Renesas ISL9105EVAL1Z

Overview

ISL9105EVAL1Z from Intersil is an evaluation board for the ISL9105 600mA synchronous buck regulator, designed to demonstrate high-efficiency DC/DC conversion in battery-powered handheld systems. It supports input voltages from 2.7V to 5.5V, delivers regulated output down to 0.8V with ±3% accuracy, and features selectable forced PWM or low-IQ skip mode (25µA quiescent current) for extended Li-ion battery life in PDAs and cellular phones.

For engineers reviewing the ISL9105EVAL1Z datasheet, ISL9105EVAL1Z pinout, ISL9105EVAL1Z application, or ISL9105EVAL1Z equivalent, this board enables rapid validation of 1.6MHz switching performance, 100% duty-cycle dropout behavior, soft-start timing, POR reset sequencing, and thermal shutdown response under real load conditions up to 600mA.

Technical Context

The ISL9105EVAL1Z implements a current-mode PWM control architecture with internal P- and N-channel MOSFETs (160mΩ/140mΩ typical R_DS(on)) and integrated loop compensation. It supports dual operating modes: fixed-frequency 1.6MHz PWM for stable light-load regulation and pulse-skipping mode for peak efficiency at sub-10mA loads.

Key system-level functions include a 216ms power-on-reset timer with RSI reset capability, logic-controlled enable with output capacitor discharge, internal digital soft-start (1.1ms), overcurrent protection (1.0A peak limit), short-circuit protection via FB monitoring, and thermal shutdown at 150°C with 25°C hysteresis.

Key Specifications

Availability

ISL9105EVAL1Z is available at Aetrix Electronics and suitable for PDA power validation, cellular phone baseband supply testing, and DSP core voltage qualification requiring stable component supply and documented reference design implementation.

Supply support for ISL9105EVAL1Z 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 analog and power management semiconductor company focused on high-performance, energy-efficient solutions for portable and industrial applications.

The ISL9105 product line was engineered specifically for ultra-low-voltage, high-efficiency power delivery in space-constrained battery-powered handheld equipment - emphasizing minimal quiescent current, fast transient response, and seamless integration with microprocessor core supplies.

FAQ

What is the primary purpose of the ISL9105EVAL1Z evaluation board?

The ISL9105EVAL1Z evaluation board is designed to accelerate development and validation of the ISL9105 600mA synchronous buck regulator in real-world applications. It provides a fully assembled, tested reference circuit with optimized layout, including the 2mm×3mm DFN-packaged ISL9105 IC, 3.3µH inductor, 10µF input/output capacitors, and resistor network for adjustable 0.8V–3.3V output. Engineers use ISL9105EVAL1Z to verify efficiency curves, load/transient response, soft-start behavior, POR timing, and thermal performance before final PCB design.

Does the ISL9105EVAL1Z support both forced PWM and skip mode operation?

Yes, the ISL9105EVAL1Z fully supports both operating modes of the ISL9105 IC. The MODE pin is accessible via test points, allowing users to configure forced PWM (MODE = GND) for constant 1.6MHz switching or skip mode (MODE = VIN) for adaptive frequency reduction at light loads. This enables direct measurement of the 25µA quiescent current in skip mode and comparison of efficiency across load ranges - critical for optimizing battery life in handheld devices using ISL9105EVAL1Z as a test platform.

How does the ISL9105EVAL1Z implement Power-On Reset (POR) functionality?

The ISL9105EVAL1Z demonstrates the ISL9105's built-in 216ms POR timer through the dedicated POR pin, which outputs an open-drain signal synchronized to output voltage stabilization. When the regulated output reaches the power-good window (±3% of setpoint), the timer starts; after 216ms (typical), POR asserts high. The RSI pin is exposed for external reset - pulling RSI low resets the timer, enabling flexible system-level reset sequencing. This behavior is verified on ISL9105EVAL1Z using oscilloscope measurements of POR timing and response to RSI transitions.

Can the ISL9105EVAL1Z be used to evaluate thermal performance of the ISL9105 IC?

Yes, the ISL9105EVAL1Z includes the ISL9105 in its thermally enhanced 2mm×3mm DFN package with exposed pad soldered to a large ground plane, matching recommended layout practices. Thermal shutdown triggers at 150°C with 25°C hysteresis, and ISL9105EVAL1Z allows direct measurement of junction temperature rise under 600mA load using IR thermography or thermocouples. The board's copper area and thermal vias facilitate accurate characterization of θ_JA = 75°C/W and θ_JC = 6°C/W as specified in the ISL9105 datasheet.

What external components are pre-installed on the ISL9105EVAL1Z board?

The ISL9105EVAL1Z comes with all critical external components populated: a 3.3µH shielded inductor (Sumida CDRH2D14NP-3R3), 10µF X5R ceramic input capacitor (Murata GRM21BR60J106KE19L), 10µF X5R ceramic output capacitor (Murata GRM21BR60J106KE19L), and precision resistor divider (R2/R3) for default 1.6V output. Test points provide access to VIN, EN, MODE, RSI, POR, PHASE, FB, and GND - enabling full signal probing without modification. No additional parts are required to operate ISL9105EVAL1Z out-of-box.