A typical application circuit using the BQ24160 with a smartphone's GSM power amplifier (PA) powered directly from the battery is shown in Figure 9-1. A typical application circuit using the BQ24161 with a smartphone's GSM PA powered from the SYS rail, to allow for calls even with a deeply discharged battery, is shown in Figure 9-2. Each circuit shows the minimum capacitance requirements for each pin and typical recommended inductance value of 1.5 µH. The TS resistor divider for configuring the TS function for the battery's specific thermistor can be computed from equations Equation 1 and Equation 2. The resistor on STAT is sized per the LED current requirements. All other configuration settings for VINDPM, input current limit, charge current and charge voltage are made in EEPROM registers using I²C commands. Options for sizing the inductor outside the 1.5 µH recommended value and additional SYS pin capacitance are explained in the next section.