Renesas ISL78235EVAL2Z

Overview

ISL78235EVAL2Z from Intersil is an evaluation board designed to demonstrate the ISL78235 5A synchronous buck regulator in automotive point-of-load applications. It supports 2.7V–5.5V input, delivers 1.8V default output (adjustable 0.8V–3.3V), operates at 2MHz default switching frequency, and features PFM/PWM mode selection via onboard toggle switch for transient optimization.

For engineers reviewing the ISL78235EVAL2Z datasheet, ISL78235EVAL2Z pinout, ISL78235EVAL2Z application, or ISL78235EVAL2Z equivalent, this board enables rapid validation of ISL78235 performance under real automotive load conditions-including 5A step transients, thermal management with 2oz copper, and AEC-Q200-compliant passive component layout.

Technical Context

The ISL78235EVAL2Z implements a complete reference design for the ISL78235 5A buck regulator in a 4-layer FR-4 PCB with 1.57mm thickness and 2oz copper. It integrates all critical components: 0.68µH Vishay IHLP inductor (13.5A saturation), four 47µF Taiyo Yuden ceramic output capacitors, internal/external compensation support via COMP pin configuration, and test points for PHASE node and VOUT monitoring.

Board-level controls include SW1 for EN enable/disable and SW2 for PFM vs forced PWM operation-directly exposing the ISL78235's light-load efficiency trade-offs. Default soft-start uses a 33nF capacitor (C6) for ~10ms ramp, while FS pin resistor R4 (95.3kΩ) sets 2MHz switching frequency per Equation 2 in UG062.

Key Specifications

Availability

ISL78235EVAL2Z is available at Aetrix Electronics and suitable for automotive ADAS domain controllers, infotainment power supplies, and body control module development requiring stable component supply, AEC-Q200-compliant validation, and fast-turn prototyping support.

Supply support for ISL78235EVAL2Z 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 semiconductor company specializing in high-performance analog and power management ICs for automotive, industrial, and aerospace applications.

The ISL78235EVAL2Z belongs to Intersil's automotive-grade buck regulator evaluation platform family, engineered specifically to accelerate qualification of ISL7823x regulators in safety-critical 12V/24V vehicle systems with stringent EMI and thermal requirements.

FAQ

What is the primary function of the ISL78235EVAL2Z?

The ISL78235EVAL2Z is a dedicated evaluation board for the ISL78235 5A synchronous buck regulator. It provides a fully assembled, tested, and characterized hardware platform to validate the ISL78235's performance-including efficiency, transient response, thermal behavior, and protection features-in automotive point-of-load applications before full-system integration.

Can the output voltage of the ISL78235EVAL2Z be adjusted, and how?

Yes, the ISL78235EVAL2Z output voltage is adjustable from 0.8V to 3.3V using the R2/R3 feedback divider. With R3 fixed at 100kΩ, R2 is selected per Equation 1 in UG062 (e.g., 200kΩ yields 1.8V). Adding 10–22pF in parallel to R2 improves transient response, and loop compensation must be re-verified when changing R2 or output capacitance.

How does the ISL78235EVAL2Z support different operating modes like PFM and PWM?

The ISL78235EVAL2Z uses SW2 to select between PFM (light-load skip mode) and forced PWM operation. In PFM mode, the ISL78235 reduces switching frequency at light loads to improve efficiency; in forced PWM mode, it maintains constant 2MHz switching regardless of load, ensuring predictable EMI and faster transient recovery-critical for DSP/FPGA power rails.

What thermal design features are implemented on the ISL78235EVAL2Z?

The ISL78235EVAL2Z uses a 4-layer PCB with 2oz copper, a solid internal ground plane, and maximized thermal pad copper area beneath the ISL78235 WFQFN package. Vias under the thermal pad (per TB389 guidelines) enhance heat transfer to inner layers, enabling sustained 5A operation with measured power dissipation ≤2.0W at 5VIN/1.8VOUT per Figure 12 in UG062.

Is the ISL78235EVAL2Z compatible with other regulators in the ISL7823x family?

Yes-the ISL78235EVAL2Z shares identical layout, component placement, and test point locations with the ISL78233EVAL2Z and ISL78234EVAL2Z boards. All three use the same schematic (Figure 4), pin-compatible ISL7823x QFN packages, and interchangeable passive components, allowing one board design to evaluate 3A, 4A, and 5A variants of the ISL7823x buck regulator family.