Extended Feature Set Application Schematic - Atmel ATmega256RFR2 Manual

Table 4-1. Bill of Materials (BoM)
Designator Description
B1 SMD balun
SMD balun / filter
CB1 LDO VREG
CB3 bypass capacitor
CB2 Power supply bypass
CB4 capacitor
CX1, CX2 16MHz crystal load
capacitor
CX3, CX4 32.768kHz crystal load
capacitor
C1, C2 RF coupling capacitor
C4 (optional) RF matching
XTAL Crystal
XTAL 32kHz Crystal

4.2 Extended Feature Set Application Schematic

ATmega256/128/64RFR2
10
Capacitors should be placed as close as possible to the pins and should have a low-
resistance and low-inductance connection to ground to achieve the best performance.
The crystal (XTAL), the two load capacitors (CX1, CX2), and the internal circuitry
connected to pins XTAL1 and XTAL2 form the 16MHz crystal oscillator for the 2.4GHz
transceiver. To achieve the best accuracy and stability of the reference frequency, large
parasitic capacitances must be avoided. Crystal lines should be routed as short as
possible and not in proximity of digital I/O signals. This is especially required for the
High Data Rate Modes.
The 32.768 kHz crystal connected to the internal low power (sub 1µA) crystal oscillator
provides a stable time reference for all low power modes including 32 Bit IEEE 802.15.4
Symbol Counter ("MAC Symbol
asynchronous timer T/C2
Total shunt capacitance including CX3, CX4 should not exceed 15pF across both pins.
The very low supply current of the oscillator requires careful layout of the PCB and any
leakage path must be avoided.
Crosstalk and radiation from switching digital signals to the crystal pins or the RF pins
can degrade the system performance. The programming of minimum drive strength
settings for the digital output signal is recommended (see
Strength Register 0").
Value
2.4 GHz
1 µF
(100nF minimum)
1 µF
(100nF minimum)
12 pF
12 ... 25 pF
22 pF
0.47 pF
CX-4025 16 MHz
SX-4025 16 MHz
The ATmega256/128/64RFR2 supports additional features like:
• Security Module (AES)
• High Data Rate Mode up to 2MBits/s
• Antenna Diversity using alternate pin function DIG1/2 at Port G and F
Counter") and real time clock application using the
("Timer/Counter2 with PWM and Asynchronous
Manufacturer Part Number
Wuerth 748421245
Johanson 2450FB15L0001
Technology
AVX 0603YD105KAT2A
Murata GRM188R61C105KA12D
AVX 06035A120JA
Murata GRP1886C1H120JA01
Epcos B37930
Epcos B37920
AVX 06035A220JAT2A
Johnstech
ACAL Taitjen XWBBPL-F-1
Siward A207-011
Operation").
"DPDS0 - Port Driver
Comment
Filter included
X5R 10% 16V
(0603)
COG 5% 50V
(0603)
C0G 5% 50V
(0402 or 0603)
Rs=100 kOhm
8393CS-MCU Wireless-09/14