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1
FEATURES
HIGH VOLTAGE -- 900V (450V)
HIGH SLEW RATE -- 500V/S
HIGH OUTPUT CURRENT -- 100mA
PROGRAMMABLE CURRENT LIMIT
APPLICATIONS
HIGH VOLTAGE INSTRUMENTATION
PROGRAMMABLE POWER SUPPLIES UP TO 430V
MASS SPECTROMETERS
SEMICONDUCTOR MEASUREMENT EQUIPMENT
DESCRIPTION
The PA94 is a high voltage, MOSFET operational amplifier
designed as a low cost solution for driving continuous output
currents up to 100mA and pulse currents up to 200mA into
capacitive loads. The safe operating area (SOA) has no sec-
ond breakdown limitations and can be observed for all load
types by choosing an appropriate current limiting resistor.
The MOSFET output stage is biased AB for linear operation.
External compensation provides flexibility in choosing band-
width and slew rate for the application. APEX's Power SIP
package uses a minimum of board space allowing for high
density circuit boards.. The Power SIP package is electrically
isolated. Isolating thermal washers (TW13) prevent arcing
from pins to heatsink.
EQUIVALENT SCHEMATIC
TYPICAL APPLICATION
Piezo positioning may be applied to the focusing of segment-
ed mirror systems. The composite mirror may be composed of
hundreds of elements, each requiring focusing under computer
control. In such complex systems the PA94 reduces the costs
of power supplies and cooling with its advantages of low cost
and low quiescent power consumption while increasing circuit
density with the SIP package.
EXTERNAL CONNECTIONS
PHASE COMPENSATION
GAIN
C
C
100
2.2pF
50
4.7pF
10
22pF
C
C
rated for full supply voltage.
.7
R
LIM
=
I
LIM
PATENTED
8-PIN SIP
PACKAGE STYLE DQ
Formed leads available
See package styles EC & EP
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
2
PARAMETER
TEST CONDITIONS
1
MIN
TYP
MAX
UNITS
INPUT
OFFSET VOLTAGE, initial
.5
5
mV
OFFSET VOLTAGE, vs. temperature
Full temperature range
15
50
V/C
OFFSET VOLTAGE, vs. supply
10
25
V/V
OFFSET VOLTAGE, vs. time
75
V/kh
BIAS CURRENT, initial
200
2000
pA
BIAS CURRENT, vs. supply
4
pA/V
OFFSET CURRENT, initial
50
500
pA
INPUT IMPEDANCE, DC
10
11
INPUT CAPACITANCE
4
pF
COMMON MODE VOLTAGE RANGE
3
Vs = 450V
3
V
S
30
V
COMMON MODE REJECTION, DC
V
CM
= 90V
80
98
dB
NOISE
10KHz BW, R
S
= 1K
2
Vrms
GAIN
OPEN LOOP, @ 15Hz
R
L
= 5K
94
115
dB
GAIN BANDWIDTH PRODUCT at 1MHz R
L
= 5K
140
MHz
POWER BANDWIDTH
R
L
= 5K
300
kHz
PHASE MARGIN, Av=100
Full temperature range
60
OUTPUT
VOLTAGE SWING
I
O
= 70mA
V
S
24
V
S
20
V
CURRENT, continuous
100
mA
SLEW RATE, A
V
= 100
C
C
=2.2pF
500
700
V/s
SETTLING TIME to .1%
2V step
1
s
RESISTANCE
no load
100
POWER SUPPLY
VOLTAGE
5
See note 5
50
300
450
V
CURRENT,
quiescent total
17
24
mA
CURRENT, quiescent output stage only
120
A
THERMAL
RESISTANCE, AC, junction to case
4
Full temperature range, F > 60Hz
2.5
C/W
RESISTANCE, DC, junction to case
Full temperature range, F < 60Hz
4.2
C/W
RESISTANCE, junction to air
Full temperature range
30
C/W
TEMPERATURE RANGE, case
Meets full range specifications
25
+85
C
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
SUPPLY VOLTAGE, +V
S
to V
S
900V
OUTPUT CURRENT, source, sink
200mA, within SOA
POWER DISSIPATION, continuous @ T
C
= 25C
30W
INPUT VOLTAGE, differential
20V
INPUT VOLTAGE, common mode
3
V
S
TEMPERATURE, pin solder - 10s max.
260C
TEMPERATURE, junction
2
150C
TEMPERATURE RANGE, storage
40 to +85C
OPERATING TEMPERATURE RANGE, case
25 to +85C
PA94
SPECIFICATIONS
NOTES: 1. Unless otherwise noted: T
C
= 25C, DC input specifications are value given. Power supply voltage is typical rating. C
c
= 4.7pF.
2. Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation to
achieve high MTTF.
3. Although supply voltages can range up to 450V the input pins cannot swing over this range. The input pins must be at least
30V from either supply rail but not more than 450V from either supply rail. See text for a more complete description of the com-
mon mode voltage range.
4. Rating applies if the output current alternates between both output transistors at a rate faster than 60Hz.
5. Derate max supply rating .625 V/C below 25C case. No derating needed above 25C case.
CAUTION
The PA94 is constructed from MOSFET transistors. ESD handling procedures must be observed.
The exposed substrate contains beryllia (BeO). Do not crush, machine, or subject to temperatures in excess of 850C to
avoid toxic fumes.
APEX MICROTECHNOLOGY CORPORATION TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
3
TYPICAL PERFORMANCE
GRAPHS
PA94
INTERNAL POWER DISSIPATION AND HEATSINK SELECTION
With the unique combination of high voltage and speed
of the PA94, traditional formulas for heatsink selection will
falsely lower the apparent power handling capability of this
amplifier. To more accurately predict operating temperatures
use Power Design
1
revision 10 or higher, or use the following
procedure:
Find internal dissipation (PD) resulting from driving the
load. Use Power Design or refer to Apex Applications Note
1, General Operating Considertaions, paragraph 7. Find total
quiescent power (PD
Q
) by multiplying 0.024A by V
SS
(total
supply voltage). Find output stage quiescent power (PD
QOUT
)
by multiplying 0.00012 by V
SS
.
Calculate a heatsink rating which will maintain the case at
85C or lower.
Where: T
C
= maximum case temperature allowed
T
A
= maximum ambient temperature encountered
Calculate a heatsink rating which will maintain output transistor
junctions at 150C or lower.
Where: T
J
= maximum junction temperature allowed.
R
JC
= AC or DC thermal resistance from the specification
table.
Use the larger heatsink of these two calculations.
Power Design is an Excel spreadsheet available free from
www.apexmicrotech.com
Tc - Ta
R
SA
=
-0.1C/W
PD + PD
Q
T
J
- Ta - (PD + PD
QOUT
) *R
JC
R
SA
=
-0.1C/W
PD + PD
Q
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
4
GENERAL
Please read Application Note 1 "General Operating Con-
siderations" which covers stability, supplies, heat sinking,
mounting, current limit, SOA interpretation, and specification
interpretation. Visit www.apexmicrotech.com for design tools
that help automate tasks such as calculations for stability,
internal power dissipation, current limit; heat sink selection;
Apex's complete Application Notes library; Technical Seminar
Workbook; and Evaluation Kits.
CURRENT LIMIT
For proper operation, the current limit resistor (R
LIM
) must
be connected as shown in the external connection diagram.
The minimum value is 3.5 ohm, however for optimum reliability
the resistor value should be set as high as possible. The value
is calculated as follows; with the maximum practical value
of 30 ohms.
.7
R
LIM
=
I
LIM
COMMON MODE INPUT RANGE
Operational amplifiers are usually designed to have a com-
mon mode input voltage range that approximates the power
supply voltage range. However, to keep the cost as low as
possible and still meet the requirements of most applications
the common mode input voltage range of the PA94 is restricted.
The input pins must always be a least 30V from either supply
voltage but never more than 450V. This means that the PA94
cannot be used in applications where the supply voltages
are extremely unbalanced. For example, supply voltages
of +800V and 100V would not be allowed in an application
where the non-inverting pin is grounded because in normal
operation both input pins would be at 0V and the difference
voltage between the positive supply and the input pins would
be 800V. In this kind of application, however, supply voltages
+450V and -100V does meet the input common mode voltage
range requirements since the maximum difference voltage
between the inputs pins and the supply voltage is 450V (the
maximum allowed). The output has no such restrictions on
its voltage swing. The output can swing within 24V of either
supply voltage regardless of value so long as the total supply
voltage does not exceed 900V.
INPUT PROTECTION
Although the PA94 can withstand differential input voltages
up to 20V, additional external protection is recommended. In
most applications 1N4148 or 1N914 signal diodes are sufficient
(D1, D2 in Figure 1a). In more demanding applications where
low leakage or low capacitance are of concern 2N4416 or
2N5457-2N5459 JFETs connected as diodes will be required
(Q1, Q2 in Figure 1b). In either case the input differential
voltage will be clamped to .7V. This is sufficient overdrive to
produce maximum power bandwidth. Note that this protection
does not automatically protect the amplifier from excessive
common mode input voltages.
POWER SUPPLY PROTECTION
Unidirectional zener diode transient suppressors are recom-
mended as protection on the supply pins. The zeners clamp
transients to voltages within the power supply rating and also
clamp power supply reversals to ground. Whether the zeners
are used or not, the system power supply should be evaluated
for transient performance including power-on overshoot and
power-off polarity reversal as well as line regulation.
Conditions which can cause open circuits or polarity reversals
on either power supply rail should be avoided or protected
against. Reversals or opens on the negative supply rail is
known to induce input stage failure. Unidirectional transzorbs
prevent this, and it is desirable that they be both electrically
and physically as close to the amplifier as possible.
STABILITY
The PA94 is stable at gains of 100 or more with a NPO (COG)
compensation capacitor of 2.2pF. The compensation capaci-
tor, Cc, in the external connections diagram must be rated at
1000V working voltage and mounted closely to pins 4 and 6
to prevent spurious oscillation. A compensation capacitor less
than 2.2pF is not recommended.
EXTERNAL COMPONENTS
The compensation capacitor Cc must be rated for the total
supply voltage. An NPO (COG) capacitor rated a 1kV is rec-
ommended.
Of equal importance are the voltage rating and voltage co-
efficient of the gain setting feedback resistor. Typical voltage
ratings of low wattage resistors are 150 to 250V. Up to 500 V
can appear across the feedback resistor. High voltage rated
resistors can be obtained. However a 1 megohm feedback
resistor composed of five 200k resistors in series will produce
the proper voltage rating.
CAUTIONS
The operating voltages of the PA94 are potentially lethal.
During circuit design develop a functioning circuit at the lowest
possible voltages. Clip test leads should be used for "hands
off" measurements while troubleshooting.
FIGURE 1. OVERVOLTAGE PROTECTION
PA94
OPERATING
CONSIDERATIONS
This data sheet has been carefully checked and is believed to be reliable, however, no responsibility is assumed for possible inaccuracies or omissions. All specifications are subject to change without notice.
PA94U REV J APRIL 2005 2005 Apex Microtechnology Corp.
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