LTC4358 datasheet(9/14 Pages) AD

9 / 14 page

LTC4450

Rev. 0

For more information www.analog.com

Automatic PowerPath™ Control

Figure 4 illustrates an application circuit for automatic

switchover of a load between a battery and a wall adapter.

With application of the battery, VOUT will initially be pulled

up by the drain-to-body diode of the LTC4450’s internal

power MOSFET. Typically, 250µs (tSTART) after application

of the battery, the LTC4450 will turn on its power MOSFET,

reducing the IN-to-OUT voltage drop from a diode voltage

to 15mV. Should the wall adapter then be applied, MP1’s

body diode will pull the VOUT voltage above the battery

voltage, and the LTC4450 will turn off its power MOSFET.

At the same time, the LTC4450 will sink current into the

STATUS pin, turning on MP1 and reducing the voltage

drop from the wall adapter to VOUT.

For wall adapter and/or battery voltages exceeding 5.5V,

a voltage source ranging from 2.75V to 5.5V must be

generated from VOUT to power VCC, as shown by devices

RCL, DZ1 and MN1 in Figure 5. DCL1 and STAT2 are used

to clamp MP1’s VGS voltage to 5V.

Figure 4. Automatic Switchover of Load Between a Battery and a Wall Adapter with Auxiliary

P-Channel MOSFET In a Low Voltage Application

Figure 5. Automatic Switchover of Load Between a Battery and a Wall Adapter with Auxiliary

P-Channel MOSFET in a High Voltage Application

APPLICATIONS INFORMATION

Si4465DY

COUT

47µF

RSTAT1

VOUT

BATTERY

CELL INPUT

(UP TO 3.7V)

SHDN#

GND

LTC4450

STATUS

VCC

OUT

WALL

ADAPTER

INPUT (5V)

MP1

4450 F04

CIN1

0.1 F

FDS4465

47µF

RSTAT1

RSTAT2

10k

RCL

10k

MN1

2N7002

VOUT

SHDN#

GND

STATUS

VCC

OUT

DCL1

BZX84C5V1L

5V GENERATED FROM VOUT

MP1

DZ1

BZX84C5V1L

4450 F05

BATTERY

INPUT

(7.2V)

WALL

ADAPTER

INPUT (12V)

LTC4450

CIN1

0.1 F

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