Renesas ISL6521CBZ

Overview

ISL6521CBZ from Intersil is a PWM buck DC-DC and triple linear power controller IC designed for multi-rail low-voltage power systems. It integrates one voltage-mode PWM controller (20A capable via external MOSFETs) and three linear regulators (120mA native, up to 3A with external NPN transistors), all delivering ±2% static regulation over 0°C to 70°C. It regulates core, I/O, memory, and auxiliary voltages in FPGA/ASIC-based boards using a single 5V bias supply.

For engineers reviewing the ISL6521CBZ datasheet, ISL6521CBZ pinout, ISL6521CBZ application, or ISL6521CBZ equivalent, key selection considerations include its 300kHz fixed-frequency synchronous buck operation, rDS(ON)-based overcurrent sensing, independent soft-start per regulator, 0.8V reference accuracy, and SOIC-16 package compatibility with FPGA power sequencing requirements.

Technical Context

The ISL6521CBZ implements a single-loop voltage-mode PWM control architecture with a high-bandwidth error amplifier (15MHz GBWP, 6V/μs slew rate) and full 0–100% duty cycle capability. Its oscillator operates at 300kHz (±25kHz) with 1.5Vpp ramp amplitude and 6.83ms typical soft-start interval.

All four regulated outputs share a common 0.800V internal reference (±2% over temperature), with feedback pins (FB, FB2–FB4) monitoring undervoltage events and enabling individual regulator disable via 1.25V pull-up. Overcurrent protection on the PWM channel uses an internal 40μA current source and OCSET pin to sense voltage drop across the upper MOSFET's rDS(ON), eliminating need for external sense resistors.

Key Specifications

Pinout & Package

ISL6521CBZ is housed in a 16-lead SOIC package (Pb-free, RoHS compliant, JEDEC MO-012AA, package drawing M16.15) with standard 1.27mm pitch and 10.3mm × 7.5mm footprint.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multi-rail power controller applications.

Compared with ISL6521CBZ, ISL6522CBZ offers extended temperature support at the cost of looser regulation, while TPS51116PWR delivers higher PWM current and phase flexibility but requires PCB redesign and firmware adaptation - neither is pin-compatible, making ISL6521CBZ optimal for cost-sensitive, commercial-temperature FPGA power applications.

Availability

ISL6521CBZ is available at Aetrix Electronics and suitable for FPGA power delivery, ASIC multi-rail sequencing, and industrial embedded processor boards requiring stable component supply across commercial temperature range.

Supply support for ISL6521CBZ 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

Intersil (now part of Renesas Electronics) is a semiconductor company specializing in high-performance analog and power management ICs for computing, communications, and industrial markets.

The ISL6521CBZ belongs to Intersil's multiphase and multi-rail power controller product line, engineered specifically for simplified, space-efficient power delivery in FPGA, ASIC, and embedded processor systems with stringent sequencing and regulation requirements.

FAQ

What is the operating temperature range of the ISL6521CBZ?

The ISL6521CBZ is specified for 0°C to 70°C ambient operation, as confirmed in the Absolute Maximum Ratings and Ordering Information tables of the FN9148 datasheet. This commercial-grade temperature range makes it suitable for indoor, non-extreme-environment applications such as desktop FPGA development boards and office-located industrial controllers. The ISL6521CBZ does not support operation below 0°C or above 70°C without derating or validation.

Does the ISL6521CBZ require an external current-sense resistor for overcurrent protection?

No, the ISL6521CBZ does not require an external current-sense resistor. Its PWM overcurrent protection uses an internal 40μA current source applied to the OCSET pin and monitors the voltage drop across the upper MOSFET's rDS(ON) via the PHASE node. This rDS(ON)-based method eliminates the need for a dedicated sense resistor, reducing component count and PCB area while maintaining accurate trip thresholds.

Can the ISL6521CBZ regulate four different output voltages simultaneously?

Yes, the ISL6521CBZ is explicitly designed to regulate four independent output voltages: one via its integrated voltage-mode PWM controller (e.g., 1.5V core) and three via dedicated linear regulators (e.g., 2.5V I/O, 1.8V memory, 3.3V aux). Each output is resistor-adjustable using external feedback dividers referenced to the 0.800V internal reference, and all four outputs maintain ±2% regulation over temperature and load.

What package type is used for the ISL6521CBZ?

The ISL6521CBZ uses a 16-lead SOIC package (Pb-free, RoHS compliant), with package drawing M16.15 and JEDEC MO-012AA outline. Its dimensions are 10.3mm × 7.5mm with 1.27mm lead pitch. This standard surface-mount package supports automated assembly and is compatible with conventional reflow profiles, including lead-free soldering at peak temperatures up to 260°C.

How does the ISL6521CBZ handle power sequencing between its four outputs?

The ISL6521CBZ implements individual soft-start circuits for each of its four regulated outputs, allowing staggered ramp-up timing. While not fully programmable, sequencing is achieved by adjusting external resistor values in the feedback networks - slower-ramping outputs use higher-value dividers that delay regulation entry. This inherent per-rail soft-start prevents sequencing violations in FPGA/ASIC systems without requiring external timing ICs or complex control logic.