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Transmitter External Parameters: Pin TX_OUT, ALC_IN, TX_ENB
To guarantee the transmitter external specifications the TX_CLK frequency must be 12 MHz ± 100 ppm.
Table 7. TRANSMITTER EXTERNAL PARAMETERS
Parameter
Maximum peak output level
Second order harmonic distortion
Third order harmonic distortion
Frequency accuracy of the gener-
ated sine wave
Capacitive output load at pin
TX_OUT
Resistive output load at pin
TX_OUT
Turn off delay of TX_ENB output
Automatic level control attenuation
step
Maximum attenuation
Low threshold level on ALC_IN
High threshold level on ALC_IN
Input impedance of ALC_IN pin
Power supply rejection ration of the
transmitter section
4. This parameter will not be tested in production.
5. This delay corresponds to the internal transmit path delay and will be defined during design.
6. Taking into account the resolution of the DDS and an accuracy of 100ppm of the crystal.
7. A sinusoidal signal of 10 kHz and 100 mVpp is injected between VDDA and VSSA. The digital AD converter generates an idle pattern. The
signal level at TX_OUT is measured to determine the parameter.
8. A sinusoidal signal of 50 Hz and 100 mVpp is injected between VDDA and VSSA. The digital AD converter generates an idle pattern. The
signal level at TX_OUT is measured to determine the parameter.
The LPF filter + amplifier must have a frequency characteristic between the limits listed below. The absolute output level
depends on the operating condition. In production the measurement will be done for relative output levels where the 0 dB
reference value is measured at 50 kHz with a signal amplitude of 100 mV.
Table 8. TRANSMITTER FREQUENCY CHARACTERISTICS
Frequency (kHz)
NCN49597
Test Conditions
f
= 23 – 75 kHz
TX_OUT
f
= 95 kHz
TX_OUT
Level control at max. output
f
= 95 kHz
TX_OUT
Level control at max. output
f
= 95 kHz
TX_OUT
Level control at max. output
(Notes 4 and 6)
(Note 4)
(Note 5)
10
95
130
165
330
660
1000
2000
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Symbol
Min
V
0.85
TX_OUT
0.76
HD2
HD3
Df
TX_OUT
CL
TX_OUT
RL
5
TX_OUT
Td
0.25
TX_ENB
ALC
2.9
step
ALC
20.3
range
VTL
−0.46
ALC_IN
VTH
−0.68
ALC_IN
R
111
ALC_IN
PSRR
10
TX_OUT
(Note 7)
Attenuation
Min
−0.5
−1.3
−4.5
10
Typ
Max
Unit
1.15
Vp
1.22
−54
dB
−53
dB
30
Hz
20
pF
kW
0.5
ms
3.1
dB
21.7
dB
−0.36
V
−0.54
V
189
kW
35
dB
(Note 8)
Max
Unit
0.5
dB
0.5
dB
−2.0
dB
−3.0
dB
−18.0
dB
−36.0
dB
−50
dB
−50
dB
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