Siemens TDA4320X Datasheet
FM-IF with Counter Output, Field Strength Indicator,
Noise Detector and MUTE Setting
1 Overview
1.1 Features
• 7-stage limiter amplifier
• Coincidence demodulator
• Counter output with request input
• Field strength output
• Multipath identification circuit
• Adjustable muting depth (with full muting ≥ 80 dB)
• This device is ESD protected
P-DSO-16-1
TDA 4320X
Type Ordering Code Package
TDA 4320X Q67000-A-5000 P-DSO-16-1
Semiconductor Group 35 04.96
1.2 Pin Configuration
(top view)
TDA 4320X
P-DSO-16-1
Figure 1
1.3 Pin Definitions and Functions
Pin No. Symbol Function
1 GND Ground
Decoupling capacitors for bias, VS and V
connected directly to Pin 1
2 Multipath
identification input
Multipath identification input
High impedance input (
the filtered field strength output (high pass or band pass).
3 Rectifier time
constant
Rectifier time constant
Determines the attack and release time of the
identification circuit.
4 Multipath
identification
output
Multipath identification output
Open npn-collector output, which is low during
(V4/V1 ≤ 0.7 V) multipath interference.
Pins are to be
REF
R
~10kΩ). This input receives
i
5 MUTE input MUTE input
For DC voltage (usually derived from field strength output
voltage) which attenuates the AF output voltage by the
setting muting depth (Pin 7). Max. attenuation when
V
= 0 V, no attenuation when V5≥ 0.5 V.
5
6 AF output AF output
Demodulated FM-IF.
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1.3 Pin Definitions and Functions (cont’d)
Pin No. Symbol Function
7 MUTE depth MUTE depth
Adjustment by connecting a dc voltage to ground the
requested muting depth can be set. Maximal attenuation
of AF output voltage with
attenuation with
V
≤ 1V (≥80 dB).
7
V
7
TDA 4320X
V
= 2.4 V (typ. 38 dB), minimal
7
= 4.8 V (typ. 0 dB). Full muting with
8 Demodulator
tank circuit
Demodulator tank circuit
Driven via two on-chip capacitors (approx.15 pF ± 25 %).
The tank circuit voltage should be typ. 400 mVpp.
9 Demodulator
Demodulator circuit
circuit
10 Reference
voltage
Reference voltage
Should be RF decoupled to Pin 1.
11 IF counter output IF counter output
Provides the IF carrier frequency (low impedance output
R
≈ 1.5 kΩ).
out
12
V
S
Supply voltage
RF decoupled to Pin 1
13 Field strength
output
Field strength output
Supplies a DC voltage proportional to the IF input level
with very low delay time.
14 Field strength
adjust
Field strength adjust
Adjustment of slope and starting point of field strength
output voltage
15 IF input bias IF input bias
To be RF decoupled to Pin 1
16 IF input IF input
FM-lF input
Semiconductor Group 37 04.96
1.4 Functional Block Diagram
TDA 4320X
Figure 2
Semiconductor Group 38 04.96
TDA 4320X
2 Functional Description
The FM-IF demodulator TDA 4320X has been developed especially for car radio
applications. The on-chip multipath identification circuit activates an interference
suppression circuit in case of multipath interferences.
3 Circuit Description
The IC includes a 7-stage capacitive coupled limiter amplifier with coincidence
demodulator and AF output. The AF output signal can be continuously attenuated to
decrease the noise. In case of multipath interferences, the TDA 4320X includes an
identification circuitry. There is a field strength output (with min. 76 dB dynamic range,
typ. ± 1 dB nonlinearity and typ. ± 3 dB temperature drift), an IF counter output and an
adjustable muting (with full muting ≥ 80 dB).
Semiconductor Group 39 04.96
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