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MAX253
Transformer Driver for Isolated RS-485 Interface


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Description
FULL DATA SHEET (PDF, 240kB)
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The MAX253 is a monolithic oscillator/power-driver, specifically designed to provide isolated power for an isolated RS-485 or RS-232 data interface. It drives a center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated voltage needed at power levels up to 1W.

The MAX253 consists of a CMOS oscillator driving a pair of N-channel power switches. The oscillator runs at double the output frequency, driving a toggle flip-flop to ensure 50% duty cycle to each of the switches. Internal delays are arranged to ensure break-before-make action between the two switches.

The SD pin puts the entire device into a low-power shutdown state, disabling both the power switches and oscillator.

Key Features   Applications/Uses
  • Power-Supply Transformer Driver for Isolated RS-485/RS-232 Data-Interface Applications
  • Single +5V or +3.3V Supply
  • Low-Current Shutdown Mode: 0.4µA
  • Pin-Selectable Frequency: 350kHz or 200kHz
  • 8-Pin DIP, SO, and µMAX Packages

 
  • Bridge Ground Differentials
  • High Noise-Immunity Communications Interface
  • Isolated and/or High-Voltage Power Supplies
  • Isolated RS-485/RS-232 Power Supply
  • Medical Equipment
  • Process Control
  • Transformer Driver

    Key Specifications:   Isolated Power Supplies
    Part Number VIN (min) (V) VIN (max) (V) Topology Features Feedback Type Frequency (kHz) Operating Current, ICC (max) (mA) EV-Kit RoHS Available Package Smallest Available Package (max w/pins) (mm2) Operating Temp. Range (°C) Price**
    MAX253  2.5 6 Push-Pull
    Thermal Shutdown
    UVLO
    Open Loop 350 0.45 No Yes Ceramic DIP/8
    DICE SALES/0
    PDIP/8
    SOIC/8
    uMAX/8
    16 -40 to +85
    -55 to +125
    0 to +70
    $1.25 @ 1k
    See All Isolated Power Supplies (29)
    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 prices and delivery, please see the price and availability page or contact an authorized distributor.

    Diagram
    MAX253: Typical Operating Circuit
    Typical Operating Circuit

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    Document Ref.: 19-0226; Rev 0; 1994-01-01
    This page last modified: 2007-05-29




             


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