U4254BM-M Datasheet, PDF (4/14 Pages) ATMEL Corporation – Low-noise AM/FM Antenna Impedance Matching IC

AGCADJ
FMOUT
Figure 5. Internal Circuit at Pin AGC
AGC
4
ESD
V_S
The threshold of the AGC can be adjusted by varying the DC current at pin AGCADJ. If
pin AGCADJ is connected directly to GND1, the threshold is set to 96 dBµV at the FM
amplifier output. If a resistor is connected between AGCADJ and GND1, the threshold is
shifted to higher values with increasing resistances. If AGCADJ is open, the threshold is
set to 106 dBµV.
Figure 6. Internal Circuit at Pin AGCADJ
65 kΩ
ESD
13 AGCADJ
The FM amplifier output is an open collector of a bipolar RF transistor. It should be con-
nected to V_S via a coil.
Figure 7. Internal Circuit at Pin FMOUT
15 FMOUT
ESD
4 U4254BM-M
4772B–AUDR–11/03