Renesas ISL6251HRZ

Overview

ISL6251HRZ from Renesas Electronics (formerly Intersil) is a highly integrated synchronous buck battery charger controller for Li-Ion/Li-Polymer and NiMH chemistries. It delivers ±0.5% charge voltage accuracy across -10°C to +100°C, supports 2–4-cell configurations up to 17.64V, and features programmable adapter current limit (±3% accuracy) and battery charge current limit (±3% accuracy). It is used in notebook computers to manage dual-path power delivery from AC adapter and battery while preventing adapter overload.

For engineers reviewing the ISL6251HRZ datasheet, ISL6251HRZ pinout, ISL6251HRZ application, or ISL6251HRZ equivalent, key selection criteria include its 28-pin 5×5 QFN package, fixed 300kHz PWM operation with diode emulation at light load, thermal shutdown at 150°C, input voltage range of 7–25V, and support for adaptive charge voltage programming via VADJ.

Technical Context

The ISL6251HRZ implements a fixed-frequency current-mode PWM control architecture with feed-forward line regulation and adaptive dead-time gate drive to prevent shoot-through. Its dual-loop regulation uses VCOMP for voltage control (via CSON feedback) and ICOMP for independent current control of both battery charge and adapter input paths.

It integrates a 5V LDO (VDD), 2.39V reference (VREF), and analog monitoring outputs including ICM (adapter current proportional voltage) and ACPRN (open-drain adapter present indicator). The controller transitions automatically from constant-current to constant-voltage charging and supports pulse charging and trickle charge modes.

Key Specifications

Pinout & Package

ISL6251HRZ is housed in a 28-lead, 5mm × 5mm, 0.5mm pitch QFN package with exposed thermal pad (PKG DWG # L28.5×5). Pin functions are validated per FN9202 Rev 3.00 datasheet, Page 2 (28 LD QFN top view) and Page 8 (Functional Pin Descriptions).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery charger controller applications.

Compared with BQ24725ARHBT and MP2639AGU-Z, the ISL6251HRZ offers superior voltage accuracy (±0.5%), lowest battery leakage (<10µA), and native AC adapter presence signaling - making it ideal for cost-sensitive, thermally constrained notebook and sub-notebook platforms requiring analog-programmed reliability without digital overhead.

Availability

ISL6251HRZ is available at Aetrix Electronics and suitable for notebook computers, sub-notebooks, and industrial portable terminals requiring stable component supply, long-term lifecycle support, and RoHS-compliant Pb-free packaging.

Supply support for ISL6251HRZ 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

Renesas Electronics Corporation is a global semiconductor leader delivering trusted embedded design innovation, with deep expertise in power management, analog, and mixed-signal ICs for computing and industrial applications.

The ISL6251HRZ belongs to Renesas' legacy Intersil battery charger controller product line, designed specifically for high-efficiency, multi-chemistry charging in space- and thermal-constrained portable computing systems.

FAQ

What battery chemistries does the ISL6251HRZ support?

The ISL6251HRZ supports Li-Ion, Li-Polymer, NiMH, NiCd, and other common rechargeable chemistries. Its programmable charge voltage (via VADJ) and current limits allow adaptation to chemistry-specific termination voltages and charge profiles - for example, setting 4.1V/cell for extended Li-ion cycle life or configuring trickle charge thresholds for NiMH. The ISL6251HRZ datasheet explicitly confirms compatibility across these chemistries without hardware modification.

How does the ISL6251HRZ prevent AC adapter overload during high system load?

The ISL6251HRZ prevents AC adapter overload using its independent adapter current regulation loop. When CSIP–CSIN differential voltage exceeds the threshold set by ACLIM (e.g., 100mV = 5.15A with 20mΩ sense resistor), the controller reduces battery charge current in real time while maintaining system bus voltage. This ensures the total input current never exceeds the programmed limit - protecting the adapter and avoiding system crashes. The ISL6251HRZ achieves ±3% accuracy in this function across temperature.

What is the purpose of the VADJ pin on the ISL6251HRZ?

The VADJ pin on the ISL6251HRZ programs the per-cell battery charge termination voltage between 3.99V and 4.41V (±5% of 4.2V). Connecting VADJ to GND selects -5%, floating selects nominal 4.2V/cell, and VREF selects +5%. A resistor divider from VREF to GND enables fine-grained adjustment. This feature allows the ISL6251HRZ to optimize capacity versus longevity across battery ages and chemistries - all while maintaining ±0.5% overall voltage accuracy.

Does the ISL6251HRZ require external MOSFETs, and what are the gate drive specifications?

Yes, the ISL6251HRZ requires two external N-channel MOSFETs - one high-side and one low-side - as it is a controller, not an integrated power stage. Its UGATE and LGATE outputs deliver 1.0A source / 1.8A sink current with 1.0–3.0Ω pull-up/pull-down resistance. The ISL6251HRZ includes adaptive dead-time control to prevent shoot-through and mandates low-inductance PGND routing from LGATE to MOSFET source for proper operation.

What is the thermal performance of the ISL6251HRZ in its QFN package?

The ISL6251HRZ in its 28-lead 5×5 QFN package has a junction-to-ambient thermal resistance (θJA) of 39°C/W and junction-to-case (θJC) of 9.5°C/W, measured per JEDEC standards. It includes thermal shutdown at 150°C with 25°C hysteresis. These characteristics enable reliable operation in thermally dense notebook PCB layouts when the exposed pad is soldered to a solid thermal plane - as confirmed in the ISL6251HRZ datasheet Absolute Maximum Ratings table.