LINEAR Ideal Diode Controller for Energy Efficiency in Power OR-ing Applications – Design Note 386 by David Laude
Summary
The Ideal Diode Controller provides advanced power path management by automatically switching between multiple external power sources. This low-loss solution eliminates energy-wasting diodes in OR-ing applications, ensuring minimal power dissipation and maximizing battery life. The system is suited for portable electronics, uninterruptible power supplies (UPS), and devices requiring robust automatic load sharing across different inputs (including wall adapters and batteries).
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Ideal Diode Controller Eliminates Energy Wasting Diodes in Power OR-ing Applications – Design Note 386 David Laude
Introduction Wide supply operating range of 2.5V to 28V (36V Many modern electronic devices need a means to auto- absolute maximum)
matically switch between power sources when prompted
Protection of MOSFET from excessive gate-to-source
by the insertion or removal of any source. The LTC®4412
voltage with VGS limiter
simplifies Power Path TM management and control by pro-
Low quiescent current of 11µA with a 3.6V supply,
viding a low loss, near ideal diode controller function. Any
independent of the load current
circuit that could otherwise use a diode OR to switch between power sources can benefit from the LTC4412.
A status pin that can be used to enable an auxiliary
The forward voltage drop of an LTC4412 ideal diode is far
MOSFET power switch or to indicate to a microcontroller
less than that of a conventional diode, and the reverse
that an auxiliary supply, such as a wall adapter, is
current leakage can be smaller for the ideal diode as well
present
(see Figure 1). The tiny forward voltage drop reduces
A control input pin for external control, such as from a
power losses and self-heating, resulting in extended
microcontroller
battery life. Features include:
Applications include anything that takes power from two
Voltage drop across the controlled external MOSFET of
or more inputs:
only 20m V (typical)
Cellular phones
Low component count helps keep overall system cost low
Portable computers
6-pin Thin SOTTM package permits a compact design
solution
MP3 players and electronic video and still cameras USB peripherals
CONSTANT RON
Wire-ORed multipowered equipment
(VGS LIMITED)
Uninterruptible power supplies for alarm and emer-
LTC4412
gency systems Systems with standby capabilities
CONSTANT VOLTAGE
Systems that use load sharing between two or more
(VGS VARIABLE) SCHOTTKY DIODE batteries
Multibattery charging from a single charger
Logic controlled power switches
FORWARD VOLTAGE (V)
DN386 F01 , LTC and LT are registered trademarks of Linear Technology Corporation.
Power Path and Thin SOT are trademarks of Linear Technology Corporation.
Figure 1. LTC4412 Ideal Diode Controller vs Schottky Diode Characteristics
Page Summary Contents For LINEAR Ideal Diode Controller for Energy Efficiency in Power OR-ing Applications – Design Note 386 by David Laude
Manual Details
| Brand | Linear |
|---|---|
| Pages | 2 |
| File Size | 56.91 KB |
| Published | June 21, 2026 |
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Frequently Asked Questions
What applications benefit from the LTC4412 ideal diode controller?
It can be used in portable computers, PDAs, MP3 players, cellular phones, and uninterruptible power supplies.
How does the LTC4412 prevent excessive MOSFET gate current draw?
The device includes a VGS limiter feature to protect the MOSFET from excess gate-to-source current during circuit operations.
What is the typical forward voltage drop of the ideal diode controlled by this chip?
The forward voltage drop across the external MOSFET is only 20mV (typical), which minimizes power loss and self-heating.
How does low quiescent current affect battery life in these systems?
The low quiescent current (11µA at 3.6V) provides a near ideal function, significantly extending microcontroller battery life by reducing power losses.