ltc4413edd-trpbf Linear Technology Corporation, ltc4413edd-trpbf Datasheet - Page 8

• Manufacturer Part Number: ltc4413edd-trpbf
• Description: Dual 2.6a, 2.5v To 5.5v, Ideal Diodes In 3mm ? 3mm Dfn
• Manufacturer: Linear Technology Corporation

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
V
20mV below V
tain the small forward voltage drop. The system is now in
forward regulation and the load at V
the supply at V
controlled to maintain V
the transistor’s (PA) ability to deliver the current as V
approaches GND. At this point the PFET behaves as a fixed
resistor with resistance R
increases slightly with increased load current. As the
magnitude of I
I
value I
parameters R
aid of Figure 2, illustrating the LTC4413 forward voltage
drop versus that of a Schottky diode.
If another supply is provided at V
regulates the gate voltage on PB to maintain the output
voltage V
8
OC
OUTA
OUTA
), the LTC4413 fixes the load current to the constant
from the gate (V
is pulled up to a forward voltage drop (V
OC
I
FWD
OUTB
I
to protect the device. The characteristics for
OC
0
0
INA
FWD
INA
just below the input voltage V
INA
OUT
SLOPE
1/R
or V
, R
, the LTC4413 regulates V
LTC4413
U
FWD
. As the load current varies, V
increases further (such that I
ON
FORWARD VOLTAGE (V)
INA
INB
SLOPE
1/R
, V
FWD
GATEA
ON
FWD
ON
Figure 2
pin. The amplifier (A) pulls a
rises above the undervoltage
, whereby the forward voltage
until the load current exceeds
and I
) of the internal PFET (PA),
INB
INA
OC
SCHOTTKY
DIODE
, the LTC4413 likewise
. This turns on PA. As
OUTA
are specified with the
4413 F02
is powered from
GATEA
INB
DD
to main-
GATEA
) will be
FWD
INA
. If this
LOAD
INA
GATEA
and
) of
pin
is
>
alternate supply, V
LTC4413 selects this input voltage as the internal supply
(V
the first ideal diode function.
When an alternate power source is connected to the load
at V
voltage at V
V
higher than V
turns off PA. The internal power source for the LTC4413
(V
only if V
now in the reverse turn-off mode. Power to the load is being
delivered from an alternate supply and only a small current
is drawn from V
When the selected channel of the LTC4413 is in reverse
turn-off mode or both channels are disabled, the STAT pin
sinks 9µA of current (I
Channel selection is accomplished using the two ENB
pins, ENBA and ENBB. When the ENBA input is asserted
(high), PA’s gate voltage is pulled to V
rate, limiting the turn-off time to avoid voltage spiking at
the input when being driven by an inductive source imped-
ance. A 3µA pull-down current on the ENB pins ensures a
low level at these inputs if left floating.
Slow Response Time
The LTC4413-1 (or LTC4413-2) is recommended for
applications with demanding load step or fast slew rate
requirements. The LTC4413-1 and LTC4413-2 provide
better load regulation in these environments at the ex-
pense of higher quiescent current. The LTC4413 is opti-
mized for lower power consumption and should not be
used in high slew rate environments or when large and fast
load transients are anticipated.
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 can supply. At the time when an overcurrent
condition is first detected, the LTC4413 takes some time
to detect this condition before reducing the current to I
GATEA
DD
DD
OUTA
). This second ideal diode operates independently of
) is then diverted to source current from the V
, reducing the current through PA. When V
OUTA
(or V
OUTA
INA
is larger than V
OUTB
INA
+ V
and amplifier A increases the voltage
INB
), the LTC4413 senses the increased
RTO
to sense the potential at V
, exceeds the voltage at V
SON
, V
GATEA
) if connected.
INB
(or V
is pulled up to V
OUTB
DD
). The system is
at a controlled
INA
DD
OUTA
.
INA
OUTA
, which
, the
MAX
4413fa
pin,
is
.