The nPM1304 EK has a flexible and configurable power supply system to allow testing with different power sources and to facilitate accurate power measurements.
The power supply to the nPM1304 Power Management Integrated Circuit (PMIC) is from Universal Serial Bus (USB) (VBUS) or battery (VBAT). The input voltage ranges from 2.3 V to 5.5 V depending on the source.
USB power is the main input source and the source for battery charging. A compatible battery connected to the EK acts as a complementary power source. The battery powers the EK if no external power source is connected to USB PMIC on J4 or VBUS on P2. You can also connect the battery through the PCB pads on the back of the EK.
The USB-C connector nPM CONTROLLER on J5 powers the nPM Controller and its circuitry when evaluating the PMIC in the nPM PowerUP computer app.
The following figures show the power supply connections on the nPM1304 EK.
The following table shows the connections for the main and complementary power input sources on the EK.
| Input source | Part | Connector type | Comment | |
|---|---|---|---|---|
|
Main |
VBUS 4.0 V to 5.5 V |
J4 | USB-C | Use only USB power on this connector. |
| P2 | Pin header | VBUS on pin 1. | ||
|
Complementary |
VBAT 2.3 V to 4.65 V |
J1 | JST S2B-PH-SM4 header (2 pins) | Use for batteries without an Negative Temperature Coefficient (NTC) thermistor. Ground on pin 1. |
| J2 | JST SM03B header (3 pins) | Use for batteries with an NTC thermistor. Ground on pin 1. | ||
| J3 | WAGO terminal block (3 pins) | Solid conductor wires from 0.14–0.34 mm2. | ||
| P1 | Pin header | VBAT on pin 3. | ||
| Pads | PCB pad | Use the pads located at the back of the PCB to solder the battery directly to the EK. The NTC pad is for batteries with an NTC thermistor. | ||
- To keep the operating temperature of the EK within safe limits, the recommended input current on VBUS is 1 A.
- The maximum allowed input current on VBUS is determined by the power delivery negotiation between host and PMIC.
- Pay attention to the polarity of the battery connectors (J1/J2). Connecting the polarity the wrong way causes the device to become very hot. The nPM1304 EK uses JST configuration B, where pin 1 is GND.
- A battery without an NTC thermistor requires an external resistor to be terminated to GND on the NTC pin on pin header P3.
Battery
The nPM1304 EK comes with a 20 mAh lithium-polymer battery with the following specifications.
| Parameter | Value |
|---|---|
| Manufacturer part number | LP181917 |
| Nominal voltage | 3.70 V |
| Maximum charge voltage (VTERM) | 4.20 V |
| Maximum charge current (ICHG) | 10 mA |
| Maximum continuous discharge current | 60 mA |
| Discharge cut-off voltage | 2.75 V |