LTC4360-1 Linear Technology, LTC4360-1 Datasheet - Page 10

• Manufacturer Part Number: LTC4360-1
• Description: Overvoltage Protection Controller
• Manufacturer: Linear Technology

LTC4360-1/LTC4360-2
APPLICATIONS INFORMATION
Figure 8 shows a particularly severe situation which can
occur in a mobile device with dual power inputs. A 20V wall
adaptor is mistakenly hot-plugged into the 5V device with
the USB input already live. As shown in Figure 9, a large
current can build up in L
N-channel MOSFET shuts off, the energy stored in L
dumped into C
LTC4360 limits this to a 1V rise in the output voltage.
10
ADAPTER
WALL
USB
Figure 8. Setup for Testing 20V Plugged into 5V System
20V
5V
20V/DIV
10V/DIV
10A/DIV
5V/DIV
I
V
CABLE
V
GATE
+
+
Figure 9. Overvoltage Protection Waveforms
When 20V Plugged into 5V System
–
–
OUT
V
IN
R
IN
FIGURE 8 CIRCUIT
R
LOAD = 10Ω, C
OUT
I
IN
CABLE
= 150mΩ, L
L
, causing a large 40V input transient . The
IN
OUT
IN
B160
IN
D1
= 2μH
1μs/DIV
= 10μF (16V, SIZE 1210)
to charge up C
R1
100k
IN
IN
Si1470DH
LTC4360
GATE
GND
M1
OUT
436012 F08
OUT
OUT
. When the
C
436012 F07
OUT
LOAD
IN
is
If the voltage rise at V
energy in L
capability of the MOSFET is exceeded, an additional exter-
nal clamp such as the SMAJ24A can be placed between
IN and GND. C
protected circuits and its value will largely be determined
by their requirements. Using a larger C
L
LTC4360 to shut off the MOSFET before V
to a dangerous voltage. A larger C
the ΔV
MOSFET BV
Layout Considerations
Figure 10 shows example PCB layouts for the single
N-channel MOSFET (SC70 package) confi guration and the
P-channel MOSFET/N-channel MOSFET (Complementary
P , N MOSFET in TSOP-6 package) confi guration. Keep the
traces to the MOSFETs wide and short. The PCB traces
associated with the power path through the MOSFETs
should have low resistance.
SUPPLY/IN
IN
Figure 10. Recommended Layout for N-Channel MOSFET
and P-/N-Channel MOSFET Confi gurations
to slow down the dV/dt at OUT, allowing time for the
OUT
1
2
3
4
LTC4360-1
Si1470DH
due to the discharge of the energy in L
IN
DSS
into C
8
7
6
5
OUT
is used as an input clamp.
OUT
OUT
is the decoupling capacitor of the
GND
is not acceptable or the avalanche
OUT
due to the discharge of the
SUPPLY
OUT
IN
www.DataSheet4U.com
also helps to lower
1
2
3
4
OUT
LTC4360-2
Si3590DV
OUT
will work with
overshoots
8
7
6
5
436012 F09
IN
if the
436012f
OUT
GND