Texas Instruments BQ24901PWRG4

Overview

BQ24901PWRG4 from Texas Instruments is a secondary-side Li-ion battery charge management IC for off-line cradle/desktop chargers. It provides precision current/voltage regulation feedback to primary-side controllers, supports pre-charge conditioning, temperature-monitored charging, and dual-status LED/host interface outputs. Designed for single-cell 4.2 V Li-ion packs in handheld devices.

For engineers reviewing the BQ24901PWRG4 datasheet, BQ24901PWRG4 pinout, BQ24901PWRG4 application, or BQ24901PWRG4 equivalent, key selection criteria include its 4.2 V ±30 mV voltage regulation accuracy, 200 mV current-sense threshold, TSSOP-14 package, optocoupler-driven feedback architecture, and integrated 5-hour charge timer with minimum-current termination.

Technical Context

The BQ24901PWRG4 implements a three-phase charge algorithm-pre-conditioning (linear regulation at 10–30 mV SNS threshold), constant-current (200 mV SNS threshold), then constant-voltage (4.20 V ±30 mV)-with independent loop compensation via ICOMP, VCOMP, and SCOMP pins. It uses external thermistor-based temperature sensing on TS pin with LTF/HTF/TCO thresholds defined as %VCC.

Charge status is communicated through open-drain STAT1/STAT2 outputs with four distinct states (battery absent, charge-in-progress, done, suspend), while OPTD drives an external optocoupler to close the primary-side control loop. Battery insertion/removal detection operates robustly even with open-circuit protection MOSFETs in the pack.

Key Specifications

Pinout & Package

14-pin TSSOP (PW) package with exposed thermal pad; 0.65 mm pitch; 5.0 mm × 4.4 mm body size; JEDEC MO-153 compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Li-ion secondary-side charge management applications.

Compared with BQ24902PWR, the BQ24901PWRG4 provides fixed 4.2 V regulation ideal for standard single-cell Li-ion, reducing BOM count. Against MAX1555ESA+, it delivers transformer-isolated feedback essential for safety-certified AC adapters - neither alternative replicates its exact secondary-side optocoupler-driven control role.

Availability

BQ24901PWRG4 is available at Aetrix Electronics and suitable for digital camera cradles, handheld medical device docks, industrial scanner chargers, and consumer audio headset bases requiring stable component supply and long-term production continuity.

Supply support for BQ24901PWRG4 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 BQ24901PWRG4 belongs to TI's battery management IC portfolio designed specifically for isolated, off-line Li-ion charger topologies - emphasizing secondary-side intelligence, robust battery detection, and seamless integration with primary-side flyback controllers.

FAQ

What is the primary function of the BQ24901PWRG4 in a charger system?

The BQ24901PWRG4 serves as a secondary-side Li-ion charge management IC that provides precise current and voltage regulation feedback to a primary-side controller via its OPTD pin. It manages the full CC/CV charge cycle-including pre-conditioning, fast charge, and termination-while monitoring battery temperature, detecting insertion/removal, and driving status LEDs through STAT1/STAT2. Its core purpose is enabling safe, accurate, and isolated charging in AC/DC offline adapters.

Does the BQ24901PWRG4 integrate a power switch or require external pass transistors?

No, the BQ24901PWRG4 does not integrate a power switch. It requires an external P-channel MOSFET or bipolar transistor controlled by the open-drain CC pin to regulate charge current and voltage. The IC provides only the control logic, sensing, and feedback signaling; the power path remains discrete to optimize thermal performance and voltage headroom in isolated designs.

How does the BQ24901PWRG4 handle battery temperature monitoring?

The BQ24901PWRG4 monitors battery temperature via the TS pin using an external NTC thermistor and voltage divider. It compares the resulting voltage against three internal thresholds: LTF (cold suspend), HTF (hot suspend), and TCO (in-charge cutoff). Charging initiates only when TS is between LTF and HTF; during charge, operation continues only if TS stays between LTF and TCO. Hysteresis prevents oscillation near thresholds.

What are the key timing protections built into the BQ24901PWRG4?

The BQ24901PWRG4 includes two independent safety timers: a 1.8-second pre-charge timer (t_PRECHG) that triggers fault if battery voltage doesn't rise above 3.05 V, and an 18-second fast-charge timer (t_CHG) that enforces maximum charge duration. Both timers reset on power-on or battery replacement. These prevent overcharging and thermal runaway in malfunctioning or deeply discharged cells.

Can the BQ24901PWRG4 operate without a battery connected?

Yes, the BQ24901PWRG4 maintains regulated 6.0 V ±0.3 V VCC supply and remains fully operational during battery-absent conditions. It continuously regulates secondary-side voltage using the SCOMP loop, allowing the system to stay ready for battery insertion while driving status outputs and supporting host communication - critical for cradle-style chargers expecting intermittent battery presence.