LSP5523

Document number: DS44073 Rev. 7 - 2

10 of 17

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LSP5523

Stability Compensation (Continued)

STEP2. Set the zero fZ1 at 1/4 of the crossover frequency. If RCOMP is less than 10KΩ, the equation for

CCOMP is:

)

(

637

.

0

1

F

fc

R

C

COMP

COMP





STEP3. If the output capacitor’s ESR is high enough to cause a zero at lower than 4 times the crossover

frequency, an additional compensation capacitor CCOMP2 is required. The condition for using CCOMP2 is:

ESRCOUT

R

1









fs

R

C

ESR

OUT



And the proper value for CCOMP2 is:

C O M P

E S R C O U T

O U T

2

C O M P

R

R

C

C



Though CCOMP2 is unnecessary when the output capacitor has sufficiently low ESR, a small value CCOMP2

such as 100pF may improve stability against PCB layout parasitic effects.

Table 4 Component Selection Guide for

Stability Compensation

Vin Range

(V)

Vout,

(V)

Cout

Rcomp,

(kΩ)

Ccomp,

(nF)

Ccomp2,

(pF)

Inductor,

(uH)

5

– 12

1.0

22uF x2

Ceramic

2.4

6.8

none

4.7

5

– 15

1.2

3

6.2

none

4.7

5

– 15

1.8

6.2

3

none

10

5

– 15

2.5

8

2.2

none

10

5

– 15

3.3

10

2.2

none

10

7

– 15

5

10

2.2

none

10

5

– 12

1.0

470uF/

6.3V/

120

mΩ

10

10

680

10

5

– 15

1.2

5

– 23

1.8

5

– 27

2.5

5

– 27

3.3

7

– 27

5

(10)

(11)

(12)