LTC4413-1/LTC4413-2
11
441312ff
For more information www.linear.com/LTC4413-1
OPERATION
Overcurrent and Short-Circuit Protection
During an overcurrent condition, the output voltage droops
as the load current exceeds the amount of current that the
LTC4413-1/LTC4413-2 can supply. At the time when an
overcurrent condition is first detected, the LTC4413-1/
LTC4413-2 take some time to detect this condition before
reducing the current to I
OC
. For short durations after the
output is shorted, until TOC, the current may exceed I
OC
.
The magnitude of this peak short-circuit current can be
large depending on the load current immediately before
the short-circuit occurs. During overcurrent operation, the
power consumption of the LTC4413-1/LTC4413-2 is 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
internal die temperature increases beyond 150°C. An
overtemperature condition will cause the gate amplifiers
(A and B) as well as the two P-channel MOSFETs (PA
and PB) to shut off. When the internal die temperature
cools to below 140°C, the amplifiers turn on and the
LTC4413-1/LTC4413-2 reverts to normal operation. Note
that prolonged operation under overtemperature conditions
degrades reliability.
Overvoltage Protection (LTC4413-2 Only)
An overvoltage condition is detected whenever the over
-
voltage input (OVI) pin is pulled above 6V. The condition
persists until the OVI voltage falls below 5.6V. The overvolt
-
age protection (OVP) output is low unless an overvoltage
condition is detected. If an overvoltage condition is present,
the OVP output is pulled up to the voltage applied to the
OVI input. This output signal can be used to enable or
disable an external PFET that is placed between the input
that is the source of the excessive voltage and the input to
the LTC4413-2, thus eliminating the potential damage that
may occur to the LTC4413-2 if its input voltage exceeds
the absolute maximum voltage of 6V. See the Applica
-
tions Information section
Dual Battery Load Sharing with
Automatic Switchover to a Wall Adapter with Overvoltage
Protection
for more information on using the overvoltage
protection function within the LTC4413-2.
Channel Selection and Status Output
Two active-high control pins independently turn off the two
ideal diodes contained within the LTC4413-1/LTC4413-2,
controlling the operation mode as described by Table 1.
When the selected channel is reverse biased, or the
LTC4413-1/LTC4413-2 is put into low power standby, the
status signal indicates this condition with a low voltage.
Table 1. Mode Control
ENBA ENBB 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 Off (Low Power Standby)
The function of the STAT pin depends on the mode that
has been selected. Table 2 describes the STAT pin output
current, as a function of the mode selected as well as the
conduction state of the two diodes.
Table 2. STAT Output Pin Function
ENBA ENBB CONDITIONS STAT
Low Low Diode A Forward Bias,
Diode B Forward Bias
I
SNK
= 0µA
Diode A Forward Bias,
Diode B Reverse Bias
I
SNK
= 0µA
Diode A Reverse Bias,
Diode B Forward Bias
I
SNK
= 11µA
Diode A Reverse Bias,
Diode B Reverse Bias
I
SNK
= 11µA
Low High Diode A Forward Bias,
Diode B Disabled
I
SNK
= 0µA
Diode A Reverse Bias,
Diode B Disabled
I
SNK
= 11µA
High Low Diode A Disabled,
Diode B Forward Bias
I
SNK
= 0µA
Diode A Disabled,
Diode B Reverse Bias
I
SNK
= 11µA
High High Diode A Disabled,
Diode B Disabled
I
SNK
= 11µA
