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7

IR1176

Fig. 4 PLL loop filter component definitions

4 -PLL Dampi

ng f

actorcalculations:

P =

ππE-3 x Rf (KOhms) x C(nF) x fn(KHz)

TypicalvalueforPis0.707.(Criticallydamped)

5 -Advanceti

m i

ng:

Tadv(nsec) = RADV (KOhms)*10 - 10

W here RADV isresistancefrom RADV1 orRADV2 toground.

Exampl

e C:RADV=10Kohms willr

esulti

n Tadv=10*10-10=90nsec.

6-Dead ti

me calculations:

Td(nsec)=0.69*Rdt(KOhms)*Cdt(pF) + 5

(For Vdd=5 V)

W hereRdt is resistance between pins DTIN1 and DTOUT1 or DTIN2 and

DTOUT2.Cdtiscapacitancefrom DTIN1 or DTIN2 t

oground.

3 -PLL Naturalfrequency:

ω

ωn =2ππfn(KHz)=

Choose Cfsuchthat

Cf=C/16

+ 6=106 nsec.

Example D: Rd=2KW and Cdt=100pF will result in Td=148.35nsec.

+ 6

Td(nsec)=0.69*Cdt(pF)*(Rdt(KΩ)+0.15) (For Vdd=5V)