The following application example uses nPM1100 and an nRF5x wireless System on Chip (SoC). Any nRF52 or nRF53 series device with USB can be configured in the same way as this application. When using a device without USB, or for other configurations, see Reference circuitry.
nRF5x is supplied by nPM1100 VOUTB at 1.8 V. BUCK mode (MODE) is controlled with a GPIO.
An application should not be supplied directly from VBAT because it can disturb the battery charging process and may cause incorrect behavior from the charger. Instead, VOUTB and/or VSYS should be used to supply an application.
nRF5x can connect to a USB host.
See USB port detection and VBUS current limiting for a detailed description.
Pins CHG and ERR indicate charging and error states. See Charging indication (CHG) and charging error indication (ERR) and Charger error conditions.
For a product using standard VTERM, the termination voltage is configured to 4.2 V. See Termination voltage (VTERMSET). The same configuration would provide 4.35 V for a product using high VTERM.
Charge current is configured to 200 mA (±10%) using a 1.5 kΩ (1%) resistor to ground on the ICHG pin. See Charge current limit (ICHG).
The NTC pin is connected to an external NTC thermistor which should be placed with thermal coupling to the battery pack. See Battery thermal protection using NTC thermistor (NTC) for more information.
Ship mode is enabled at production time through an off-board circuit with a probe point on the SHIPACT pin.
An external button is in the circuit to exit Ship mode. If another circuit is present instead of a button, any signal that is able to pull the SHIPHLD pin low for the required period can be connected to that net. See Using Ship mode for more information.
The battery monitoring circuit allows the battery voltage to be sampled by the nRF5x ADC.
The transistors enable battery voltage sensing through a resistive divider. When not sampling, the transistors prevent current leakage to ground. The circuit is designed to ensure the voltage range on an analog input pin over the battery voltage is within the limits required by the nRF5x GPIO and ADC. A battery voltage of 2.8 V to 4.2 V is scaled down to 360 mV to 540 mV at P0.xx for sampling.
If software on nRF5x determines that the battery on nPM1100 is low, the Low Bat LED can be switched on through GPIO. This circuit sources the LED current from VSYS. VSYS will not be supplied after VBAT drops below VBATBOR because CHARGER will isolate the battery when a brownout reset occurs. See Power-on reset (POR) and brownout reset (BOR).