LTC4007_15 Datasheet, PDF (6/24 Pages) Linear Technology – 4A, High Effi ciency, Standalone Li-Ion Battery Charger

LTC4007
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency at 19VDC V_IN
100
16.8V
95
12.6V
90
85
80
75
0.50
1.00 1.50 2.00 2.50 3.00
CHARGE CURRENT (A)
4007 G10
Efficiency at 12.6V with 15VDC V_IN
100
95
90
85
80
75
0.50
1.00 1.50 2.00 2.50 3.00
CHARGE CURRENT (A)
4007 G11
PIN FUNCTIONS
DCIN (Pin 1): External DC Power Source Input. Bypass this
pin with at least 0.01μF. See Applications Information.
CHG (Pin 2): Charge Status Output. When the battery is
being charged, the CHG pin is pulled low by an internal
N-channel MOSFET. Internal 10μA pull-up to 3.5V. If
V_LOGIC is greater than 3.3V, add an external pull-up. The
timer charge termination can be defeated by forcing this
pin below 1V (or connecting it to GND).
ACP (Pin 3): Open-Drain output to indicate if the AC adapter
voltage is adequate for charging. This pin is pulled low
by an internal N-channel MOSFET if DCIN is below BAT. A
pull-up resistor is required. The pin is capable of sinking
at least 100μA.
R_T (Pin 4): Timer Resistor. The timer period is set by placing
a resistor, R_RT, to GND. This resistor is always required.
The timer period is t_TIMER = (1hour • R_RT/154K).
If this resistor is not present, the charger will not start.
FAULT (Pin 5): Active low open-drain output that indicates
charger operation has stopped due to a low-battery
conditioning error, or that charger operation is suspended
due to the thermistor exceeding allowed values. A pull-
up resistor is required if this function is used. The pin is
capable of sinking at least 100μA.
GND (Pin 6): Ground for Low Power Circuitry.
3C4C (Pin 7): Select 3-cell or 4-cell float voltage by
connecting this pin to GND or open, respectively. Internal
14μA pull-up to 5.3V. This pin can also be driven with open-
collector/drain logic levels. High: 4 cell. Low: 3 cell.
LOBAT (Pin 8): Low-Battery Indicator. Active low digital
output. Internal 10μA pull-up to 3.5V. If the battery voltage is
below 2.5V/cell (or 2.44V/cell for 4.1V chemistry batteries)
LOBAT will be low. The pin is capable of sinking at least
100μA. If V_LOGIC is greater than 3.3V, add an external
pull-up.
NTC (Pin 9): A thermistor network is connected from NTC
to GND. This pin determines if the battery temperature is
safe for charging. The charger and timer are suspended
and the FAULT pin is driven low if the thermistor indicates
a temperature that is unsafe for charging. The thermistor
function may be disabled with a 300k to 500k resistor
from DCIN to NTC.
4007fc
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