Product Specs

Page 21

nRF51802 Product Specification v1.2

3.4.2.2 System ON mode

In system ON mode the system is fully operational and the CPU and selected peripherals can be brought

into a state where they are functional and more or less responsive depending on the sub-power mode

selected.

There are two sub-power modes:

•Low power

• Constant latency

Low Power

In Low Power mode the automatic power management system is optimized to save power. This is done by

keeping as much as possible of the system powered down. The cost of this is that you will have varying CPU

wakeup latency and PPI task response.

The CPU wakeup latency will be affected by the startup time of the 1V7 regulator. The PPI task response will

vary depending on the resources required by the peripheral where the task originated.

The resources that could be involved are:

• 1V7 with the startup time t

1V7

• 1V2 with the startup time t

1V2

• One of the following clock sources

• RC16 with the startup time t

START,RC16

• XO16M/XO32M with the startup time the clock management system t

Constant Latency

In Constant Latency mode the system is optimized towards keeping the CPU latency and the PPI task

response constant and at a minimum. This is secured by forcing a set of base resources on while in sleep

mode. The cost is that the system will have higher power consumption.

The following resources are kept active while in sleep mode:

• 1V7 regulator with the standby current of I

1V7

• 1V2 regulator. Here the current consumption is specified in combination with the clock

source

• One of the following clock sources:

• RC16 with the standby current of I

1V2RC16

• XO16M with the standby current of I

1V2XO16

• XO32M with the standby current of I

1V2XO32

1. For the clock source XO16M and XO32M we assume that the crystal is already running (standby). This will give an increase of the

power consumption in sleep mode given by I

STBY,X16M

/ I

STBY,X32M