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FireWire Current Limiter and Low-Drop ORing Switch Controller

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

Product Details

Key Features

Parametric specs for ORing MOSFET Controllers
Reverse Current Protect. Yes
Under Voltage Protect Yes
Charge Pump Cap. No
Soft Start Yes
Enable Yes
Fault Indicator Yes
Package/Pins QSOP/16
Parametric specs for Hot Swap Controllers
VIN (V) (min) 7.5
VIN (V) (max) 37
# Channels 1
Circuit Breaker/ Current Limit Circuit Breaker
Current Limit
Circuit Breaker/Current Limit Threshold (mV) Adjustable
Fault Condition Control Latched Off
Periodic Retry
Positive/Negative Rail Positive
Features Single Firewire Controller
Package/Pins QSOP/16
Budgetary
Price (See Notes)
2.19
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Simplified Block Diagram

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Parameters

Parametric specs for ORing MOSFET Controllers
Reverse Current Protect. Yes
Under Voltage Protect Yes
Charge Pump Cap. No
Soft Start Yes
Enable Yes
Fault Indicator Yes
Package/Pins QSOP/16
Parametric specs for Hot Swap Controllers
VIN (V) (min) 7.5
VIN (V) (max) 37
# Channels 1
Circuit Breaker/ Current Limit Circuit Breaker
Current Limit
Circuit Breaker/Current Limit Threshold (mV) Adjustable
Fault Condition Control Latched Off
Periodic Retry
Positive/Negative Rail Positive
Features Single Firewire Controller
Package/Pins QSOP/16
Budgetary
Price (See Notes)
2.19

Key Features

  • 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

Applications/Uses

  • FireWire® Desktop/Notebook Port
  • FireWire® Hub
  • FireWire® Peripheral Device Current Limit
  • Hot Swap

Description

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.

Simplified Block Diagram

MAX5943: Typical Operating Circuit MAX5943: Typical Operating Circuit Zoom icon

Technical Docs

Support & Training

Search our knowledge base for answers to your technical questions.

Filtered Search

Our dedicated team of Applications Engineers are also available to answer your technical questions. Visit our support portal .