lt6559cud-trpbf Linear Technology Corporation, lt6559cud-trpbf Datasheet - Page 10

• Manufacturer Part Number: lt6559cud-trpbf
• Description: Low Cost 5v/?5v 300mhz Triple Video Amplifier In 3mm X 3mm Qfn
• Manufacturer: Linear Technology Corporation

TYPICAL APPLICATIONS
LT6559
3-Input Video MUX Cable Driver
The application on the fi rst page of this data sheet shows
a low cost, 3-input video MUX cable driver. The scope
photo below (Figure 4) displays the cable output of a
30MHz square wave driving 150Ω. In this circuit the ac-
tive amplifi er is loaded by the sum of R
disabled amplifi er. Resistor values have been chosen to
keep the total back termination at 75Ω while maintaining
a gain of 1 at the 75Ω load. The switching time between
any two channels is approximately 32ns when both enable
pins are driven (Figure 5).
When building the board, care was taken to minimize trace
lengths at the inverting inputs. The ground plane was also
pulled a few millimeters away from R
sides of the board to minimize stray capacitance.
10
200mV/DIV
OUTPUT
R
R
f = 10MHz
L
F
= 150Ω
= R
Figure 4. Square Wave Response
G
= 301Ω
5ns/DIV
V
F
OUT
V
F
IN
and R
and R
V
R
Figure 6. Large-Signal Pulse Response
S
F
6559 F04
= 301Ω
= ±5
G
G
on both
of each
R
R
G
S
= 16.9Ω
= 150Ω
20ns/DIV
C
Using the LT6559 to Drive LCD Displays
Driving a variety of XGA and UXGA LCD displays can be
a diffi cult problem because they are usually a capacitive
load of over 300pF, and require fast settling.
The LT6559 is particularly well suited for driving these LCD
displays because it can drive large capacitive loads with a
small series resistor at the output, minimizing settling time.
As seen in Figure 6, at a gain of +3 with a 16.9Ω output
series resistor and a 330pF load, the LT6559 is capable
of settling to 0.1% in 30ns for a 6V step.
L
= 330pF
Figure 5. 3-Input Video MUX Switching Response (A
V
V
at 3.58MHz
S
INA
= ±5
= V
6559 F06
INB
= 2V
P-P
20ns/DIV
6559 F05
EN A
EN B
OUTPUT
V
= 2)
6559f