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Texas Instruments BQ4015YMA-85
- Part No.:
- BQ4015YMA-85
- Manufacturer:
- Texas Instruments
- Category:
- Memory
- Package:
- 32-DIP Module (0.610", 15.49mm)
- Datasheet:
-
BQ4015YMA-85.pdf
- Description:
- IC NVSRAM 4MBIT PAR 32DIP MODULE
- Quantity:
- Payment:
- Shipping:
Inventory:1,233
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Product details
Overview
BQ4015YMA-85 from Texas Instruments is a 512 k × 8 nonvolatile static RAM (NVSRAM) with integrated lithium backup, 85 ns access time, 5 V operation, and -40°C to +85°C industrial temperature range. It functions as a standard SRAM during normal power and automatically preserves data during power loss in applications such as industrial PLCs, medical data loggers, and telecom base station configuration storage.
For engineers reviewing the BQ4015YMA-85 datasheet, BQ4015YMA-85 pinout, BQ4015YMA-85 application, or BQ4015YMA-85 equivalent, key selection considerations include its 5-V power-fail-detect threshold (4.37 V), 10-year data retention without external power, write-protection timing (tCER = 85 ms max), and compatibility with industry-standard 32-pin DIP SRAM layouts.
Technical Context
The BQ4015YMA-85 integrates a CMOS SRAM core, analog power-fail detection circuitry, and a sealed lithium coin cell within a single 32-pin DIP module. Its VPFD threshold is fixed at 4.37 V (typical), optimized for 5-V systems with ±10% supply tolerance.
During power-down, it switches to internal backup power when VCC falls below VPFD, disables all I/O (high-Z), and enforces unconditional write-protection within 100 μs (tWPT). On power-up, it maintains write-protection for up to 85 ms (tCER) to allow processor stabilization before resuming normal operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Memory Density | 512 k × 8 (4,194,304 bits); supports full byte-wide data bus interfacing without address multiplexing. |
| Access Time | 85 ns maximum; enables direct interface with legacy microcontrollers and FPGAs operating at ≤12 MHz bus speeds. |
| Power-Fail Threshold | 4.37 V typical; triggers automatic write-protection and backup switchover in 5-V systems with 10% tolerance. |
| Data Retention | ≥10 years without VCC; achieved via isolated lithium cell with <0.5% annual self-discharge prior to first power-up. |
| Operating Voltage | 4.50 V to 5.50 V; compatible with standard 5-V logic rails and tolerant of common supply ripple and droop. |
| Temperature Range | -40°C to +85°C; qualified for industrial environments including factory automation and outdoor telecom equipment. |
| Standby Current | ≤2 μA (ISB1); minimizes battery drain during extended power-loss events while preserving memory integrity. |
Pinout & Package
32-pin dual in-line package (DIP), MA package type, through-hole mounting. Pin 1 is A18 (top-left corner, notch indicator on top edge).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| A0–A18 | Address inputs | 19-bit address bus supporting full 512 k-word decoding; no address multiplexing required. |
| DQ0–DQ7 | Data input/output | 8-bit bidirectional data bus; high-impedance state enforced during power-fail detection to prevent bus contention. |
| CE | Chip-enable input | Active-low enable; controls device selection and initiates tCER delay upon reassertion after power-up. |
| OE | Output-enable input | Active-low control for output drivers; independent of CE/WE for flexible read timing (e.g., OE-controlled reads). |
| WE | Write-enable input | Active-low write strobe; combined with CE to define write cycle boundaries per JEDEC SRAM timing conventions. |
| VCC | Supply voltage input | Primary 5-V power rail; monitored continuously for VPFD violation to trigger nonvolatile protection sequence. |
| VSS | Ground | Reference return path for all digital and analog circuitry; shared between SRAM core and power-fail detection block. |
Key Features
| Feature | Design Value |
|---|---|
| Automatic Power-Fail Response | Switches to lithium backup and enforces write-protection within 100 μs of VCC falling below 4.37 V - no firmware or external supervision required. |
| Zero External Components | Self-contained module requires no external capacitors, regulators, or battery management ICs - reduces BOM count and layout complexity. |
| Standard SRAM Interface | Fully compatible with JEDEC 32-pin DIP SRAM pinout and timing (e.g., tRC = 85 ns, tAA = 85 ns), enabling drop-in replacement in legacy designs. |
| Lithium Cell Isolation | Internal coin cell remains electrically disconnected until first VCC application, limiting pre-use self-discharge to <0.5% per year. |
| Industrial Temperature Support | Guaranteed operation from -40°C to +85°C with validated AC/DC parameters across full range - suitable for uncontrolled ambient deployments. |
Applications
| Industrial Data Logging | Medical Device Configuration Storage |
|---|---|
|
Use Scenario: Persistent storage of calibration coefficients, usage counters, and fault history in programmable logic controllers and CNC machine controllers. IC Role / Device Role / Timing Role: Nonvolatile SRAM providing immediate-read/write access during runtime and guaranteed data retention during unexpected mains failure or battery swap. Use Value: Eliminates need for EEPROM wear-leveling or flash programming delays; retains critical operational data for >10 years without maintenance. |
Use Scenario: Storing patient-specific therapy parameters and device settings in portable infusion pumps and diagnostic monitors. IC Role / Device Role / Timing Role: Fail-safe memory holding life-critical configuration data that must survive power interruption during clinical use or transport. Use Value: Meets IEC 62304 Class C software data retention requirements with deterministic tCER (≤85 ms) and no write-cycle limitations. |
| Telecom Base Station Settings | Energy Meter Firmware Parameters |
|
Use Scenario: Holding network synchronization keys, RF calibration tables, and provisioning data in outdoor small-cell radios exposed to wide thermal swings. IC Role / Device Role / Timing Role: Industrial-grade NVSRAM ensuring parameter persistence across frequent grid brownouts and thermal cycling (-40°C to +85°C). Use Value: Avoids field failures caused by corrupted configuration due to partial writes - guaranteed atomic protection at VPFD = 4.37 V. |
Use Scenario: Archiving tariff schedules, demand-response commands, and metering registers in ANSI C12.22-compliant smart electricity meters. IC Role / Device Role / Timing Role: Tamper-resistant memory retaining billing-critical data during battery replacement or utility-side firmware updates. Use Value: Provides 10-year data retention with zero reliance on supercapacitors or external backup batteries - simplifies certification and reduces field service cost. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar nonvolatile SRAM applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| STK15C88-85I | 4-Mbit NVSRAM with 85 ns access, but uses capacitor-based backup (shorter retention: ~72 hours) and lacks programmable VPFD. | Suitable only for short-duration hold-up; not viable for decade-long data retention without periodic refresh. | Select only if system has reliable short-term backup power and long-term retention is not required. |
| DS1248-120+T&R | Real-time clock + 256 k × 8 NVSRAM, 120 ns access, integrated RTC oscillator; no separate VPFD tuning - fixed at 4.25 V. | Provides time-stamped logging capability but slower access and higher standby current (10 μA vs. 2 μA). | Choose when timestamped event logging is mandatory and 85 ns speed is not critical. |
Compared with STK15C88-85I and DS1248-120+T&R, the BQ4015YMA-85 uniquely delivers 10-year lithium-backed retention, precise 4.37 V VPFD for ±10% 5-V systems, and lowest standby current - making it optimal for industrial applications demanding long-term, maintenance-free data integrity.
Availability
BQ4015YMA-85 is available at Aetrix Electronics and suitable for industrial data logging, medical device configuration storage, and telecom base station settings requiring stable component supply despite its OBSOLETE status per TI's packaging addendum.
Supply support for BQ4015YMA-85 includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a global semiconductor company headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.
The BQ4015YMA-85 belongs to TI's legacy NVSRAM product line, designed specifically to replace battery-backed SRAM modules in systems requiring guaranteed data retention during unpredictable power interruptions.
FAQ
What is the power-fail-detect voltage threshold for the BQ4015YMA-85?
The BQ4015YMA-85 has a fixed power-fail-detect (VPFD) threshold of 4.37 V (typical), optimized for 5-V systems with ±10% supply tolerance. This value is factory-trimmed and not user-adjustable. The threshold ensures write-protection activates before VCC drops low enough to cause unreliable SRAM operation, and is confirmed in TI's SLUS125B datasheet Table 5 under "bq4015Y" conditions. The BQ4015YMA-85 does not support 3.3-V operation or adjustable VPFD.
Does the BQ4015YMA-85 require external components for nonvolatile operation?
No, the BQ4015YMA-85 requires zero external components for full nonvolatile functionality. Its integrated lithium coin cell, power-fail detection circuitry, and SRAM core are fully self-contained within the 32-pin DIP module. TI explicitly states in the datasheet: "The bq4015/Y/LY requires no external circuitry." Unlike capacitor-backed alternatives, the BQ4015YMA-85 provides 10-year data retention without external hold-up capacitors, regulators, or charge controllers - simplifying design and reducing bill-of-materials cost.
Is the BQ4015YMA-85 pin-compatible with standard 512 k × 8 SRAMs?
Yes, the BQ4015YMA-85 uses the industry-standard 32-pin DIP package (MA) and matches the JEDEC pinout for 512 k × 8 SRAMs, including identical A0–A18, DQ0–DQ7, CE, OE, WE, VCC, and VSS assignments. TI confirms compatibility in the General Description: "compatible with the industry-standard 4-Mb SRAM pinout." This allows direct replacement of volatile SRAMs like the AS6C4008 or IS61LV5128 in existing PCB layouts without redesign - provided the system operates within the BQ4015YMA-85's 5-V and -40°C to +85°C specifications.
How long does the BQ4015YMA-85 retain data without power?
The BQ4015YMA-85 retains data for at least 10 years without external power, as verified by TI's accelerated life testing and specified in the Features section of SLUS125B. This retention relies on its internal lithium coin cell, which exhibits <0.5% annual self-discharge when isolated prior to first use. After initial VCC application, the cell powers the SRAM during outages. Retention time is measured from first power application and accumulates only during actual VCC absence - not calendar time - and is valid across the full -40°C to +85°C operating range.
What happens to the BQ4015YMA-85 outputs during power failure?
When VCC falls below the 4.37 V VPFD threshold, the BQ4015YMA-85 immediately places all DQ0–DQ7 pins into high-impedance (high-Z) state and treats all address and control inputs as "don't care." This prevents bus contention and unintended writes during brownout conditions. The transition occurs within 100 μs (tWPT max), and outputs remain in high-Z until VCC rises above VPFD and the 85 ms tCER recovery window expires. This behavior is defined in the Functional Description and Truth Table sections of the datasheet and requires no external intervention.
BQ4015YMA-85 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 32-DIP Module (0.610", 15.49mm)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Programmable:
- Not Verified
- Memory Type:
- Non-Volatile
- Memory Format:
- NVSRAM
- Technology:
- NVSRAM (Non-Volatile SRAM)
- Memory Size:
- 4Mbit
- Memory Organization:
- 512K x 8
- Memory Interface:
- Parallel
- Clock Frequency:
- -
- Write Cycle Time - Word, Page:
- 85ns
- Access Time:
- 85 ns
- Voltage - Supply:
- 4.5V ~ 5.5V
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Through Hole
- Supplier Device Package:
- 32-DIP Module (18.42x42.8)
BQ4015YMA-85 FAQ
1.How can I place an order for BQ4015YMA-85 through Aetrix?
Please submit a Request for Quotation (RFQ) for BQ4015YMA-85 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for BQ4015YMA-85 reliable?
The price and inventory of BQ4015YMA-85 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for BQ4015YMA-85 is usually 5 days.
3.What payment methods are accepted for BQ4015YMA-85?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for BQ4015YMA-85 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for BQ4015YMA-85?
BQ4015YMA-85 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your BQ4015YMA-85 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for BQ4015YMA-85?
For technical support, including BQ4015YMA-85 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your BQ4015YMA-85 requirements.
6.How does Aetrix verify that BQ4015YMA-85 is sourced from the original manufacturer or authorized distributors?
All BQ4015YMA-85 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that BQ4015YMA-85 meets industry standards.
7.What is the process for return or replacement of BQ4015YMA-85?
All BQ4015YMA-85 units undergo pre-shipment inspection (PSI). If there is an issue with BQ4015YMA-85, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The BQ4015YMA-85 part is unused and in its original packaging.
Return procedure for BQ4015YMA-85:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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