36V H-Bridge Transformer Driver for Isolated Supplies

Wide-Range Transformer Driver Simplifies Isolated Power Designs
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Status Explanations for product status codes

Part Number Status
MAX13256 Active: In Production.


The MAX13256 H-bridge transformer driver provides a simple solution for making isolated power supplies up to 10W. The device drives a transformer's primary coil with up to 300mA of current from a wide 8V to 36V DC supply. The transformer's secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any isolated output voltage.

The device features adjustable current limiting, allowing indirect limiting of secondary-side load currents. The current limit of the MAX13256 is set by an external resistor. An active-low FAULT output asserts when the device detects an overtemperature or overcurrent condition. In addition, the device features a low-power mode to reduce the overall supply current to 0.65mA (typ) when the driver is not in use.

The device features an internal oscillator for autonomous operation and an external clock source input to synchronize multiple MAX13256 devices and precisely set the switching frequency. Internal circuitry guarantees a fixed 50% duty cycle to prevent DC current flow through the transformer, regardless of which clock source is used.

The device is available in a small 10-pin (3mm x 3mm) TDFN package and is specified over the -40°C to +125°C automotive temperature range.

Data Sheet

Download this datasheet in PDF formatDownload Rev 1 (PDF, 1.7MB)
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An evaluation board is available: MAX13256EVKIT MAXREFDES9 MAXREFDES12

Key Features

  • Simple, Flexible Design
    • 8V to 36V Supply Range
    • Up to 90% Efficiency
    • Provides Up to 10W to the Transformer
    • Undervoltage Lockout
    • 2.5V to 5V Compatible Logic Interface
    • Internal or External Clock Source
    • Adjustable Overcurrent Threshold
  • Integrated System Protection
    • Fault Detection and Indication
    • Overcurrent Limiting
    • Overtemperature Protection
  • Saves Space on Board
    • Small 10-Pin TDFN Package (3mm x 3mm)


  • 24V PLC Supply Isolation
  • Isolated Fieldbus Interfaces
  • Medical Equipment
  • Motor Controls
  • Power Meters

Key Specifications:

Transformer Drivers
Part Number Application (VIN) VIN
Driver Output Resistance
Topology Features Freq.
Oper. Temp.
min max max See Notes
MAX13256  Industrial (24V) 8 36 2.5 0.3 Full-Bridge
Adjustable Frequency
Current Limiting
Fault Detection
Internal Power MOSFET(s)
Synchronizable Frequency
Thermal Shutdown
425 9 -40 to +125 $2.92 @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.


MAX13256: Typical Operating Circuit
Typical Operating Circuit

Technical Documents

App Note 5072  Snubber Design for the MAX13256
App Note 5355  Using an H-Bridge Transformer Driver to Charge a Supercapacitor
Tutorial 5445  Stuxnet and Other Things that Go Bump in the Night
Sub-System Board 5509  Oceanside (MAXREFDES9#): 3.3V to 15V Input, ±15V (±12V) Output, Isolated Power Supply
Sub-System Board 5611  Corona (MAXREFDES12#): Isolated Industrial Octal Digital Input Translator/Serializer
User Guides & Manuals 5613  Corona (MAXREFDES12#) Nexys 3 Quick Start Guide
User Guides & Manuals 5614  Corona (MAXREFDES12#) ZedBoard Quick Start Guide
Full System Design 5670  Newport Smart Meter Reference Platform
App Note 5766  Choosing the Right Transformer with the MAX13256

Product Guides

Interface (PDF)

Reliability Reports

Reliability Report: MAX13256.pdf
Show FIT data for:

Ordering Information

Filters: Part Number Package: Temperature: Tape and Reel Sample
Part Number Free
Buy Status Explanations for product status codes Package:
Temp RoHS/Lead-Free?
Materials Analysis
Active TDFN-EP;10 pin;9.6 mm²
-40°C to +125°C See data sheet
Active TDFN-EP;10 pin;9.6 mm²
-40°C to +125°C See data sheet
MAX13256DEVBRD     N/A Future Product KIT;
-40°C to +85°C See data sheet

  1. Other options and links for purchasing parts are listed at:
  2. Didn't Find What You Need? Ask our applications engineers. Expert assistance in finding parts, usually within one business day.
  3. Part number suffixes: T or T&R = tape and reel; + = RoHS/lead-free; # = RoHS/lead-exempt; -D = drypack; -U/+U on DS parts = cut tape. More: See Full Data Sheet or Maxim Product Naming Conventions.
  4. * Some packages have variations, listed on the drawing. "PkgCode/Variation" tells which variation the product uses. Note that "+", "#", "-" in the part number suffix describes RoHS status. Package drawings may show a different suffix character.

Similar Products by Function

See All Transformer Drivers (6Products)

Similar Products by Application

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Evaluation Kits

MAX13256EVKIT Evaluation Kit for the MAX13256
MAXREFDES9 Oceanside (MAXREFDES9#): 3.3V to 15V Input, ±15V (±12V) Output, Isolated Power Supply
MAXREFDES12 Corona (MAXREFDES12#): Isolated Industrial, Octal, Digital Input Translator/Serializer

Products with Similar Part Numbers

MAX13256EVKIT Evaluation Kit for the MAX13256

More Information

Topmark Coding MAX13256
New Product Press Release   2013-08-27 ] [ 2011-08-24 ]
Transformer Information

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Information Index

Document Ref.: 19-5847 Rev 1; 2011-09-20
This page last modified: 2012-02-13