MAX5943

PRODUCTION

FireWire Current Limiter and Low-Drop ORing Switch Controller

Industry's First IEEE 1394/FireWire-Compliant Hot-Swap Controllers

Data Sheet (Rev. 2) Product Selection Table
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Overview

  • Provides Safe Hot Swap for 7.5V to 37V Power Supplies
  • UL-Recognized FireWire/IEEE 1394 Protective Circuit
  • Low-Drop Power ORing with Ultra-Fast Turn-Off
  • Programmable Active Current Limit (MAX5943A)
  • Programmable Circuit Breaker (MAX5943B–MAX5943E)
  • ±5% Current-Limit Sensing Accuracy
  • Programmable Current-Limit/Circuit-Breaker Timeout
  • Fast Current-Limit Response to Output Short-Circuit Conditions (MAX5943A)
  • Drives External n-Channel Power MOSFETs
  • Overcurrent Fault Status Output
  • Latched or Autoretry Overcurrent Fault Management
  • 10µA Shutdown Current
  • ON/OFF Control Allows Undervoltage Lockout Programming
  • Fast Load Disconnect Control Through ON Input

The MAX5943 is a fully integrated power-management IC for FireWire® applications. This device controls two external power n-channel MOSFETs to regulate current from the input power supply to the load and performs low-voltage-drop, power-supply ORing. The MAX5943 operates over a 7.5V to 37V input range and provides inrush and output current limit in addition to a diode ORing function suitable for FireWire applications. The MAX5943 FireWire/IEEE 1394™ protective circuit (Figure 12 of the full data sheet) is UL® recognized.

The MAX5943 allows the safe insertion and removal of FireWire peripherals into a live FireWire port by providing inrush current control and an output current-limiting function. The ORing feature provides a very efficient way to protect the FireWire port when connected to another FireWire peripheral that sources a higher voltage. By turning off both external MOSFETS, the MAX5943 provides a true bidirectional load disconnect. A low-current shutdown mode disables the MAX5943, resulting in less than 10µA supply current. A pin-selectable input allows latched or autoretry fault management after a fault.

The MAX5943A features a current-limit function that actively limits the current drawn by the load with a programmable timeout. The MAX5943B–MAX5943E do not actively limit the load current but provide a circuit-breaker function. See the Selector Guide in the full data sheet for the default and programmable circuit-breaker timeouts.

The MAX5943 operates over the -40°C to +85°C extended temperature range and is available in a 16-pin QSOP package.

Applications

  • FireWire® Desktop/Notebook Port
  • FireWire® Hub
  • FireWire® Peripheral Device Current Limit
  • Hot Swap
MAX5943
FireWire Current Limiter and Low-Drop ORing Switch Controller
MAX5943: Typical Operating Circuit
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Documentation

Data Sheet 1

Reliability Data 1

Technical Articles 3

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Evaluation Kits

MAX5943AEVKIT

Evaluation Kit for the MAX5943A/B/C/D/E

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Features and Benefits

  • Safely Hot Swaps 7.5V to 37V Power Supplies
  • Low-Voltage-Drop Power ORing
  • Evaluates MAX5943A/B/C/D/E Controllers
  • Demonstrates Active-Current-Limit Feature
  • Programmable Output-Load Current Limit
  • Programmable Current-Limit Timer
  • Fast Current-Limit Response Time
  • Latch or Autoretry Fault Management
  • Programmable Undervoltage Lockout
  • Overcurrent Active-Low FAULT Status Indicator
  • Surface-Mount Construction
  • Fully Assembled and Tested

Product Details

The MAX5943A evaluation kit (EV kit) circuit demonstrates the hot-swap, current-limiting, and power-ORing functions of the MAX5943A. The MAX5943A EV kit is intended for 7.5V to 37V IEEE 1394™/FireWire® applications. The MAX5943A controls two n-channel MOSFETs to regulate load current from an input power supply and perform low-voltage-drop power-supply ORing. The MAX5943A EV kit can also be used to evaluate the MAX5943B/C/D/E versions (refer to the MAX5943 IC data sheet).

The MAX5943A EV kit features several jumpers to evaluate different configurations of the MAX5943A. The output current limit, current-limit timeout period, ORing threshold, and fault-management features are programmable. The undervoltage lockout threshold is configurable by installing external components. Shutdown mode can be controlled with an on-board switch or with an external logic signal. A active-low FAULT output signal is provided for fault condition monitoring.

Applications

  • FireWire® Desktop/Notebook Port
  • FireWire® Hub
  • FireWire® Peripheral Device Current Limit
  • Hot Swap
MAX5943AEVKIT
Evaluation Kit for the MAX5943A/B/C/D/E

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