Texas Instruments BQ24045DSQT

Overview

BQ24045DSQT from Texas Instruments is a single-input, single-cell Li-Ion/Li-Pol linear battery charger IC with integrated power FET, JEITA-compliant thermal regulation, and 4.35 V high-voltage chemistry support. It delivers ±1% charge voltage accuracy, ±10% charge current accuracy, and programmable precharge/termination thresholds via external resistors. Designed for space-constrained wearables, it operates from USB or unregulated DC adapters up to 30 V input and includes 6.6 V input overvoltage protection.

For engineers reviewing the BQ24045DSQT datasheet, BQ24045DSQT pinout, BQ24045DSQT application, or BQ24045DSQT equivalent, key selection considerations include its 4.35 V regulation voltage (vs. 4.20 V in BQ24040), JEITA-based temperature-adaptive charging, 10-hour safety timer, TTDM mode for thermistor-absent operation, and DFN-10 (2 mm × 2 mm) package with exposed thermal pad.

Technical Context

The BQ24045DSQT implements a three-phase linear charging algorithm-conditioning, constant-current, and constant-voltage-with internal junction temperature monitoring that dynamically reduces charge current above 125°C. Its input voltage dynamic power management (DPM) activates at 4.4 V to prevent adapter collapse under heavy load.

JEITA compliance is enforced via the TS pin connected to a 10 kΩ NTC thermistor: charging halts below 0°C (VTS < 1.23 V), reduces to 50% current between 0–10°C, maintains full rate from 10–45°C, lowers regulation to 4.20 V above 45°C, and suspends above 60°C (VTS < 0.178 V). Termination and precharge thresholds are resistor-programmable using the PRE-TERM pin.

Key Specifications

Pinout & Package

Package: DFN-10 (WSON), 2.0 mm × 2.0 mm body size with exposed thermal pad (must be soldered to VSS-connected ground plane).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar single-cell Li-ion linear charging applications.

Compared with BQ24040DSQT, the BQ24045DSQT adds 4.35 V regulation for next-gen cells but shares identical JEITA, safety timer, and package; versus BQ24075RGER, it trades current capability and integration for ultra-small size and thermal adaptability in wearables.

Availability

BQ24045DSQT is available at Aetrix Electronics and suitable for TWS headsets, smartwatches, and portable medical devices requiring stable component supply, long-term lifecycle support, and certified safety compliance.

Supply support for BQ24045DSQT 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 delivering analog, embedded processing, and connectivity solutions for industrial, automotive, and personal electronics markets.

The BQ2404x family targets space-constrained portable applications with highly integrated linear charging, emphasizing compactness, JEITA compliance, and USB/adapter flexibility - optimized for wearables and small-format battery-powered devices.

FAQ

What is the maximum input voltage rating for the BQ24045DSQT?

The BQ24045DSQT has an absolute maximum input voltage rating of 30 V on the IN pin. Its input overvoltage protection (OVP) activates at 6.6 V nominal, clamping input transients to protect internal circuitry. This allows safe operation with low-cost unregulated 5 V, 9 V, or 12 V wall adapters while maintaining robustness against surge events.

Does the BQ24045DSQT support JEITA-compliant charging, and how is it implemented?

Yes, the BQ24045DSQT fully supports JEITA-compliant charging via its TS pin, which interfaces with a standard 10 kΩ NTC thermistor in the battery pack. It enforces temperature-based rules: halting charge below 0°C, reducing current to 50% between 0–10°C, maintaining full rate at 10–45°C, lowering regulation voltage to 4.20 V above 45°C, and disabling charge above 60°C - all without external MCU intervention.

How is the charge termination current programmed on the BQ24045DSQT?

The BQ24045DSQT uses the PRE-TERM pin to set both precharge and termination current thresholds via an external resistor to VSS. With R_PRE-TERM = 2 kΩ to 10 kΩ, termination current is programmable from 5% to 50% of the fast-charge current (I_SET). For example, with I_SET = 500 mA and R_PRE-TERM = 4 kΩ, termination occurs at ~250 mA - critical for optimizing capacity and longevity in small Li-ion cells.

What is the purpose of TTDM mode on the BQ24045DSQT, and how is it activated?

TTDM (Termination and Timer Disable Mode) on the BQ24045DSQT disables charge termination, safety timer, and JEITA monitoring to allow continuous charging when no NTC thermistor is present - useful for cost-sensitive or production-test scenarios. It activates when the TS pin is left floating or pulled above 1.6 V, and deactivates when TS is connected to a valid 10 kΩ NTC network.

Can the BQ24045DSQT be used with both USB and DC adapter inputs, and how is input current limited?

Yes, the BQ24045DSQT supports dual-input sources via the ISET2 pin: logic HIGH enables 500 mA USB current limit, FLOAT configures 100 mA for USB enumeration, and logic LOW selects the full ISET-programmed current for DC adapter operation. This eliminates external switches or detection circuitry while ensuring compliance with USB specifications and adapter capabilities.