TDA7421 datasheet(4/38 Pages) STMICROELECTRONICS

4 / 38 page

PIN DESCRIPTION (continued)

Name

Function

DIG GND

Digital circuits ground

28(*)

IFC SSTOP

AM STEREO OUT

Search stop signal or

Output (single ended) of AM IF amplifier

CLN GND

"Clean" ground

IF2 GND

IF 2nd ground

AM AGC2 TC

AM 2nd AGC time constant

AM DET

Connection to the capacitor of the AM diode-capacitor detector

AM BPF

Connection to the AM IF filter

AM REF

Reference voltage of AM IF amplifier

AM IF2 in

Input (single ended) of AM 2nd IF amplifier

IF2 VCC

IF 2nd positive supply

FM QUOD -

"-" Insertion pt. of FM quadrature network (differential)

FM QUAD +

"+" Insertion pt. of FM quadrature network (differential)

AUDIO OUT

Audio frequency output (single ended)

40 (*)

FM SD

AM SD

FM Station detector output or

AM Station detector output

41(*)

FM SMETER

AM SMETER

FM DET ADJ

FM S-meter output or

AM S-meter output or

FM detuning adjustment

FM MUTE DRIVE

FM mute time constant

FM BW TC

FM detuning detector time constant

IF1 GND

IF 1st ground

FM LIM IN -

Input "-" of FM limiter (differential input)

FM LIM IN +

Input "+" of FM limiter (differential input)

IF1 VCC

IF 1st positive supply

FM IF AMP2 OUT

Output (single ended) of the FM IF 2nd amplifier buffer

FM IF AMP2 IN -

Input "-" of the FM IF 2nd amplifier (differential input)

FM IF AMP2 IN +

Input "+" of the FM IF 2nd amplifier (differential input)

FM IF AMP1 OUT

Output (single ended) of the FM IF 1st amplifier buffer

FM IF AMP1 IN -

Input "-" of the FM IF 1st amplifier (differential input)

FM IF AMP1 IN +

Input "+" of the FM IF 1st amplifier (differential input)

AM MIX2 OUT -

Output "-" of the AM 2nd mixer (differential output)

AM MIX2 OUT +

Output "+" of the AM 2nd mixer (differential output)

RF VCC

RF stage positive supply

AM MIX2 IN -

Input "-" to the AM 2nd mixer (differential input)

AM MIX2 IN +

Input "+" to the AM 2nd mixer (differential input)

FM IF AGC IN

Input FM IF AGC circuit

MIX OUT -

Output "-" of the FM/AM 1st mixer (differential output)

MIX OUT +

Output "+" of the FM/AM 1st mixer (differential output)

AM AGC1 TC

AM 1st AGC time constant

AM AGC1 RF AMP

Voltage output of the AM 1st AGC, to the transistor of the RF AF amplifier

AM AGC1 PIN

Current output of the AM 1st AGC, to the PIN diodes antenna AM attenuator

(*) Pin function is user-defined by software.

TDA7421

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