9

LTC4413

4413f

OPERATIO

occurs. During overcurrent operation, the power consump-

tion of the LTC4413 will be large, and is likely to cause an

overtemperature condition as the internal die temperature

exceeds the thermal shutdown temperature.

Overtemperature Protection

The overtemperature condition is detected when the inter-

nal die temperature increases beyond 150°C. An overtem-

perature condition will cause the gate amplifiers (A and B)

as well as the two P-channel MOSFETs (PA and PB) to be

shut off. When the internal die temperature cools to below

140°C, the amplifiers will turn on and revert to normal

operation. Note that prolonged operation under overtem-

perature conditions will degrade reliability.

Channel Selection and Status Output

Two active-high control pins independently turn off the

two ideal diodes contained within the LTC4413, control-

ling the operation mode as described by Table 1. When the

selected channel is reverse biased, or the LTC4413 is put

into low power standby, the status signal indicates this

condition with a low voltage.

Table 1. Mode Control

ENB1

ENB2

STATE

Low

Low

Diode OR (NB: The Two Outputs are Not Connected

Internal to the Device)

Low

High

Diode A = Enabled, Diode B = Disabled

High

Low

Diode A = Disabled, Diode B = Enabled

High

High

All 0ff (Low Power Standby)

Table 2. STAT Output Pin Funtion

ENB1

ENB2

CONDITIONS

STAT

Low

Low

Diode A Forward Bias,

Diode B Forward Bias

Diode A Forward Bias,

Diode B Reverse Bias

Diode A Reverse Bias,

Diode B Forward Bias

Diode A Reverse Bias,

Diode B Reverse Bias

Low

High

Diode A Forward Bias,

Diode B Disabled

Diode A Reverse Bias,

Diode B Disabled

High

Low

Diode A Disabled,

Diode B Forward Bias

Diode A Disabled

Diode B Reverse Bias

High

High

Diode A Disabled,

Diode B Disabled

The function of the STAT pin depends on the mode that has

been selected. The following table describes the STAT pin

output current as a function of the mode selected, as well

as the conduction state of the two diodes.

APPLICATIO S I FOR ATIO

Introduction

The LTC4413 is intended for power control applications

that include low loss diode ORing, fully automatic

switchover from a primary to an auxiliary source of power,

microcontroller controlled switchover from a primary to

an auxiliary source of power, load sharing between two or

more batteries, charging of multiple batteries from a

single charger and high side power switching.

Dual Battery Load Sharing with Automatic Switchover

to a Wall Adapter

An application circuit for dual battery load sharing with

automatic switchover of load from batteries to a wall adapter

is shown in Figure 3. When the wall adapter is not present,

whichever battery that has the higher voltage will provide

the load current until it has discharged to the voltage of the

other battery. The load will then be shared between the two

batteries according to the capacity of each battery. The

higher capacity battery will provide proportionally higher