Texas Instruments BQ25015RHLTG4

Overview

BQ25015RHLTG4 from Texas Instruments is a single-chip Li-ion/Li-polymer battery charger and synchronous DC-DC converter IC for portable electronics. It integrates AC/USB autonomous power source selection, 500 mA charge current regulation, 300 mA DC-DC output, 1.8 V fixed or adjustable (0.7–VBAT) output voltage, and thermal shutdown protection. It powers and charges systems in MP3 players, PDAs, and digital cameras.

For engineers reviewing the BQ25015RHLTG4 datasheet, BQ25015RHLTG4 pinout, BQ25015RHLTG4 application, or BQ25015RHLTG4 equivalent, key selection criteria include its dual-function integration (charger + buck converter), RHL 20-pin QFN package with exposed thermal pad, USB/AC input prioritization logic, precharge/taper/termination detection thresholds, and forced-PWM vs. power-save mode control via FPWM pin.

Technical Context

The BQ25015RHLTG4 implements a three-phase linear+switching charge algorithm (preconditioning → constant-current → constant-voltage) with programmable ISET1-based current setpoints and automatic recharge at VREG(BAT) − 100 mV. Its integrated DC-DC converter uses synchronous P/N-channel MOSFETs, operates at 1 MHz nominal switching frequency, and transitions between PWM and PFM modes based on load current and FPWM pin state.

Power path management autonomously selects AC adapter over USB input; reverse leakage protection prevents battery drain during input absence. Charge termination relies on dual criteria: minimum current (I(TERM) = 11–25 mV × K(SET)/RSET) and backup timer (t(CHG) = 16.2–19.3 s), while thermal shutdown triggers at 165°C with 15°C hysteresis.

Key Specifications

Pinout & Package

The BQ25015RHLTG4 is housed in a 20-pin RHL package: 4×4 mm QFN with 0.5 mm pitch and exposed thermal pad connected internally to VSS. All VSS pins (3, 9, 18) must be soldered to PCB ground plane; thermal pad requires ≥6 vias to inner ground layer for reliable thermal dissipation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery charger + DC-DC converter applications.

Compared with BQ25015RHLTG4, BQ24075RHLR offers higher charge current but adds system complexity via external DC-DC, while BQ25100YFPT provides superior leakage control and configurability at the cost of losing hardware-based dual-input arbitration - making BQ25015RHLTG4 optimal for cost-sensitive, space-constrained portable devices needing seamless AC/USB fallback.

Availability

BQ25015RHLTG4 is available at Aetrix Electronics and suitable for MP3 players, PDAs, digital cameras, and Bluetooth headsets requiring stable component supply across high-mix, low-volume production runs.

Supply support for BQ25015RHLTG4 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, embedded processing, and power management technologies with over 50 years of innovation in energy-efficient IC design.

The BQ25015RHLTG4 belongs to TI's battery management portfolio, engineered specifically for highly integrated, space-constrained portable electronics that demand simultaneous charging and system power delivery from a single compact IC.

FAQ

What is the function of the FPWM pin on the BQ25015RHLTG4?

The FPWM pin on the BQ25015RHLTG4 controls the DC-DC converter's operating mode: logic-high forces fixed-frequency PWM (1 MHz), ensuring low-noise performance for noise-sensitive circuits like audio codecs; logic-low enables automatic power-save mode (PFM), reducing quiescent current to 15 µA at light loads. This dual-mode capability allows designers to optimize efficiency or EMI behavior without changing hardware. The BQ25015RHLTG4's FPWM pin does not affect charger operation - only the buck converter stage.

How does the BQ25015RHLTG4 handle power source arbitration between AC and USB inputs?

The BQ25015RHLTG4 implements hardware-based autonomous power source selection: it prioritizes the AC adapter (Pin 5) over USB (Pin 6) when both are present, eliminating MCU involvement. If AC is removed, it seamlessly switches to USB without interrupting charge or system power. Reverse leakage protection prevents battery discharge into inactive inputs. This behavior is fixed in silicon - no configuration registers or firmware updates are needed. The BQ25015RHLTG4 achieves this using internal comparators and analog arbitration logic, ensuring deterministic response within microseconds.

Can the BQ25015RHLTG4 charge a deeply discharged battery below 2.5 V?

Yes, the BQ25015RHLTG4 supports preconditioning (precharge) for batteries with voltage below 2.8 V, down to 0 V. When BAT/OUT voltage falls below the V(LOWV) threshold (2.8–3.2 V), it activates a controlled precharge current (5–100 mA, set by RSET and V(PRECHG)) to safely recover deeply discharged cells. A dedicated t(PRECHG) safety timer (1620–1930 s) prevents indefinite precharge. If the threshold isn't reached before timeout, STAT1/STAT2 indicate fault. This feature ensures reliable startup from storage-discharged states - a critical capability for consumer devices. The BQ25015RHLTG4 performs this entirely in analog hardware.

What is the maximum DC-DC output current capability of the BQ25015RHLTG4 and how is it limited?

The BQ25015RHLTG4 delivers up to 300 mA DC-DC output current at TA < 40°C, derating linearly above that temperature (21 mW/°C). Current limit is enforced by internal N-channel MOSFET on-resistance (430–620 mΩ at 3.6 V) and peak-switch-current detection. Thermal shutdown (165°C) and junction temperature monitoring provide secondary protection. Unlike current-mode controllers, the BQ25015RHLTG4 uses voltage-mode control with input feedforward - so output current capability depends on input voltage, duty cycle, and inductor saturation. The BQ25015RHLTG4 datasheet specifies 300 mA as the guaranteed continuous output under JEDEC High-K board conditions with proper thermal pad layout.

Does the BQ25015RHLTG4 support USB Battery Charging (BC) 1.2 specification?

No, the BQ25015RHLTG4 does not implement USB BC 1.2 detection circuitry. It supports basic USB 2.0 power profiles only: ISET2 pin selects between 100 mA (low) and 500 mA (high) - matching USB 2.0 default and high-power port definitions. It lacks D+/D− data-line sensing, CDP/DCP identification, or proprietary charger detection. For BC 1.2 compliance, external circuitry or a dedicated BC detector IC is required. The BQ25015RHLTG4's USB interface is intentionally simplified to reduce cost and footprint - its USB functionality is strictly current-limited power delivery, not protocol-aware charging. This makes the BQ25015RHLTG4 suitable for cost-driven designs where BC 1.2 is not mandated.