AN543
Rev. 0.9
127
Property 0x2200 FM_CHBW_SQ_MIN_MAX
The FM_CHBW_SQ_MIN_MAX property sets the maximum and minimum Channel Filter Bandwidth in kHz based
on RSSI/STRONGDEV (for Si475x-A20 and later) or RSSI/SNR (for Si475x-A10), as selected with through
property 0x1306, FM_ACF_CONTROL. For Si475x-A20 and later, this engine is only enabled when RSSI is below
the FM_CHBW_WEAKSIG_THR (property 0x220F). To force a given Channel Filter Bandwidth, set the min and
max to the same value. The CTS bit (and optional interrupt) is set when it is safe to send the next command. This
property may only be set or read in powerup mode.
Notes:
1.
The Si4750/51/52/53 do not support dynamic bandwidth control, hence MIN[7:0] = MAX[7:0]. The minimum of MAX[7:0]
of properties 0x2200, 0x2205, and 0x220A determines the Channel Filter Bandwidth. Default for Si4750/51/52/53-A10 is
110 kHz; default for Si4750/51/52/53-A20/A30 is 150 kHz.
2.
RSSI/SNR can be used to control this engine for Si475x-A10. RSSI/STRONGDEV can be used to control this engine for
Si475x-A20 and later.
Si4754/55/56/57 Default: 0x9637
Si4750/51/52/53 Default: 0x6E6E
Units: kHz
FM_CHBW_SQ_MIN_MAX
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
MAX[7:0]
MIN[7:0]
0x96
0x37
Bit
Name
Function
15:8
MAX [7:0]
Sets the maximum Channel Filter Bandwidth in kHz.
Si4754/55/56/57 default is 150 kHz.
Si4750/51/52/53 default is 110 kHz.
Range is 1–150 kHz.
7:0
MIN [7:0]
Sets the minimum Channel Filter Bandwidth in kHz.
Si4754/55/56/57 default is 55 kHz.
Si4750/51/52/53 default is 110 kHz.
Range is 1–150 kHz.
