鈥?WIDE SUPPLY RANGE 鈥?/div>
鹵15V
TO
鹵40V
APPLICATIONS
鈥?VIDEO DISTRIBUTION AND AMPLIFICATION
鈥?HIGH SPEED DEFLECTION CIRCUITS
鈥?POWER TRANSDUCERS UP TO 5 MHz
鈥?MODULATION OF RF POWER STAGES
鈥?POWER LED OR LASER DIODE EXCITATION
TYPICAL APPLICATION
This fast power driver utilizes the 900V/碌s slew rate of the
PA19 and provides a unique interface with a current output
DAC. By using the DAC鈥檚 internal 1K鈩?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 鈥?.5/mA. The DAC鈥檚 internal 1K resistor together
with the external 500鈩?and 110鈩?form a 鈥渢ee network鈥?in the
feedback path around the PA19. This effective resistance
equals 6.5K鈩?. Therefore the entire circuit can be modeled as
6.5K鈩?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
= 鈥揑
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 com-
mon 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 as-
sured 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 pro-
vided by two internal clamping diodes. External phase com-
pensation 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 maxi-
mize reliability, minimize size, and give top performance.
Ultrasonically bonded aluminum wires provide reliable inter-
connections at all operating temperatures. The 8-pin TO-3
package is hermetically sealed and electrically isolated. The
use of compressible thermal washers and/or improper mount-
ing torque will void the product warranty. Please see 鈥淕eneral
Operating Considerations鈥?
EQUIVALENT SCHEMATIC
3
Q1
Q3
Q5
8
Q2
2
Q4
Q7
Q8
Q9
Q10
Q11
Q15
Q12
Q13
Q16
D1
Q20
1
5
Q19
Q21
Q17A
4
Q17B
Q23
D2
6
Q22
Q24
Q25
7
TYPICAL
APPLICATION
1K
DAC
+40V
鹵5mA
R
CL+
PA19
R
CL鈥?/div>
5.6pF
110
鈩?/div>
500
鈩?/div>
鹵32.5V
Up to 4A
EXTERNAL CONNECTIONS
R
CL+
+V
+IN
4
3
2
1
PHASE COMPENSATION
OUT
C
C
GAIN
1
10
100
1000
C
C
330pF
22pF
2.2pF
none
5
TOP
VIEW
8
6
7
鈥揑N
鈥揤
鈥?0V
PA19 AS FAST POWER DRIVER
R
CL鈥?/div>
APEX MICROTECHNOLOGY CORPORATION
鈥?TELEPHONE (520) 690-8600 鈥?FAX (520) 888-3329 鈥?ORDERS (520) 690-8601 鈥?EMAIL prodlit@apexmicrotech.com
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