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FEATURES
• VERY FAST SLEW RATE — 900 V/µs
• POWER MOS TECHNOLOGY — 4A peak rating
• LOW INTERNAL LOSSES — 2V at 2A
• PROTECTED OUTPUT STAGE — Thermal Shutoff
• WIDE SUPPLY RANGE — ±15V TO ±40V
APPLICATIONS
• VIDEO DISTRIBUTION AND AMPLIFICATION
• HIGH SPEED DEFLECTION CIRCUITS
• POWER TRANSDUCERS UP TO 5 MHz
• MODULATION OF RF POWER STAGES
• POWER LED OR LASER DIODE EXCITATION
8-PIN TO-3
PACKAGE STYLE CE
TYPICAL APPLICATION
This fast power driver utilizes the 900V/µs slew rate of the
PA19 and provides a unique interface with a current output
DAC. By using the DAC’s internal 1KΩ feedback resistor,
temperature drift errors are minimized, since the temperature
drift coefficients of the internal current source and the internal
feedback resistor of the DAC are closely matched. Gain of
V
OUT
to I
IN
is –6.5/mA. The DAC’s internal 1K resistor together
with the external 500Ω and 110Ω form a “tee network” in the
feedback path around the PA19. This effective resistance
equals 6.5KΩ . Therefore the entire circuit can be modeled as
6.5KΩ feedback resistor from output to inverting input and a
5mA current source into the inverting input of the PA19. Now
we see the familiar current to voltage conversion for a DAC
where V
OUT
= –I
IN
x R
FEEDBACK
.
DESCRIPTION
The PA19 is a high voltage, high current operational ampli-
fier optimized to drive a variety of loads from DC through the
video frequency range. Excellent input accuracy is achieved
with a dual monolithic FET input transistor which is cascoded
by two high voltage transistors to provide outstanding common
mode characteristics. All internal current and voltage levels
are referenced to a zener diode biased on by a current source.
As a result, the PA19 exhibits superior DC and AC stability
over a wide supply and temperature range.
High speed and freedom from second breakdown is assured
by a complementary power MOS output stage. For optimum
linearity, especially at low levels, the power MOS transistors
are biased in a class A/B mode. Thermal shutoff provides
full protection against overheating and limits the heatsink
requirements to dissipate the internal power losses under
normal operating conditions. A built-in current limit of 0.5A
can be increased with the addition of two external resistors.
Transient inductive load kickback protection is provided by
two internal clamping diodes. External phase compensation
allows the user maximum flexibility in obtaining the optimum
slew rate and gain bandwidth product at all gain settings. A
heatsink of proper rating is recommended.
This hybrid circuit utilizes thick film (cermet) resistors, ceramic
capacitors, and silicon semiconductor chips to maximize reli-
ability, minimize size, and give top performance. Ultrasonically
bonded aluminum wires provide reliable interconnections at all
operating temperatures. The 8-pin TO-3 package is hermeti-
cally sealed and electrically isolated. The use of compressible
thermal washers and/or improper mounting torque will void
the product warranty. Please see “General Operating Con-
siderations”.
EQUIVALENT SCHEMATIC
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APPLICATION
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APEX MICROTECHNOLOGY CORPORATION • TELEPHONE (520) 690-8600 • FAX (520) 888-3329 • ORDERS (520) 690-8601 • EMAIL prodlit@apexmicrotech.com
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