TDA7541W STMicroelectronics, TDA7541W Datasheet - Page 35

• Manufacturer Part Number: TDA7541W
• Description: IC TUNER AM/FM CAR RADIO 64-LQFP
• Manufacturer: STMicroelectronics

Specifications of TDA7541W

• Modulation Or Protocol: AM, FM
• Applications: Automotive Audio
• Current - Receiving: 48mA
• Data Interface: PCB, Surface Mount
• Antenna Connector: PCB, Surface Mount
• Voltage - Supply: 7.7 V ~ 9 V
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Features: -
• Frequency: -
• Sensitivity: -
• Memory Size: -
• Data Rate - Maximum: -
• Lead Free Status / Rohs Status: Compliant

TDA7541
Figure 6.
Automatic deviation controlled threshold adjustment
If the system is tuned to stations with a high deviation the noise blanker can trigger on the
higher frequencies of the modulation. To avoid this wrong behavior, which causes noise in
the output signal, the noise blanker offers a deviation-dependent threshold adjustment. By
rectifying the MPX signal a further signal representing the actual deviation is obtained. It is
used to increase the PEAK voltage. The gain of this circuit is programmable in 3 steps
(NBDC) of the stereo decoder-byte (the first step turns off the detector).
Figure 7.
Multipath influence on noise blanker
To react on high repetitive spikes caused by a Multipath-situation, the discharge-time of the
V
two ways to do this.
PEAK
a)
b)
voltage can be decreased depending on the voltage-level at Pin MPTC. There are
Switch on the linear influence of the Multipath-Level on the PEAK-signal . In this
case the discharge slew rate is 1 V/ms. The slew rate is measured with
RDischarge=infinite and VMPTC = 2.5 V
Activate a function, which switches to the 18k discharge resistor if the Multipath-
Level is below 2.5 V. If multipath influence on noise blanker is switched ON than
MPF bit has to be set to 0.
V PEAK
≈ 3V
Stereo blend controlled threshold adjust
Deviation controlled threshold adjust
NOISE
V PEAK
[V ]
OP
2.0
1.5
1.0
0.8
noisy signal
20
Doc ID 13686 Rev 4
MONO
32.5
45
ATC_SB OFF (11)
STEREO
75
1.6V (01)
1.4V (10)
2.0V (00)
good signal
00
01
10
11
Detector off
DEVIATION [KHz]
Functional description
0.8V
E'
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