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Maxim > Products > [Interface and Interconnect]  [Protection and Isolation] 
MAX253
Transformer Driver for Isolated RS-485 Interface


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Data Sheet
FULL DATA SHEET (PDF, 240kB)
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Description
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) Operating Temp. Range (°C) Price**
    MAX253  2.5 6 Push-Pull
    •Thermal Shutdown
    •UVLO
    		 Open Loop 350 0.45 -55 to +125
    -40 to +85
    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

    Application Notes
  		• Application Note 1167: Practical Aspects of EMI Protection - MAX253
  		• Application Note 1923: Draw 150mW Of Isolated Power From Off-Hook Phone Line - MAX253
  		• Application Note 2116: RS-485 Data Interface Gives Isolated, Full-Duplex Operation - MAX253

    Evaluation Kits
    none

    Reliability Reports
  		• Reliability Report: MAX253.pdf
  		• Show FIT data for:

    Software/Models
    none

    Ordering Information
    Notes:

    1. Other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales.
    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. More: SeeFull Data Sheet or Part 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.


    Devices: 1-20 of 20

    MAX253 Free
    Sample    		 Buy
    Package: TYPE PINS FOOTPRINT
      DRAWING CODE/VAR *
    		Temp RoHS/Lead-Free?
    Materials Analysis
    MAX253MJA  
    		CDIP(N);8 pin;83 mm²
    Outline Drawing: 21-0045 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: J8-2*
    		-55°C to +125°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253C/D  


    Land Pattern: Not Available

    		See data sheet
    MAX253CPA+  
    		PDIP(N);8 pin;80 mm²
    Outline Drawing: 21-0043 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P8+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253CPA  
    		PDIP(N);8 pin;80 mm²
    Outline Drawing: 21-0043 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P8-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253EPA+  
    		PDIP(N);8 pin;80 mm²
    Outline Drawing: 21-0043 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P8+1*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253EPA  
    		PDIP(N);8 pin;80 mm²
    Outline Drawing: 21-0043 (PDF)
    Land Pattern: Not Applicable
    Use pkgcode/variation: P8-1*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253CSA+  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253CSA  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253CSA-T  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8-4*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253CSA+T  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8+4*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253ESA+T  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253ESA  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253ESA-T  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8-4*
    		-40°C to +85°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253ESA+  
    		SOIC(N);8 pin;31 mm²
    Outline Drawing: 21-0041 (PDF)
    Land Pattern: 90-0096 (PDF)
    Use pkgcode/variation: S8+4*
    		-40°C to +85°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253EUA-T  


    Land Pattern: Not Available

    		0°C to +70°C See data sheet
    MAX253CUA  
    		µMAX;8 pin;16 mm²
    Outline Drawing: 21-0036 (PDF)
    Land Pattern: 90-0092 (PDF)
    Use pkgcode/variation: U8-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253CUA-T  
    		µMAX;8 pin;16 mm²
    Outline Drawing: 21-0036 (PDF)
    Land Pattern: 90-0092 (PDF)
    Use pkgcode/variation: U8-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253EUA  
    		µMAX;8 pin;16 mm²
    Outline Drawing: 21-0036 (PDF)
    Land Pattern: 90-0092 (PDF)
    Use pkgcode/variation: U8-1*
    		0°C to +70°C RoHS/Lead-Free: No
    Materials Analysis
    MAX253CUA+  
    		µMAX;8 pin;16 mm²
    Outline Drawing: 21-0036 (PDF)
    Land Pattern: 90-0092 (PDF)
    Use pkgcode/variation: U8+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis
    MAX253CUA+T  
    		µMAX;8 pin;16 mm²
    Outline Drawing: 21-0036 (PDF)
    Land Pattern: 90-0092 (PDF)
    Use pkgcode/variation: U8+1*
    		0°C to +70°C RoHS/Lead-Free: Lead Free
    Materials Analysis

    Notes and Comments
  		• Isolated power driver of 0.75W for RS-485

    More Information
  		• New Product Press Release 2008-11-25 

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


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