DC1575A Linear Technology, DC1575A Datasheet - Page 9

• Manufacturer Part Number: DC1575A
• Description: LTC4362-1/LTC4362-2 Overvoltage/Overcurrent Protector With LatchOff/Auto-Retry
• Manufacturer: Linear Technology
• Series: -r

Specifications of DC1575A

• Design Resources: DC1575A Schematic DC1575 Design Files
• Main Purpose: Overvoltage/Overcurrent Protection
• Embedded: No
• Utilized Ic / Part: LTC4362-2
• Primary Attributes: -
• Secondary Attributes: -
• Kit Application Type: Power Management
• Application Sub Type: Overvoltage Protection
• Features: Demonstrates Two Protection Schemes Selected At JP2, Provides Connection For USB Protection
• Lead Free Status / Rohs Status: Not applicable / Not applicable

APPLICATIONS INFORMATION
Thermal Shutdown
The internal N-channel MOSFET is protected by a thermal
shutdown circuit. If its temperature reaches 150°C, it will
shut off immediately and the PWRGD pull-down releases.
It will turn on again after its temperature drops below
140°C.
Input Transients
Figure 3 shows a typical setup when an AC wall adaptor
charges a mobile device. The inductor L
lumped equivalent inductance of the cable and the EMI fi lter
found in some wall adaptors. R
resistance of the cable, adaptor output capacitor ESR and
the connector contact resistance.
WALL ADAPTOR
AC/DC
WALL ADAPTOR
AC/DC
+
+
R
R
IN
IN
I
CABLE
CABLE
I
CABLE
CABLE
L
IN
L
IN
IN
is the lumped equivalent
IN
IN
LT4362
IN
GND
Figure 3. 20V Hot-Plug Into a 10μF Capacitor
OUT
IN
Figure 4. 20V Hot-Plug Into the LTC4362
represents the
MOBILE DEVICE
OUT
C
OUT
LOAD
436212 F03a
C
MOBILE DEVICE
OUT
LOAD
436212 F04a
L
at IN. If the wall adaptor is powered-up fi rst, plugging the
wall adaptor output to IN does the equivalent of applying
a voltage step to this LC circuit. The resultant voltage
overshoot at IN can rise to twice the DC output voltage of
the wall adaptor (or more if ceramic capacitors with large
voltage coeffi cients are used) as shown in Figure 3. Figure 4
shows the 20V adaptor output applied to the LTC4362.
Due to the low capacitance at the IN pin, the plug-in transient
has been brought down to a manageable level.
Input transients also occur when the current through
the cable inductance changes abruptly. This can hap-
pen when the LTC4362 turns off its internal N-channel
MOSFET quickly in an overvoltage or overcurrent event.
IN
and R
10V/DIV
20A/DIV
10V/DIV
1V/DIV
1A/DIV
I
I
CABLE
CABLE
V
IN
OUT
V
V
IN
IN
form an LC tank circuit with any capacitance
LTC4362-1/LTC4362-2
R
LOAD = 10Ω, C
R
LOAD = 10Ω, C
IN
IN
= 150mΩ, L
= 150mΩ, L
OUT
OUT
IN
IN
= 0.7μH
= 0.7μH
= 10μF
= 10μF
5μs/DIV
5μs/DIV
436212 F03b
436212 F04b
436212fa
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