FX613(1997) 데이터 시트보기 (PDF) - CML Microsystems Plc
부품명
상세내역
일치하는 목록
FX613 Datasheet PDF : 2 Pages
| |||
FX613 Sensitivity Threshold Adjustment ......
The Data Sheet Specification
VDD
(V)
Must Decode Level
(dBu) (mVp-p)
(mVp)
3.3
-25.2 120
60
5.0
-21.6 181.8 90.0
Must Not Decode Level
(dBu) (mVp-p) (mVp)
-46 11
-42.4 16.7
5.5
8.35
Sensitivity Threshold
(dB)
20.8
20.8
Example, to reduce the Sensitivity Threshold to 6.0dB
By adjusting the dc level (-ve I/P of the comparator) of LEVEL IN pin with external resistors, see Figure 1; Va
is referenced to VBIAS (VDD/2).
At 5.0V:
Sensitivity Threshold = (90.9mVp + Va)/ (8.35mVp + Va) = 2 = 6.0dB
Va
= 74.2mVp
For 6.0 dB Sensitivity Threshold:
Must Decode level
=
Must Not Decode level =
165.1mVp =
82.55mVp =
330.2mVp-p
165.1mVp-p
= -16.44 dBu
= -22.46 dBu
External Resistors
Referrence to Figure 1. The resistor selection criteria:
1.
R1 + R2 + R3 + R4 < = 70kΩ
2.
R1 + R2 = R3 + R4
For the above example of 6.0dB, sensitivity threshold =
Va
R3
which gives
= R3/(R3 + R4) x 2.5Vp = 74.2mVp
= (R3 + R4) x 74.2mVp/2.5Vp
R4
= 33 x R3
If R3 = 1kΩ then R4 = 33kΩ and R1 + R2 = 34kΩ, or R1 + R2 + R3 = 35kΩ.
0
-5
-10
-15
Must Decode Level
-20
-25
12dB
-30
-35
20.8dB
Must-Not Decode Level
19.34mV
-40
-45
0
20
40
Fig.2
3dB
6dB
SENSITIVITY THRESHOLD LEVELS
74.2mV
191.8mV
60
80
100
120
140
160
180
200
Va (mV)
2
Share Link: 