AT86RF230_07 Datasheet, PDF (9/98 Pages) ATMEL Corporation – Low Power 2.4 GHz Radio Transceiver for ZigBee™ and IEEE 802.15.4™ Applications

AT86RF230
The power supply decoupling capacitors (CB2, CB4) are connected to the external
analog supply pin (EVDD, pin 28) and the external digital supply pin (DEVDD, pin 15).
Capacitors CB1 and CB3 are bypass capacitors for the integrated analog and digital
voltage regulators to ensure stable operation (1 µF recommended value). All decoupling
and bypass capacitors should be placed as close as possible to the AT86RF230 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 crystal oscillator. To achieve the best
accuracy and stability of the reference frequency, large parasitic capacitances should
be avoided. Crystal lines should be routed as short as possible and not in proximity of
digital I/O signals.
Crosstalk from digital signals on the crystal pins or the RF pins can degrade the system
performance. Therefore, a low-pass filter (C3, R2) is placed close to the CLKM output
pin to reduce the radiation of signal harmonics. This is not needed if the CLKM pin is
not used. Then the output should be turned off during device initialization.
The application board ground plane should be separated into four independent
fragments, the analog, the digital, the antenna and the XTAL ground plane. The
exposed paddle shall act as reference of the individual grounds.
For further details see application note AVR2005 "Design Considerations for the
AT86RF230".
Table 5-1. Example Bill of Materials
Designator Description
Value
Manufacturer Part Number
Comment
B1
CB1
CB2
CB3
CB4
CX1
CX2
C1
C2
C3
R1
R2
XTAL
SMD balun
LDO VREG
bypass capacitor
Power supply
decoupling
LDO VREG
bypass capacitor
Power supply
decoupling
Crystal load capacitor
Crystal load capacitor
RF coupling capacitor
RF coupling capacitor
CLKM low-pass
filter capacitor
Pull-down resistor
CLKM low-pass
filter resistor
Crystal
2.4 GHz
1 µF
1 µF
1 µF
1 µF
12 pF
12 pF
22 pF
22 pF
2.2 pF
10 kΩ
Wuerth
AVX
Murata
AVX
Murata
Epcos
Epcos
AVX
AVX
Murata
680Ω
CX-4025 16 MHz ACAL Taitjen
SX-4025 16 MHz Siward
748421245
0603YD105KAT2A
X5R 10% 16V
GRM188R61C105KA12D (0603)
06035A120JA
GRP1886C1H120JA01
B37930
B37920
06035A220JAT2A
06035A229DA
GRP1886C1H2R0DA01
COG 5% 50V
(0603)
C0G 5% 50V
(0402 or 0603)
COG ±0.5 pF 50V
(0603)
Designed for fCLKM = 1 MHz
Recommended 0Ω, if
continuous transmission is
not required
Designed for fCLKM = 1 MHz
XWBBPL-F-1
A207-011
9
5131D-ZIGB-12/03/07