Texas Instruments LM5157EVM-FLY

Overview

LM5157EVM-FLY from Texas Instruments is an evaluation module designed to demonstrate the LM5157-Q1 wide-input non-synchronous flyback controller for multi-rail isolated power conversion in 3-phase inverter gate driver bias supplies. It delivers a regulated 10 V/250 mA main output and three isolated 20 V outputs (75 mA, 75 mA, 150 mA) from 8–16 V input at 250 kHz switching frequency, with peak efficiency >90% and ±1% main output regulation.

For engineers reviewing the LM5157EVM-FLY datasheet, LM5157EVM-FLY test setup, LM5157EVM-FLY application schematic, or LM5157EVM-FLY bill of materials, this module enables rapid validation of cross-regulated flyback topologies, hiccup-mode protection configuration, thermal performance under full load, and Bode plot-based loop stability analysis across input and load variations.

Technical Context

The LM5157EVM-FLY implements a transformer-coupled flyback architecture using the LM5157QRTERQ1 controller IC, supporting adjustable UVLO via external resistors and optional hiccup-mode overcurrent protection enabled by R13/C29. Its standard configuration uses Coilcraft ZB1324-AL transformer with five secondary windings and defined turns ratios (1:1, 1:1.2, 1:2.4) to achieve tight main output regulation and cross-regulation among isolated rails.

Test data confirms stable operation across –40°C to 150°C junction temperature range, with measured ripple <50 mV on Vo1 at 250 mA and <100 mV on Vo4 at 150 mA, while maintaining >91% peak efficiency at 12 V input and full load. The two-layer PCB (3.5 × 2.3 in) integrates all critical components-including polymer capacitors, Schottky rectifiers, and precision resistors-for automotive-grade reliability per AEC-Q200.

Key Specifications

Availability

LM5157EVM-FLY is available at Aetrix Electronics and suitable for automotive inverter design, industrial motor control development, and isolated auxiliary supply validation requiring stable component supply, documented test procedures, and production-ready reference schematics.

Supply support for LM5157EVM-FLY 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

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management technologies, with leadership in automotive-grade power solutions and evaluation platforms.

The LM5157EVM-FLY belongs to TI's automotive-qualified flyback evaluation module family, engineered specifically to accelerate design-in of isolated bias supplies for IGBT and SiC gate drivers in traction inverters and industrial drives.

FAQ

What is the primary function of the LM5157EVM-FLY?

The LM5157EVM-FLY is an evaluation module that demonstrates the LM5157-Q1 non-synchronous flyback controller for generating multiple isolated output voltages from a single wide-input source. It provides a complete, tested hardware platform to validate performance metrics such as cross-regulation, efficiency, transient response, and thermal behavior-enabling engineers to rapidly assess feasibility before custom design. The LM5157EVM-FLY specifically targets gate driver bias applications in 3-phase inverters.

Can the LM5157EVM-FLY be used with input voltages outside 8–16 V?

No-the LM5157EVM-FLY is validated only for 8 V to 16 V input operation, with absolute maximum input voltage rated at 18 V. Operation below 7.5 V may prevent startup due to UVLO threshold, and exceeding 18 V risks damage to the LM5157QRTERQ1 controller and associated components like the ZB1324-AL transformer and DFLS160-7 rectifier. The LM5157EVM-FLY does not support extended input ranges without hardware modification and revalidation.

How are the three 20-V isolated outputs cross-regulated on the LM5157EVM-FLY?

Cross-regulation on the LM5157EVM-FLY is achieved through transformer coupling and shared feedback control: only the main 10-V output (Vo1) is directly regulated via the FB pin; Vo2, Vo3, and Vo4 derive their voltage from secondary windings with fixed turns ratios relative to the primary, relying on magnetic coupling and load balancing to maintain ±3% regulation across varying loads. Test data (Figures 6-3 to 6-7) confirms this behavior under 10–100% load conditions and 8–16 V input.

Does the LM5157EVM-FLY include thermal imaging data?

Yes-the LM5157EVM-FLY User's Guide includes a thermal image (Figure 6-28) captured at 12 V input and 100% load, showing hotspot temperatures within safe limits for the LM5157QRTERQ1 controller and power components. This data validates the two-layer PCB's thermal performance and confirms junction temperature remains below the 150°C maximum rating under full operational stress, supporting use in demanding automotive environments.

Is hiccup-mode protection enabled by default on the LM5157EVM-FLY?

No-hiccup-mode protection is optional and disabled by default (R13 = 0 Ω). It can be enabled by populating R13 as 62 kΩ and C29 as 47 nF, per Figure 6-25. The LM5157EVM-FLY User's Guide documents both configurations and provides oscilloscope waveforms comparing continuous current-limit versus hiccup recovery behavior, allowing designers to select the appropriate fault-handling strategy for their target application.