Si4708/09-B
Confidential Rev. 1.4 25
Reset value = 0x0000
Register 05h. System Configuration 2
BitD15D14D13D12D11D10D9D8D7D6D5D4D3D2D1D0
Name SEEKTH[7:0] BAND[1:0] SPACE[1:0] VOLUME[3:0]
Type R/W R/W R/W R/W
Bit Name Function
15:8 SEEKTH[7:0] RSSI Seek Threshold.
0x00 = min RSSI (default).
0x7F = max RSSI.
SEEKTH presents the logarithmic RSSI threshold for the seek operation. The
Si4708/09 will not validate channels with RSSI below the SEEKTH value. SEEKTH is
one of multiple parameters that can be used to validate channels. For more informa-
tion, see "AN349: Si4708/09 Programming Guide."
7:6 BAND[1:0] Band Select.
00 = 87.5–108 MHz (US/Europe, Default).
01 = 76–108 MHz (Japan wide band).
10 = 76–90 MHz (Japan).
11 = Reserved.
5:4 SPACE[1:0] Channel Spacing.
00 = 200 kHz (USA, Australia) (default).
01 = 100 kHz (Europe, Japan).
10 = 50 kHz.
3:0 VOLUME[3:0] Volume.
Relative value of volume is shifted –30 dBFS with the VOLEXT 06h[8] bit.
VOLEXT = 0 (default).
0000 = mute (default).
0001 = –28 dBFS.
:
:
1110 = 2 dBFS.
1111 = 0 dBFS.
VOLEXT = 1.
0000 = mute.
0001 = –58 dBFS.
:
:
1110=–32dBFS.
1111 = –30 dBFS.
FS = full scale.
Volume scale is logarithmic.
Si4708/09-B
26 Confidential Rev. 1.4
Reset value = 0x0000
Register 06h. System Configuration 3
Bit D15 D14 D13 D12 D11 D10 D9 D8 D7D6D5D4D3D2D1D0
Name SMUTER[1:0] SMUTEA[1:0] 0 0 0 VOLEXT SKSNR[3:0] SKCNT[3:0]
Type R/W R/W R/W R/W R/W R/W R/W R/W
Bit Name Function
15:14 SMUTER[1:0] Softmute Attack/Recover Rate.
00 = fastest (default).
01 = fast.
10 = slow.
11 = slowest.
13:12 SMUTEA[1:0] Softmute Attenuation.
00 = 16 dB (default).
01 = 14 dB.
10 = 12 dB.
11 = 10 dB.
11:9 Reserved Reserved.
Always write to zero.
8 VOLEXT Extended Volume Range.
0 = disabled (default).
1 = enabled.
This bit attenuates the output by 30 dB. With the bit set to 0, the 15 volume settings
adjust the volume between 0 and –28 dBFS. With the bit set to 1, the 15 volume set-
tings adjust the volume between –30 and –58 dBFS.
Refer to 4.5. "Stereo Audio Processing" on page 14.
7:4 SKSNR[3:0] Seek SNR Threshold.
0000 = disabled (default).
0001 = min (most stops).
1111 = max (fewest stops).
Required channel SNR for a valid seek channel.
3:0 SKCNT[3:0] Seek FM Impulse Detection Threshold.
0000 = disabled (default).
0001 = max (most stops).
1111 = min (fewest stops).
Allowable number of FM impulses for a valid seek channel.
Si4708/09-B
Confidential Rev. 1.4 27
Reset value = 0x0100
Reset value = 0x0000
Register 07h. Test 1
Bit D15 D14 D13D12D11D10D9 D8D7D6D5D4D3D2D1D0
Name Reserved AHIZEN Reserved
Type R/W R/W R/W
Bit Name Function
15 Reserved Reserved.
Always write to zero.
14 AHIZEN Audio High-Z Enable.
0 = Disable (default).
1 = Enable.
Setting AHIZEN maintains a dc bias of 0.5 x V
IO
on the LOUT and ROUT pins to pre-
vent the ESD diodes from clamping to the V
IO
or GND rail in response to the output
swing of another device. Register 07h containing the AHIZEN bit must not be written
during the powerup sequence and high-Z only takes effect when in powerdown and
V
IO
is supplied. Bits 13:0 of register 07h must be preserved as 0x0100 while in pow-
erdown and as 0x3C04 while in powerup.
13:0 Reserved Reserved.
If written, these bits should be read first and then written with their pre-existing values.
Do not write during powerup.
Register 08h. Test 2
Bit D15D14D13D12D11D10D9 D8D7D6D5D4D3D2D1D0
Name Reserved
Type R/W
Bit Name Function
15:0 Reserved Reserved.
If written, these bits should be read first and then written with their pre-existing values.
Do not write during powerup.

SI4709-B-GM

Mfr. #:
Manufacturer:
Silicon Labs
Description:
RF RCVR FM 76MHZ-108MHZ 16QFN
Lifecycle:
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