Cypress against all charges. Use may be limited by and subject to the applicable Cypress software license agreement. Document Number: 001-54952 Rev. *F Revised January 17, 2011 Page 19 of 19 All products and company names mentioned in this document may be the trademarks of their respective holders. [+] Feedback