LTC4007_15 Datasheet, PDF(7/24 Page) Linear Technology – 4A, High Effi ciency, Standalone Li-Ion Battery Charger

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LTC4007_15 Datasheet, PDF (7/24 Pages) Linear Technology – 4A, High Effi ciency, Standalone Li-Ion Battery Charger

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LTC4007

PIN FUNCTIONS

ITH (Pin 10): Control Signal of the Inner Loop of the

Current Mode PWM. Higher ITH voltage corresponds to

higher charging current in normal operation. A 6k resistor,

in series with a capacitor of at least 0.1Î¼F to GND provides

loop compensation. Typical full-scale output current is

40Î¼A. Nominal voltage range for this pin is 0V to 3V.

PROG (Pin 11): Current Programming/Monitoring Input/

Output. An external resistor to GND programs the peak

charging current in conjunction with the current sensing

resistor. The voltage at this pin provides a linear indication of

charging current. Peak current is equivalent to 1.19V. Zero

current is approximately 0.3V. A capacitor from PROG to

ground is required to ï¬lter higher frequency components.

The maximum resistance to ground is 100k. Values higher

than 100k can cause the charger to shut down.

NC (Pin 12): No Connect.

ICL (Pin 13): Input Current Limit Indicator. Active low

digital output. Internal 10Î¼A pull-up to 3.5V. Pulled low if

the charger current is being reduced by the input current

limiting function. The pin is capable of sinking at least

100Î¼A. If VLOGIC is greater than 3.3V, add an external

pull-up.

CSP (Pin 14): Current Ampliï¬er CA1 Input. The CSP and

BAT pins measure the voltage across the sense resistor,

RSENSE, to provide the instantaneous current signals

required for both peak and average current mode

operation.

BAT (Pin 15): Battery Sense Input and the Negative

Reference for the Current Sense Resistor. A precision

internal resistor divider sets the ï¬nal ï¬oat potential on

this pin. The resistor divider is disconnected during

shutdown.

CHEM (Pin 16): Select 4.1V or 4.2V cell chemistry by

connecting the pin to GND or open, respectively. Internal

14Î¼A pull-up to 5.3V. Can also be driven with open-

collector/drain logic levels.

FLAG (Pin 17): Active low open-drain output that indicates

when charging current has declined to 10% of maximum

programmed current. A pull-up resistor is required if this

function is used. The pin is capable of sinking at least

100Î¼A.

CLP (Pin 18): Positive input to the supply current limiting

ampliï¬er, CL1. The threshold is set at 100mV above the

voltage at the CLN pin. When used to limit supply current, a

ï¬lter is needed to ï¬lter out the switching noise. If no current

limit function is desired, connect this pin to CLN.

CLN (Pin 19): Negative Reference for the Input Current

Limit Ampliï¬er, CL1. This pin also serves as the power

supply for the IC. A 10Î¼F to 22Î¼F bypass capacitor should

be connected as close as possible to this pin.

TGATE (Pin 20): Drives the top external P-channel MOSFET

of the battery charger buck converter.

PGND (Pin 21): High Current Ground Return for the

BGATE Driver.

BGATE (Pin 22): Drives the bottom external N-channel

MOSFET of the battery charger buck converter.

INFET (Pin 23): Drives the Gate of the External Input PFET.

SHDN (Pin 24):

Charger is shut down and timer is reset when this pin is

HIGH. Internal 10Î¼A pull-up to 3.5V. This pin can also be

used to reset the charger by applying a positive pulse that

is a minimum of 0.1Î¼s long.

4007fc

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