500mA Push-Pull Transformer Driver for Isolated Power Supplies

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. Applications

* Isolated Analog Front-End * Isolated Fieldbus Interface * Medical Equipment * Power Meter Data Interface

* 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)