LTC4100_09 datasheet(8/30 Pages) LINER

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LTC4100

4100fb

PIN FUNCTIONS

ILIM(Pin13):Anexternalresistorisconnectedbetweenthis

pin and GND. The value of the external resistor programs

the range and resolution of the programmed charger cur-

rent. This is a digital, not an analog, function.

VLIM (Pin 14): An external resistor is connected between

this pin and GND. The value of the external resistor pro-

grams the range and resolution of the charging voltage.

This is a digital, not an analog, function.

THB (Pin 15): SafetySignal Force/Sense Pin to Smart

Battery. See description of operation for more detail. The

maximum allowed combined capacitance on THA, THB and

SafetySignal is 1nF (see Figure 4). A series resistor 54.9k

needs to be connected between this pin and the battery’s

SafetySignal for this circuit to work correctly.

THA (Pin 16): SafetySignal Force/Sense Pin to Smart

Battery. See description of operation for more detail. The

maximum allowed combined capacitance on THA, THB

and SafetySignal is 1nF (see Figure 4). A series resistor

1130Ω needs to be connected between this pin and the

battery’s SafetySignal for this circuit to work correctly.

VDD (Pin 17): Power Supply Input for the LTC4100 Digital

Circuitry. Bypass this pin with 0.1μF. Typically between

3.3V and 5VDC.

VSET (Pin 18): Tap Point of the Programmable Resistor

Divider, which Provides Battery Voltage Feedback to the

Charger.

ITH (Pin 19): Control Signal of the Inner Loop of the Current

Mode PWM. Higher ITH corresponds to higher charging

current in normal operation. A 0.0015μF capacitor to GND

ﬁlters out PWM ripple. Typical full-scale output current is

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

IDC (Pin 20): Bypass to GND with a 0.068μF Capacitor.

CSP (Pin 21): Current Ampliﬁer CA1 Input. This pin

and the BAT pin 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 22): Battery Sense Input and the Negative Refer-

ence for the Current Sense Resistor. A bypass capacitor

of at least 10μF is required.

CLN (Pin 23): Negative Input to the Input Current Limiting

Circuit Block. If no current limit function is desired, connect

this pin to CLP. The threshold is set at 100mV below the

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

a ﬁlter is needed to ﬁlter out the switching noise.

CLP (Pin 24): Positive Input to the Input Current Limiting

Circuit Block. This pin also serves as a power supply for

the IC.

LTC4100 Datasheet(PDF) 8 Page - Linear Technology

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