Texas Instruments BQ2205LYPWRG4

Overview

BQ2205LYPWRG4 from Texas Instruments is a CMOS SRAM non-volatile controller with integrated reset, designed to convert standard CMOS SRAM into battery-backed non-volatile memory. It supports one or two banks of SRAM, provides 3.3-V operation with 3-V primary cell backup, delivers <20-ns chip-enable propagation delay, and features dual conditioned CE outputs (CECON1/CECON2) for hardware write-protection during power failure - used in NVSRAM modules and medical instrumentation.

For engineers reviewing the BQ2205LYPWRG4 datasheet, BQ2205LYPWRG4 pinout, BQ2205LYPWRG4 application, or BQ2205LYPWRG4 equivalent, key selection criteria include VPFD = 2.9 V (typ), tCER = 30–85 ms write-protect hold time after power-up, VOUT switching between VCC and BCP, open-drain RST/BW outputs, and TSSOP-16 package compatibility with industrial temperature range (−20°C to 70°C).

Technical Context

The BQ2205LYPWRG4 implements autonomous power-fail detection using a precision comparator monitoring VCC against VPFD (2.9 V typ); when VCC falls below VPFD, it forces CECON1 and CECON2 inactive and switches VOUT from VCC to the backup cell (BCP) to maintain SRAM retention. During power-up, VOUT transitions back to VCC once VCC exceeds VPFD, and CECONx outputs remain disabled for tCER (30–85 ms) to ensure microprocessor stabilization before memory access resumes.

Bank selection is performed via input A, which routes the active-low CE signal to either CECON1 (A = L) or CECON2 (A = H), enabling hardware-based decoding of dual-SRAM banks without external logic. The RST output provides synchronized power-on/power-fail reset (open-drain, 0.4 V max at 1 mA), while BW latches battery voltage status (VBW = 0.677×VCC) at tCER after power-valid detection.

Key Specifications

Pinout & Package

Package: 16-pin TSSOP (PW), JEDEC MO-153 compliant, 4.4 mm × 5.0 mm footprint, 1.2 mm max height, lead pitch 0.65 mm, NIPDAU finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar SRAM non-volatile controller applications.

Compared with MAX6900APL+ and DS1230YP-120+, the BQ2205LYPWRG4 uniquely combines dual-bank hardware decoding, sub-25 ns CE propagation, integrated VOUT switching, and battery warning latching - enabling compact, high-reliability NVSRAM modules without external components or firmware dependency.

Availability

BQ2205LYPWRG4 is available at Aetrix Electronics and suitable for point-of-sale systems, medical instrumentation, and industrial PLCs requiring stable component supply with long-term lifecycle support and traceable sourcing.

Supply support for BQ2205LYPWRG4 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 leader specializing in analog, embedded processing, and digital signal technologies, with over 90 years of innovation in power management and interface solutions.

The BQ2205LYPWRG4 belongs to TI's legacy non-volatile memory controller product line, engineered specifically for industrial and medical applications demanding robust, zero-software SRAM backup with deterministic power-fail response.

FAQ

What is the primary function of the BQ2205LYPWRG4 in an SRAM-based system?

The BQ2205LYPWRG4 serves as a hardware-based SRAM non-volatile controller that autonomously manages power switchover, write-protection, and system reset. It converts standard CMOS SRAM into battery-backed memory by monitoring VCC, switching VOUT between main and backup supplies, forcing CECON1/CECON2 inactive during power failure, and asserting RST for processor initialization - all without firmware involvement. Its core value lies in deterministic, sub-millisecond response to voltage anomalies.

Does the BQ2205LYPWRG4 support dual-bank SRAM configurations, and how is bank selection implemented?

Yes, the BQ2205LYPWRG4 natively supports dual-bank SRAM via its A input pin and dual CECON outputs (CECON1 and CECON2). When A = low, the active-low CE signal passes to CECON1; when A = high, it routes to CECON2. This hardware decoding eliminates external logic, allowing scalable NVSRAM designs using lower-density SRAM devices. The truth table in the datasheet confirms this behavior is independent of power state - functional only during VCC-valid operation.

What is the role of the BW pin on the BQ2205LYPWRG4, and how is its threshold determined?

The BW (Battery Warning) pin on the BQ2205LYPWRG4 is an open-drain output that latches low when the backup cell voltage (BCP) falls below 0.677×VCC during power-up. This threshold is internally generated and fixed - not user-adjustable. The latched state persists until next power cycle, enabling host systems to detect weak batteries before critical power loss. External pull-up is required; TI specifies ≤10 kΩ for reliable logic-level interpretation.

How does the BQ2205LYPWRG4 handle power-up sequencing, and what is the significance of tCER?

During power-up, the BQ2205LYPWRG4 holds CECON1 and CECON2 inactive for tCER (30–85 ms) after VCC crosses VPFD (2.9 V), regardless of CE input state. This enforced write-protection window ensures the connected microprocessor completes reset and initialization before SRAM access begins - preventing data corruption from premature writes. tCER is guaranteed across temperature and voltage, making it a deterministic design parameter for system timing budgets.

Can the BQ2205LYPWRG4 operate with rechargeable backup cells, or is it limited to primary lithium cells?

The BQ2205LYPWRG4 is specified for use with 3-V primary (non-rechargeable) lithium cells only, as stated in the Functional Description: "Backup energy source, BCP, input is provided [...] for use with an external primary cell." Its BCP input rating (2.0–4.0 V) and lack of charge control circuitry make it unsuitable for rechargeable chemistries like Li-ion or NiMH. Using rechargeables risks overvoltage damage or uncontrolled charging; TI explicitly designs this device for single-use lithium coin or cylindrical cells.