Renesas ISL81805EVAL3Z

Overview

ISL81805EVAL3Z from Renesas Electronics is a dual-output evaluation board designed to validate the ISL81805 80V dual synchronous boost controller in negative-to-positive voltage conversion applications. It delivers regulated 12V/20A and 5V/20A outputs from a -36V to -60V input, operates at 200kHz switching frequency, and integrates OVP, OTP, UVP, and programmable OCP protection.

For engineers reviewing the ISL81805EVAL3Z datasheet, ISL81805EVAL3Z application, ISL81805EVAL3Z test setup, or ISL81805EVAL3Z design guidelines, this board provides complete functional validation of the ISL81805 controller's inverting buck-boost operation, dual-phase synchronization, soft-start sequencing, and protection features under high-power, high-voltage conditions.

Technical Context

The ISL81805EVAL3Z implements an inverting buck-boost topology where the ISL81805's GND pin connects to VIN−, establishing a floating ground reference for output-side loads. It uses discrete N-channel MOSFETs (BSC160N15NS5ATMA1, BSC110N15NS5ATMA1, IPD200N15N3GATMA1) and high-current power inductors (7443640680, 7443640470) to support up to 40A total continuous output current without forced airflow.

Control functions include independent EN1/EN2 jumpers for per-output enable/disable, programmable soft-start via CSS1/CSS2 capacitors, selectable DEM/PWM mode, and dual-level OCP (input average and hiccup). The board supports pre-bias start-up and provides PGOOD indication for both outputs.

Key Specifications

Availability

ISL81805EVAL3Z is available at Aetrix Electronics and suitable for industrial power supply validation, telecom DC-DC converter development, high-voltage embedded system prototyping, and automotive test bench applications requiring stable component supply and full functional verification capability.

Supply support for ISL81805EVAL3Z 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 specializing in microcontrollers, analog, power management, and timing solutions for industrial, automotive, and infrastructure markets.

The ISL81805EVAL3Z belongs to Renesas' high-voltage DC/DC evaluation platform family, designed specifically to accelerate development of robust, high-efficiency power converters using the ISL81805 dual boost controller in demanding negative-input applications.

FAQ

What is the primary function of the ISL81805EVAL3Z evaluation board?

The ISL81805EVAL3Z evaluation board is a fully assembled, tested platform for validating the ISL81805 dual synchronous boost controller in negative-to-positive voltage conversion applications. It demonstrates 12V/20A and 5V/20A regulated outputs from a -36V to -60V input, supporting design verification of protection features, soft-start behavior, phase synchronization, and thermal performance under real-world load conditions.

Can the ISL81805EVAL3Z be used for non-inverting boost applications?

No - the ISL81805EVAL3Z is specifically configured for inverting buck-boost operation, with the ISL81805's GND pin tied to VIN−. Its schematic, component selection (e.g., feedback network using current mirrors), and layout are optimized for negative-input, positive-output conversion. Non-inverting boost use requires redesign of grounding, feedback, and component ratings, and is not supported by this board's default configuration.

How is output enable/disable controlled on the ISL81805EVAL3Z?

Output enable/disable is controlled via two 2-pin headers: J3 disables the 12V output when pins 1–2 are shorted, and J8 disables the 5V output under the same condition. When left floating, both outputs remain enabled. This hardware-based control allows independent testing and sequencing of each output without software or external logic.

What are the key thermal limitations of the ISL81805EVAL3Z?

The ISL81805EVAL3Z delivers up to 40A total continuous output current (-36V to -60V input) at ambient room temperature without airflow. At higher ambient temperatures (>+40°C) or sustained full-load operation, forced airflow is required to maintain MOSFET and inductor junction temperatures within safe limits. Thermal performance is validated per the board's PCB layout, copper weight, and component derating as specified in the R16UH0012EU0100 manual.

Does the ISL81805EVAL3Z support PWM-only or diode-emulation mode?

Yes - the ISL81805EVAL3Z supports both forced PWM and optional diode-emulation (DEM) operation modes, selectable via configuration resistors and jumpers. DEM mode improves light-load efficiency by disabling synchronous rectification when output current falls below threshold, while PWM mode ensures consistent switching frequency and ripple characteristics across the full load range.