Key Selection Information
| Selection Parameter | Confirmed Information |
|---|---|
| Battery Configuration | 1-cell Li-Ion / Li-Polymer, 4.2 V regulation |
| Programmable Fast-Charge Current | 10 mA to 1 A using RISET |
| USB Input Current Limits | 100 mA or 500 mA selectable through ISET2 |
| Input Operating Window | 4.45 V to 6.45 V, bounded by DPM and OVP behavior |
| Pre-Charge / Termination | Externally programmable through PRETERM |
| Battery Temperature Control | 10 kΩ NTC; JEITA-related charge-current / regulation-voltage changes |
| Safety / Thermal Control | Fixed 10-hour safety timer; 125°C thermal regulation |
| Exact Package / Packing | WSON (DSQ), 10 pins, 2 mm × 2 mm; 3000-piece large tape and reel |
Product Overview
BQ24040DSQR is a Texas Instruments single-cell linear charger that combines up to 1 A programmable fast-charge current with selectable USB input-current limits, programmable pre-charge and termination thresholds, battery NTC monitoring, and a 4.2 V regulation target. The 2 mm × 2 mm WSON package is intended for space-constrained battery-powered hardware where the charger can be placed close to the cell and power connector.
The programmed fast-charge current and the available input current are separate constraints. RISET can request as much as 1 A, but ISET2 can limit the input source to 100 mA or 500 mA in USB modes, and the input DPM loop can reduce charger output when the source voltage sags. A 1 A programmed setting therefore does not mean the battery always receives 1 A.
BQ24040 also changes charging behavior with battery temperature rather than simply enabling or disabling charge at one threshold. TI documents reduced fast-charge current in the cold region and a reduced regulation voltage in the hot region, making the NTC network part of the charge profile rather than a simple fault input.
For related single-cell charger options, see HKEQGOO’s Battery Chargers category.
Technical Specifications
| Parameter | Verified Information |
|---|---|
| Manufacturer | Texas Instruments |
| Exact MPN | BQ24040DSQR |
| Charger Architecture | Linear, single-input, single-cell charger |
| Normal Battery Regulation | 4.20 V typical; 4.16 V minimum, 4.23 V maximum under the stated normal-temperature test condition |
| Hot-Region Battery Regulation | 4.06 V typical for BQ24040 under TI’s stated TS condition |
| Fast-Charge Current Range | 10 mA to 1000 mA programmed with RISET |
| Fast-Charge Factor | 540 AΩ typical for 50 mA to 1000 mA range |
| Input OVP Threshold | 6.65 V typical for BQ24040 |
| Input DPM | 4.4 V typical in USB mode; 4.3 V typical in adaptor mode under the stated test conditions |
| USB Input Limit | 92 mA typical in 100 mA mode; 462 mA typical in 500 mA mode |
| Pre-Charge Transition | 2.5 V typical |
| Default Pre-Charge Current | 20% of fast-charge current |
| Default Termination Threshold | 10% of fast-charge current |
| Thermal Regulation | 125°C junction-temperature regulation |
| Package | WSON (DSQ), 10 pins, 2 mm × 2 mm |
| Manufacturer Status | Active / Production |
| Part Marking | NXE |
Functional Highlights
Source-current limit can override the programmed charge-current target
BQ24040 separates the fast-charge setting from the input-source limit. RISET programs the charger’s current target, while ISET2 provides USB-oriented input limits. If the selected input limit or the source itself cannot support the requested charging power, the battery current must fall below the RISET target.
The input DPM loop adds another constraint: when input voltage approaches the DPM threshold, the charger reduces output current to avoid pulling the source lower. Charger-current calculations should therefore start with both the programmed battery current and the actual source capability.
PRETERM changes the low-battery and end-of-charge current thresholds
BQ24040 does not lock pre-charge and termination to only one fixed percentage. The PRETERM resistor can program these thresholds, with 20% pre-charge and 10% termination as the default conditions shown in the electrical table.
This matters when a cell or application requires a gentler pre-charge current or a different end-of-charge threshold. Changing PRETERM affects charge-profile behavior and should be evaluated together with the selected RISET current rather than treated as an unrelated setting.
Battery temperature changes the charge profile
The TS input supports a 10 kΩ NTC network and JEITA-related operation. The BQ24040 feature set includes reduced fast-charge current in the cold region and reduced battery regulation voltage in the hot region; the electrical table lists 4.06 V typical hot-region regulation for this variant.
That behavior can reduce battery stress at temperature extremes, but it also means charge time and final battery voltage are temperature dependent. The thermistor network and its placement need to represent the battery temperature that the charger is intended to protect.
Design Considerations
- Check input limit before assuming the RISET current reaches the battery. A 1 A charge setting can still be constrained by the 100 mA / 500 mA USB limit, source impedance, DPM, or thermal regulation.
- Account for a parallel system load. The charger has a single battery output; an active system load can consume part of the charger current and can interfere with normal termination if battery current never falls through the programmed threshold.
- Use the exposed-pad WSON package as part of the thermal design. A linear charger dissipates approximately the input-to-battery voltage difference multiplied by charge current; PCB copper and thermal layout affect when the 125°C regulation loop begins reducing current.
- Program PRETERM from the required cell behavior, not from a default percentage alone. Pre-charge and termination thresholds are tied to fast-charge current and should be checked against the battery manufacturer’s charging requirements.
- Treat TS as part of the battery interface. Incorrect thermistor values or placement can change charge-current and regulation-voltage behavior across temperature.
Product Status and Exact Order Code
Manufacturer status: Active / Production
Texas Instruments lists BQ24040DSQR as a 10-pin WSON DSQ device in a 3000-piece large tape-and-reel carrier with part marking NXE and Level-2-260C-1 YEAR MSL rating. BQ24040DSQT uses the same DSQ package but is supplied as a 250-piece small tape-and-reel option. The R/T order-code difference is therefore relevant to purchasing and assembly quantity, not to the core BQ24040 charging function.
Related Engineering Resources
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