500mA Push-Pull Transformer Driver for Isolated Power Supplies

Simplifies Isolated Power Designs


The MAX258 is a 500mA, push-pull transformer driver designed to provide a simple solution for isolated power supplies. The IC has an internal oscillator and operates from a single +3.0V to +5.5V supply. The transformer’s secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any isolated output voltage with galvanic isolation.

The device features an integrated oscillator driving a pair of n-channel power switches. Internal circuitry guarantees a fixed 50% duty cycle to prevent DC current flow through the transformer.

The IC operates with up to 500mA of continuous current and features undervoltage lockout and thermal shutdown.

The IC includes a low-current shutdown mode to reduce the overall supply current to less than 5µA (max) when the driver is disabled.

The MAX258 is available in a small 8-pin (2mm x 3mm) TDFN package and is specified over the -40°C to +125°C temperature range.

MAX258: Typical Operating Circuit MAX258: Typical Operating Circuit Enlarge+

Key Features

  • Simple, Flexible Design
    • +3.0V to +5.5V Supply Range
    • Low RON 300mΩ (max) at 4.5V
    • Up to 90% Efficiency
    • Provides Up to 500mA to the Transformer
    • 250kHz or 600kHz Internal Oscillator Frequency
    • -40°C to +125°C Temperature Range
  • Integrated System Protection
    • Undervoltage Lockout
    • Thermal Shutdown
  • Saves Space on Board
    • Small 8-Pin TDFN Package (2mm x 3mm)


  • Isolated Analog Front-End
  • Isolated Fieldbus Interface
  • Medical Equipment
  • Power Meter Data Interface
Part Number VIN
Driver Output Resistance
Topology ICC
Package/Pins Oper. Temp.
min max max max See Notes
MAX258  3 5.5 0.3 0.5 Push-Pull 3.5
-40 to +125 $1.15 @1k
See All Transformer Drivers (6)
Pricing Notes:
This pricing is BUDGETARY, for comparing similar parts. Prices are in U.S. dollars and subject to change. Quantity pricing may vary substantially and international prices may differ due to local duties, taxes, fees, and exchange rates. For volume-specific and version-specific prices and delivery, please see the price and availability page or contact an authorized distributor.

MAX258EVKIT: Evaluation Kit for the MAX258

Quality and Environmental Data

Request Reliability Report for: MAX258 
Lead-Free Package Tin (Sn) Whisker Reports

Additional Resources

Topmark Coding MAX258

Tools & Models

MAX258 IBIS Model

Related Resources