STMicroelectronics STEVAL-L7983ADJ

Overview

STEVAL-L7983ADJ from STMicroelectronics is an evaluation board for the L7983PUR 12 V/300 mA synchronous step-down DC/DC converter, operating from 12 V to 60 V input, featuring 1 MHz switching frequency, dynamic Low Consumption Mode (LCM)/Low Noise Mode (LNM) selection, and internal soft-start. It supports industrial bus standards (12 V/24 V/48 V) and delivers regulated 12 V output for MCU/FPGA power sequencing.

For engineers reviewing the STEVAL-L7983ADJ datasheet, STEVAL-L7983ADJ pinout, STEVAL-L7983ADJ application, or STEVAL-L7983ADJ equivalent, this board enables rapid validation of L7983PUR's buck regulation, UVLO adjustability, RST-driven reset timing, and LNM/LCM noise-efficiency trade-off in real-world 12–60 V supply designs.

Technical Context

The board implements the L7983PUR monolithic buck regulator using peak current mode control with synchronous rectification, enabling high efficiency across light-to-heavy loads. Its 1 MHz fixed-frequency operation-adjustable via external clock or resistor-supports compact magnetics and low EMI in space-constrained industrial systems.

L7983PUR integrates a programmable UVLO threshold, open-drain RST output for digital load reset supervision, and pulse-by-pulse overcurrent protection on both high- and low-side switches. The internal compensation network eliminates external loop components while maintaining stability under varying line/load conditions.

Key Specifications

Availability

STEVAL-L7983ADJ is available at Aetrix Electronics and suitable for industrial automation, smart sensor nodes, and programmable logic controller (PLC) I/O modules requiring stable component supply and fast evaluation of wide-input buck regulators.

Supply support for STEVAL-L7983ADJ 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, Switzerland, designing and manufacturing microcontrollers, power management ICs, sensors, and analog devices for industrial, automotive, and consumer markets.

The STEVAL-L7983ADJ belongs to ST's high-voltage DC/DC evaluation platform family, developed specifically to accelerate design-in of robust, low-quiescent-current buck converters for harsh industrial environments with wide input voltage variation.

FAQ

What is the purpose of the LNM/LCM pin on STEVAL-L7983ADJ?

The LNM/LCM pin selects between Low Noise Mode (constant 1 MHz frequency, low EMI) and Low Consumption Mode (variable frequency, higher light-load efficiency). Toggling this pin dynamically adapts regulator behavior to real-time system power/noise requirements without firmware changes.

Can STEVAL-L7983ADJ be used to evaluate adjustable-output versions of L7983?

No - STEVAL-L7983ADJ is configured for fixed 12 V output using the L7983PUR variant. To evaluate adjustable outputs, ST recommends STEVAL-L7983V33 or STEVAL-L7983ADJ33, which use FB-resistor networks and different L7983 variants supporting external feedback.

How does the RST output function during power-up?

The open-drain RST output asserts low until VOUT reaches 90% of nominal 12 V and remains stable for ≥10 ms, then releases high. This provides a clean, sequenced reset signal to MCUs or FPGAs, eliminating need for external supervisor ICs in digital power domains.

Is external synchronization supported, and how is it implemented?

Yes - the L7983PUR supports external clock synchronization via the FSW pin. On STEVAL-L7983ADJ, applying a 0.8× to 1.2× 1 MHz square wave to TP7 (LNM/LCM pin) overrides internal oscillator and locks switching frequency to the external source, reducing beat frequencies in multi-rail systems.