LMH0303 Datasheet, PDF (17/27 Pages) National Semiconductor (TI) – 3 Gbps HD/SD SDI Cable Driver with Cable Detect

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8.2 Typical Application
Figure 5 shows the application circuit for the LMH0303.
V_CC
V_CC
LMH0303
SNLS285H – APRIL 2008 – REVISED MAY 2016
FAULT
RSTO
10 kΩ
75 Ω
49.9 Ω
Differential
Input
0.1 μF
V_CC
49.9 Ω
1
SDI
2
SDI
3
V_EE
4
R_REF
LMH0303
SDO ¹²
11
SDO
10
SD/HD
9
V_CC
75 Ω
0.1 μF
6.8 nH
75 Ω
4.7 μF ^{Coaxial Cable}
75 Ω
4.7 μF ^{Coaxial Cable} 75 Ω
6.8 nH
75 Ω
RSTI
750 Ω
ENABLE
SDA
SCL
V_CC
V_CC
10 kΩ
10 kΩ
0.1 μF
SD/HD
Copyright © 2016, Texas Instruments Incorporated
Figure 5. Application Circuit
8.2.1 Design Requirements
For the LMH0303 design example, Table 2 lists the design parameters.
Table 2. LMH0303 Design Parameters
Input termination
PARAMETER
Output AC-coupling capacitors
DC power supply coupling capacitors
Distance from device to BNC
High speed SDI and SDI trace impedance
High speed SDO and SDO trace impedance
REQUIREMENT
Required, 49.9 Ω are recommended (see Figure 5).
Required. Both SDO and SDO require AC-coupling capacitors. SDO AC-
coupling capacitors are expected to be 4.7 µF to comply with SMPTE
wander requirement.
To minimize power supply noise, place 0.1-µF capacitor as close to the
device V_CC pin as possible.
Keep this distance as short as possible.
Design differential trace impedance of SDI and SDI with 100 Ω.
Single-ended trace impedance for SDO and SDO with 75 Ω.
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