link to page 7 link to page 7 link to page 7 LTC4124 PIN FUNCTIONS ISEL1 (Pin 6): Charge Current Select Bit 1. Tie this pin to NTC (Pin 9): Thermistor Input. Connect a 100kΩ thermis- VCC or GND to program the battery charge current. Do not tor from NTC to GND. This pin is internally pulled up with leave this pin open. Refer to Table 3 for programming the a 100kΩ, 1% resistor to VCC. The voltage level on this pin desired charge current. determines if the battery temperature is safe for charging. ISEL2 (Pin 7): Charge Current Select Bit 2. Tie this pin to Charging and the charge timer are paused if the thermis- V tor indicates temperature that is unsafe for charging. Once CC or GND to program the battery charge current. Do not leave this pin open. Refer to Table 3 for programming the the temperature returns to the safe region, charging and desired charge current. the charge timer resume. Connect this pin to VCC to dis- able the temperature qualified charging feature. Table 3. Battery Charge Current ProgrammingBAT (Pin 10): Battery. Connect the Li-Ion battery to ISEL1ISEL2Charge Current this pin. High High 100mA High Low 50mA ACIN (Pin 11): AC Input Supply Voltage. Connect the Low High 25mA external LC tank (receive inductor and capacitor) to this Low Low 10mA pin. An internal diode is connected from this pin (anode) to the VCC pin (cathode). This pin supplies power to the VCC pin when its peak voltage is higher than the DCIN pin LBSEL (Pin 8): Low Battery Disconnect Voltage Select. voltage. Short this pin to GND when not used. Tie this pin to VCC or GND to program the low battery disconnect voltage level. Do not leave this pin open. Refer DCIN (Pin 12): Optional DC Input Supply Voltage: 3.3V to to Table 4 for programming the desired low battery dis- 5.5V. An internal diode is connected from this pin (anode) connect voltage level. to the VCC pin (cathode). This pin supplies power to the VCC pin when its voltage is higher than the peak voltage Table 4. Low Battery Disconnect Voltage Programming of the ACIN pin. Short this pin to GND when not used. LBSELDisconnect VoltageGND (Exposed Pad, Pin 13): Device Ground. Connect High 3.2V this ground pin to a suitable PCB copper ground plane for Low 2.7V proper electrical operation and rated thermal performance. Rev. A For more information www.analog.com 7 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Pin Configuration Electrical Characteristics Typical Performance Characteristics Pin Functions Functional Block Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts