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36V H-Bridge Transformer Driver for Isolated Supplies

Wide-Range Transformer Driver Simplifies Isolated Power Designs

Product Details

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.

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)

Applications/Uses

  • 24V PLC Supply Isolation
  • Isolated Fieldbus Interfaces
  • Medical Equipment
  • Motor Controls
  • Power Meters
Parametric specs for Transformer Drivers
Application (VIN) Industrial (24V)
VIN (V) (min) 8
VIN (V) (max) 36
Driver Output Resistance (Ω) (max) 1.5
Max. IOUT (A) 0.3
Topology Full-Bridge
Switching Frequency (kHz) 425
ICC (mA) (max) 9
Package/Pins TDFN-CU/10
Oper. Temp. (°C) -40 to +125
Budgetary
Price (See Notes)
$2.78 @1k
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Simplified Block Diagram

MAX13256: Typical Operating Circuit MAX13256: Typical Operating Circuit Zoom icon

Design & Development

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Description

The MAX13256 evaluation kit (EV kit) is a fully assembled and tested PCB that contains the MAX13256 10W isolated H-bridge DC-DC converter. The EV kit operates from an 8V to 36V DC power source and the on-board 1:1 turns-ratio transformer from HALO sets the output voltage range from 6.8V to 34.8V with a 300mA current limit.
The EV kit provides greater than 90% overall efficiency at +24V between 2.2W and up to 8.3W output power using an H-bridge DC-DC converter topology. Input-ripple current and radiated noise are minimized by the inherent balanced nature of the design with no interruption in the input current. Undervoltage lockout (UVLO), adjustable current limit, and thermal shutdown provide for a robust 10W isolated supply. The surface-mount transformer provides galvanic isolation with the output powered from a full-wave rectifier circuit, reducing the output-voltage ripple.
The EV kit circuit is configured as a full-wave rectifier, with an output voltage that follows the input voltage but is configurable for other topologies including a voltage doubler, bipolar outputs, half-wave rectification, and a push-pull rectifier.
Use HALO's TGMR-512V6LF transformer for 4:1 turns-ratio operation providing up to 1A load capability.
The device is available in a 10-pin (3mm x 3mm) TDFN package with an exposed pad.

View Details

Features

  • 8V to 36V Input Supply Range
  • Up to 90% Efficiency
  • Full-Wave Rectified Output
  • Configurable for a Voltage Doubler, Bipolar Half-Wave Rectifier, and Push-Pull Rectifier Outputs
  • Internal or External Clock Operation Option
  • Designed for 1500VRMS Isolation
  • Proven PCB Layout
  • Fully Assembled and Tested

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Parameters

Parametric specs for Transformer Drivers
Application (VIN) Industrial (24V)
VIN (V) (min) 8
VIN (V) (max) 36
Driver Output Resistance (Ω) (max) 1.5
Max. IOUT (A) 0.3
Topology Full-Bridge
Switching Frequency (kHz) 425
ICC (mA) (max) 9
Package/Pins TDFN-CU/10
Oper. Temp. (°C) -40 to +125
Budgetary
Price (See Notes)
$2.78 @1k

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)

Applications/Uses

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

Description

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.

Simplified Block Diagram

MAX13256: Typical Operating Circuit MAX13256: Typical Operating Circuit Zoom icon

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal