Texas Instruments BQ4015MA-70

Overview

BQ4015MA-70 from Texas Instruments is a 512 k × 8 nonvolatile static RAM (NVSRAM) with integrated lithium backup, 70 ns access time, 5 V operation, and 32-pin DIP module packaging. It functions as a standard SRAM during normal power, automatically switching to battery-backed retention during power loss - used in industrial control data logging where persistent memory without EEPROM write delays is required.

For engineers reviewing the BQ4015MA-70 datasheet, BQ4015MA-70 pinout, BQ4015MA-70 application, or BQ4015MA-70 equivalent, this page delivers verified timing parameters, power-fail detection thresholds, pin-level functional roles, and real-world use cases for embedded systems requiring guaranteed data retention across uncontrolled power cycles.

Technical Context

The BQ4015MA-70 integrates a 4,194,304-bit CMOS SRAM array with on-chip power-fail detection circuitry that triggers at VPFD = 4.62 V (typical), plus automatic lithium cell activation when VCC falls below VSO ≈ 3 V. Its control logic enforces unconditional write-protection within 100 μs of power failure and sustains data retention for ≥10 years without external power.

It supports full SRAM read/write protocols via CE/OE/WE controls, maintains high-impedance I/O during standby, and features dual-mode operation: conventional 5 V SRAM behavior under valid supply, and seamless transition to nonvolatile mode during brownout - all without external components or firmware intervention.

Key Specifications

Pinout & Package

Package: 32-pin DIP module (MA package), through-hole mounting, 0.6-inch width, compatible with standard 4-Mb SRAM footprints.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar nonvolatile SRAM applications.

Compared with BQ4015YMA-70 and BQ4015LYMA-70N, the BQ4015MA-70 offers optimal trade-off between power-fail robustness (4.62 V threshold) and compatibility with legacy 5 V infrastructure, while avoiding the obsolescence constraints and voltage mismatch of its variants.

Availability

BQ4015MA-70 is available at Aetrix Electronics and suitable for industrial data loggers, medical device configuration stores, and point-of-sale terminals requiring stable component supply across extended product lifecycles.

Supply support for BQ4015MA-70 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 specializing in analog, embedded processing, and connectivity technologies, with over 50 years of leadership in memory and power management ICs.

The BQ4015MA-70 belongs to TI's nonvolatile SRAM product line, engineered specifically for mission-critical data retention in industrial and medical equipment where EEPROM endurance or battery-backed DRAM complexity is unacceptable.

FAQ

What is the power-fail detection voltage threshold for BQ4015MA-70?

The BQ4015MA-70 features a fixed power-fail detect (VPFD) threshold of 4.62 V (typical), calibrated for 5 V systems with ±5% supply tolerance. This value is factory-trimmed and not user-adjustable. When VCC drops below this level, the device immediately enters write-protect mode and activates its internal lithium cell to sustain memory contents. The BQ4015MA-70 relies on this precise threshold to prevent data corruption during brownout conditions without requiring external supervision circuitry.

Does BQ4015MA-70 require external components to operate as nonvolatile memory?

No, the BQ4015MA-70 requires zero external components to deliver full nonvolatile functionality. Its monolithic design integrates a 512 k × 8 SRAM array, lithium coin cell, power-fail comparator, isolation switch, and control logic into a single 32-pin DIP module. The lithium cell remains electrically isolated until the first application of VCC, after which it automatically engages during power loss. This eliminates the need for external capacitors, regulators, or discrete backup controllers - a key differentiator from discrete SRAM + battery solutions.

Is BQ4015MA-70 pin-compatible with standard 4-Mb SRAMs?

Yes, the BQ4015MA-70 uses an industry-standard 32-pin DIP footprint and pinout identical to JEDEC-compliant 4-Mb (512 k × 8) SRAMs. Address lines A0–A18, data lines DQ0–DQ7, and control signals CE/OE/WE map directly to conventional SRAM layouts. This allows direct substitution in existing PCBs designed for devices like the AS6C4008 or CY62148EV30 without layout changes - provided system timing (70 ns access) and 5 V supply requirements are met.

How long does BQ4015MA-70 retain data without power?

The BQ4015MA-70 guarantees ≥10 years of data retention in the absence of VCC, based on TI's characterization of its integrated lithium coin cell and ultra-low standby current (1–2 μA). This retention period begins after the first application of VCC, which breaks internal isolation and activates the cell. Shelf-life prior to first use exceeds 10 years due to <0.5% annual self-discharge in the isolated state. Real-world retention depends on ambient temperature and cumulative backup usage, but TI specifies 10 years minimum at 25°C per datasheet Table 7.

What happens to BQ4015MA-70 outputs during power failure?

When VCC falls below the 4.62 V VPFD threshold, the BQ4015MA-70 forces all DQ0–DQ7 pins into high-impedance state within 100 μs (tWPT), disables write capability unconditionally, and treats all address and control inputs as "don't care." This prevents bus contention and invalid reads/writes during unstable supply conditions. Outputs remain in high-Z until VCC rises above VPFD and completes the 120 ms chip-enable recovery window (tCER), after which normal SRAM operation resumes - ensuring deterministic behavior across power transitions.