LTC4412 Datasheet, PDF (1/12 Pages) Linear Technology – Low Loss PowerPathTM Controller in ThinSOT

LTC4412
Low Loss PowerPath^TM
Controller in ThinSOT
FEATURES
s _{Very Low Loss Replacement for Power Supply}
OR’ing Diodes
s _{Minimal External Components}
s _{Automatic Switching Between DC Sources}
s _{Simplifies Load Sharing with Multiple Batteries}
s _{Low Quiescent Current: 11µA}
s _{3V to 28V AC/DC Adapter Voltage Range}
s _{2.5V to 28V Battery Voltage Range}
s _{Reverse Battery Protection}
s _{Drives Almost Any Size MOSFET for Wide Range of}
Current Requirements
s _{MOSFET Gate Protection Clamp}
s _{Manual Control Input}
s _{Low Profile (1mm) ThinSOT}^TM _Package
U
APPLICATIO S
s _{Cellular Phones}
s _{Notebook and Handheld Computers}
s _{Digital Cameras}
s _{USB-Powered Peripherals}
s _{Uninterruptable Power Supplies}
s _{Logic Controlled Power Switch}
, LTC and LT are registered trademarks of Linear Technology Corporation.
PowerPath and ThinSOT are trademarks of Linear Technology Corporation.
DESCRIPTIO
The LTC^®4412 controls an external P-channel MOSFET to
create a near ideal diode function for power switchover or
load sharing. This permits highly efficient OR’ing of mul-
tiple power sources for extended battery life and low self-
heating. When conducting, the voltage drop across the
MOSFET is typically 20mV. For applications with a wall
adapter or other auxiliary power source, the load is auto-
matically disconnected from the battery when the auxiliary
source is connected. Two or more LTC4412s may be
interconnected to allow load sharing between multiple
batteries or charging of multiple batteries from a single
charger.
The wide supply operating range supports operation from
one to six Li-Ion cells in series. The low quiescent current
(11µA typical) is independent of the load current. The gate
driver includes an internal voltage clamp for MOSFET
protection.
The STAT pin can be used to enable an auxiliary P-channel
MOSFET power switch when an auxiliary supply is
detected. This pin may also be used to indicate to a
microcontroller that an auxiliary supply is connected. The
control (CTL) input enables the user to force the primary
MOSFET off and the STAT pin low.
The LTC4412 is available in a low profile (1mm) ThinSOT
package.
TYPICAL APPLICATIO
WALL
ADAPTER
INPUT
BATTERY
CELL(S)
1N5819
FDN306P
1 ^LTC4412 6
V_IN SENSE
2
5
GND GATE
3
4
CTL STAT
C_OUT
V_CC
TO LOAD
470k
STATUS OUTPUT
LOW WHEN WALL
4412 F01 _{ADAPTER PRESENT}
Figure 1. Automatic Switchover of Load Between a Battery and a Wall Adapter
LTC4412 vs Schottky Diode
Forward Voltage Drop
1
CONSTANT
R_ON
LTC4412
CONSTANT
VOLTAGE
SCHOTTKY
DIODE
0
0.02
FORWARD VOLTAGE (V)
0.5
4412 F01b
4412f
1