Current-mode forward converter controller for isolated and non-isolated designs
The Texas Instruments LM5026MT is a current-mode PWM controller built for forward converter topologies, supporting both step-up and step-down output configurations. It drives two external transistors with a switching frequency adjustable from 200 kHz to 590 kHz, giving the designer room to optimize magnetics size against switching losses. The controller includes dead time control, frequency control, reset, and soft start — features that help shape the power stage response and manage inrush on startup.
Maximum duty cycle is 70% and 80%.
The controller runs from an 8 V to 15 V supply rail — typical for a bias supply derived from the main DC bus or an auxiliary winding. The two outputs drive external transistors directly; the output configuration is positive and isolation-capable, meaning an optocoupler or pulse transformer can close the feedback loop across the isolation barrier. There is no synchronous rectifier driver on-chip, so the secondary-side rectification uses Schottky or ultrafast diodes, which keeps the BOM simple for lower-output-current designs.
It is listed as RoHS non-compliant, which matters for designs that must meet EU RoHS directives — verify your exemption or alternate compliance path if your BOM requires full RoHS conformance.