LTC4096EDD 데이터 시트보기 (PDF) - Linear Technology

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LTC4096EDD

Dual Input Standalone Li-Ion Battery Chargers

Linear Technology 

LTC4096/LTC4096X

APPLICATIONS INFORMATION

Using a Single Charge Current Program Resistor

In applications where the programmed wall adapter charge

current and USB charge current are the same, a single

program resistor can be used to set both charge currents.

Figure 3 shows a charger circuit that uses one charge cur-

rent program resistor. In this circuit, one resistor programs

the same charge current for each input supply.

ICHRG(DC)

=

ICHRG(USB)

=

1000V

RISET

The LTC4096 can also program the wall adapter charge

current and USB charge current independently using two

program resistors, RIDC and RIUSB. Figure 4 shows a

charger circuit that sets the wall adapter charge current

to 800mA and the USB charge current to 500mA.

DCIN

1

Stability Considerations

The constant-voltage mode feedback loop is stable without

any compensation provided a battery is connected to the

charger output. However, a 4.7µF capacitor with a 1Ω

series resistor is recommended at the BAT pin to keep

the ripple voltage low when the battery is disconnected.

When the charger is in constant-current mode, the charge

current program pin (IDC or IUSB) is in the feedback loop,

not the battery. The constant-current mode stability is

affected by the impedance at the charge current program

pin. With no additional capacitance on this pin, the charger

is stable with program resistor values as high as 20KΩ

(ICHRG = 50mA); however, additional capacitance on these

nodes reduces the maximum allowed program resistor.

USBIN

2

+

4.2V –

DCIN UVLO

+

BAT

10 –

∆V

+–

–

CURR-LIM

+

DCON

DCON USBON

4V

USBIN UVLO

BAT

10

∆V

CURR-LIM

12

3 120mA MAX

PWR

4096 BD

Figure 2. Input Power Present Output (PWR) Circuit

4096xf

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