Power Management

Introduction

The BGX supports two power modes: Active Mode and Sleep Mode.

Active Mode

Active Mode Device Configuration

In active mode, the BGX has the following configuration:

Active Mode Current Consumption

The current drawn in active mode is determined by both the UART baud rate (ua b) and the current Bluetooth radio state.

Assuming the Bluetooth radio is idle (i.e. not advertising, scanning, or connected), the current consumption is:

Sleep Mode

Sleep Mode Device Configuration

In sleep mode, the Bluetooth radio is either turned off or put into a limited mode of operations where it can advertise but not scan or maintain an active Bluetooth connection. The radio's operational mode is selected with the sleep mode variable (sy s sm)

In sleep mode, the UART is still operational if its baud rate is 9600 bps or less. If it is greater than 9600 bps, the UART is not operational, and the host controller must wake the BGX before using the UART.

If UART flow control is enabled and the UART is not operational due to the device being in sleep mode, the UART will deassert its RTS pin to indicate to the host that it cannot not receive UART data.

Sleep Mode Current Consumption

When sy s sm is set to deep, the estimated current consumption is 3 uA.

Additional Notes

The Wake on CTS variable (sy w c) only applies when the UART baud rate (ua b) is greater than 9600 bps. For baud rates of 9600 bps and below, the host can send the wake command across the UART to wake the device.

The Wake on CTS variable (sy w c) setting only takes effect when the device transitions from Active Mode to sleep mode. For example, if baud rate is 9600 and sy w c is 1, the Wake on CTS feature will be disabled when the device enters Sleep Mode. While in sleep mode, the UART is operational, so the user could set ua b to 115200. At this point, the user might expect a falling edge on CTS to wake the device from sleep. However, the device will not wake, because there was no power state transition to force the new Wake on CTS setting to take effect.

Power Modes Diagram

The Diagram below illustrates the power modes as well as the entry methods into each mode.