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MAX253

MAX253

1W Primary-Side Transformer H-Bridge Driver for Isolated Supplies

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Overview

Description

The MAX253 monolithic oscillator/power-driver is specifically designed to provide isolated power for an isolated RS-485 or RS-232 data interface. The device 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.
MAX253: Typical Operating Circuit MAX253: Typical Operating Circuit Enlarge+

Key Features

  • Simple Power-Supply Transformer Driver Design 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 Take Minimal Board Space

Applications/Uses

  • 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

Parametric Specs

Part NumberVIN
(V)		VIN
(V)		Driver Output Resistance
(Ω)		Max. IOUT
(A)		TopologyFreq.
(kHz)		ICC
(mA)		Package/PinsOper. Temp.
(°C)		Budgetary
Price
minmaxmaxmaxSee Notes
MAX253 2.5640.2Push-Pull3500.45
CDIP/8
PDIP/8
SOIC (N)/8
UMAX/8
-55 to +125
-40 to +85
0 to +70
$1.49 @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.

Design Resources

Technical Documents

Tutorial 4993 Reduce the Chances of Human Error: Part 2, Super Amps and Filters for Analog Interface
Tutorial 4992 Reduce the Chances of Human Error: Part 1, Power and Ground
Tutorial 4991 Oops...Practical ESD Protection vs. Foolhardy Placebos
App Note 4620 Set Your Holiday Lights to Music
App Note 2659
App Note 2116 RS-485 Data Interface Gives Isolated, Full-Duplex Operation
App Note 1923 Draw 150mW of Isolated Power from Off-Hook Phone Line
Tutorial 1167 Practical Aspects of EMI Protection
App Note 674 Push-Pull Driver Provides Isolated 5V at 1A
Tutorial 658 Choose the Right Ultra-Thin DC-DC Converter for a Compact PCMCIA Card

Quality and Environmental Data

Product Reliability Reports: MAX253.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

Tools & Models

  • MAX253 Macromodel

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    Quality And Environmental

    Device   Fab Process   Technology   Sample size   Rejects   FIT at 25°C   FIT at 55°C  

    Note : The failure rates are summarized by technology and mapped to the associated material part numbers. The failure rates are highly dependent on the number of units tested.

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    Related Resources

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    Technical Docs