Atmel AT01607: XMEGA C Schematic ChecklistAtmel AT01607: XMEGA C Schematic Checklist
3
1.
Power supplies
1.1
Power supply connections
All power supply pins of the device must be connected to the microcontroller supply.
Both V
CC
(digital) and AV
CC
(analog) must be connected to the same microcontroller positive supply, thus ensuring that
they both share an identical supply profile. Likewise both ground pins must be connected to the same microcontroller
ground reference supply.
Figure 1-1. Power supply schematic.
10
μF
GND
AVCC
AGND
Close to device
POWER
SUPPLY
10
μH
100nF
VCC
100nF
10
μF
Ferrite
Bead
Close to power
supply
Close to device
Close to device
Table 1-1.
Power supply checklist.
Signal name
Recommended pin connection
Description
V
CC
1.6V to 3.6V
Decoupling/filtering capacitors 100nF
(1)(2)
and 10µF
(1)
Decoupling/filtering inductor 10µH
(1)(3)
Digital supply voltage
AV
CC
1.6V to 3.6V
Decoupling/filtering capacitors 100nF
(1)(2)
and 10µF
(1)
Ferrite bead
(4)
prevents the VCC noise interfering the AV
CC
Analog supply voltage
GND
Ground
Notes:
1. These values are given only as a typical example (that is, ceramic capacitors: 100nF, SMD 0402, X7R,
16V and 10µF, SMD1206, X5R, 6.3V) (that is, inductor: 10µH, 1.2A).
2.
Decoupling capacitor should be placed close to the device for each supply pin pair in the signal group, low
ESR caps should be used for better decoupling.
3.
Wire wound inductor should be added between the external power and the V
CC
for power filtering.
4.
Ferrite bead has better filtering performance than the common inductor at high frequency. It can be added
between V
CC
and AV
CC
for preventing digital noise from entering the analog power. The BEAD should
provide enough impedance (for example, 220
Ω at 100MHz, rated current 200mA, that is, Murata
BLM15BB221SN1D) for separating the digital power to the analog power.
