Application circuits, 1 basic application schematic – Rainbow Electronics AT86RF231 User Manual
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8111A–AVR–05/08
AT86RF231
5.
Application Circuits
5.1
Basic Application Schematic
A basic application schematic of the AT86RF231 with a single-ended RF connector is shown in
. The 50
Ω single-ended RF input is transformed to the 100Ω differential
RF port impedance using balun B1. The capacitors C1 and C2 provide AC coupling of the RF
input to the RF port, capacitor C4 improve matching.
Figure 5-1.
Basic Application Schematic
The power supply decoupling capacitors (CB2, CB4) are connected to the external analog sup-
ply pin (EVDD, pin 28) and external digital supply pin (DEVDD, pin 15). Capacitors CB1 and
CB3 are bypass capacitors for the integrated analog and digital voltage regulators to ensure sta-
ble operation. All decoupling and bypass 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 crystal oscillator. To achieve the best accuracy and stability of
8
7
6
5
4
3
2
1
9
10
11
12
13
14
15
16
25
26
27
28
29
30
31
32
AT86RF231
DIG3
AV
SS
DIG4
AV
SS
AVSS
RFP
RFN
AVSS
DVSS
DI
G1
DI
G2
SL
P
_
TR
DVS
S
DVDD
DVDD
XTA
L
2
DEV
D
D
DVS
S
AVS
S
AV
DD
EV
DD
AV
SS
XT
AL
1
17
18
19
20
21
22
23
24
DVSS
CLKM
IRQ
MISO
DVSS
MOSI
SCLK
CB3
CB4
D
ig
it
a
l In
te
rf
a
c
e
/RST
/SEL
V
DD
XTAL
CX1
CX2
CB1
V
DD
CB2
C1
C2
B1
RF
C3
R1
C4