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Design Notes

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  Using a Current Sharing Controller with Non-Redundant Supplies &mdash DN1036
  PDF, 209 Kb, File published: Nov 30, 2015
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  Using a Current Sharing Controller with
  Non-Redundant Supplies
  Design Note 1036
  Bob Smith
  Introduction
  The LTCВ®4370 is a 2-supply current sharing, diodeORing controller that uses MOSFETs to form ideal
  diodes. In this way, the LTC4370 can actively balance
  the output currents of two supplies, even those with
  unequal output voltages. For two unequal voltage input
  supplies, the forward voltage of the higher voltage supply
  diode is servoed to balance the shared load current. The
  maximum allowable voltage drop is programmed by a
  resistor at the RANGE pin of the LTC4370.
  A typical diode-OR system is a winner-take-all system
  where the highest voltage supply sources the entire
  load current. This one-supply-at-a-time scheme underutilizes the two supplies. The LTC4370’s current sharing
  diode-OR solution, on the other hand, reaps the benefits
  of sourcing and sharing current from both supplies: Supply lifetimes are extended if each takes on half
  the load, spreading the supply heat and reducing
  thermal stresses on supply components. Because the lower voltage supply is always operational, there is no surprise when transitioning
  to a backup supply that may have already silently
  failed—a possibility in a simple diode-OR system. The recovery dynamics on supply failure are
  smoother and faster, since the supply changes are …

Articles

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  Easy Balanced Load Sharing for Three or Four Supplies, Even with Unequal Supply Voltages &mdash LT Journal
  PDF, 137 Kb, File published: Apr 14, 2016
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  Easy Balanced Load Sharing for Three or Four Supplies,
  Even with Unequal Supply Voltages
  Vladimir Ostrerov and Chris Umminger Using multiple small power supplies is often more
  economical and more reliable than using a single large
  power supply. For instance, separate batteries can be
  used for higher reliability. In a multi-supply system, it
  is important that the load is equally shared; otherwise,
  one supply may attempt to carry the entire load.
  This article shows how to easily load balance three
  or four supplies by cascading LTC4370 circuits.
  The LTC4370 controller enables current
  sharing between two supplies with a
  modest difference between the output
  voltages, as shown in Figure 1. To perfectly
  balance the current in both sides, the
  controller regulates the gate-source voltage
  of an N-channel MOSFET in whichever
  side has the higher voltage. This creates
  a voltage drop across the MOSFET’s
  RDS(ON) plus the current sense resistor.
  The LTC4370 can compensate for a voltage
  difference between two rails of up to
  0.5V. If the voltage difference of the two …

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  Novel Current-Sharing IC Balances Two Supplies with Ease &mdash LT Journal
  PDF, 2.2 Mb, File published: Jul 20, 2012
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  Novel Current-Sharing IC Balances Two Supplies with Ease
  Pinkesh Sachdev Failure is not an option. That’s the likely motto for the architects of today’s alwaysup electrical infrastructure—think telecommunications networks, the Internet and
  the electrical grid. The problem is that the bricks of this infrastructure, from the
  humble capacitor to the brainy blade-servers, have a limited lifetime usually ending
  at the most Murphy of moments. The usual workaround to the mortality problem is
  redundancy—backup systems ready to take over whenever a critical component fails.
  For instance, high availability computer
  servers typically ship with two similar
  DC supplies feeding power to each individual board. Each supply is capable of
  taking on the entire load by itself, with
  the two supplies diode-ORed together
  via power diodes to create a single 1В +В 1
  redundant supply. That is, the higher
  voltage supply delivers power to the load,
  while the other supply idly stands by. If the
  active supply voltage drops or disappears,
  due to failure or removal, the once lowervoltage supply becomes the higher voltage
  supply, so it takes over the load. The
  diodes prevent back-feeding and crossconduction between supplies while protecting the system from a supply failure. 5A
  12.2V NC Supply lifetimes are extended if each
  takes on half the load, spreading the
  supply heat and reducing thermal
  stresses on supply components. A rule …

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  Using a Current Sharing Controller when the Sum Current of Both Supplies is Required to Support the Load &mdash LT Journal
  PDF, 142 Kb, File published: Aug 11, 2016
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  Using a Current Sharing Controller when the Sum Current of
  Both Supplies is Required to Support the Load
  Bob Smith The LTC4370 is a 2-supply current sharing, diode-ORing controller that uses
  MOSFETs to form ideal diodes. In this way, the LTC4370 can actively balance the
  output currents of two supplies, even those with unequal output voltages. For two
  unequal voltage input supplies, the forward voltage of the higher voltage supply
  diode is servoed to balance the shared load current. The maximum allowable
  voltage drop is programmed by a resistor at the RANGE pin of the LTC4370.
  Normally the LTC4370 is used to current
  share the outputs of two supplies, either
  of which is capable of providing the entire
  load current when its mate drops below
  the sharing voltage threshold set by the
  RANGE pin of the LTC4370 (see sidebar). Figure 1. Block diagram of
  current summing circuitry VINA LTC4370 VINB –
  – VTH VTH + –
  + + –
  + A > (B + TH) FEED TO LOAD DIODE-OR
  CURRENT SHARING
  CONTROLLER
  (ON 200ms, OFF 3.2s) HICCUP
  CIRCUIT ENABLE TO LOAD B > (A + TH) Load Summing Advantage
  A typical diode-OR system is a winner-take-all …

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Manufacturer's Classification

• Monitor, Control and Protection > PowerPath Controllers & Ideal Diodes

Other Names:

LTC4370IDEPBF, LTC4370IDE PBF