Renesas ISL6421AERZ

Overview

ISL6421AERZ from Intersil is a single-output LNB supply and control voltage regulator with integrated I²C interface, designed for satellite set-top box (STB) applications. It delivers regulated 13V or 18V output (±2.6% accuracy), supports DiSEqC™ 22kHz tone generation, provides up to 450mA output current, and integrates a current-mode boost PWM (>92% efficiency) and low-noise linear post-regulator. Its primary circuit role is powering and digitally controlling the low-noise block (LNB) over coaxial cable.

For engineers reviewing the ISL6421AERZ datasheet, ISL6421AERZ pinout, ISL6421AERZ application, or ISL6421AERZ equivalent, key selection considerations include I²C-configurable 13V/18V output with 1V line-length compensation, integrated 22kHz tone oscillator with DSQIN modulation input, dynamic/programmable overcurrent protection, thermal shutdown with diagnostic flag, and QFN-32 package compatibility with satellite STB power delivery and DiSEqC protocol implementation.

Technical Context

The ISL6421AERZ implements a two-stage architecture: a current-mode boost PWM converter generates VSW, which feeds a low-dropout linear regulator delivering precise VOUT. The VSW voltage tracks VOUT + ~1.0V dropout to minimize dissipation while maintaining adequate headroom for tone injection. All digital control-including VSEL, LLC, ENT, EN, and DCL-is managed via a fully compliant I²C interface operating at up to 400kHz with slave address 000100XX.

DiSEqC™ functionality is embedded via a factory-trimmed 22kHz oscillator (20–24kHz tolerance), modulated either by the DSQIN pin (for burst encoding) or the ENT bit (for continuous tone). Internal diagnostics-overload flag (OLF) and overtemperature flag (OTF)-are readable via I²C registers, enabling real-time system monitoring without external sensors.

Key Specifications

Pinout & Package

ISL6421AERZ is housed in a RoHS-compliant, Pb-free 32-lead QFN package (5mm × 5mm, 0.5mm pitch, JEDEC MO-220 VHHD-2 compliant) with exposed thermal pad. The near chip-scale footprint supports high-density satellite STB PCB layouts and enables efficient heat transfer to internal ground planes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LNB supply and control applications.

Compared with MAX2221ETG+, ISL6421AERZ delivers complete DiSEqC™ compliance in one device, reducing layout complexity and eliminating external tone circuitry; compared with LM4871MTX/NOPB, it serves a fundamentally different application domain-satellite power delivery versus audio amplification-and is not interchangeable.

Availability

ISL6421AERZ is available at Aetrix Electronics and suitable for satellite set-top box designs, DiSEqC™-enabled antenna control systems, and LNB power delivery modules requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL6421AERZ 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 Corporation (now part of Renesas Electronics) is a U.S.-based semiconductor company specializing in precision analog, power management, and interface ICs for communications, computing, and consumer electronics.

The ISL6421AERZ belongs to Intersil's satellite power management product line, engineered specifically to integrate LNB supply regulation, DiSEqC™ tone generation, and I²C control into a single QFN package for next-generation STB platforms.

FAQ

What is the maximum output current capability of the ISL6421AERZ?

The ISL6421AERZ delivers up to 450mA typical output current. Its dynamic overcurrent protection limits peak current between 500mA and 625mA depending on configuration (DCL bit setting), and it includes both static and dynamic current limiting modes to ensure reliable operation under short-circuit or high-capacitance load conditions. This rating applies across the full -20°C to +85°C operating temperature range specified for the ISL6421AERZ.

Does the ISL6421AERZ support both 13V and 18V LNB output voltages?

Yes, the ISL6421AERZ supports both 13V and 18V nominal output voltages. Selection is achieved via the I²C VSEL bit or the dedicated SEL18V pin on the QFN package. When VSEL = LOW, output is 13V (12.74–13.26V); when VSEL = HIGH, output is 18V (17.64–18.36V). An additional 1V line-length compensation (LLC bit) can be applied to either base voltage, yielding 14V or 19V outputs as needed for long coaxial runs.

How does the ISL6421AERZ implement DiSEqC™ 22kHz tone generation?

The ISL6421AERZ integrates a factory-trimmed 22kHz oscillator (20–24kHz tolerance) that meets EUTELSAT DiSEqC™ specifications. Tone modulation is controlled either by the ENT bit via I²C (for continuous tone) or the DSQIN pin (for hardware-triggered burst encoding). The internal oscillator operates at 220kHz (10× tone frequency) to drive both the PWM and tone circuits, ensuring precise synchronization and eliminating external components required by discrete solutions.

What thermal protection features are built into the ISL6421AERZ?

The ISL6421AERZ includes integrated thermal shutdown that disables both the boost PWM and linear regulator when junction temperature exceeds 150°C (typical), with 20°C hysteresis for recovery at ~130°C. The overtemperature flag (OTF) is accessible via I²C register SR2, allowing host microcontrollers to monitor thermal status in real time. This protection is fully internal-no external components or configuration are required for basic operation of the ISL6421AERZ thermal safety system.

Is the ISL6421AERZ pin-compatible with earlier ISL6421 variants?

Yes, the ISL6421AERZ is pin-compatible with the ISL6421AER and other members of the ISL6421A family in the same 32-lead QFN package (L32.5x5). The "Z" suffix denotes Pb-free/RoHS-compliant construction, with identical mechanical dimensions, thermal pad layout, and pin assignment. No PCB redesign is required when upgrading from ISL6421AER to ISL6421AERZ, and all electrical specifications-including I²C address, register map, and functional behavior-remain unchanged.