Data Sheet

Bluegiga – A Silicon Labs Company 13
Power mode
CPU
clocks
CPU
core
Radio
Wakeup
delay
UART
Current
consumption *
Active
ON
Running
On
-
Active
10 - 20 mA
Power mode 1
ON
Stopped
On
< 7μs
Active
4 - 10 mA
Power mode 2
OFF
Powered off
On
< 70 μs
Off
50 - 100 μA
Table 3 Power modes with corresponding wakeup delays and current consumption
* Current consumption with radio inactive
The logic flow of the power saving modes in relation to each other is shown in Figure 5 below. It is to be noted
that the processor will not lose RAM contents regardless of the power mode used.
Figure 5 Power modes in relation to each other and to active mode
4.3 Reset
BT121 can be reset by several methods: by pulling the RESET pin low, by the internal system power-up reset
functionality or by the internal watchdog timer. The RESET pin is internally connected to a pull-up resistor with
a resistance of approximately 40 kohm. The RESET pin should be connected to a push-button, header or test
point to enable the use of the system recovery mode.