Texas Instruments BQ29728DSET

Overview

BQ29728DSET from Texas Instruments is a single-cell Li-ion/Li-polymer battery protection IC that integrates overvoltage (4.280 V), undervoltage (2.800 V), charge/discharge overcurrent (–0.100 V / 0.150 V), and short-circuit (0.5 V) detection with factory-programmed thresholds and fixed timing delays (1.25 s OVP, 144 ms UVP, 8 ms OCD/OCC, 250 µs SCP). It operates from –40°C to +85°C with 4 µA NORMAL-mode current and drives external CHG/DSG FETs in a 1.50 mm × 1.50 mm WSON-6 package for compact portable power systems.

For engineers reviewing the BQ29728DSET datasheet, BQ29728DSET pinout, BQ29728DSET application, or BQ29728DSET equivalent, this device delivers precise, low-quiescent-current cell-level protection without requiring external microcontroller supervision - critical for space-constrained, battery-powered designs where reliability and zero-voltage charging capability (≥1.7 V start threshold) are essential.

Technical Context

The BQ29728DSET implements analog voltage and current sensing across external FETs using differential inputs (V–/VSS) to detect overcurrent conditions with ±10 mV accuracy at 25°C and ±15 mV over full temperature range. Its internal comparators trigger fixed-delay timers before asserting COUT (charge FET gate drive) or DOUT (discharge FET gate drive) low, enabling controlled FET turn-off during fault events.

It features factory-programmed protection thresholds and timing parameters - including 4.280 V overcharge detection with 1.25 s delay and 2.800 V undervoltage detection with 144 ms delay - eliminating configuration registers or firmware dependencies. The device supports zero-voltage charging initiation when BAT ≥ 1.7 V and inhibits charging below 0.75 V, ensuring safe recovery of deeply depleted cells.

Key Specifications

Pinout & Package

Package: WSON-6 (DSE), 1.50 mm × 1.50 mm × 0.75 mm body size, wettable flank terminals, RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BQ29728DSET, BQ29729DSET offers faster undervoltage response but reduced margin against load-induced voltage droop, while BQ29732DSET raises discharge overcurrent trip point by 27% - enabling higher-power operation without changing layout or FET selection.

Availability

BQ29728DSET is available at Aetrix Electronics and suitable for smartphone battery packs, tablet PC secondary protection circuits, and handheld data terminal power management systems requiring stable component supply, long-term lifecycle support, and guaranteed authenticity.

Supply support for BQ29728DSET 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 and embedded processing technologies, with decades of expertise in battery management and power integrity solutions.

The BQ297xx family was designed specifically for cost-sensitive, space-constrained single-cell Li-ion/Li-polymer applications requiring autonomous, ultra-low-power protection - targeting consumer portables, wearables, and industrial handhelds.

FAQ

What protection functions does the BQ29728DSET provide?

The BQ29728DSET provides five core hardware-based protections: overcharge detection (4.280 V), over-discharge detection (2.800 V), charge overcurrent detection (–0.100 V), discharge overcurrent detection (0.150 V), and load short-circuit detection (0.5 V). Each function uses factory-programmed thresholds and fixed delay timers, and all operate autonomously without software intervention. The BQ29728DSET also supports zero-voltage charging initiation above 1.7 V and inhibits charging below 0.75 V.

Does the BQ29728DSET require external configuration components?

No, the BQ29728DSET requires no external resistors, capacitors, or configuration pins to set protection thresholds or timing delays. All parameters - including OVP (4.280 V), UVP (2.800 V), OCD (0.150 V), OCC (–0.100 V), SCP (0.5 V), and associated delay times (1.25 s, 144 ms, 8 ms, 250 µs) - are factory-laser-trimmed and permanently programmed. Only two external FETs and basic decoupling (0.1 µF on BAT) are needed for full operation.

How does the BQ29728DSET handle deeply discharged batteries?

The BQ29728DSET enables zero-voltage charging by allowing the CHG FET to turn on when BAT ≥ 1.7 V, permitting safe trickle recharge of fully depleted cells. It simultaneously inhibits charging if BAT falls below 0.75 V - preventing lithium metal plating and irreversible damage. This dual-threshold behavior is implemented entirely in analog hardware and requires no external control logic or firmware.

What is the operating temperature range of the BQ29728DSET?

The BQ29728DSET is specified to operate continuously from –40°C to +85°C ambient temperature, with full performance validation across this range for all key parameters including OVP/UVP accuracy (±20 mV/±50 mV), OCD/OCC detection (±15 mV), and timer delays. Its 4 µA NORMAL-mode current remains stable across temperature, making it suitable for outdoor or industrial handheld devices subject to thermal cycling.

Can the BQ29728DSET be used with both N-channel and P-channel FETs?

The BQ29728DSET is optimized for use with external N-channel FETs: COUT drives the gate of the charge FET (high-side configuration relative to pack–), and DOUT drives the gate of the discharge FET (low-side configuration relative to pack–). Its output voltage swing (3.4–3.7 V high, ≤0.5 V low) and drive strength are designed for standard logic-level N-channel devices. It does not support direct P-channel FET control due to lack of high-side gate drive referencing pack+.