LTC1520CS#TRPBF Linear Technology, LTC1520CS#TRPBF Datasheet - Page 7

• Manufacturer Part Number: LTC1520CS#TRPBF
• Description: IC LINE RCVR HI-SPD QUAD 16-SOIC
• Manufacturer: Linear Technology
• Type: Line Receiverr

Specifications of LTC1520CS#TRPBF

• Number Of Drivers/receivers: 0/4
• Protocol: LVDS
• Voltage - Supply: 4.75 V ~ 5.25 V
• Mounting Type: Surface Mount
• Package / Case: 16-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

LTC1520 receiving differential data from a PECL driver. As
in the single-ended configurations, care must be taken to
properly terminate the differential data lines to avoid
unwanted reflections, etc.
Alternate Uses
The tightly controlled propagation delay of the LTC1520
allows the part to serve as a fixed delay element. Figure 9
shows the LTC1520 used as a tapped delay line with 18ns
to form longer delay lines. Each tap in the delay line is
accurate to within 17% over temperature.
As shown in Figure 10, the LTC1520 can be used to create
a temperature stable ring oscillator with period incre-
ments of 36ns. Low skew and good channel-to-channel
matching enable this oscillator to achieve better than a 45/
55 duty cycle (the duty cycle approaches 50/50 as more
LTC1520s are used for lower frequencies). Note that the
fixed voltage bias may either be created externally with a
resistor divider or generated internally using a bypass
capacitor and the internal open circuit bias point (approxi-
mately 3.3V). The use of the internal bias point will result
in a 1% to 2% distortion of the duty cycle.
APPLICATIONS
3ns steps. Several LTC1520s may be connected in series
5V
*
Figure 8. Differential Transmission Over Long Distances
5V
100
100
5V
100
100
U
100-FT TWISTED PAIR
0.01 F
*MC10116
INFORMATION
U
INPUT
5V
3.3k
3.3k
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-
tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
0ns DELAY
1/4 LTC1520
W
+
–
R
120
Figure 9. Tapped Delay Line with 18ns Steps
T
1/4 LTC1520
–
+
U
18ns DELAY
1/4 LTC1520
+
–
1520 F08
0.01 F
Layout Considerations
A ground plane is recommended when using a high
frequency device like the LTC1520. A 0.1 F ceramic by-
pass capacitor less than 1/4 inch away from the V
also recommended. Good bypassing is especially needed
when all four channels are driven simultaneously by the
same input. Under these conditions, and with a bypass
capacitor more than 1 1/4 inches away from the V
the parasitic inductances will cause ringing in the V
output pins. This in turn can cause false triggering of the
output short-circuit detector (Figure 11). When the by-
pass capacitor is placed close to the V
LTC1520 operates normally (Figure 12).
36ns DELAY
+
1/4 LTC1520
–
0.01 F
+
1/4 LTC1520
–
Figure 10. Temperature Stable Ring Oscillators
5V
3.3k
3.3k
54ns DELAY
+
1/4 LTC1520
–
1/4 LTC1520
–
+
1/4 LTC1520
–
+
1/4 LTC1520
1/4 LTC1520
+
–
+
–
72ns DELAY
1/4 LTC1520
–
1/4 LTC1520
1520 F09
+
+
–
DD
pin, however, the
TYPICAL STABILITY
LTC1520
5% OVER TEMPERATURE
6.9MHz
OSCILLATOR
OUTPUT
DD
9.3MHz
OSCILLATOR
WITH BETTER
THAN 45/55
DUTY CYCLE
DD
DD
pin is
1520 F10
pin,
7
and