Renesas ISL85415DEMO2Z

Overview

ISL85415DEMO2Z from Renesas Electronics is a demonstration board designed to evaluate the ISL85415 wide-input synchronous buck regulator with isolated secondary output, configured for 3.3V primary output, 3V–36V input range, ±1% regulation at 300mA, and optimized PCB layout for low-noise point-of-load applications.

For engineers reviewing the ISL85415DEMO2Z datasheet, ISL85415DEMO2Z pinout, ISL85415DEMO2Z application, or ISL85415DEMO2Z equivalent, this board enables rapid validation of isolated dual-output DC/DC performance under real-world VIN/VOUT combinations, switching frequency tuning (300kHz–2MHz), soft-start configuration, and power-good signaling in industrial and embedded power systems.

Technical Context

The ISL85415DEMO2Z implements a fixed 3.3V primary output using the ISL85415 IC in a 4mm×3mm 12-lead DFN package, with external transformer-based isolation enabling independent secondary output regulation. It supports programmable frequency via resistor on FS pin and selectable operation modes (PWM/PFM) via SYNC pin configuration.

Board-level features include internal/external soft-start selection (R15), internal/external compensation (R11), EN pin hardwired to VIN for always-on operation, and PG signal routed to test point P6. Input capacitors C1/C2 and output capacitors C5/C6 are placed with direct GND vias to minimize high dI/dt loop area and EMI.

Key Specifications

Availability

ISL85415DEMO2Z is available at Aetrix Electronics and suitable for point-of-load power design, isolated auxiliary supply validation, and wide-VIN buck regulator qualification requiring stable component supply, full documentation support, and production-representative layout fidelity.

Supply support for ISL85415DEMO2Z 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 is a global semiconductor leader delivering microcontrollers, analog power, and SoC solutions for industrial, automotive, and infrastructure markets, with deep expertise in high-efficiency power conversion.

The ISL85415DEMO2Z belongs to Renesas' evaluation platform series for its ISL85415 synchronous buck regulator family, engineered specifically for isolated dual-output point-of-load applications demanding ultra-low quiescent current and wide input voltage tolerance.

FAQ

What is the primary output voltage of the ISL85415DEMO2Z and can it be adjusted?

The ISL85415DEMO2Z is factory-configured with a fixed 3.3V primary output using R1 = 90.9kΩ and R2 = 20kΩ. However, output voltage is fully adjustable from 0.6V to 15V by changing the R1/R2 feedback divider per Equation 1 in the user's manual. The ISL85415DEMO2Z schematic and BOM confirm this flexibility, and Table 1 lists resistor values for common outputs including 1.8V, 2.5V, 3.3V, 5V, and 12V.

Does the ISL85415DEMO2Z support external synchronization or PFM mode?

Yes, the ISL85415DEMO2Z supports both modes via the SYNC pin. Default configuration uses R6 = 200kΩ to VCC for PWM operation at the selected switching frequency. To enable PFM mode, remove R6 and populate R9 (0Ω) to tie SYNC to GND - a hardware-modifiable feature explicitly documented in Section "SYNC Control" of AN1945 Rev 1.00.

What is the maximum input voltage the ISL85415DEMO2Z can handle safely?

The ISL85415DEMO2Z is rated for continuous operation from 3V to 36V input, as confirmed in the "Specifications" section of AN1945. This range aligns with the ISL85415 IC's absolute maximum rating and has been validated across Figures 10 and 11 for regulation performance at VIN = 5V, 12V, and 24V. Input electrolytic capacitor C11 (optional) is provided for transient suppression at higher VIN.

How is the enable function implemented on the ISL85415DEMO2Z?

The ISL85415DEMO2Z hardwires the EN pin to VIN through R7 (200kΩ), ensuring the ISL85415 remains continuously enabled. To disable the regulator, users must remove R7 and install a 0Ω resistor at R8 - a documented hardware modification in the "Disabling/Enabling Function" section of AN1945, enabling controlled shutdown during system-level testing.

What type of transformer is used on the ISL85415DEMO2Z and what is its role?

The ISL85415DEMO2Z uses Würth Elektronik custom transformer 750314712 (22µH, 10%, 2.5A), mounted as L1. It provides galvanic isolation between primary and secondary outputs, enabling independent regulation of the secondary rail without optical feedback - a core architecture feature of the ISL85415 that eliminates optocouplers and simplifies isolated design.