AN602

2

Rev. 0.3

2. Si4822/26/27/40/44 Default Frequency Band Definition and Selection

For Si4822/26/27/40/44, there are two methods for defining a frequency band, one is to select one of the chip

internal default bands by using the slide switch and resistor ladder. Another method is to use the host MCU

sending command to make the chip work in the desired band. Refer to application note, “AN610: Si48xx ATDD

Programming Guide”, for information on how to use the Si4822/26/27/40/44 to define a frequency band and set a

band property. This section describes how to select the default frequency band by using the slide switch and

resistors ladder.

The Si4822/40 has five defined FM bands and five defined AM bands. The Si4826/27/44 has an added 16 SW

bands. In each FM band, the parts also offer two de-emphasis selections and two LED stereo separation threshold

selections, which results in a total 41 combinations to choose from.

The Si4822/26/40/44-A supports FM band range less than 23 MHz and SW band range less than 1.15 MHz. The

Si4827-A/44-B supports wider FM/SW band range. Refer to application note, “AN610: Si48xx ATDD Programming

Guide” for details.

2.1. Si4822/26/27/40/44 Default Band Definition

For Si4822/26/27/40/44, the FM band definition is in fact 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

Band

Name

Band Frequency

Range

De-emphasis (FM)

Channel Space (AM)

Stereo LED on

Conditions

(Only for Si4840/44)

Total R to GND

(k

, 1%)

Band1

FM1

87–108 MHz

75 µs

Separation = 6 dB,

RSSI = 20

　47

Band2

FM1

87–108 MHz

75 µs

Separation = 12 dB,

RSSI = 28

　57

Band3

FM1

87–108 MHz

50 µs

Separation = 6dB,

RSSI = 20

　67

Band4

FM1

87–108 MHz

50 µs

Separation = 12 dB,

RSSI = 28

　77

Band5

FM2

86.5–109 MHz

75 µs

Separation = 6 dB,

RSSI = 20

　87

Band6

FM2

86.5–109 MHz

75 µs

Separation = 12 dB,

RSSI = 28

　97

Band7

FM2

86.5–109 MHz

50 µs

Separation = 6 dB,

RSSI = 20

　107

Band8

FM2

86.5–109 MHz

50 µs

Separation = 12 dB,

RSSI = 28

　117

Band9

FM3

87.3–108.25 MHz

75 µs

Separation = 6 dB,

RSSI = 20

　127