STK16C88-3 256 Kbit (32K x 8) AutoStore+ nvSRAM Features Functional Description ■ Fast 35ns Read access and R/W cycle time ■ Directly replaces battery-backed SRAM modules such as Dallas/Maxim DS1230W ■ Automatic nonvolatile STORE on power loss ■ Nonvolatile STORE under Software control ■ Automatic RECALL to SRAM on power up ■ Unlimited Read/Write endurance ■ 1,000,000 STORE cycles The Cypress STK16C88-3 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 3.3V+0.3V power supply ■ Commercial and Industrial Temperatures ■ 28-pin (600 mil) PDIP package ■ RoHS compliance Logic Block Diagram Cypress Semiconductor Corporation Document Number: 001-50594 Rev. ** • 198 Champion Court • San Jose, CA 95134-1709 • 408-943-2600 Revised January 29, 2009 [+] Feedback STK16C88-3 Pin Configurations Figure 1. Pin Diagram - 28-Pin PDIP $ 9&& $ $ :( $ $ $ $ $ $ 2( $ $ &( $ '4 '4 723 $ $ $ '4 '4 '4 '4 '4 966 '4 Table 1. Pin Definitions - 28-Pin PDIP Pin Name Alt IO Type A0–A14 Input DQ0-DQ7 Input or Output Description Address Inputs. Used to select one of the 32,768 bytes of the nvSRAM. Bidirectional Data IO lines. Used as input or output lines depending on operation. WE W Input Write Enable Input, Active LOW. When the chip is enabled and WE is LOW, data on the IO pins is written to the specific address location. CE E Input Chip Enable Input, Active LOW. When LOW, selects the chip. When HIGH, deselects the chip. OE G Input Output Enable, Active LOW. The active LOW OE input enables the data output buffers during read cycles. Deasserting OE HIGH causes the IO pins to tri-state. VSS VCC Ground Ground for the Device. The device is connected to ground of the system. Power Supply Power Supply Inputs to the Device. Document Number: 001-50594 Rev. ** Page 2 of 14 [+] Feedback STK16C88-3 Device Operation The AutoStore+ STK16C88-3 is a fast 32K x 8 SRAM that does not lose its data on power down. The data is preserved in integral QuantumTrap non-volatile storage elements when power is lost. Automatic STORE on power down and automatic RECALL on power up guarantee data integrity without the use of batteries. SRAM Read The STK16C88-3 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. SRAM Write 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 IO 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 IO lines. If OE is left LOW, internal circuitry turns off the output buffers tHZWE after WE goes LOW. AutoStore+ Operation The STK16C88-3’s automatic STORE on power down is completely transparent to the system. The STORE initiation takes less than 500 ns when power is lost (VCC<VSWITCH) at which point the part depends only on its internal capacitor for STORE completion. If the power supply drops faster than 20 μs/volt before Vcc reaches Vswitch, then a 2.2 ohm resistor should be inserted between Vcc and the system supply to avoid a momentary excess of current between Vcc and internal capacitor. In order to prevent unneeded STORE operations, automatic STOREs 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 or not 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. Document Number: 001-50594 Rev. ** If the STK16C88-3 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. Software STORE Data is transferred from the SRAM to the nonvolatile memory by a software address sequence. The STK16C88-3 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. 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. 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 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. Software RECALL 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 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 3 of 14 [+] Feedback STK16C88-3 Hardware Protect Figure 3. Current Versus Cycle Time (WRITE) The STK16C88-3 offers hardware protection against inadvertent STORE operation and SRAM WRITEs during low voltage conditions. When VCAP<VSWITCH, all externally initiated STORE operations and SRAM WRITEs are inhibited. Noise Considerations The STK16C88-3 is a high speed memory. It must have a high frequency bypass capacitor of approximately 0.1 µF connected between VCC and VSS, using leads and traces that are as short as possible. As with all high speed CMOS ICs, careful routing of power, ground, and signals helps prevent noise problems. Low Average Active Power CMOS technology provides the STK16C88-3 the benefit of drawing significantly less current when it is cycled at times longer than 50 ns. Figure 2 and Figure 3 shows the relationship between ICC and READ or WRITE cycle time. Worst case current consumption is shown for both CMOS and TTL input levels (commercial temperature range, VCC = 5.5V, 100% duty cycle on chip enable). Only standby current is drawn when the chip is disabled. The overall average current drawn by the STK16C88-3 depends on the following items: 1. The duty cycle of chip enable 2. The overall cycle rate for accesses 3. The ratio of READs to WRITEs 4. CMOS versus TTL input levels 5. The operating temperature 6. The VCC level 7. IO loading Figure 2. Current Versus Cycle Time (READ) Document Number: 001-50594 Rev. ** Best Practices nvSRAM products have been used effectively for over 15 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 an nvSRAM are programmed on the test floor during final test and quality assurance. Incoming inspection routines at customer or contract manufacturer’s sites will 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 a NV array is in a set programmed state. Routines that check memory content values to determine first time system configuration and cold or warm boot status, should always program a unique NV pattern (for example, 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. ■ Power up boot firmware routines should rewrite the nvSRAM into the desired state. 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 (program bugs or incoming inspection routines). Page 4 of 14 [+] Feedback STK16C88-3 Table 2. Software STORE/RECALL Mode Selection CE L WE H L H A13 – A0 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0FC0 0x0E38 0x31C7 0x03E0 0x3C1F 0x303F 0x0C63 Mode Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM Nonvolatile STORE Read SRAM Read SRAM Read SRAM Read SRAM Read SRAM Nonvolatile RECALL IO Output Data Output Data Output Data Output Data Output Data Output Data Output Data Output Data Output Data Output Data Output Data Output Data Notes [1, 2] [1, 2] Notes 1. The six consecutive addresses must be in the order listed. WE must be high during all six consecutive CE controlled cycles to enable a nonvolatile cycle. 2. While there are 15 addresses on the STK16C88-3, only the lower 14 are used to control software modes. Document Number: 001-50594 Rev. ** Page 5 of 14 [+] Feedback STK16C88-3 Maximum Ratings Voltage on DQ0-7 ...................................–0.5V to Vcc + 0.5V Exceeding maximum ratings may shorten the useful life of the device. These user guidelines are not tested. Storage Temperature ................................. –65°C to +150°C Power Dissipation ......................................................... 1.0W DC output Current (1 output at a time, 1s duration) .... 15 mA Operating Range Range Temperature under bias .............................. –55°C to +125°C Supply Voltage on VCC Relative to GND.......... –0.5V to 4.5V Commercial Voltage on Input Relative to Vss ............–0.6V to VCC + 0.5V Industrial Ambient Temperature VCC 0°C to +70°C 3.0V to 3.6V -40°C to +85°C 3.0V to 3.6V DC Electrical Characteristics Over the operating range (VCC = 3.0V to 3.6V) Parameter ICC1 Description Average VCC Current Test Conditions tRC = 35 ns Dependent on output loading and cycle rate. Values obtained without output loads. IOUT = 0 mA. Min Max Unit Commercial 50 mA Industrial 52 mA ICC2 Average VCC Current during STORE All Inputs Do Not Care, VCC = Max Average current for duration tSTORE 3 mA ICC3 Average VCC Current at WE > (VCC – 0.2V). All other inputs cycling. tRC= 200 ns, 5V, 25°C Dependent on output loading and cycle rate. Values obtained Typical without output loads. 8 mA ISB1 [3] Average VCC Current (Standby, Cycling TTL Input Levels) Commercial 18 mA Industrial 19 mA ISB2[3] VCC Standby Current CE > (VCC – 0.2V). All others VIN < 0.2V or > (VCC – 0.2V). (Standby, Stable CMOS Input Levels) 1 mA IIX Input Leakage Current VCC = Max, VSS < VIN < VCC -1 +1 μA IOZ Off State Output Leakage Current VCC = Max, VSS < VIN < VCC, CE or OE > VIH or WE < VIL -1 +1 μA VIH Input HIGH Voltage 2.2 VCC + 0.5 V VIL Input LOW Voltage VSS – 0.5 0.8 V VOH Output HIGH Voltage IOUT = –4 mA VOL Output LOW Voltage IOUT = 8 mA tRC=35ns, CE > VIH 2.4 V 0.4 V Data Retention and Endurance Parameter Description DATAR Data Retention NVC Nonvolatile STORE Operations Min Unit 100 Years 1,000 K Note 3. CE > VIH will not produce standby current levels until any nonvolatile cycle in progress has timed out. Document Number: 001-50594 Rev. ** Page 6 of 14 [+] Feedback STK16C88-3 Capacitance In the following table, the capacitance parameters are listed.[4] Parameter Description CIN Input Capacitance COUT Output Capacitance Test Conditions TA = 25°C, f = 1 MHz, VCC = 0 to 3.0 V Max Unit 5 pF 7 pF Thermal Resistance In the following table, the thermal resistance parameters are listed.[4] Parameter ΘJA ΘJC Description Thermal Resistance (Junction to Ambient) Thermal Resistance (Junction to Case) Test Conditions 28-PDIP Unit Test conditions follow standard test methods and procedures for measuring thermal impedance, per EIA / JESD51. TBD °C/W TBD °C/W Figure 4. AC Test Loads R1 317Ω 3.3V Output 30 pF R2 351Ω AC Test Conditions Input Pulse Levels .................................................. 0 V to 3 V Input Rise and Fall Times (10% - 90%)........................ <5 ns Input and Output Timing Reference Levels ................... 1.5 V Note 4. These parameters are guaranteed by design and are not tested. Document Number: 001-50594 Rev. ** Page 7 of 14 [+] Feedback STK16C88-3 AC Switching Characteristics SRAM Read Cycle Parameter Cypress Parameter tACE tRC [5] tAA [6] tDOE tOHA [6] tLZCE [7] tHZCE [7] tLZOE [7] tHZOE [7] tPU [4] tPD [3, 4] 35 ns Description Alt tELQV tAVAV, tELEH tAVQV tGLQV tAXQX tELQX tEHQZ tGLQX tGHQZ tELICCH tEHICCL Min Chip Enable Access Time Read Cycle Time Address Access Time Output Enable to Data Valid Output Hold After Address Change Chip Enable to Output Active Chip Disable to Output Inactive Output Enable to Output Active Output Disable to Output Inactive Chip Enable to Power Active Chip Disable to Power Standby Max 35 35 35 15 5 5 13 0 13 0 35 Unit ns ns ns ns ns ns ns ns ns ns ns Switching Waveforms Figure 5. SRAM Read Cycle 1: Address Controlled [5, 6] W5& $''5(66 W $$ W2+$ '4'$7$287 '$7$9$/,' Figure 6. SRAM Read Cycle 2: CE and OE Controlled [5] W5& $''5(66 W$&( W3' W/=&( &( W+=&( 2( W+=2( W'2( W/=2( '4'$7$287 '$7$9$/,' W 38 ,&& $&7,9( 67$1'%< Notes 5. WE must be HIGH during SRAM Read Cycles. 6. I/O state assumes CE and OE < VIL and WE > VIH; device is continuously selected. 7. Measured ±200 mV from steady state output voltage. Document Number: 001-50594 Rev. ** Page 8 of 14 [+] Feedback STK16C88-3 Table 3. SRAM Write Cycle Parameter Cypress Alt Parameter tWC tAVAV tWLWH, tWLEH tPWE tELWH, tELEH tSCE tSD tDVWH, tDVEH tWHDX, tEHDX tHD tAVWH, tAVEH tAW tSA tAVWL, tAVEL tWHAX, tEHAX tHA [7,8] tWLQZ tHZWE tLZWE [7] tWHQX 35 ns Description Min 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 Output Active After End of Write Max 35 25 25 12 0 25 0 0 13 5 Unit ns ns ns ns ns ns ns ns ns ns Switching Waveforms Figure 7. SRAM Write Cycle 1: WE Controlled [9] tWC ADDRESS tHA tSCE CE tAW tSA tPWE WE tSD tHD DATA VALID DATA IN tHZWE DATA OUT tLZWE HIGH IMPEDANCE PREVIOUS DATA Figure 8. SRAM Write Cycle 2: CE Controlled [9] tWC ADDRESS CE WE tHA tSCE tSA tAW tPWE tSD DATA IN DATA OUT tHD DATA VALID HIGH IMPEDANCE Notes 8. If WE is Low when CE goes Low, the outputs remain in the high impedance state. 9. CE or WE must be greater than VIH during address transitions. Document Number: 001-50594 Rev. ** Page 9 of 14 [+] Feedback STK16C88-3 AutoStorePlus or Power Up RECALL Parameter tHRECALL [10] tSTORE tstg[4, 6] VRESET VSWITCH Alt tRESTORE tHLHZ STK16C88-3 Min Max 550 10 500 2.4 2.7 2.95 Description Power up RECALL Duration STORE Cycle Duration Power-down AutoStore Slew Time to Ground Low Voltage Reset Level Low Voltage Trigger Level Unit μs ms ns V V Switching Waveforms Figure 9. AutoStorePlus/Power Up RECALL 9&& 9 96:,7&+ 95(6(7 WVWJ $XWR6WRUH W6725( 32:(583 5(&$// W+5(&$// :( '4'$7$287 32:(583 %52:1287 5(&$// 12 6725('8(72 1265$0:5,7(6 12 5(&$// 9&&','127*2 %(/2:95(6(7 %52:1287 $XWR6WRUH3OXVH %52:1287 $XWR6WRUH3OXVH 12 5(&$// 9&&','127*2 %(/2:95(6(7 5(&$//:+(1 9&&5(78516 $%29(96:,7&+ Notes 10. tHRECALL starts from the time VCC rises above VSWITCH. Document Number: 001-50594 Rev. ** Page 10 of 14 [+] Feedback STK16C88-3 Software Controlled STORE/RECALL Cycle The software controlled STORE/RECALL cycle follows. [11, 12] Parameter tRC tSA [11] tCW[11] tHACE[7, 11] Alt 35 ns Description Min Max Unit tAVAV STORE/RECALL Initiation Cycle Time 35 ns tAVEL Address Setup Time 0 ns tELEH Clock Pulse Width 25 ns tELAX Address Hold Time 20 ns RECALL Duration tRECALL 20 μs Switching Waveforms Figure 10. CE Controlled Software STORE/RECALL Cycle [12] tRC ADDRESS # 1 ADDRESS tSA tRC ADDRESS # 6 tSCE CE tHACE OE t STORE / t RECALL DQ (DATA) DATA VALID DATA VALID HIGH IMPEDANCE Notes 11. The software sequence is clocked on the falling edge of CE without involving OE (double clocking will abort the sequence). 12. The six consecutive addresses must be read in the order listed in the Mode Selection table. WE must be HIGH during all six consecutive cycles. Document Number: 001-50594 Rev. ** Page 11 of 14 [+] Feedback STK16C88-3 Part Numbering Nomenclature STK16C88 - 3W F 35 I Temperature Range: Blank - Commercial (0 to 70°C) I - Industrial (-40 to 85°C) Speed: 35 - 35 ns Lead Finish F = 100% Sn (Matte Tin) Package: W = Plastic 28-pin 600 mil DIP Ordering Information Speed (ns) 35 Ordering Code STK16C88-3WF35 STK16C88-3WF35I Package Diagram 51-85017 Package Type 28-pin PDIP Operating Range Commercial Industrial All parts are Pb-free. The above table contains Final information. Please contact your local Cypress sales representative for availability of these parts Document Number: 001-50594 Rev. ** Page 12 of 14 [+] Feedback STK16C88-3 Package Diagrams Figure 11. 28-Pin (600 Mil) PDIP (51-85017) 51-85017 *B Document Number: 001-50594 Rev. ** Page 13 of 14 [+] Feedback STK16C88-3 Document History Page Document Title: STK16C88-3 256 Kbit (32K x 8) AutoStore+ nvSRAM Document Number: 001-50594 Rev. ECN No. Orig. of Change Submission Date ** 2625096 GVCH/PYRS 12/19/08 Description of Change New data sheet 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.com/sales. Products PSoC Clocks & Buffers PSoC Solutions psoc.cypress.com clocks.cypress.com General Low Power/Low Voltage psoc.cypress.com/solutions psoc.cypress.com/low-power Wireless wireless.cypress.com Precision Analog Memories memory.cypress.com LCD Drive psoc.cypress.com/lcd-drive image.cypress.com CAN 2.0b psoc.cypress.com/can USB psoc.cypress.com/usb Image Sensors psoc.cypress.com/precision-analog © Cypress Semiconductor Corporation, 2008-2009. 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. 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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: 001-50594 Rev. ** Revised January 29, 2009 Page 14 of 14 AutoStore and QuantumTrap are registered trademarks of Cypress Semiconductor Corporation. All products and company names mentioned in this document may be the trademarks of their respective holders. [+] Feedback