NX2154 datasheet(9/17 Pages) MICROSEMI

9 / 17 page

NX2154/2154A

Rev.1.2

02/26/07

Case 1:

LC<FESR<FO

40dB/decade

20dB/decade

loop gain

ESR

compensator

power stage

FZ1 Z2

FP2

Figure 4 - Bode plot of Type III compensator

LC<FESR<FO)

If electrolytic capacitors are used as output

capacitors, typical design example of type III

compensator in which the crossover frequency is

selected as F

LC<FESR<FO and FO<=1/10~1/5Fs is shown

as the following steps. Here one SANYO 6ME1000WG

with 30 m

Ω is chosen as output capacitor.

1. Calculate the location of LC double pole F

and ESR zero F

ESR.

OUT

15uH 1000uF

1.3kHz

×π ××

ESR

OUT

ESRC

30m

1000uF

5.3kHz

×π ××

×π ×

Ω×

2. Set R

2 equal to 10kΩ.

REF

OUT

REF

10k

0.8V

R =

1.91k

-V

5V-0.8V

Ω×

=Ω

Choose R

1=1.91kΩ.

3. Set zero F

Z2 = FLC and Fp1 =FESR .

4. Calculate C

3 .

C =

(-)

10k

1.3kHz 5.3kHz

=9.2nF

×π×

×π ×Ω

Choose C

3=10nF.

5. Calculate R

3 .

P13

5.3kHz 10nF

×π ××

=Ω

Choose R

3 =3kΩ.

6. Calculate R

4 with FO=30kHz.

OSC

ESR

1.5V

30kHz 15uH 10k

33V

30m

10k

=9.9k

×π ×

××

×π ×

Ω ×Ω

××

Ω

Ω +Ω

Ω

Choose R

4=10kΩ.

7. Calculate C

2 with zero Fz1 at 75% of the LC

double pole by equation (11).

Z14

0.75 1.3kHz 10k

12.2nF

×π ××

×π ×

×Ω

Choose C

2=12nF.

8. Calculate C

1 by equation (14) with pole Fp2 at

half the switching frequency.

10k

150kHz

106pF

×π ××

×π ×

Ω×

Choose C

1=100pF.

NX2154 Scheda tecnica(PDF) 9 Page - Microsemi Corporation

NX2154 Scheda tecnica(HTML) 9 Page - Microsemi Corporation

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17

Scheda tecnica Scarica

Link URL