Renesas ISL6446IAZ-T

Overview

ISL6446IAZ-T from Renesas Electronics (formerly Intersil) is a triple-output power controller integrating two 180° out-of-phase voltage-mode PWM buck controllers and one linear controller for broadband, DSL, and networking point-of-load regulation. It delivers precise 0.6V reference-based output regulation (±1.5% tolerance), programmable 100kHz–2.5MHz switching frequency, lossless r_DS(ON)-based overcurrent protection, and PGOOD monitoring with 75% linear output validation threshold.

For engineers reviewing the ISL6446IAZ-T datasheet, ISL6446IAZ-T pinout, ISL6446IAZ-T application, or ISL6446IAZ-T equivalent, this device supports prebiased soft-start, independent enable/soft-start per channel, voltage tracking, and robust hiccup-mode OCP with latch-off - critical for ATX, FPGA, and industrial PoL designs requiring input ripple reduction and thermal-safe operation up to +85°C.

Technical Context

The ISL6446IAZ-T implements dual synchronous buck converters operating in strict 180° interleaved phase to reduce input RMS current and capacitor stress. Each PWM channel uses voltage-mode control with a high-bandwidth error amplifier (88dB DC gain, 15MHz GBWP) and 0.6V internal reference, enabling stable regulation down to 0.6V with ±1.5% total tolerance across line, load, and temperature.

Its linear controller employs a transconductance amplifier (2A/V) driving an external PNP or PMOS pass device, with LCFB feedback referenced to 0.595V (±25mV over –40°C to +85°C). Protection includes independent UVP/OVP (8-cycle and 32-cycle detection), thermal shutdown at +150°C, and lossless current sensing via OCSET pins sourcing 110µA to set trip points using upper MOSFET r_DS(ON).

Key Specifications

Pinout & Package

ISL6446IAZ-T is housed in a 24-lead QSOP (RoHS-compliant, M24.15 package) with exposed pad thermal enhancement. Pin layout supports dual-buck interleaving and linear regulator integration with dedicated gate drivers, feedback, compensation, and protection terminals.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ISL6446IAZ-T, ISL65414IRZ-T offers higher frequency and phase count but omits linear regulation, while TPS51220ARUKT provides simpler dual-PWM control at lower cost but requires external sensing and lacks sequencing flexibility - making ISL6446IAZ-T uniquely suitable for triple-rail, mixed-mode (PWM+linear) PoL systems.

Availability

ISL6446IAZ-T is available at Aetrix Electronics and suitable for ATX power supplies, FPGA point-of-load regulation, and industrial networking equipment requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for ISL6446IAZ-T 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 acquired Intersil in 2017 and maintains full product support, documentation, and manufacturing continuity for the ISL6446 family.

The ISL6446 product line targets high-efficiency, multi-rail DC/DC control in broadband, DSL, and networking infrastructure - emphasizing interleaved ripple reduction, lossless protection, and flexible sequencing for space-constrained PoL applications.

FAQ

What is the minimum output voltage supported by the ISL6446IAZ-T PWM controllers?

The ISL6446IAZ-T PWM controllers support output voltages as low as 0.6V, set by the internal precision reference (0.600V ±8.5mV over –40°C to +85°C). This enables direct regulation of modern low-voltage cores such as 0.8V FPGA VCCINT or 1.0V ASIC supplies without external reference scaling. The ISL6446IAZ-T achieves ±1.5% total regulation tolerance across line, load, and temperature when using matched 1% feedback resistors.

How does the ISL6446IAZ-T implement lossless overcurrent protection?

The ISL6446IAZ-T implements lossless overcurrent protection by sourcing a precise 110µA current from each OCSET pin to develop a voltage across an external resistor (ROCSET) and the upper MOSFET's r_DS(ON). During high-side conduction, the PHASE node voltage is compared to this OCSET voltage; if PHASE falls below OCSET, an overcurrent is detected. This eliminates the need for a power-dissipating sense resistor - preserving efficiency and simplifying thermal design in the ISL6446IAZ-T application.

Can the ISL6446IAZ-T soft-start into a prebiased output voltage?

Yes, the ISL6446IAZ-T supports soft-start into prebiased loads on both PWM outputs. When the SS/EN pin voltage ramp exceeds the prebiased output voltage, the controller seamlessly begins regulation without reverse current flow. This behavior is confirmed in Figure 14 of the FN7944 datasheet and applies to ISL6446IAZ-T under all operating conditions. The linear controller follows its input supply ramp but has no dedicated soft-start function.

What is the PGOOD assertion delay for the ISL6446IAZ-T and how is it calculated?

The ISL6446IAZ-T PGOOD delay is inversely proportional to switching frequency and calculated as t_PGOOD = 0.065 / f_SW (with f_SW in MHz). At 1.4MHz, the delay is 46ms; at 524kHz, it extends to 125ms. The delay starts only after both PWM outputs complete soft-start and enter regulation within ±10%, and the linear output exceeds 75% of nominal. No external adjustment is possible - the ISL6446IAZ-T ties delay directly to oscillator frequency.

What package type and thermal characteristics does the ISL6446IAZ-T use?

The ISL6446IAZ-T uses a 24-lead QSOP package (M24.15 drawing) with RoHS-compliant matte tin plating. Its thermal resistance is θ_JA = 75°C/W and θ_JC = 36°C/W (typical). The device incorporates thermal shutdown at +150°C with 20°C hysteresis, and the exposed pad variant (IAZ) enhances heat dissipation. Layout best practices require separate SGND and PGND planes, plus tight decoupling at VIN and VCC pins - all validated in the ISL6446EVAL1Z evaluation board design for the ISL6446IAZ-T.