bq4011/bq4011Y 32Kx8 Nonvolatile SRAM Features General Description ➤ Data retention in the absence of power The CMOS bq4011 is a nonvolatile 262,144-bit static RAM organized as 32,768 words by 8 bits. The integral control circuitry and lithium energy source provide reliable nonvolatility coupled with the unlimited write cycles of standard SRAM. ➤ Automatic write-protection during power-up/power-down cycles ➤ Industry-standard 28-pin 32K x 8 pinout ➤ Conventional SRAM operation; unlimited write cycles ➤ 10-year minimum data retention in absence of power At this time the integral energy source is switched on to sustain the memory until after VCC returns valid. The bq4011 uses an extremely low standby current CMOS SRAM, coupled with a small lithium coin cell to provide nonvolatility without long write-cycle times and the write-cycle limitations associated with EEPROM. The control circuitry constantly monitors the single 5V supply for an out-of-tolerance condition. When VCC falls out of tolerance, the SRAM is unconditionally write-protected to prevent inadvertent write operation. The bq4011 requires no external circuitry and is socket-compatible with industry-standard SRAMs and most EPROMs and EEPROMs. Pin Names Block Diagram ➤ Battery internally isolated until power is applied Pin Connections A0 –A14 Address inputs DQ0–DQ7 Data input/output CE Chip enable input OE Output enable input WE Write enable input VCC +5 volt supply input VSS Ground Selection Guide Part Number Maximum Access Time (ns) Negative Supply Tolerance Part Number bq4011Y-70 bq4011 -100 100 bq4011 -150 150 bq4011 -200 200 Maximum Access Time (ns) Negative Supply Tolerance 70 -10% -5% bq4011Y -100 100 -10% -5% bq4011Y -150 150 -10% -5% bq4011Y -200 200 -10% Aug. 1993 C 1 bq4011/bq4011Y As VCC falls past VPFD and approaches 3V, the control circuitry switches to the internal lithium backup supply, which provides data retention until valid VCC is applied. Functional Description When power is valid, the bq4011 operates as a standard CMOS SRAM. During power-down and power-up cycles, the bq4011 acts as a nonvolatile memory, automatically protecting and preserving the memory contents. When VCC returns to a level above the internal backup cell voltage, the supply is switched back to VCC. After VCC ramps above the VPFD threshold, write-protection continues for a time tCER (120ms maximum) to allow for processor stabilization. Normal memory operation may resume after this time. Power-down/power-up control circuitry constantly monitors the VCC supply for a power-fail-detect threshold VPFD. The bq4011 monitors for VPFD = 4.62V typical for use in systems with 5% supply tolerance. The bq4011Y monitors for VPFD = 4.37V typical for use in systems with 10% supply tolerance. The internal coin cell used by the bq4011 has an extremely long shelf life and provides data retention for more than 10 years in the absence of system power. When VCC falls below the VPFD threshold, the SRAM automatically write-protects the data. All outputs become high impedance, and all inputs are treated as “don’t care.” If a valid access is in process at the time of power-fail detection, the memory cycle continues to completion. If the memory cycle fails to terminate within time tWPT, write-protection takes place. As shipped from Benchmarq, the integral lithium cell is electrically isolated from the memory. (Self-discharge in this condition is approximately 0.5% per year.) Following the first application of VCC, this isolation is broken, and the lithium backup cell provides data retention on subsequent power-downs. Truth Table CE WE OE I/O Operation Power Not selected Mode H X X High Z Standby Output disable L H H High Z Active Read L H L DOUT Active Write L L X DIN Active Absolute Maximum Ratings Symbol Parameter Value Unit VCC DC voltage applied on VCC relative to VSS -0.3 to 7.0 V VT DC voltage applied on any pin excluding VCC relative to VSS -0.3 to 7.0 V TOPR Operating temperature TSTG Storage temperature TBIAS Temperature under bias TSOLDER Soldering temperature Note: Conditions VT ≤ VCC + 0.3 0 to +70 °C Commercial -40 to +85 °C Industrial “N” -40 to +70 °C Commercial -40 to +85 °C Industrial “N” -10 to +70 °C Commercial -40 to +85 °C Industrial “N” +260 °C For 10 seconds Permanent device damage may occur if Absolute Maximum Ratings are exceeded. Functional operation should be limited to the Recommended DC Operating Conditions detailed in this data sheet. Exposure to conditions beyond the operational limits for extended periods of time may affect device reliability. Aug. 1993 C 2 bq4011/bq4011Y Recommended DC Operating Conditions (TA = TOPR) Symbol Parameter Minimum Typical Maximum Unit 4.5 5.0 5.5 V bq4011Y/bq4011Y-xxxN 4.75 5.0 5.5 V bq4011 0 0 0 V VCC Supply voltage VSS Supply voltage VIL Input low voltage -0.3 - 0.8 V VIH Input high voltage 2.2 - VCC + 0.3 V Note: Typical values indicate operation at TA = 25°C. DC Electrical Characteristics (TA = TOPR, VCCmin Symbol Notes Parameter ≤ VCC ≤ VCCmax) Minimum Typical Maximum Unit Conditions/Notes ILI Input leakage current - - ±1 µA VIN = VSS to VCC ILO Output leakage current - - ±1 µA CE = VIH or OE = VIH or WE = VIL VOH Output high voltage 2.4 - - V IOH = -1.0 mA VOL Output low voltage - - 0.4 V IOL = 2.1 mA ISB1 Standby supply current - 4 7 mA CE = VIH ISB2 Standby supply current - 2.5 4 mA CE ≥ VCC - 0.2V, 0V ≤ VIN ≤ 0.2V, or VIN ≥ VCC - 0.2V ICC Operating supply current - 55 75 mA Min. cycle, duty = 100%, CE = VIL, II/O = 0mA 4.55 4.62 4.75 V bq4011 VPFD Power-fail-detect voltage 4.30 4.37 4.50 V bq4011Y VSO Supply switch-over voltage - 3 - V Note: Typical values indicate operation at TA = 25°C, VCC = 5V. Capacitance (TA = 25°C, F = 1MHz, VCC = 5.0V) Minimum Typical Maximum Unit CI/O Symbol Input/output capacitance - - 10 pF Output voltage = 0V CIN Input capacitance - - 10 pF Input voltage = 0V Note: Parameter These parameters are sampled and not 100% tested. Aug. 1993 C 3 Conditions bq4011/bq4011Y AC Test Conditions Parameter Test Conditions Input pulse levels 0V to 3.0V Input rise and fall times 5 ns Input and output timing reference levels 1.5 V (unless otherwise specified) Output load (including scope and jig) See Figures 1 and 2 Figure 1. Output Load A Read Cycle (TA = TOPR, VCCmin Figure 2. Output Load B ≤ VCC ≤ VCCmax) -70/-70N Symbol Parameter -100 -150/-150N Min. Max. Min. Max. Min. 70 - 100 - 150 - -200 Max. Min. Max. Unit 200 - ns Conditions tRC Read cycle time tAA Address access time - 70 - 100 - 150 - 200 ns Output load A tACE Chip enable access time - 70 - 100 - 150 - 200 ns Output load A tOE Output enable to output valid - 35 - 50 - 70 - 90 ns Output load A tCLZ Chip enable to output in low Z 5 - 5 - 10 - 10 - ns Output load B tOLZ Output enable to output in low Z 5 - 5 - 5 - 5 - ns Output load B tCHZ Chip disable to output in high Z 0 25 0 40 0 60 0 70 ns Output load B tOHZ Output disable to output in high Z 0 25 0 35 0 50 0 70 ns Output load B tOH Output hold from address change 10 - 10 - 10 - 10 - ns Output load A Aug. 1993 C 4 bq4011/bq4011Y Read Cycle No. 1 (Address Access) 1,2 Read Cycle No. 2 (CE Access) 1,3,4 Read Cycle No. 3 (OE Access) 1,5 Notes: 1. WE is held high for a read cycle. 2. Device is continuously selected: CE = OE = VIL. 3. Address is valid prior to or coincident with CE transition low. 4. OE = VIL. 5. Device is continuously selected: CE = VIL. Aug. 1993 C 5 bq4011/bq4011Y Write Cycle (TA = TOPR, VCCmin ≤ VCC ≤ VCCmax) -70/-70N Symbol Parameter -100 -150/-150N -200 Min. Max. Min. Max. Min. Max. Min. Max. Units Conditions/Notes tWC Write cycle time 70 - 100 - 150 - 200 - ns tCW Chip enable to end of write 55 - 90 - 100 - 150 - ns (1) tAW Address valid to end of write 55 - 80 - 90 - 150 - ns (1) tAS Addr ess time 0 - 0 - 0 - 0 - ns Measured from address valid to beginning of write. (2) tWP Write pulse width 55 - 75 - 90 - 130 - ns Measured from beginning of write to end of write. (1) tWR1 Write recovery time (write cycle 1) 5 - 5 - 5 - 5 - ns Measured from WE going high to end of write cycle. (3) tWR2 Write recovery time (write cycle 2) 15 - 15 - 15 - 15 - ns Measured from CE going high to end of write cycle. (3) tDW Data valid to end of write 30 - 40 - 50 - 70 - ns Measured from first low-to-high transition of either CE or WE. tDH1 Data hold time (write cycle 1) 0 - 0 - 0 - 0 - ns Measured from WE going high to end of write cycle. (4) tDH2 Data hold time (write cycle 2) 0 - 0 - 0 - 0 - ns Measured from CE going high to end of write cycle.(4) tWZ Write enabled to output in high Z 0 25 0 35 0 50 0 70 ns I/O pins are in output state. (5) tOW Output active from end of write 5 - 5 - 5 - 5 - ns I/O pins are in output state. (5) Notes: setup 1. A write ends at the earlier transition of CE going high and WE going high. 2. A write occurs during the overlap of a low CE and a low WE. A write begins at the later transition of CE going low and WE going low. 3. Either tWR1 or tWR2 must be met. 4. Either tDH1 or tDH2 must be met. 5. If CE goes low simultaneously with WE going low or after WE going low, the outputs remain in high-impedance state. Aug. 1993 C 6 bq4011/bq4011Y Write Cycle No. 1 (WE-Controlled) 1,2,3 Write Cycle No. 2 (CE-Controlled) 1,2,3,4,5 Notes: 1. CE or WE must be high during address transition. 2. Because I/O may be active (OE low) during this period, data input signals of opposite polarity to the outputs must not be applied. 3. If OE is high, the I/O pins remain in a state of high impedance. 4. Either tWR1 or tWR2 must be met. 5. Either tDH1 or tDH2 must be met. Aug. 1993 C 7 bq4011/bq4011Y Power-Down/Power-Up Cycle (TA = TOPR) Minimum Typical Maximum Unit tPF Symbol VCC slew, 4.75 to 4.25 V 300 - - µs tFS VCC slew, 4.25 to VSO 10 - - µs tPU VCC slew, VSO to VPFD (max.) 0 - - µs tCER Chip enable recovery time 40 80 120 ms tDR Data-retention time in absence of VCC 10 - - years TA = 25°C. (2) tDR-N Data-retention time in absence of VCC 6 - - years TA = 25°C (2); industrial temperature range (-N) only. tWPT Write-protect time 40 100 150 µs Delay after VCC slews down past VPFD before SRAM is write-protected. Notes: Parameter Conditions Time during which SRAM is write-protected after VCC passes VPFD on power-up. 1. Typical values indicate operation at TA = 25°C, VCC = 5V. 2. Battery is disconnected from circuit until after VCC is applied for the first time. tDR is the accumulated time in absence of power beginning when power is first applied to the device. Caution: Negative undershoots below the absolute maximum rating of -0.3V in battery-backup mode may affect data integrity. Power-Down/Power-Up Timing Aug. 1993 C 8 bq4011/bq4011Y Data Sheet Revision History Change No. Page No. 1 2, 3, 4, 6, 8, 9 2 1, 4, 6, 9 Notes: Description Added industrial temperature range for bq4011YMA-150N. Added 70 ns speed grade for bq4011Y-70 and added industrial temperature range for bq4011YMA-70N. Change 1 = Sept 1992 B changes from Sept. 1990 A. Change 2 = Aug. 1993 C changes from Sept. 1991 B. 28-Pin MA (A-type module) 28-Pin MA (A-Type Module) Dimension A A1 Minimum 0.365 0.015 Maximum 0.375 - B C D 0.017 0.008 1.470 0.023 0.013 1.500 E e G 0.710 0.590 0.090 0.740 0.630 0.110 L 0.120 S 0.075 All dimensions are in inches. Aug. 1993 C 9 0.150 0.110 bq4011/bq4011Y Ordering Information bq4011 MA Temperature: blank = Commercial (0 to +70°C) N = Industrial (-40 to +85°C)* Speed Options: 70 = 70 ns 100 = 100 ns 150 = 150 ns 200 = 200 ns Package Option: MA = A-type module Supply Tolerance: no mark = 5% negative supply tolerance Y = 10% negative supply tolerance Device: bq4011 *Note: 32K x 8 NVSRAM Only 10% supply (“Y”) version is available in industrial temperature range; contact factory for speed grade availability. 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