LTC4413EDD Linear Technology, LTC4413EDD Datasheet - Page 8

• Manufacturer Part Number: LTC4413EDD
• Description: IC,Power Control/Management,CMOS,LLCC,10PIN,PLASTIC
• Manufacturer: Linear Technology

Specifications of LTC4413EDD

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

OPERATIO
LTC4413
The LTC4413 is described with the aid of the Block
Diagram (Figure 1). Operation begins when the power
source at V
lockout (UVLO) voltage of 2.4V and either of the ENBA or
ENBB control pins is low. If only the voltage at the V
is present, the power source to the LTC4413 (V
supplied from the V
current proportional to the difference between V
V
driving this gate voltage below V
As V
20mV below V
maintain the small forward voltage drop. The system is
now in forward regulation and the load at V
powered from the supply at V
varies, V
load current exceeds the transistor’s (PA) ability to deliver
the current as V
PFET will behave as a fixed resistor with resistance R
whereby the forward voltage will increase slightly with
increased load current. As the magnitude of I
further (such that I
current to the constant value I
characteristics for parameters R
are specified with the aid of Figure 2, illustrating the
LTC4413 forward voltage drop versus that of a Schottky
diode.
8
OUTA
OUTA
from the gate (V
GATEA
I
FWD
is pulled up to a forward voltage drop (V
I
OC
0
0
INA
will be controlled to maintain V
INA
GATEA
SLOPE
1/R
or V
LTC4413
U
, the LTC4413 will regulate V
LOAD
FWD
FORWARD VOLTAGE (V)
INA
INB
SLOPE
1/R
approaches GND. At this point the
> I
GATEA
pin. The amplifier (A) will pull a
ON
Figure 2
OC
rises above the undervoltage
), the LTC4413 will fix the load
) of the internal PFET (PA),
OC
INA
to protect the device. The
INA
FWD
SCHOTTKY
DIODE
. As the load current
. This will turn on PA.
, R
4413 F02
ON
, V
OUT
FWD
OUTA
FWD
DD
increases
GATEA
until the
) will be
INA
and I
FWD
will be
INA
and
) of
pin
ON
OC
to
,
If another supply is provided at V
likewise regulate the gate voltage on PB to maintain the
output voltage V
this alternate supply, V
LTC4413 will select this input voltage as the internal
supply (V
dently of the first ideal diode function.
When an alternate power source is connected to the load
at V
voltage at V
V
higher than V
which will turn off PA. The internal power source for the
LTC4413 (V
from the V
V
Power to the load is being delivered from an alternate
supply and only a small current is drawn from V
sense the potential at V
When the selected channel of the LTC4413 is in reverse
turn-off mode or both channels are disabled, the STAT pin
will sink 9µA of current (I
Channel selection is accomplished using the two ENB
pins, ENBA and ENBB. When the ENBA input is asserted
(high), PA will have its gate voltage pulled to V
controlled rate, limiting the turn-off time to avoid voltage
spiking at the input when being driven by an inductive
source impedance. A 3µA pull-down current on the ENB
pins will ensure a low level at these inputs if left floating.
Overcurrent and Short-Circuit Protection
During an overcurrent condition, the output voltage will
droop as the load current exceeds the amount of current
that the LTC4413 can supply. At the time when an over-
current condition is first detected, the LTC4413 will take
some time to detect this condition before reducing the
current to I
shorted, the current may exceed I
this peak short-circuit current can be large, depending on
the load current immediately before the short circuit
GATEA
OUTB
OUTA
). The system is now in the reverse turn-off mode.
, reducing the current through PA. When V
(or V
DD
OUTA
OUTA
MAX
). This second ideal diode operates indepen-
DD
INA
OUTB
) will then be diverted to source current
. For short durations after the output is
pin, only if V
OUTB
and amplifier A will increase the voltage
+ V
), the LTC4413 will sense the increased
RTO
just below the input voltage V
INB
INA
, V
, exceeds the voltage at V
SON
GATEA
.
OUTA
) if connected.
will be pulled up to V
MAX
is larger than V
INB
, the LTC4413 will
. The magnitude of
DD
INA
OUTA
INB
INA
INB
, the
at a
4413f
DD
(or
. If
to
is
,