Datasheet LTC4360-1, LTC4360-2 (Analog Devices) - 9

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APPLICATIONS INFORMATION Input Transients
LIN and RIN form an LC tank circuit with any capacitance Figure 4 shows a typical set-up when an AC wall adap- at IN. If the wall adaptor is powered up first, plugging the tor charges a mobile device. The inductor L wall adaptor output to IN does the equivalent of applying IN represents the lumped equivalent inductance of the cable and the a voltage step to this LC circuit. The resultant voltage EMI filter found in some wall adaptors. R overshoot at IN can rise to twice the DC output voltage IN is the lumped of the wall adaptor as shown in Figure 4. Figure 5 shows equivalent resistance of the cable, adaptor output capaci- the 20V adaptor output applied to the LTC4360. Due to tor ESR and the connector contact resistance. the low capacitance at the IN pin, the plug-in transient has been brought down to a manageable level. WALL ADAPTOR MOBILE AC/DC RIN L DEVICE IN IN ICABLE VIN C + OUT 10V/DIV CABLE LOAD ICABLE 20A/DIV 436012 F04a 5µs/DIV 436012 F04b RIN = 150mΩ, LIN = 0.7µH LOAD = 10Ω, COUT = 10µF
Figure 4. 20V Hot-Plug into a 10µF Capacitor
WALL ADAPTOR MOBILE M1 AC/DC RIN L DEVICE IN IN Si1470DH OUT ICABLE V C IN + OUT 10V/DIV GATE CABLE LOAD IN OUT LTC4360 VOUT 1V/DIV GND ICABLE 20A/DIV 436012 F04a 5µs/DIV 436012 F04b RIN = 150mΩ, LIN = 0.7µH LOAD = 10Ω, COUT = 10µF
Figure 5. 20V Hot-Plug into the LTC4360
Rev B For more information www.analog.com 9 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Pin Configuration Order Information Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Applications Information Package Description Revision History Typical Application Related Parts