el2021 Intersil Corporation, el2021 Datasheet - Page 5

• Manufacturer Part Number: el2021
• Description: Monolithic Pin Driver
• Manufacturer: Intersil Corporation

Typical Performance Curves
Applications Information
Output Stage
To meet the requirements of low output impedance, wide
bandwidth, and large capacitive load driving capability, the
EL2021 has a fairly exotic output stage. Figure 1 shows a
simplified schematic of the circuit, only applicable in normal,
low impedance mode. External transistors are used to
handle the large load currents and peak power dissipations.
Since there is no need for good AC crossover distortion
performance in a pin driver, the output transistors are
operated class C. That is, for small output currents, neither
output transistor will conduct bias current, and when load
currents do flow, one of the devices is off. This is
accomplished by biasing the output transistors from Schottky
Overshoot vs VSR
V
OUT
vs Load Current
5
Supply Current vs VSR
(Continued)
Overshoot vs VSR
EL2021
Supply Current vs
Supply Voltage
diodes D1 and D2. In operation, the diode forward voltage is
about 0.4V, whereas the “on” output transistor will have a
V
transistor's base-emitter junction, not nearly enough to
cause bias currents to flow in it. Schottky diodes have a
temperature drift similar to silicon transistors, so the class C
bias maintains over temperature. One caution is that the
diodes are in the IC package and are thermally separate
from the transistors, so there can exist temperature
differences between packages that can cause thermal
runaway. Runaway is avoided as long as the external
transistors are not hotter than the EL2021 package by more
than 80°C. The only way runaway has been induced as of
this writing is to use “freeze spray” on the IC package while
the output transistors are very hot.
BE
of 0.6V. This leaves only 0.2V across the “off”
Power Dissipation vs
Temperature
Slew Rate vs VSR
Tri-State Leakage vs
Output Voltage