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MAXIM New Products - MAX258 & MAX31850, MAX31851
2013-07-16
MAX258

500mA Push-Pull Transformer Driver for Isolated Power Supplies

Simplifies Isolated Power Designs


Description

The MAX258 is a 500mA, push-pull transformer driver designed to provide a simple solution for isolated power supplies. The IC has an internal oscillator and operates from a single +3.0V to +5.5V supply. The transformer’s secondary-to-primary winding ratio defines the output voltage, allowing selection of virtually any isolated output voltage with galvanic isolation.
The device features an integrated oscillator driving a pair of n-channel power switches. Internal circuitry guarantees a fixed 50% duty cycle to prevent DC current flow through the transformer.
The IC operates with up to 500mA of continuous current and features undervoltage lockout and thermal shutdown.
The IC includes a low-current shutdown mode to reduce the overall supply current to less than 5µA (max) when the driver is disabled.
The MAX258 is available in a small 8-pin (2mm x 3mm) TDFN package and is specified over the -40°C to +125°C temperature range.



Key Features

  • Simple, Flexible Design
    • +3.0V to +5.5V Supply Range
    • Low RON 300mΩ (max) at 4.5V
    • Up to 90% Efficiency
    • Provides Up to 500mA to the Transformer
    • 250kHz or 600kHz Internal Oscillator Frequency
    • -40°C to +125°C Temperature Range
  • Integrated System Protection
    • Undervoltage Lockout
    • Thermal Shutdown
  • Saves Space on Board
    • Small 8-Pin TDFN Package (2mm x 3mm)

MAX31850, MAX31851

Cold-Junction Compensated, 1-Wire Thermocouple-to-Digital Converters

Accurate 1-Wire Thermocouple-to-Digital Converter ICs Ease Design Effort and Lower System Cost

Description

The MAX31850/MAX31851 cold-junction compensated, 1-Wire® thermocouple-to-digital converters perform cold-junction compensation and digitize the signal from a K-, J-, N-, T-, S-, R-, or E-type thermocouple. The converters resolve temperatures to 0.25°C, allow readings as high as +1768°C and as low as -270°C, and exhibit thermocouple accuracy of 8 LSBs (2°C) for temperatures ranging from -200°C to +700°C.
Communication with the master microcontroller is over a 1-Wire bus that by definition requires only one data line (and ground) for communication. Operating power can be obtained directly from the data line (“parasite power”), eliminating the need for an external power supply.
Each device has a unique 64-bit serial code, which allows multiple units to function on the same 1-Wire bus. Therefore, it is simple to use one microcontroller (the master device) to monitor temperature from many thermocouples distributed over a large area.
Four location address inputs simplify mapping of individual units to specific locations.

Key Features

  • Cold-Junction Compensation
  • 14-Bit, 0.25°C Resolution
  • Versions Available for K-, J-, N-, T-, S-, R-, and E-Type Thermocouples (see Table 1 in the full data sheet)
  • 1-Wire Interface (Read-Only); Power Can Be Obtained from Interface (Parasite-Powered Mode)
  • Detects Thermocouple Shorts to GND or VDD
  • Detects Open Thermocouple
 

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