Apex PA94 Datasheet

HIGH VOLTAGE POWER OPERATIONAL AMPLIFIER

F

R

PA94

IN

R

PIEZO DRIVE

S

–V

S

+V

OUT

V

COMPUTER

FOCUS

COMMAND

VOLTAGE

CL

R

1

2

10

8

7

12

MICROTECHNOLOGY

HTTP://WWW.APEXMICROTECH.COM (800) 546-APEX [phone]

FEATURES

• HIGH VOLTAGE — 900V (±450V)

• HIGH SLEW RATE — 500V/µS

• 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
second 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 band­width and slew rate for the application. APEX’s Power SIP04
package uses a minimum of board space allowing for high
density circuit boards.

PA94

PATENT PENDING

TYPICAL APPLICATION

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 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.

EQUIVALENT SCHEMATIC

12

+V

S

1

–IN

2

+IN

–V

S

10

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Q1 Q2

Q5

R5

R8

Q15

R11

R1 R2 C1

Q6

CC1

R9

R3

Q3

6

CC2

4

R6

Q8

Q12

Q16

R12

Q11

Q13

R4

R10

R7

Q4
ILIM

OUT

Q14

8

EXTERNAL CONNECTIONS PACKAGE SIP04

7

–IN +IN CC1 CC2 OUT I

12 4 678 10

C

c

*

.01µF or greater ceramic power supply bypassing required.

PHASE COMPENSATION

GAIN

≥100

≥50
≥10

=

R

LIM

C

2.2pF

4.7pF
22pF

.7

I

LIM

lim

R

LIM

C

–Vs +Vs

**

12

PA94

ABSOLUTE MAXIMUM RATINGS

SPECIFICATIONS

ABSOLUTE MAXIMUM RATINGS

SUPPLY VOLTAGE, +VS to –V
OUTPUT CURRENT, source, sink 200mA, within SOA
POWER DISSIPATION, continuous @ TC = 25°C 30W
INPUT VOLTAGE, differential ±20V
INPUT VOLTAGE, common mode
TEMPERATURE, pin solder - 10s max 220°C
TEMPERATURE, junction
TEMPERATURE, storage –65 to +150°C
OPERATING TEMPERATURE RANGE, case –55 to +125°C

S

3

2

900V

±V

S

150°C

SPECIFICATIONS

PARAMETER TEST CONDITIONS
INPUT

OFFSET VOLTAGE, initial .5 5 mV
OFFSET VOLTAGE, vs. temperature Full temperature range 15 50 µV/°C
OFFSET VOLTAGE, vs. supply 10 25 µV/V
OFFSET VOLTAGE, vs. time 75 µV/√kh
BIAS CURRENT, initial 200 2000 pA
BIAS CURRENT, vs. supply 4 pA/V
OFFSET CURRENT, initial 50 500 pA
INPUT IMPEDANCE, DC 10
INPUT CAPACITANCE 4pF
COMMON MODE VOLTAGE RANGE3Vs=±250V SEE NOTE 3 ±VS 30 V
COMMON MODE REJECTION, DC VCM = ±90V 80 98 dB
NOISE 10KHz BW, RS = 1KΩ 2 µVrms

GAIN

OPEN LOOP, @ 15Hz RL = 5KΩ 94 115 dB
GAIN BANDWIDTH PRODUCT at 1MHz RL = 5KΩ 140 MHz
POWER BANDWIDTH RL = 5KΩ 300 kHz
PHASE MARGIN, Av=100 Full temperature range 60 °

OUTPUT

VOLTAGE SWING IO = 100mA ±VS 24 ±VS 20 V
CURRENT, continuous 100 mA
SLEW RATE, AV = 100 CC =2.2pF 500 700 V/µs
SETTLING TIME to .1% 2V step 1 µs
RESISTANCE no load 100 Ω

POWER SUPPLY

VOLTAGE
CURRENT, quiescent total 17 24 mA
CURRENT, quiescent output stage only 120 µA

THERMAL

RESISTANCE, AC, junction to case
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

5

See note 5 ±50 ±300 ±450 V

4

Full temperature range, F > 60Hz 2.5 °C/W

1

MIN TYP MAX UNITS

11

Ω

±

±

±

NOTES: 1. Unless otherwise noted: TC = 25°C, DC input specifications are ± value given. Power supply voltage is typical rating. Cc= 4.7pF.

APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: [phone]

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 500V from either supply rail. See text for a more complete description of the
common 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 25°C case. No derating needed above 25°C case.

CAUTION

The PA94 is constructed from MOSFET transistors. ESD handling procedures must be observed.

TYPICAL PERFORMANCE
GRAPHS

PA94

30

POWER DERATING

25

T = T

20

C

15

T = T

10

A

5
0

0 25 50 75 100 125 150

INTERNAL POWER DISSIPATION, P(W)

120

TEMPERATURE, T (°C)

SMALL SIGNAL RESPONSE

100

2.2pF

=

C

80

60

40

20

OPEN LOOP GAIN, A (dB)

C

C

C

4.7pF

=

C

22 pF

=

C

0

10 100 1K 10K 1M100K 20M10M

FREQUENCY, F (Hz)

-90

PHASE RESPONSE

-120

-150

-180

PHASE, φ(°)

-210

-240
1M 20M10M

FREQUENCY, F (Hz)

OUTPUT VOLTAGE SWING

24

SO

20

16

12

8

4

20

0

OUTPUT CURRENT, I (mA)

VOLTAGE DROP FROM SUPPLY, V – V (V)

C

T = 125°C

40

C

22 pF

C =

C

C = 4.7pF

C

C = 2.2pF

C

T = 85

C

T = 25

T = –55°C

C

60

80

O

1.08

QUIESCENT CURRENT

1.04

1.00

.96

.92

QUIESCENT CURRENT, I(X)

.88

0 200 600 800 1000

TOTAL SUPPLY VOLTAGE, V (V)

1K

°C

O P-P

500

°C

200

100

OUTPUT VOLTAGE, V (V )

100

50

10K

400

POWER RESPONSE

C

C

C

=

2.2pF

C

=

4.7pF

C

C

=

22 pF

100K 1M 2M

FREQUENCY, F (Hz)

S

200

CURRENT LIMIT

120
100

LIM

70
50

30
20

CURRENT LIMIT, I (mA)

10

550

3 10 20 100

CURRENT LIMIT RESISTOR, R

150

Ω

( )

CL

SAFE OPERATING AREA

250

, (mA)

S

150
100

OR –V

S

50

25
15

10

PULSE CURVES @ 10% DUTY CYCLE MAX

5

100

50

SUPPLY TO OUTPUT DIFFERENTIAL, VS –VO (V)

OUTPUT CURRENT FROM +V

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 Design1 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 (PDQ) by multiplying 0.024A by VSS (total
supply voltage). Find output stage quiescent power (PD

0.00012 by VSS.

Calculate a heatsink rating which will maintain the case at 85°C or lower.

=

Tc - Ta

PD + PD

R

∅SA

- 0.1°C/W

Q

) by multiplying

QOUT

200mS

DC, T

DC

C

, T

C

C

= 125

= 85

DC, T

°C

200

500 1K

Where: TC = maximum case temperature allowed

Calculate a heatsink rating which will maintain output transistor junctions at

150°C or lower.

Where: TJ = maximum junction temperature allowed.
R

∆JC

Use the larger heatsink of these two calculations.
Power Design is an Excel spreadsheet available free from

www.apexmicrotech.com

INPUT NOISE

100mS

20

(nV/√Hz)

15

N

10

= 25

°C

°C

7
5

3

2

INPUT NOISE VOLTAGE, V

10 100 10K 1M

1K

FREQUENCY, F (Hz)

TA = maximum ambient temperature encountered

R

∅SA

= AC or DC thermal resistance from the specification table.

TJ - Ta - (PD + PD

=

PD + PD

) *R

QOUT

∅JC

Q

-0.1°C/W

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OPERATING
CONSIDERATIONS

PA94

GENERAL

Please read Application Note 1 "General Operating Consid­erations" 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
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.

R

LIM

.7

=

I

LIM

) must be

LIM

COMMON MODE INPUT RANGE

Operational amplifiers are usually designed to have a com­mon 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 500V. 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,
+500V 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 500V (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

supply voltages

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
capacitor, 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
recommended.

Of equal importance are the voltage rating and voltage
coefficient 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.

A.

+V

S

Z1

does not exceed 900V.

12

INPUT PROTECTION

–IN

Although the PA94 can withstand differential input voltages

up to ±20V, additional external protection is recommended. In

+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-

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.

APEX MICROTECHNOLOGY CORPORATION • 5980 NORTH SHANNON ROAD • TUCSON, ARIZONA 85741 • USA • APPLICATIONS HOTLINE: [phone]

PA94U REV. C AUGUST 2000 © 2000 Apex Microtechnology Corp.

FIGURE 1. OVERVOLTAGE PROTECTION

1

D2D1

PA94

2

10

+V

Z2

–V

S

B.

–IN

Q1 Q2

+IN

S

Z1

12

1

PA94

2

10

Z2

–V

S