STMicroelectronics STEVAL-ISA159V1

Overview

STEVAL-ISA159V1 from STMicroelectronics is an evaluation board based on the L6984 monolithic synchronous step-down regulator, delivering up to 400 mA DC output current from a 4.5 V–36 V input, with fixed 3.3 V output requiring no external resistor divider and supporting both Low Consumption Mode (100 µA IQ at light load) and Low Noise Mode for audio/sensor applications.

For engineers reviewing the STEVAL-ISA159V1 datasheet, STEVAL-ISA159V1 pinout, STEVAL-ISA159V1 application, or STEVAL-ISA159V1 equivalent, this board enables rapid validation of L6984's constant-on-time control, PGOOD sequencing, VBIAS efficiency optimization, and valley-current-limited protection in industrial power supply designs.

Technical Context

The board implements the L6984 IC in a fixed 3.3 V output configuration using internal feedback, eliminating external resistors. Its constant-on-time (COT) control scheme ensures fast transient response and stable operation across wide input voltage (4.5–36 V) and load (0–400 mA) ranges.

Two selectable operating modes-Low Consumption Mode (LCM) with 100 µA quiescent current and Low Noise Mode (LNM) with near-constant switching frequency-are implemented via jumper J4. PGOOD open-collector output supports power sequencing, while VBIAS connection improves light-load efficiency.

Key Specifications

Availability

STEVAL-ISA159V1 is available at Aetrix Electronics and suitable for industrial power validation, home appliance reference design, and factory automation prototyping requiring stable component supply and documented STMicroelectronics evaluation hardware.

Supply support for STEVAL-ISA159V1 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing microcontrollers, power ICs, sensors, and analog/mixed-signal devices for industrial, automotive, and consumer markets.

The STEVAL-ISA159V1 belongs to ST's ST EVAL series of application-specific evaluation boards, developed to accelerate adoption of its high-efficiency DC-DC regulators like the L6984 in cost-sensitive, space-constrained power subsystems.

FAQ

What is the primary function of the STEVAL-ISA159V1 evaluation board?

The STEVAL-ISA159V1 is a fully assembled and tested demonstration platform for the L6984 synchronous step-down regulator. It validates key performance metrics-including 400 mA output capability, 4.5–36 V input range, fixed 3.3 V output, and dual-mode operation (LCM/LNM)-using ST's recommended layout and component selection per the official application schematic.

How do I configure Low Noise Mode (LNM) versus Low Consumption Mode (LCM)?

LNM and LCM are selected via jumper J4 on the board: open J4 enables LCM (optimized for light-load efficiency, 100 µA IQ); closed J4 enables LNM (near-constant switching frequency for reduced EMI in audio/sensor circuits). The mode selection directly controls internal biasing and oscillator behavior of the L6984 IC.

Does the board support adjustable output voltage?

No-the STEVAL-ISA159V1 is configured exclusively for fixed 3.3 V output using the L6984's internal feedback network. Output voltage adjustment requires a different evaluation board (e.g., STEVAL-ISA158V1) or custom design with external resistor divider on the FB pin.

What is the role of the VBIAS pin on this board?

VBIAS is connected to the 3.3 V output rail via TP1 and R8 (0 Ω), supplying a dedicated bias voltage to the L6984's internal circuitry. This reduces switching losses at light loads, improving overall efficiency by up to 10% compared to VCC-only biasing, as confirmed in ST's L6984 datasheet Section 7.3.