APPLICATION INFORMATION

Input Capacitance Calculation

V

i

R

i

L

i

C

i

R

c

V

IN

Charger

I

IN

t

t

e

t

e

t

t

i

t

i

R

2L

i

C

IN

IN

C

Ci

i

I

i

R

2L

t

Ci

i

I

i

t

t

i

C

In

i

i

i

2

R - R

V (t)

I (t) x R

+ V (t) = V - V

sin t + cos

L

R

V (t)

V - V

sin t + cos

2 L

R

I

R

R + R

I (t)

L C

2L

w

w

w

w

w

w

w

é

ù

ê

ú

=

ê

ú

ë

û

é

ù

ê

ú

=

ê

ú

ë

û

æ

ö÷

ç

÷

=

=

-ç

÷

ç

÷

çè

ø

t

e

t

i

R

2L

i

i

V

=

sin t

L

w

w

(6)

bq24705

Table 2. Component List for Typical System Circuit of Figure 2

PART DESIGNATOR

QTY

DESCRIPTION

Q1, Q2, Q3

3

P-channel MOSFET, –30V,-6A, SO-8, Vishay-Siliconix, Si4435

Q4, Q5

2

N-channel MOSFET, 30V, 12.5A, SO-8, Fairchild, FDS6680A

D1, D2

2

Diode, Dual Schottky, 30V, 200mA, SOT23, Fairchild, BAT54C

2

Sense Resistor, 10 m

Ω, 1%, 1W, 2010, Vishay-Dale, WSL2010R0100F

L1

1

Inductor, 4.7

µH, Vishay-Dale, IHLP5050CE-01

C6, C7, C11, C12

4

Capacitor, Ceramic, 10

µF, 25V, 20%, X5R, 1206, Panasonic, ECJ-3YB1E106M

C4, C10

2

Capacitor, Ceramic, 1

µF, 25V, 10%, X7R, 2012, TDK, C2012X7R1E105K

C2, C3, C8, C9, C13, C14, C15

7

Capacitor, Ceramic, 0.1

µF, 50V, 10%, X7R, 0805, Kemet, C0805C104K5RACTU

C5

1

Capacitor, Ceramic, 100pF, 25V, 10%, X7R, 0805, Kemet, C0805C101K5RACTU

C1

1

Capacitor, Ceramic, 2.2

µF, 25V, 10%, X7R, 2012, TDK, C2012X7R1E225K

R3, R4

2

Resistor, Chip, 10 k

Ω, 1/16W, 5%, 0402

R1

1

Resistor, Chip, 432 k

Ω, 1/16W, 1%, 0402

R2

1

Resistor, Chip, 66.5 k

Ω, 1/16W, 1%, 0402

R10

1

Resistor, Chip, 2

Ω, 1W, 1%, 1210

R6

1

Resistor, Chip, 30 k

Ω, 1/16W, 1%, 0402

During the adapter hot plug-in, the ACFET has not been turned on. The AC switch is off and the simplified

equivalent circuit of the input is shown in Figure 30.

A.

B.

C.

D.

Figure 30. Simplified Equivalent Circuit During Adapter Insertion

The voltage on the input capacitor(s) is given by:

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