Texas Instruments BQ29209TDRBRQ1

Overview

BQ29209TDRBRQ1 from Texas Instruments is a functional-safety-capable secondary overvoltage protection IC for 2-series Li-ion battery packs, featuring ±25-mV overvoltage detection accuracy (0°C to 60°C), fixed 4.30-V protection threshold, and automatic cell imbalance correction with ±30-mV enable/0-mV disable thresholds. It delivers internal balancing up to 15 mA and supports external balancing via CB_EN-controlled switching, used in automotive eCall systems and portable power tools.

For engineers reviewing the BQ29209TDRBRQ1 datasheet, BQ29209TDRBRQ1 pinout, BQ29209TDRBRQ1 application, or BQ29209TDRBRQ1 equivalent, key selection considerations include its AEC Q100 Grade 2 qualification, VSON-8 (3.0 mm × 3.0 mm) package, <3 µA quiescent current under protection-disable conditions, and programmable delay timing via external capacitor on CD pin.

Technical Context

The BQ29209TDRBRQ1 implements dual independent voltage comparators against a factory-trimmed 4.30-V reference, triggering a capacitor-based delay timer before asserting high-level output on OUT. Its cell balancing logic monitors differential voltage between VC2–VC1 and VC1–GND, enabling internal FETs when mismatch exceeds ±30 mV and disabling them at ≤±9 mV.

Operation includes NORMAL mode (OUT low, cells below VPROTECT), PROTECTION mode (OUT high after delay), and Customer Test Mode (CTM) with reduced 0.08 s/µF delay scaling for production verification. Thermal management relies on the exposed PWR PAD connected to PCB ground plane, achieving RθJB = 19.3°C/W.

Key Specifications

Pinout & Package

Package: VSON-8 (DRB), 3.00 mm × 3.00 mm body size with exposed thermal pad (PWR PAD) requiring solder connection to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar secondary overvoltage protection applications.

Compared with BQ29209TDRBRQ1, BQ29200DRBRQ1 removes balancing capability but retains identical protection specs and footprint, while BD750L5FP-E2 offers lower cost in non-automotive contexts but sacrifices 2S support, accuracy, and functional safety documentation.

Availability

BQ29209TDRBRQ1 is available at Aetrix Electronics and suitable for automotive emergency call (eCall) systems, industrial power tools, and portable medical instrumentation requiring stable component supply and AEC Q100-compliant second-level battery protection.

Supply support for BQ29209TDRBRQ1 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 delivering analog and embedded processing solutions, with leadership in battery management ICs and automotive electronics.

The BQ29209TDRBRQ1 belongs to TI's automotive-grade battery protector family, designed specifically for functional-safety-aware secondary protection in 2-series Li-ion battery packs used in safety-critical mobility and portable power applications.

FAQ

What is the primary function of the BQ29209TDRBRQ1 in a 2-series Li-ion battery system?

The BQ29209TDRBRQ1 serves as a secondary overvoltage protection device that independently monitors each cell voltage in a 2-series Li-ion stack and triggers an output signal when either cell exceeds 4.30 V. It also provides automatic voltage-based cell balancing to correct inter-cell mismatches, extending pack life and safety margin. The BQ29209TDRBRQ1 integrates precision voltage references, delay timing, and balancing control logic in a single VSON-8 package.

How does the BQ29209TDRBRQ1 achieve accurate overvoltage detection across temperature?

The BQ29209TDRBRQ1 achieves ±25 mV overvoltage detection accuracy from 0°C to 60°C through factory-trimmed internal voltage references and temperature-compensated comparator design. Its VOA_DRIFT specification is limited to ±0.4 mV/°C in this range, minimizing threshold drift during automotive cabin operation. This accuracy is verified across production lots and documented in the SLUSC62D datasheet's Electrical Characteristics table.

Can the BQ29209TDRBRQ1 be used without external cell balancing components?

Yes, the BQ29209TDRBRQ1 supports fully internal cell balancing up to 15 mA without external FETs-only RCBext resistor is needed to set current level. Its integrated switches (RCB1int = 300 Ω, RCB2int = 235 Ω) connect VC1_CB to GND or VDD depending on which cell requires discharge. External balancing is optional and used only when higher currents (>15 mA) are required for large-format or high-imbalance packs.

What is the role of the CD pin on the BQ29209TDRBRQ1, and how is it configured?

The CD pin on the BQ29209TDRBRQ1 hosts an external capacitor that sets the overvoltage protection delay time using the formula td = CCD × XDELAY (nominally 9 s/µF). For example, a 0.33 µF capacitor yields ~3 s delay. The internal current source charges CCD until it reaches ~1.2 V, at which point the OUT pin asserts. If overvoltage clears early, CCD discharges rapidly (<100 ms) to reset the timer. This prevents false trips from transient spikes.

Is the BQ29209TDRBRQ1 pin-compatible with other devices in the BQ292xx-Q1 family?

No, the BQ29209TDRBRQ1 is not pin-compatible with other BQ292xx-Q1 variants such as BQ29200DRBRQ1 or BQ29204DRBRQ1. While all share the VSON-8 DRB package, pin functions differ significantly-e.g., BQ29200 lacks VC1_CB and CB_EN pins entirely, and BQ29204 uses different pin assignments for balancing control. PCB layout must be specific to BQ29209TDRBRQ1's pinout shown in Figure 6-1 of SLUSC62D.