Texas Instruments BQ2201SN-NTR

Overview

BQ2201SN-NTR from Texas Instruments is an 8-pin SOIC nonvolatile SRAM controller IC that monitors +5V VCC supply, detects power-fail conditions at 4.62V (THS = VSS) or 4.37V (THS = VCC), switches SRAM to 3V backup cells (BC1/BC2), and provides conditioned chip-enable output (CECON) with <10ns propagation delay during valid operation - used in industrial data-logging systems requiring battery-backed memory retention.

For engineers reviewing the BQ2201SN-NTR datasheet, BQ2201SN-NTR pinout, BQ2201SN-NTR application, or BQ2201SN-NTR equivalent, key selection criteria include power-fail detection threshold selectability (THS), dual 3V primary cell support with automatic BC1→BC2 switchover below 2.5V, VOUT current capability up to 160mA, data-retention current ≤100nA, and industrial temperature range (-40°C to +85°C).

Technical Context

The BQ2201SN-NTR implements a precision comparator-based power-fail detection circuit with two selectable VPFD thresholds (4.62V/4.37V), coupled to a bidirectional analog switch that routes VOUT between VCC and either BC1 or BC2 based on voltage comparison and isolation logic. It features hardware-controlled write-protection timing: tWPT (40–150µs) ensures SRAM cycle completion before CECON assertion, while tCER (40–120ms) enforces post-power-up write-protection for processor stabilization.

Its CE-to-CECON path operates transparently during normal VCC operation with sub-10ns propagation delay, but overrides CE input unconditionally during power failure via internal threshold sensing and latch control. Battery isolation is triggered only when CE transitions low across both VPFD and VSO with precise voltage timing (0.48–0.52×VCC held ≥700ns), preventing inadvertent backup activation.

Key Specifications

Pinout & Package

Package: 8-pin narrow SOIC (D), body width 3.9mm, RoHS-compliant NIPDAU lead finish, MSL Level-1, tape-and-reel packaging (2500 pcs/reel).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690TCSA+ and DS1230Y-120, the BQ2201SN-NTR uniquely supports dual 3V lithium cells with automatic switchover, offers selectable VPFD thresholds, delivers sub-10ns CE propagation for high-speed systems, and achieves ≤100nA data-retention current - making it optimal for long-life, high-reliability industrial SRAM backup where external memory sizing and timing control are critical.

Availability

BQ2201SN-NTR is available at Aetrix Electronics and suitable for industrial data loggers, programmable logic controllers, smart metering endpoints, and railway signaling controllers requiring stable component supply and long-term lifecycle support.

Supply support for BQ2201SN-NTR 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, specializing in analog, embedded processing, and power management technologies for industrial, automotive, and communications markets.

The BQ2201SN-NTR belongs to TI's legacy battery-management and nonvolatile memory controller product line, designed specifically to enable reliable, hardware-governed SRAM backup in mission-critical industrial systems without firmware dependency.

FAQ

What is the function of the THS pin on the BQ2201SN-NTR?

The THS pin on the BQ2201SN-NTR selects the power-fail detection threshold: when tied to VSS, VPFD is 4.62V (for 5% VCC tolerance); when tied to VCC, VPFD is 4.37V (for 10% tolerance). It must be hard-wired - floating or dynamically driven will cause undefined behavior. This setting directly determines the BQ2201SN-NTR's response point during supply sag and is critical for matching system-level voltage tolerance specifications.

Can the BQ2201SN-NTR support both BC1 and BC2 simultaneously in active backup mode?

No - the BQ2201SN-NTR sources VOUT from BC1 exclusively while its voltage remains above 2.5V; only when BC1 falls below that threshold does the internal isolation switch transfer VOUT to BC2. Both inputs cannot supply current concurrently. This sequential handoff is fully hardware-managed within the BQ2201SN-NTR and requires no external control signals or sequencing logic.

What is the maximum VOUT current the BQ2201SN-NTR can deliver, and under what conditions?

The BQ2201SN-NTR delivers up to 160mA on VOUT when VOUT > VCC − 0.3V (IOUT1 condition), sufficient for powering standard 32K×8 or 64K×8 CMOS SRAMs. At light loads (<100µA), VOUT regulates to VBC − 0.3V (IOUT2 condition). Exceeding 160mA risks thermal shutdown or output droop, and sustained operation above 100mA should verify junction temperature remains within −40°C to +85°C limits for the BQ2201SN-NTR.

How does the BQ2201SN-NTR ensure SRAM write-protection during power-up?

The BQ2201SN-NTR holds CECON inactive (high) for tCER = 40–120ms after VCC rises above VPFD, regardless of CE input state - this enforced window prevents premature SRAM writes before the host processor stabilizes. The BQ2201SN-NTR generates this delay autonomously using internal timing circuitry, eliminating need for external RC networks or firmware delays in the system design.

Is the BQ2201SN-NTR pin-compatible with other TI nonvolatile controllers like the BQ2205?

No - the BQ2201SN-NTR is not pin-compatible with the BQ2205 or other members of TI's BQ22xx family. The BQ2205 uses a 16-pin SOIC package with different pin assignments (e.g., dedicated VBAT, RST outputs), whereas the BQ2201SN-NTR uses an 8-pin SOIC with VOUT, BC1, BC2, and THS arranged for minimal external component count. Board-level replacement requires redesign; the BQ2201SN-NTR must be used per its specific footprint and signal routing.