48.
Schematic Checklist
48.1. Introduction
This chapter describes a common checklist which should be used when starting and reviewing the
schematics for a SAM L22 design. This chapter illustrates recommended power supply connections, how
to connect external analog references, programmer, debugger, oscillator and crystal.
48.1.1. Operation in Noisy Environment
If the device is operating in an environment with much electromagnetic noise it must be protected from
this noise to ensure reliable operation. In addition to following best practice EMC design guidelines, the
recommendations listed in the schematic checklist sections must be followed. In particular placing
decoupling capacitors very close to the power pins, a RC-filter on the RESET pin, and a pull-up resistor
on the SWCLK pin is critical for reliable operations. It is also relevant to eliminate or attenuate noise in
order to avoid that it reaches supply pins, I/O pins and crystals.
48.2. Power Supply
The SAM L22 supports a single or dual power supply from 1.62V to 3.63V. The same voltage must be
applied to both VDDIN and VDDANA.
The internal voltage regulator has four different modes:
•
Linear mode: this mode does not require any external inductor. This is the default mode when CPU
and peripherals are running
•
Switching mode (Buck): the most efficient mode when the CPU and peripherals are running.
•
Low Power (LP) mode: This is the default mode used when the chip is in standby mode
•
Shutdown mode: When the chip is in backup mode, the internal regulator is turned off
Selecting between switching mode and linear mode can be done by software on the fly, but the power
supply must be designed according to which mode is to be used.
48.2.1. Power Supply Connections
The following figures show the recommended power supply connections for switched/linear mode, linear
mode only and with battery backup.
Atmel SAM L22G / L22J / L22N [DATASHEET]
Atmel-42402E-SAM L22G / L22J / L22N_Datasheet_Complete-07/2016
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