AN555
Si483
X
-B/Si4820/24 A
NTENNA
, S
CHEMATIC
, L
AYOUT
,
AND
D
E S I G N
G
U ID ELINE S
1. Introduction
This document provides general Si483x-B/Si4820/24 design and AM/FM/SW antenna selection guidelines,
including schematic, BOM and PCB layout. All users should follow the Si483x-B/Si4820/24 design guidelines
presented in Section 2 and Section 3 and choose the appropriate antennas based on the applications and device
used according to Sections 4 through 8.
Table 1. Part Selection Guide
SW Antenna
Air Loop
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AN555
SW Receiver
AM Receiver
FM Receiver
Ferrite Loop
Headphone
FM Receiver
Whip
AM Antenna
FM Antenna
Function
†Part
Number
†General
Description
Si4831-B30
Si4835-B30
Si4835-B31
Si4820-A10
Si4824-A10
Wheel-tuned AM/FM Receiver
Wheel-tuned AM/FM/SW Receiver
Wheel-tuned AM/FM/SW Receiver,
Enhanced SW Tuning Feel
Entry Level Wheel-tuned AM/FM
Receiver, Mono Audio
Entry Level Wheel-tuned AM/FM/SW
Receiver, Mono Audio
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Rev. 0.2 11/11
Copyright © 2011 by Silicon Laboratories
Whip
AN555
2. Frequency Band Definition and Selection
Five FM bands and five AM bands are defined for the Si4831-B/Si4820. The Si4835-B/Si4824 has 16 SW bands
available. In each FM band, the parts also offer two de-emphasis selections and two LED stereo separation
threshold selections, which result in a total of 41 combinations. This section shows the detailed band definition and
selection information.
2.1. Band Definition
For the Si483x-B/Si4820/24, the FM band definition is a combination of frequency range, de-emphasis and LED
stereo separation threshold. Customers should choose the band according to not only frequency range, but also
de-emphasis setting and LED stereo separation requirements. For AM and SW, simply choose the band according
to the frequency range desired.
Table 2. Band Sequence Definition
Band
Number
Band1
Band2
Band3
Band4
Band5
Band6
Band7
Band8
Band9
Band10
Band11
Band12
Band13
Band14
Band Name Band Frequency
Range
FM1
FM1
FM1
FM1
FM2
FM2
FM2
FM2
FM3
FM3
FM3
FM3
FM4
FM4
87–108 MHz
87–108 MHz
87–108 MHz
87–108 MHz
86.5–109 MHz
86.5–109 MHz
86.5–109 MHz
86.5–109 MHz
87.3–108.25 MHz
87.3–108.25 MHz
87.3–108.25 MHz
87.3–108.25 MHz
76–90 MHz
76–90 MHz
De-emphasis
Stereo LED on
Threshold
(Only for Si483x-B)
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Total R to GND
(k, 1%)
47
57
67
77
87
97
107
117
127
137
147
157
167
177
50 µs
50 µs
75 µs
75 µs
50 µs
50 µs
75 µs
75 µs
50 µs
50 µs
75 µs
75 µs
50 µs
50 µs
2
Rev. 0.2
AN555
Table 2. Band Sequence Definition (Continued)
Band
Number
Band15
Band16
Band17
Band18
Band19
Band20
Band21
Band22
Band23
Band24
Band25
Band26
Band27
Band28
Band29
Band30
Band31
Band32
Band33
Band34
Band35
Band36
Band37
Band38
Band39
Band40
Band41
Band Name Band Frequency
Range
FM4
FM4
FM5
FM5
FM5
FM5
AM1
AM2
AM3
AM4
AM5
SW1
SW2
SW3
SW4
SW5
SW6
SW7
SW8
SW9
SW10
SW11
SW12
SW13
SW14
SW15
SW16
76–90 MHz
76–90 MHz
64–87 MHz
64–87 MHz
64–87 MHz
64–87 MHz
520–1710 kHz
522–1620 kHz
504–1665 kHz
520–1730 kHz
510–1750 kHz
5.6–6.4 MHz
5.95–6.2 MHz
6.8–7.6 MHz
7.1–7.6 MHz
9.2–10 MHz
9.2–9.9 MHz
11.45–12.25 MHz
11.6–12.2 MHz
13.4–14.2 MHz
13.57–13.87 MHz
15–15.9 MHz
15.1–15.8 MHz
17.1–18 MHz
17.48–17.9 MHz
21.2–22 MHz
21.45–21.85 MHz
De-emphasis
Stereo LED on
Threshold
(Only for Si483x-B)
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Separation = 6 dB,
RSSI = 20
Separation = 12 dB,
RSSI = 28
Total R to GND
(k, 1%)
187
197
207
217
227
237
247
257
267
277
287
297
307
317
327
337
347
357
367
377
387
397
407
417
427
437
447
75 µs
75 µs
50 µs
50 µs
75 µs
75 µs
Rev. 0.2
3
AN555
2.2. Si483x-B/Si4820/24 Band Selection
Refer to Figure 1 below for the band selection circuits. Selecting a band determines the resistance value from the
band select pin to GND.
To select a specific band, you need to ensure two things:
1. Total value of resistance from the BAND to GND is equal to the value specified in Table 2
2. Total resistance from TUNE1 to GND is 500 k in 1% tolerance
The following sections describe some commonly used bands and their respective selection circuits.
2.2.1. Typical 12-band application
Figure 1 and Table 3 illustrate the band and resistor value details for a typical 12-band application.
4
Rev. 0.2
AN555
TUNE1
R36
33k 1%
R43
30k 1%
SW15 (21.2MHz - 22MHz)
R35
20k 1%
SW13 (17.1MHz - 18MHz)
R15
20k 1%
SW11 (15MHz - 15.9MHz)
Si4835/24 only
R10
20k 1%
SW9 (13.4MHz - 14.2MHz)
R12
20k 1%
S2
BAND
1
2
3
4
5
6
7
8
9
10
11
12
13
R11
20k 1%
SW7(11.45MHz - 12.25MHz)
SW5(9.2MHz - 10.0MHz)
R14
20k 1%
SW3(6.8MHz - 7.6MHz)
R9
20k 1%
SW1 (5.6MHz - 6.4MHz)
R8
50k 1%
AM1 (520kHz - 1710kHz)
R7
20k 1%
FM5 (64MHz - 87MHz)
R28
40k 1%
FM4 (76MHz - 90MHz)
R29
120k 1%
FM1 (87MHz - 108MHz)
R33
20k 1%
R44
47k 1%
Figure 1. Typical 12-Band Selection Circuit
Rev. 0.2
5
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