TDA7420 Datasheet, PDF (9/29 Pages) STMicroelectronics – MULTIFUNCTIONAUDIO PROCESSOR

TDA7420
NOISE BLANKER PART
FEATURES:
INTERNAL 2nd ORDER 140KHz HIGH-PASS
FILTER
NOISE RECTIFIER OUTPUT FOR SIGNAL
QUALITY DETECTION
PROGRAMMABLE TRIGGER THRESHOLD
TRIGGER THRESHOLD DEPENDENT ON
HIGH FREQUENCY NOISE WITH PRO-
GRAMMABLE GAIN
ADDITIONAL CIRCUITS FOR DEVIATION
AND FIELD STRENGTH -DEPENDENT TRIG-
GER ADJUSTMENT
BLANKING TIME PROGRAMMABLE BY EX-
TERNAL CAPACITOR
VERY LOW OFFSET CURRENT DURING
HOLD TIME DUE TO OPAMPS WITH MOS
INPUTS
ELECTRICAL CHARACTERISTICS (continued)
Symbol
Parameter
V_TRMIN Trigger Threshold (*) ¹⁾ minimum
V_TRMIN Trigger Threshold ¹⁾ maximum
VTRSTEP Trigger Threshold Step Size
V_TRNOISE Noise Adjusted Trigger Threshold ²⁾
V_PEAK
Rectifier Voltage
D2 on byte 2 = 1
V_RECTDEV Deviation Dependent Rectifier
Voltage ³⁾
V_RECTFS Field Strength Controlled Rectifier
Voltage ⁴⁾
T_S
Suppression Pulse Duration
I_OS
Input Offset Current During
Suppression Time
Test Condition
Measured with
NBT = 000
VPEAK = 1.2V
D2 on byte 2 = 1
D2 on byte 2 = 0
Measured with
NBT = 111
V_PEAK = 1.2V
D2 on byte 2 = 1
D2 on byte 2 = 0
Min.
100
130
Measured with
V_PEAK = 1.4V
D2 on byte 2 = 0
VMPX = 0mV
V_MPX = 50mV
f = 200KHz
V_MPX = 100mV
f = 200KHz
Measured with
V_MPX = 500mV
(75KHz dev.)
Measured with
V_MPX = 0mV
VSB-VR = -500mV
(fully mono.)
CBLANK = 330pF
NAT = 00
NAT = 01
NAT = 10
NAT = 11
OVD = 00(off)
OVD = 01
OVD = 10
OVD = 11
FSC = 00(off)
FSC = 01
FSC = 10
FSC = 11
Typ.
150
30
185
65
5
140
180
240
280
0.9
1.5
2.0
0.9
1.2
2.0
2.8
0.9
1.3
1.9
2.4
40
10
Max. Unit
200 mVp
250 mVp
mVp
mVp
mVp
mVp
mVp
V
V
V
V
V
V
V
V
V
V
V
µs
pA
(*) All thresholds are measured by using a pulse with TR = 2µs, THIGH = 2µs and TF = 10µs.
The repetition rate must not increase the PEAK voltage.
1) NTB represents bits D0 - D2 of NB byte 1
2) NAT represents bits D3 - D4 of NB byte 1
3) OVD represents bits D5 - D6 of NB byte 1
4) FSC represents bits D0 - D1 of NB byte 2
VMPX
VTH
DC-LEVEL
D94AU185
TR THIGH
TF
Time
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