LTC4361-1_12 LINER [Linear Technology], LTC4361-1_12 Datasheet - Page 11

• Manufacturer Part Number: LTC4361-1_12
• Description: Overvoltage/Overcurrent Protection Controller
• Manufacturer: LINER [Linear Technology]

applicaTions inFormaTion
As the IN pin can withstand up to 80V, a high voltage
N-channel MOSFET can be used to protect the system
against rugged abuse from high transient or DC voltages
up to the BV
input plugged into the LTC4361 controlling a 60V rated
MOSFET.
Input transients also occur when the current through the
cable inductance changes abruptly. This can happen when
the LTC4361 turns off the N-channel MOSFET rapidly in an
overvoltage or overcurrent event. Figure 7 shows an input
transient after an overcurrent. The current in L
V
C
1.3 • (BV
IN
OUT
to overshoot and avalanche the N-channel MOSFET to
. Typically, IN will be clamped to a voltage of V
20V/DIV
5A/DIV
1V/DIV
I
CABLE
DSS
V
OUT
V
Figure 6. 50V Hot-Plug into the LTC4361
IN
DSS
of Si1470DH) = 45V. This is well below the
FDC5612
R
R
IN
SENSE
= 150m , L
of the MOSFET. Figure 6 shows a 50V
= 25m , LOAD = 10 , C
IN
= 0.7µH
5µs/DIV
OUT
= 10µF
436112 F06
IN
will cause
OUT
+
85V absolute maximum voltage rating of the LTC4361.
The single, nonrepetitive, pulse of energy (E
by the MOSFET during this avalanche breakdown with a
peak current I
For L
the I
the Si1470DH. So in most instances, the LTC4361 can
ride through such transients without a bypass capacitor,
transient voltage suppressor or other external components
at IN. Note that if an IN bypass capacitor is used, the V
transients will overshoot less but last longer. If V
below V
latch in the LTC4361-1 could be inadvertently reset.
Figure 7. Overcurrent Turn-Off and Resulting Input Transient
E
AS
AS
IN
20V/DIV
10V/DIV
= 0.5 • L
= 0.7μH and I
and E
5V/DIV
5A/DIV
I
IN(UVL)
V
CABLE
V
GATE
OUT
V
IN
LTC4361-1/LTC4361-2
AS
FIGURE 5 CIRCUIT
R
R
AS
IN
SENSE
for more than 10µs, the internal latch-off
IN
capabilities of most MOSFET’s including
= 150m , L
is approximated by the formula:
• I
= 25m , LOAD = 10 , C
AS
AS
= 4A, then E
2
IN
= 0.7µH
2µs/DIV
AS
OUT
= 5.6μJ. This is within
= 10µF
436112 F07
AS
) absorbed
11
IN
436112fb
dips
IN