PA91

4

PA91U

P r o d u c t I n n o v a t i o n F r o m

®

TYPICAL APPLICATION

LOW POWER, PIEZOELECTRIC POSITIONING

Piezopositioningmaybeappliedtothefocusingofseg-

mented mirror systems. The composite mirror may be

composedofhundredsofelements,eachrequiringfocus-

ingundercomputercontrol.Insuchcomplexsystemsthe

PA91 reduces the costs of power supplies and cooling

withitsadvantagesoflowcostandlowquiescentpower

consumptionwhileincreasingcircuitdensitywiththeSIP

package.

GENERAL

PleasereadApplicationNote1"GeneralOperatingConsiderations"whichcoversstability,supplies,heatsinking,

mounting,currentlimit,SOAinterpretation,andspecificationinterpretation.Visitwww.cirrus.comfordesigntools

thathelpautomatetaskssuchascalculationsforstability,internalpowerdissipation,currentlimit;heatsinkselec-

tion;ApexPrecisionPower’scompleteApplicationNoteslibrary;TechnicalSeminarWorkbook;andEvaluationKits.

CURRENT LIMIT

Forproperoperation,thecurrentlimitresistor(R

gram.Foroptimumreliabilitytheresistorvalueshouldbesetashighaspossible.Thevalueiscalculatedasfollows;

withthemaximumpracticalvalueof32ohms.

.65

R

I

LIM

10

HARMONIC DISTORTION

100K

100

1K

10K

100k

FREQUENCY F (Hz)

135

90

PHASE RESPONSE

10

100

10K

100K

FREQUENCY, F (Hz)

100K

FREQUENCY, F (Hz)

–10

0

30

SMALL SIGNAL RESPONSE

10

20

40

50

0

0.15

0.2

OUTPUT CURRENT, I

5

6

OUTPUT VOLTAGE SWING

4.5

4

5.5

0

8

12

20

24

RESISTOR VALUE, R

0

.05

.2

CURRENT LIMIT

.1

.15

0.1

EXT. COMPENSATION CAPACITOR, C

10

SLEW RATE

50

40

30

20

1K

10

100

FREQUENCY, F (Hz)

1

25

50

100

CASE TEMPERATURE, T

1.1

NORMALIZED QUIES. CURRENT

1.0

4

16

INPUT NOISE VOLTAGE

1K

2

7

10

20

5

3

15

.05

225

75

.001

1M

10M

270

180

125

1.2

1.3

0.1

3.5

700

300

200

100

70

500

1

.01

.1

1M

10M

C

C

C

C

C

C

C

C

0

25

50

75

100 125

150

CASE TEMPERATURE, T

0

8

24

32

POWER DERATING

16

40

R

V

A

P

P

P

OUTPUT STAGE

POWER RESPONSE

FREQUENCY, F (Hz)

10K

100K

1M

50

60

70

80

90

100

200

300

500

400

F

R

PA91

IN

R

1

2

6

7,8

9,10

11,12

PIEZO DRIVE

S

–V

S

+V

OUT

V

COMPUTER

FOCUS

COMMAND

VOLTAGE

CL

R

PHASE COMPENSATION

GAIN

C

R

C

≥1

68pF

100Ω

≥5

10pF

100Ω

≥10

4.7pF

0Ω

≥30

NONE

0Ω

*C

UseNPOceramic(COG)type.