LTC4076EDD#TR Linear Technology, LTC4076EDD#TR Datasheet - Page 12

• Manufacturer Part Number: LTC4076EDD#TR
• Description: IC CHARG BATT LI-ON USB 10DFN
• Manufacturer: Linear Technology

Specifications of LTC4076EDD#TR

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Voltage - Supply: 4.3 V ~ 8 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 10-WFDFN Exposed Pad
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

APPLICATIO S I FOR ATIO
LTC4076
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 2 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.
12
ADAPTER
I
CHRG DC
WALL
PORT
USB
Figure 2. Dual Input Charger Circuit. The Wall
Adapter Charge Current and USB Charge Current
are Both Programmed to be 500mA
(
)
1 F
=
I
CHRG USB
U
1 F
(
R
2k
1%
)
ISET
U
=
1000
DCIN
USBIN
IUSB
IDC
R
ADAPTER
ISET
LTC4076
WALL
PORT
GND
USB
V
W
ITERM
HPWR
BAT
Figure 3. Full Featured Dual Input Charger Circuit
R
IUSB
1%
2k
(USB, HPWR = LOW)
1 F
R
1k
1%
ITERM
1.24k
R
100mA
500mA
1%
IDC
U
+
4076 F02
1 F
DCIN
USBIN
HPWR
IUSB
IDC
LTC4076
GND
ITERM
The LTC4076 can also program the wall adapter charge
current and USB charge current independently using two
program resistors, R
charger circuit that sets the wall adapter charge current
to 800mA and the USB charge current to 500mA.
Stability Considerations
The constant-voltage mode feedback loop is stable without
any compensation provided a battery is connected to the
charger output. However, a 1µF 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 char-
ger is stable with program resistor values as high as 20k
(I
nodes reduces the maximum allowed program resistor.
CHRG
PWR
BAT
CHRG
= 50mA); however, additional capacitance on these
1k
R
1k
1%
ITERM
100mA/500mA (USB)
800mA (WALL)
1k
+
4076 F03
4.2V
1-CELL
Li-Ion
BATTERY
IDC
and R
IUSB
. Figure 3 shows a
4076fa