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1
FEATURES
HIGH VOLTAGE -- 450V (225V)
LOW QUIESCENT CURRENT -- 2mA
HIGH OUTPUT CURRENT -- 100mA
PROGRAMMABLE CURRENT LIMIT
LOW BIAS CURRENT -- FET Input
APPLICATIONS
PIEZOELECTRIC POSITIONING
HIGH VOLTAGE INSTRUMENTATION
ELECTROSTATIC TRANSDUCERS
PROGRAMMABLE POWER SUPPLIES UP TO 440V
DESCRIPTION
The PA88 is a high voltage, low quiescent current MOS-
FET operational amplifier designed for output currents up to
100mA. Output voltages can swing up to 215V with a dual
supply and up to +440 volts with a single supply. The safe
operating area (SOA) has no second breakdown limitations
and can be observed with all types of loads by choosing an
appropriate current limiting resistor. High accuracy is achieved
with a cascode input circuit configuration. All internal biasing is
referenced to a bootstrapped zener-MOSFET current source.
As a result, the PA88 features an unprecedented supply range
and excellent supply rejection. The MOSFET output stage is
biased on for linear operation. External compensation provides
user flexibility.
This hybrid circuit utilizes beryllia (BeO) substrates, thick
film resistors, ceramic capacitors and semiconductor chips to
maximize 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 isolation washers and/or improper
mounting torque will void the product warranty. Please see
"General Operating Considerations".
EQUIVALENT SCHEMATIC
TYPICAL APPLICATION
LOW POWER, PIEZOELECTRIC POSITIONING
Piezo positioning may be applied to the focusing of
segmented mirror systems. The composite mirror may be
composed of hundreds of elements, each requiring focusing
under computer control. In such complex systems the PA88's
advantage of low quiescent power consumption reduces
the costs of power supplies and cooling, while providing the
interface between the computer and the high voltage drive to
the piezo positioners.
EXTERNAL CONNECTIONS
PATENTED
8-PIN TO-3
PACKAGE STYLE CE
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
2
ABSOLUTE MAXIMUM RATINGS
SPECIFICATIONS
ABSOLUTE MAXIMUM RATINGS
SUPPLY VOLTAGE, +V
S
to V
S
450V
OUTPUT CURRENT, source, sink
See SOA
POWER DISSIPATION, continuous @ T
C
= 25C
15W
INPUT VOLTAGE, differential
25V
INPUT VOLTAGE, common mode
V
S
TEMPERATURE, pin solder - 10s max
300C
TEMPERATURE, junction
2
150C
TEMPERATURE, storage
65 to +150C
OPERATING TEMPERATURE RANGE, case
55 to +125C
PA88 PA88A
SPECIFICATIONS
PA88
PA88A
PARAMETER
TEST CONDITIONS
1
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
INPUT
OFFSET VOLTAGE, initial
.5
2
.25
.5
mV
OFFSET VOLTAGE, vs. temperature
Full temperature range
10
30
5
10
V/C
OFFSET VOLTAGE, vs. supply
1
5
*
*
V/V
OFFSET VOLTAGE, vs. time
75
*
V/kh
BIAS CURRENT, initial
3
5
50
3
10
pA
BIAS CURRENT, vs. supply
.01
*
pA/V
OFFSET CURRENT, initial
3
2.5
100
3
20
pA
INPUT IMPEDANCE, DC
10
11
*
INPUT CAPACITANCE
4
*
pF
COMMON MODE VOLTAGE RANGE
4
V
S
15
*
V
COMMON MODE REJECTION, DC
V
CM
= 90V
90
110
*
*
dB
NOISE
100kHz BW, R
S
= 1K, C
C
= 15pf
2
*
Vrms
GAIN
OPEN LOOP, @ 15Hz
R
L
= 2K, C
C
= OPEN
96
111
*
*
dB
GAIN BANDWIDTH PRODUCT at 1MHz R
L
= 2K, C
C
= 15pf, R
C
= 100
2.1
*
MHz
POWER BANDWIDTH
R
L
= 2K, C
C
= 15pf, R
C
= 100
6
*
kHz
PHASE MARGIN
Full temperature range
60
*
OUTPUT
VOLTAGE SWING
4
Full temp. range, I
O
= 75mA
V
S
16 V
S
14
*
*
V
VOLTAGE SWING
4
Full temp. range, I
O
= 20mA
V
S
10 V
S
5.2
*
*
V
CURRENT, continuous
T
C
= 85C
100
*
mA
SLEW RATE, A
V
= 20
C
C
= 15pf, R
C
= 100
8
*
V/s
SLEW RATE, A
V
= 100
C
C
= OPEN
30
*
V/s
CAPACITIVE LOAD, A
V
= +1
Full temperature range
470
*
pf
SETTLING TIME to .1%
C
C
= 15pf, R
C
= 100, 2V step
10
*
s
RESISTANCE, no load
R
CL
= 0
100
*
POWER SUPPLY
VOLTAGE
6
See note 6
15
200
225
*
*
*
V
CURRENT, quiescent,
1.7
2
*
*
mA
THERMAL
RESISTANCE, AC, junction to case
5
Full temperature range, F > 60Hz
5.0
*
C/W
RESISTANCE, DC, junction to case
Full temperature range, F < 60Hz
8.3
*
C/W
RESISTANCE, junction to air
Full temperature range
30
*
C/W
TEMPERATURE RANGE, case
Meets full range specifications
25
+85
*
*
C
NOTES: * The specification of PA88A is identical to the specification for PA88 in applicable column to the left.
1. Unless otherwise noted: T
C
= 25C, compensation = C
C
= 68pF, R
C
= 100. DC input specifications are value given. Power
supply voltage is typical rating.
2. Long term operation at the maximum junction temperature will result in reduced product life. Derate internal power dissipation to
achieve high MTTF.
3. Doubles for every 10C of temperature increase.
4. +V
S
and V
S
denote the positive and negative power supply rail respectively.
5. Rating applies if the output current alternates between both output transistors at a rate faster than 60Hz.
6. Derate max supply rating .625 V/C below 25C case. No derating needed above 25C case.
The PA88 is constructed from MOSFET transistors. ESD handling procedures must be observed.
The internal substrate contains beryllia (BeO). Do not break the seal. If accidentally broken, do not crush, machine, or
subject to temperatures in excess of 850C to avoid generating toxic fumes.
CAUTION
APEX MICROTECHNOLOGY CORPORATION TELEPHONE (520) 690-8600 FAX (520) 888-3329 ORDERS (520) 690-8601 EMAIL prodlit@apexmicrotech.com
3
TYPICAL PERFORMANCE
GRAPHS
PA88 PA88A
APEX MICROTECHNOLOGY CORPORATION 5980 NORTH SHANNON ROAD TUCSON, ARIZONA 85741 USA APPLICATIONS HOTLINE: 1 (800) 546-2739
4
OPERATING
CONSIDERATIONS
PA88 PA88A
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
CL
) 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
150 ohms.
.7
R
CL
=
I
LIM
SAFE OPERATING AREA (SOA)
The MOSFET output stage of this power operational ampli-
fier has two distinct limitations:
1. The current handling capability of the MOSFET geometry
and the wire bonds.
2. The junction temperature of the output MOSFETs.
NOTE: The output stage is protected against transient flyback.
However, for protection against sustained, high energy flyback,
external fast-recovery diodes should be used.
INPUT PROTECTION
Although the PA88 can withstand differential input voltages
up to 25V, additional external protection is recommended,
and required at total supply voltages above 300 volts. In most
applications 1N4148 or 1N914 signal diodes are sufficient (D1,
D2 in Figure 2a). 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 2b). In either case the input differential voltage will
be clamped to .7V. This is sufficient overdrive to produce
maximum power bandwidth.
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 PA88 has sufficient phase margin to be stable with
most capacitive loads at a gain of 4 or more, using the rec-
ommended phase
compensation.
The PA88 is exter-
nally compensated
and performance can
be tailored to the
application. Use the
graphs of small signal
response and power
response as a guide.
The compensation
capacitor C
C
must
be rated at 500V
working voltage. An
NPO capacitor is
recommended. The
compensation net-
work C
C
R
C
must be
mounted closely to
the amplifier pins 7
and 8 to avoid spuri-
ous oscillation.
FIGURE 2. OVERVOLTAGE PROTECTION
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 notic
PA88U REV L FEBRUARY 2005 2005 Apex Microtechnology Corp.
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