ADP3189

Rev. 0 | Page 30 of 36

The first step is to compute the time constants for all of the poles and zeros in the system:

(

)

VID

O

X

RT

VID

RT

L

DS

D

O

E

V

R

C

n

V

D

n

L

V

V

R

R

A

R

n

R

×

×

×

×

×

−

×

×

+

×

+

×

+

×

=

1

2

(

)

Ω

m

9

.

2

2

V

1.3

Ω

m

1

mF

6

.

5

4

V

51

0.

0.432

1

nH

320

2

V

1.3

V

51

0.

Ω

m

1.4

Ω

m

2.4

5

Ω

m

1

4

=

×

×

×

×

−

×

×

+

×

+

×

+

×

=

E

R

(31)

()

()

μs

0

0

.

3

Ω

m

0.6

Ω

m

0.5

Ω

m

1

Ω

m

1

pH

0

24

Ω

m

0.5

Ω

m

1

mF

6

.

5

'

'

=

−

×

+

−

×

=

−

×

+

−

×

=

X

O

O

X

O

X

A

R

R

R

R

L

R

R

C

T

(32)

(

)

(

)

ns

0

6

5

mF

6

.

5

Ω

m

1

Ω

m

0.5

Ω

m

0.6

'

=

×

−

+

=

×

−

+

=

X

O

X

B

C

R

R

R

T

(33)

μs

17

.

5

Ω

m

9

.

2

2

V

1.3

kHz

330

2

Ω

m

2.4

5

nH

320

V

51

0.

2

=

×

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

×

×

−

×

=

×

⎟

⎟

⎠

⎞

⎜

⎜

⎝

⎛

×

×

−

×

=

E

VID

SW

DS

D

RT

C

R

V

f

R

A

L

V

T

(34)

()

(

)

()

ns

8

33

Ω

m

1

μF

180

Ω

m

0.5

Ω

m

1

mF

6

.

5

Ω

m

1

μF

180

mF

6

.

5

'

2

2

=

×

+

−

×

×

×

=

×

+

−

×

×

×

=

O

Z

O

X

O

Z

X

D

R

C

R

R

C

R

C

C

T

(35)

where, for the ADP3189,

on resistance per phase. In this example,

board), and

The compensation values can then be solved using

pF

524

Ω

k

00

1.

Ω

m

9

.

2

2

μs

0

0

.

3

Ω

m

1

4

=

×

×

×

=

×

×

×

=

B

E

A

O

A

R

R

T

R

n

C

(36)

Ω

k

87

.

9

pF

524

μs

17

.

5

=

=

=

A

C

A

C

T

R

(37)

pF

560

Ω

k

00

1.

ns

0

6

5

=

=

=

B

B

B

R

T

C

(38)

pF

2

.

34

Ω

k

87

.

9

ns

8

33

=

=

=

A

D

FB

R

T

C

(39)

These are the starting values prior to tuning the design to account for layout and other parasitic effects (see the Tuning the ADP3189

section). The final values selected after tuning are