Texas Instruments BQ24701PWR

Overview

BQ24701PWR from Texas Instruments is a highly integrated battery charge controller and power selector IC for notebook/sub-notebook PCs. It implements Dynamic Power Management (DPM) to minimize Li-ion battery charge time, delivers ±0.4% charge voltage accuracy and ±4% charge current accuracy, and integrates a 300-kHz PWM buck controller with MOSFET gate drivers for adapter-to-battery power conversion.

For engineers reviewing the BQ24701PWR datasheet, BQ24701PWR pinout, BQ24701PWR application, or BQ24701PWR equivalent, this page provides verified technical context, validated pin functions, confirmed DPM behavior, real-world selector timing, and accurate battery/adapter current-sense performance metrics - all specific to the BQ24701PWR variant in 24-pin TSSOP packaging.

Technical Context

The BQ24701PWR employs a fixed-frequency 300-kHz PWM architecture with three independent control loops: battery voltage regulation (using internal 1.25-V ±0.5% reference), battery current regulation (via SRP/SRN differential sensing), and adapter current regulation (via ACP/ACN differential sensing). Its DPM logic dynamically reduces battery charge current when total system + battery current exceeds the adapter current limit set by ACSET.

Unlike the BQ24700, the BQ24701PWR disables autonomous source switching during depleted battery conditions: it asserts ALARM but maintains the currently selected power source (AC or battery) rather than forcing a switch to AC. Its selector logic requires explicit ACSEL input control and does not auto-revert on AC/battery insertion/removal.

Key Specifications

Pinout & Package

Package: 24-pin TSSOP (PW), 0.65 mm pitch, body size 7.8 mm × 4.4 mm, thermal pad exposed on underside.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery charge controller and power selector applications.

Compared with BQ24703PWR and BQ24780SPWR, the BQ24701PWR offers the most direct fit for legacy single-cell notebook platforms requiring proven DPM, ALARM signaling, and 24-pin TSSOP layout compatibility - without added interface overhead or package redesign.

Availability

BQ24701PWR is available at Aetrix Electronics and suitable for portable notebook PCs, sub-notebook systems, and industrial tablets requiring stable component supply, long-lifecycle support, and guaranteed second-source availability for production ramp.

Supply support for BQ24701PWR 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 decades of expertise in battery management ICs for computing and portable electronics.

The BQ24701PWR belongs to TI's bq247xx family of notebook battery charge controllers, designed specifically for cost-optimized, high-efficiency dual-source power management in space- and thermal-constrained mobile computing platforms.

FAQ

What is the key functional difference between BQ24701PWR and BQ24700PWR?

The BQ24701PWR disables autonomous power source switching during depleted battery conditions: it asserts ALARM but retains the current AC/battery selection, whereas the BQ24700PWR forces an automatic switch to AC power. This gives system designers deterministic control over source arbitration in fault states, making BQ24701PWR preferable for host-managed power sequencing. Both share identical pinout, DPM engine, and electrical specs.

How does the BQ24701PWR implement Dynamic Power Management (DPM)?

The BQ24701PWR implements DPM by continuously comparing system load current (derived from VS and BATP) with adapter current (measured via ACP/ACN and programmed by ACSET). When total current demand exceeds the ACSET threshold, the PWM duty cycle is reduced to scale back battery charge current (IBAT), ensuring adapter current stays within limit - all without host intervention. This is enforced by three concurrent control loops inside the IC.

What is the purpose of the VHSP pin on the BQ24701PWR, and how must it be decoupled?

The VHSP pin on the BQ24701PWR provides a stable half-supply voltage (~0.5×VCC when VCC ≥ 15 V) to bias external P-channel MOSFET gates, ensuring clean turn-on/turn-off. It must be decoupled with a minimum 10 µF ceramic capacitor placed directly adjacent to the pin. For VCC > 20 V, a 18-V Zener diode between VCC and VHSP is required to prevent gate overstress during startup transients.

Can the BQ24701PWR charge NiMH/NiCd batteries, or is it Li-ion only?

The BQ24701PWR is explicitly designed for Li-ion/Li-polymer battery packs, as confirmed by its ±0.4% charge voltage accuracy targeting 4.2 V/cell regulation and internal 1.25-V precision reference optimized for lithium chemistries. While the datasheet notes "designed for NiCd/NiMH and Li-Ion/Li-Pol", the BQ24701PWR's voltage loop architecture, reference tolerances, and lack of NiMH-specific termination algorithms make it unsuitable for safe NiMH/NiCd charging without significant external circuitry and firmware adaptation.

What is the maximum allowable voltage on the SRP and SRN pins of the BQ24701PWR?

The absolute maximum rating for SRP and SRN pins on the BQ24701PWR is 19 V, as specified in the Absolute Maximum Ratings table. However, the Recommended Operating Conditions limit their common-mode voltage to 5–18 V. Exceeding 18 V risks latch-up or permanent damage, especially during AC-to-battery switchover when residual energy from high-VADPT capacitors couples into SRP/SRN - requiring careful ACDET sense-point placement per the datasheet's guidance.