The nRF52840 typically consumes under 40 mA during its peak operational modes, such as when the radio is transmitting at maximum power and the CPU is actively running.
Understanding Peak Current Draw
The maximum practical current consumption of the nRF52840 occurs under specific high-demand conditions, particularly when its integrated radio is active and transmitting at its highest power level.
- High-Power Radio Transmission: When the nRF52840 operates in LDO (Low-Dropout Regulator) mode and the radio is transmitting at its maximum output power of 8dBm, the radio alone can draw approximately 30 mA from the VDD supply.
- Combined Operations: In addition to the radio's current, the active CPU and other miscellaneous internal components contribute to the overall power draw. Even with these combined elements, the total current consumption generally remains under 40 mA in these demanding scenarios.
Factors Influencing Power Consumption
Several factors can influence the actual current consumption of the nRF52840:
- Operating Regulator Mode: The chip can operate using an internal LDO regulator or a more efficient DCDC (buck) converter. DCDC mode typically offers lower power consumption for similar operations compared to LDO mode, especially for the radio.
- Radio Activity: Transmitting at maximum power (8dBm) consumes significantly more current than receiving data, being in an idle state, or in deep sleep modes.
- CPU Load: A CPU running complex calculations or at a higher clock speed will consume more power than an idle or sleeping CPU.
- Peripheral Usage: Activating and utilizing various on-chip peripherals (e.g., USB, SPI, I2C, UART, ADC) will add to the overall current draw.
Practical Considerations for Power Supply Design
When designing a system utilizing the nRF52840, it is advisable to ensure that the power supply can reliably deliver sufficient current to meet these peak demands. A common recommendation is to provide a power supply capable of supplying at least 50 mA. This provides a comfortable margin for the nRF52840's peak consumption as well as any other minor components that might share the same supply rail.
Typical Current Consumption Breakdown (Example Peak Scenario):
| Component/Operation | Approximate Current Draw | Notes |
|---|---|---|
| Radio (8dBm TX, LDO Mode) | ~30 mA | Transmitting at maximum output power |
| CPU (Active) & Miscellaneous | <10 mA | Active CPU, internal operations, other peripherals |
| Total (Peak Practical) | <40 mA | Combined high-demand scenario |
