7. Power Management and Internal Regulators
7.1 Introduction
Control over the device power consumption can be achieved by enabling/disabling individual peripherals as needed. Each analog pe-
ripheral can be disabled when not in use and placed in low power mode. Digital peripherals, such as timers and serial buses, have their
clocks gated off and draw little power when they are not in use.
Power Distribution
Core LDO
Analog
Muxes
VDD
GND
Digital I/O
Interface
Port I/O Pins
CPU Core
RAM
Flash
Oscillators
1.8V
Peripheral
Logic
VREGIN
5V LDO
VIO
3.3V
USB PHY
D+
D-
Figure 7.1. Power System Block Diagram
Table 7.1. Power Modes
Power Mode
Details
Mode Entry
Wake-Up Sources
Normal
Core and all peripherals clocked and fully operational
—
—
Idle
• Core halted
• All peripherals clocked and fully operational
• Code resumes execution on wake event
Set IDLE bit in PCON0
Any interrupt
Suspend
• Core and peripheral clocks halted
• HFOSC0 and HFOSC1 oscillators stopped
• Regulators in normal bias mode for fast wake
• Timer 3 and 4 may clock from LFOSC0
• Code resumes execution on wake event
1. Switch SYSCLK to
HFOSC0
2. Set SUSPEND bit in
PCON1
• USB0 Bus Activity
• Timer 4 Event
• SPI0 Activity
• Port Match Event
• Comparator 0 Falling
Edge
• CLUn Interrupt-Enabled
Event
EFM8UB3 Reference Manual
Power Management and Internal Regulators
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