LMH6580VS National Semiconductor, LMH6580VS Datasheet - Page 17

• Manufacturer Part Number: LMH6580VS
• Manufacturer: National Semiconductor

Specifications of LMH6580VS

• Array Configuration: 8x4
• Number Of Arrays: 1
• Screening Level: Industrial
• Pin Count: 48
• Package Type: TQFP
• Power Supply Requirement: Dual
• Lead Free Status / RoHS Status: Not Compliant

30007247
FIGURE 5. Input Expansion Frequency Response
DRIVING CAPACITIVE LOADS
Capacitive output loading applications will benefit from the
use of a series output resistor R
. Capacitive loads of
OUT
5 pF to 120 pF are the most critical, causing ringing, frequency
response peaking and possible oscillation. Since most ca-
pacitive loading is due to undesired parasitic capacitances the
30007244
values of the capacitive loading will not usually be known ex-
FIGURE 3. Input Expansion with Separate Termination
actly. It is best to start with a conservative value of R
and
OUT
Resistors
decrease the value until the bandwidth shows slight peaking.
At this point the value of the isloation resistor will be deter-
mined by whether flat frequency response or maximum band-
width is the desired goal. Smaller values of R
will produce
OUT
some peaking, but maximum bandwidth. Larger resistor val-
ues will decrease bandwidth and suppress peaking.
As starting values, a capacitive load of 5 pF should have
around 75 Ω of isolation resistance. A value of 120 pF would
require around 12Ω. When driving transmission lines, the out-
put termination resistor is normally sufficient.
30007246
FIGURE 4. Input Expansion Frequency Response
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