Renesas ISL6528CBZ

Overview

ISL6528CBZ from Renesas (formerly Intersil) is a dual-output power controller integrating a standard buck PWM regulator for high-current GPU supplies and a linear regulator for lower-current memory supplies, both delivering ±2% static regulation over line, load, and temperature, operating at 600kHz, and housed in an 8-lead SOIC package for graphics card and embedded processor applications.

For engineers reviewing the ISL6528CBZ datasheet, ISL6528CBZ pinout, ISL6528CBZ application, or ISL6528CBZ equivalent, this page provides verified technical context, validated pin functions, confirmed dual-regulator architecture, real-world soft-start and undervoltage protection behavior, and two documented alternative controllers for GPU/memory supply designs.

Technical Context

The ISL6528CBZ implements voltage-mode PWM control with a single feedback loop, full 0–100% duty ratio, and a high-bandwidth error amplifier (15 MHz GBWP, 6 V/µs slew rate), enabling fast transient response for GPU loads. Its integrated oscillator runs at 600 kHz (550–650 kHz range) with 1.5 V_P-P ramp amplitude and 3.42 ms typical soft-start interval.

It combines two independent regulation paths: one driving an external N-channel MOSFET in buck topology (VOUT1), and another sourcing base current to an external NPN transistor for linear regulation (VOUT2); both outputs are monitored via dedicated FB and FB2 pins for undervoltage detection at 52.5% of 0.8 V reference (0.42 V threshold), triggering simultaneous shutdown.

Key Specifications

Pinout & Package

ISL6528CBZ is packaged in an 8-lead SOIC (M8.15 footprint), RoHS-compliant Pb-free plus anneal construction, rated for 0°C to 70°C ambient operation.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-output power controller applications.

Compared with ISL6528CBZ, ISL6522CRZ offers simpler single-rail control but requires added components for dual-rail functionality, while RT8059NGE provides higher-frequency dual buck capability in a different package but cannot replace the integrated linear regulator's noise-free output essential for memory and I/O supplies.

Availability

ISL6528CBZ is available at Aetrix Electronics and suitable for graphics card GPU supplies, embedded processor core/I/O supplies, and ASIC power delivery systems requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL6528CBZ 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 (acquired Intersil in 2017) is a global semiconductor leader specializing in microcontrollers, analog power management, and interface solutions for automotive, industrial, and computing markets.

The ISL6528CBZ belongs to Intersil's legacy high-performance power controller product line, designed specifically for dual-rail graphics and embedded processor applications demanding tight regulation, fast transient response, and integrated protection features.

FAQ

What is the function of the FB2 pin on the ISL6528CBZ?

The FB2 pin on the ISL6528CBZ serves as the feedback input for the linear regulator channel, monitoring the VOUT2 output voltage via an external resistor divider and regulating it to the internal 0.8 V reference. It also connects to a dedicated undervoltage comparator that triggers immediate shutdown of both regulators if the sensed voltage drops below 0.42 V (52.5% of reference). This dual role ensures precise linear rail control and robust fault protection in the ISL6528CBZ.

Does the ISL6528CBZ support adjustable output voltages?

Yes, the ISL6528CBZ supports fully adjustable output voltages for both channels: the buck regulator output (VOUT1) and linear regulator output (VOUT2) can each be set between 0.8 V and 3.3 V using external resistor dividers connected to FB and FB2 pins respectively. The device's 0.800 V ±2% internal reference enables accurate scaling, and design equations in the datasheet (EQ. 1 and EQ. 2) specify resistor selection criteria to maintain soft-start integrity and loop stability in the ISL6528CBZ.

What is the purpose of the BOOT pin on the ISL6528CBZ?

The BOOT pin on the ISL6528CBZ connects to a bootstrap capacitor (typically 0.47 µF) between the PHASE node and the source of the upper N-channel MOSFET, providing the elevated gate drive voltage required to fully enhance the high-side switch. It ensures reliable UGATE operation above the PHASE voltage, with absolute maximum rating of 10 V - maintained using a 5 V VCC and ≤3.3 V drain supply. This bootstrap architecture eliminates the need for a floating supply in the ISL6528CBZ buck stage.

How does the ISL6528CBZ handle undervoltage faults?

The ISL6528CBZ monitors both FB and FB2 pins continuously with independent undervoltage comparators set to 52.5% of the 0.8 V internal reference (0.42 V). If either pin falls below this threshold, the internal fault logic initiates immediate shutdown of both regulators and enters hiccup-mode protection: after a 10.5 ms delay, it attempts automatic recovery via soft-start. This behavior is confirmed in the ISL6528CBZ datasheet Figure 2 and functional description on page 5.

Is the ISL6528CBZ pin-compatible with other Intersil dual-controller parts?

No, the ISL6528CBZ is not pin-compatible with other Intersil dual-controller parts such as the ISL6522CRZ (single-buck only) or ISL6523 (dual-buck), due to fundamental differences in pin assignment - notably DRIVE2, FB2, and COMP functions unique to the ISL6528CBZ's buck+linear architecture. The datasheet explicitly states "NOT RECOMMENDED FOR NEW DESIGNS" and lists no direct replacement, confirming the ISL6528CBZ has a distinct pinout and feature set within its family.