PA93/27U

5

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

PA93/27

PHASE COMPENSATION

GAIN

C

R

C

≥1

220pF

100Ω

≥2

100pF

100Ω

≥4

47pF

0Ω

≥17

10pF

0Ω

*C

C

Nevertobe<10pF.C

GENERAL

PleasereadApplicationNote1"GeneralOperatingConsiderations"whichcoversstability,supplies,heatsinking,

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

thathelpautomatetaskssuchascalculationsforstability,internalpowerdissipation,currentlimit;heatsinkselec-

tion;Apex’scompleteApplicationNoteslibrary;TechnicalSeminarWorkbook;andEvaluationKits.

CURRENT LIMIT

Forproperoperation,thecurrentlimitresistor(R

gram.Foroptimumreliabilitytheresistorvalueshouldbesetashighaspossible.Thevalueiscalculatedasfollows;

withthemaximumpracticalvalueof16ohms.

.65

R

I

LIM

SAFE OPERATING AREA (SOA)

TheMOSFEToutputstageofthispoweroperationalam-

plifierhastwodistinctlimitations:

1. The current handling capability of the MOSFET ge-

ometryandthewirebonds.

2. ThejunctiontemperatureoftheoutputMOSFETs.

NOTE:The output stage is protected against transient

flyback.However,forprotectionagainstsustained,high

energyflyback,externalfast-recoverydiodesshouldbe

used.

SAFE OPERATING CURVES

Thesafeoperatingareacurvesdefinethemaximumad-

ditionalinternalpowerdissipationtheamplifiercantoler-

atewhenitproducesthenecessaryoutputtodrivean

externalload.

INPUT PROTECTION

AlthoughthePA93/27canwithstanddifferentialvoltages

upto±20V,additionalexternalprotectionisrecommend-

ed.Lowleakage,lowcapacitanceJFETsconnectedas

diodesarerecommended(e.g.2N4416,Q1-Q4inFigure2).Thedifferentialinputvoltagewillbeclampedto±1.4V.

Thisissufficientoverdrivetoproducemaximumpowerbandwidth.

SUPPLY TO OUTPUT DIFFERENTIAL, V

10

20

30 40

100

200 300

500

.1

.08

.06

.6

.4

.3

.2

.8

3

2

1

4

6

8

20

10

DC,T

C

= 125C

100mS

60 80

200mS

DC, T

DC,T

C

= 85C

SOA