el2150 Intersil Corporation, el2150 Datasheet - Page 16

• Manufacturer Part Number: el2150
• Description: 125mhz Single Supply, Clamping Op Amps
• Manufacturer: Intersil Corporation

Video Sync Pulse Remover Application
All CMOS Analog to Digital Converters (A/Ds) have a
parasitic latch-up problem when subjected to negative input
voltage levels. Since the sync tip contains no useful video
information and it is a negative going pulse, we can chop it
off. Figure 7 shows a unity gain connected EL2150 and
EL2157. Figure 8 shows the complete input video signal
applied at the input, as well as the output signal with the
negative going sync pulse removed.
Multiplexing with the EL2157
The ENABLE pin on the EL2157 allows for multiplexing
applications. Figure 9 shows two EL2157s with their outputs
tied together, driving a back terminated 75: video load. A
2V
5MHz sinewave to the other. Figure 10 shows the CLOCK
signal which is applied, and the resulting output waveform at
V
OUT
P-P
. Switching is complete in about 50ns. Notice the
10MHz sinewave is applied at one input, and a 1V
Propagation Delay vs Overdrive
EL2157 as a Comparator
FIGURE 6.
FIGURE 7.
FIGURE 8.
16
EL2150, EL2157
P-P
outputs are tied directly together. Decoupling resistors at
each output are not necessary. In fact, adding them
approximately doubles the switching time to 100ns.
Short Circuit Current Limit
The EL2150 and EL2157 have internal short circuit
protection circuitry that protect it in the event of its output
being shorted to either supply rail. This limit is set to around
100mA nominally and reduces with increasing junction
temperature. It is intended to handle temporary shorts. If an
output is shorted indefinitely, the power dissipation could
easily increase such that the part will be destroyed.
Maximum reliability is maintained if the output current never
exceeds ±90mA. A heat sink may be required to keep the
junction temperature below absolute maximum when an
output is shorted indefinitely.
Power Dissipation
With the high output drive capability of the EL2150 and
EL2157, it is possible to exceed the 150°C Absolu te
Maximum junction temperature under certain load current
conditions. Therefore, it is important to calculate the
maximum junction temperature for the application to
determine if power-supply voltages, load conditions, or
FIGURE 10.
FIGURE 9.