lt1715cms-trpbf Linear Technology Corporation, lt1715cms-trpbf Datasheet - Page 12

• Manufacturer Part Number: lt1715cms-trpbf
• Description: 4ns, 150mhz Dual Comparator With Independent Input/output Supplies
• Manufacturer: Linear Technology Corporation

APPLICATIONS
LT1715
operation and performance of the output stage can be
impaired above 100 A of forward current. R4 prevents
this with the minimum additional power dissipation.
Finally, Figure 8d shows the case of driving standard,
negative-rail, ECL with the LT1715. Resistor values are
given for both ECL interface types and for both a 5V and 3V
LT1715 supply rail. Again, a fourth resistor, R4 is needed
to prevent the low state current from flowing out of the
LT1715, turning on the internal ESD/substrate diodes.
Resistor R4 again prevents this with the minimum addi-
tional power dissipation.
12
(a) STANDARD TTL TO PECL TRANSLATOR
(b) LT1715 OUTPUT TO PECL TRANSLATOR
(c) 3V LT1715 OUTPUT TO PECL TRANSLATOR
(d) LT1715 OUTPUT TO STANDARD ECL TRANSLATOR
U
1/2 LT1715
1/2 LT1715
1/2 LT1715
V
V
V
V
V
V
CC
CC
CC
EE
EE
EE
LSTTL
INFORMATION
+V
3V
U
S
5V
180
270
820
R1
R4
R4
W
R1
+V
R1
S
V
R2
R3
ECL
5V
R2
R3
R2
10KH/E
R3
U
V
ECL
DO NOT USE FOR LT1715
LEVEL TRANSLATION. SEE TEXT
10KH/E
100K/E
10KH/E
100K/E
Figure 8
5V OR 5.2V
ECL FAMILY
Of course, if the V
negative supply, the GND pin can be tied to it as well and
+ V
rails as the ECL and the circuits of Figure 8b can be used.
For all the dividers shown, the output impedance is about
110 . This makes these fast, less than a nanosecond,
with most layouts. Avoid the temptation to use speedup
capacitors. Not only can they foul up the operation of the
ECL gate because of overshoots, they can damage the
ECL inputs, particularly during power-up of separate
supply configurations.
5V OR 5.2V
4.5V
+ V
10KH/E
100K/E
S
V
4.5V
ECL
S
grounded. Then the output stage has the same power
510
620
R1
– 5.2V
– 4.5V
300
330
V
R1
ECL
180
180
R2
180
180
+ V
R2
5V
3V
5V
3V
S
750
510
EE
R3
1500
OMIT
560
270
680
330
R3
of the LT1715 is the same as the ECL
R1
1000
560
270
510
270
390
R4
R2
330
300
300
270
R3
1200
1500
330
430
R4
1715 F08