Datasheet

TEF6901A_3 © NXP B.V. 2008. All rights reserved.
Product data sheet Rev. 03 — 20 March 2008 17 of 107
NXP Semiconductors
TEF6901A
Integrated car radio
8.1.3 Read mode: data byte USN/WAM
After AF update sampling the USN and WAM read value is held (indicated by IFCM = 10)
for easy I
2
C-bus read-out. The USN and WAM detectors remain active in the background.
The USN and WAM data hold is released after I
2
C-bus read.
Fig 7. FM RF antenna input signal and level output voltage
V
ANT
(mV)
10
−4
10
2
10110
−3
10
−1
10
−2
001aab521
2
1
3
4
V
LEVEL
(V)
0
Table 11. USN/WAM - format of data byte 2
7 6 5 4 3 2 1 0
USN3 USN2 USN1 USN0 WAM3 WAM2 WAM1 WAM0
Table 12. USN/WAM - data byte 2 bit description
Bit Symbol Description
7 to 4 USN[3:0] ultrasonic noise detector; this value indicates the USN content of the
MPX audio signal; see
Figure 24
3 to 0 WAM[3:0] wideband AM detector; this value indicates the WAM content of the
LEVEL voltage; see
Figure 24