AN543
Rev. 0.9
105
Property 0x1305 FM_ACF_BLEND_THRESHOLD
The FM_ACF_BLEND_THRESHOLD property sets the interrupt trigger threshold for stereo blend. The threshold is
expressed as a percentage in terms of L minus R (L – R) gain factor K. When the L–R gain falls below this
threshold and the BLEND_INT is enabled through the FM_ACF_INTERRUPT_SOURCE property, the BLEND_INT
will be asserted. 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.
Note:
Stereo Separation S = (1 + K) / (1 – K), where K is the L minus R gain factor. Stereo separation of 1 implies mono mode
and stereo separation of >1 implies that the part is in stereo with up to 20 log(S) dB of stereo separation. This property
expresses the threshold value of K as a percentage. For example, value 0x0032 = a K of 50%, or a stereo separation of
S = (1.5 / 0.5) = 3. The interrupt would then trigger at 20 log(3) = 9.5 dB of stereo separation.
Default: 0
Units: % L–R gain
FM_ACF_BLEND_THRESHOLD
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
0x000
BLEND_THRESH[6:0]
0x000
0x00
Bit
Name
Function
15:7
Reserved
Always write 0.
6:0
BLEND_
THRESH
[6:0]
Stereo Blend Interrupt threshold in units of % L–R gain, which triggers the Blend threshold
interrupt when L–R gain falls below this threshold.
Default is 0%.
Range is 0–100%.
