SA2104/SA2104S

HANGZHOU SILAN MICROELECTRONICS CO.,LTD

REV:2.0

2004.07.31

Http: www.silan.com.cn

Page 7 of 13

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Pin voltage (Typ.) (V)

Pin

No.

Symbol

Pin description

Internal circuit

AM

FM

22

AM RF IN

AM RF input pin.

3.0

3.0

23

--

3.0

3.0

24

FM RF OUT

FM RF output pin.

3.0

3.0

FUNCTION DESCRIPTION

Application note:

1. AM low-cut circuit

When pin3 is open, no AF signal can pass through the AMP stage because of the common mode.

When the value of C3 that connected to pin3 is over 1uF, all AF signal can pass through the AMP stage.

The cut-off frequency fL is determined by the internal resistance 22k

Ω (Typ.) and the external capacitor C3 as

below:

C3

x

3

10

x

22

x

x

2

1

=

(Hz)

It is possible to reduce the recovered output level at AM mode, by additional resistance between the pin (3)

and GND line.

2. FM detection circuit

Recommended circuit and recommended coil are as follows. (Test frequency is 10.7M)