LTC4100 pin FuncTions VLIM (Pin 14): An external resistor is connected between ITH (Pin 19): Control Signal of the Inner Loop of the Current this pin and GND. The value of the external resistor pro- Mode PWM. Higher ITH corresponds to higher charging grams the range and resolution of the charging voltage. current in normal operation. A 0.0015µF capacitor to GND This is a digital, not an analog, function. filters out PWM ripple. Typical full-scale output current THB (Pin 15): SafetySignal Force/Sense Pin to Smart is 40µA. Nominal voltage range for this pin is 0V to 3V. Battery. See description of operation for more detail. The IDC (Pin 20): Bypass to GND with a 0.068µF Capacitor. maximum allowed combined capacitance on THA, THB and CSP (Pin 21): Current Amplifier CA1 Input. This pin and SafetySignal is 1nF (see Figure 4). A series resistor 54.9k the BAT pin measure the voltage across the sense resis- needs to be connected between this pin and the battery’s tor, R SafetySignal for this circuit to work correctly. SENSE, to provide the instantaneous current signals required for both peak and average current mode operation. THA (Pin 16): SafetySignal Force/Sense Pin to Smart BAT (Pin 22): Battery Sense Input and the Negative Refer- Battery. See description of operation for more detail. The ence for the Current Sense Resistor. A bypass capacitor maximum allowed combined capacitance on THA, THB of at least 10µF is required. and SafetySignal is 1nF (see Figure 4). A series resistor 1130Ω needs to be connected between this pin and the CLN (Pin 23): Negative Input to the Input Current Limiting battery’s SafetySignal for this circuit to work correctly. Circuit Block. If no current limit function is desired, connect this pin to CLP. The threshold is set at 100mV below the VDD (Pin 17): Power Supply Input for the LTC4100 Digital voltage at the CLP pin. When used to limit supply current, Circuitry. Bypass this pin with 0.1µF. Typically between a filter is needed to filter out the switching noise. 3.3V and 5VDC. CLP (Pin 24): Positive Input to the Input Current Limiting VSET (Pin 18): Tap Point of the Programmable Resistor Circuit Block. This pin also serves as a power supply for Divider, which Provides Battery Voltage Feedback to the the IC. Charger. 4100fc 8 For more information www.linear.com/LTC4100