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MAX845

MAX845

Isolated Transformer Driver for PCMCIA Applications

Internal Power MOSFETs Save Space and Deliver 750mW

Data Sheet
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Overview

Description

The MAX845 provides an isolated power supply small enough to fit in thin PCMCIA cards and space-sensitive applications. It drives a low-profile center-tapped transformer primary from a 5V or 3.3V DC power supply. The secondary can be wound to provide any isolated positive or negative voltage at powers up to 750mW.

The MAX845 consists of an oscillator followed by a toggle flip-flop. The flip-flop generates two 50% duty-cycle square waves, which are complementary at half the oscillator frequency (450kHz, min). These two signals drive the ground-referenced N-channel power switches. Internal circuitry ensures break-before-make action between the two switches.

A low-power shutdown disables both the switches and the oscillator, reducing power consumption. An evaluation kit (MAX845EVKIT-MM) is available to evaluate low-profile 5V 40mA and 5V 100mA applications.
MAX845: Typical Operating Circuit MAX845: Typical Operating Circuit Enlarge+

Key Features

  • Transformer Driver for Ultra-Thin 5V-µs Transformers
  • Isolated DC-to-DC Power Supply for PCMCIA Applications
  • 450kHz Minimum Switching Frequency
  • Ultra-Low Input Supply Current Ripple
  • Single +5V or +3.3V Supply
  • 5µW Low-Power Shutdown Mode
  • 8-Pin SO and µMAX Packages
  • Low Output Ripple Permits Miniature Output Capacitors

Applications/Uses

  • Bridge Ground Differentials
  • Isolated Data Acquisition
  • Isolated Interface Power Supply
  • Low-Power LAN Networks
  • Medical Equipment
  • Noise-Immunity Communications Interface
  • PCMCIA Modem Cards
  • Process Control

Key Specs

Part Number VIN
(V)		 VIN
(V)		 Driver Output Resistance
(Ω)		 Max. IOUT
(A)		 Topology Freq.
(kHz)		 ICC
(mA)		 Package/Pins Oper. Temp.
(°C)		 Budgetary
Price
min max max max See Notes
MAX845  2.5 6 4 0.2 Push-Pull 860 1.1
µMAX/8
SOIC(N)/8
 -40 to +85 $2.23 @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


MAX845EVKIT: Evaluation Kit for the MAX845

Technical Documents

App Note 4568 Bipolar DC-Voltage Detector Offers Sensitivity and Precision
App Note 4432 Isolated Temperature Sensor
App Note 3754 Single-Wire Serial Bus Carries Isolated Power and Data
App Note 3465 Simple Power-FET Driver is Isolated and DC-Coupled
App Note 2661
App Note 2571
App Note 1096 Transformer-Driver IC Controls Bidirectional Switch
App Note 998 5V Step-Down Converter Has Transformer-Isolated Feedback

Quality and Environmental Data

Product Reliability Reports: MAX845.pdf 
Lead-Free Package Tin (Sn) Whisker Reports

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Related Resources

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Technical Docs

Reference Designs

Type ID Title
Evaluation Board1203MAX845EVKIT Evaluation Kit for the MAX845