EL2004G ELANTEC [Elantec Semiconductor], EL2004G Datasheet - Page 8

• Manufacturer Part Number: EL2004G
• Description: 350 MHz FET Buffer
• Manufacturer: ELANTEC [Elantec Semiconductor]

Circuit Operation
Capacitive Loading
The EL2004 is designed to drive capacitive loads
up to several thousand picofarads without oscil-
lation However peak current resulting from
charging currents on fast edges should be limited
below the absolute maximum peak current rating
of 250 mA In some cases it may be necessary to
employ one of the current limit schemes shown
below
Short Circuit Protection
Dynamic response of the EL2004 was preserved
by excluding current limit circuits which are not
needed in most applications However in situa-
tions where operating conditions are not con-
trolled short circuit protection can be added by
inserting resistors between the output device col-
lectors and supplies as illustrated
Suitable resistor values can be calculated as fol-
lows
R
where I
EL2004 EL2004C
350 MHz FET Buffer
SC
e
V
SC s
I
SC
a
e
100 mA for EL2004
V
Offset Zero Adjust
I
Current Limiting
SC
b
Using Resistor
Contd
2004 – 10
2004 – 11
8
The inclusion of limiting resistors in the collec-
tors of the output devices will reduce the output
voltage swing and speed Decoupling V
V
full output swing for transient pulses
An alternate active current limit technique that
retains full DC output swing is shown above
Here the current sources are saturated during
normal operation thus applying full supply volt-
age to the V
voltage decreases as the current source reaches its
limit
R
Power Supplies
The EL2004 has been characterized for both
and
nations can also be useful For example in many
video applications it is only necessary for the out-
put to swing
tion are important In this situation the input
stage can be operated at the full
while the output collectors are returned to
The speed and distortion will be almost as good
as if the whole circuit was operating at
but the dissipation is substantially reduced and
higher load currents can be safely accommodat-
ed
C
LIM
b
g
pins with capacitors to ground will retain
e
5V dual supply operation but other combi-
V
I
SC
BE
Using Current Sources
C
g
e
pins Under fault conditions the
Current Limiting
2V or less but speed and distor-
100 mA
0 6V
e
6
g
15V supply
C
a
g
2004 – 12
g
15V
g
and
5V
15