Si3402-EVB

Rev. 1.0

9

5. BOM Options

The Si3402 non-isolated EVB has been compensated for eight different output voltage and filter combinations:



3.3 V output standard ESR 1000 µF 6.3 V filter



5 V output standard ESR 1000 µF 6.3 V filter



9 output standard ESR 470 µF 16 V filter



12 V output standard ESR 470 µF 16 V filter



3.3 V output low ESR 560 µF 6.3 V filter



5 V output low ESR 560 µF 6.3 V filter



9 V output low ESR 330 µF 16 V filter



12 V output low ESR 330 µF 16 V filter

For the standard ESR capacitor, the ESR increase at very low temperatures may cause a loop stability issue. A

typical evaluation board has been shown to exhibit instability under very heavy loads at –20 °C. Due to

self-heating, this condition is not a great concern. However, using a low ESR filter capacitor solves this problem

(but requires some re-compensation of the feedback loop). The low ESR capacitor also improves load transient

response and output ripple.

The Si3402 (non–isolated) EVB was designed with a very simple pole-zero compensation consisting of R7 and C7.

Capacitors C19 and C20 can be added in parallel with resistors R6 and R7 for optimized performance.

The standard evaluation board is shipped with C19 and is optimized for a standard ESR filter capacitor for 5 V

output.

The following table gives the options that have been tested for other situations.

R6

(To Adjust

Output Voltage)

Filter Cap C5

(Type FM are

Low ESR)

Filter Cap Part

Number

(Panasonic)

R7

C7

C19

C20

3.3 V

4.87 k

1000 µF, 6.3 V

ECA0JM102

21 k

4.7 nF

150 pF

NP

3.3 V

4.87 k

560 µF, 6.3 V

EEUFM0J561

30.1 k

4.7 nF

150 pF

4.7 nF

5.0 V

8.66 k

100 0 µF, 6.3 V

ECA0JM102

30.1 k

3.3 nF

150 pF

NP

5.0 V

8.66 k

560 µF, 6.3 V

EEUFM0J561

30.1 k

3.3 nF

150 pF

3.3 nF

9.0 V

18.2 k

470 µF, 16 V

ECA1CM471

21 k

4.7 nF

150 pF

NP

9.0 V

18.2 k

330 µF, 16 V

EEUFM1C331

30.1 k

4.7 nF

150 pF

3.3 nF

12.0 V

24.9 k

470 µF, 16 V

ECA1CM471

30.1 k

3.3 nF

150 pF

NP

12.0 V

24.9 k

330 µF, 16 V

EEUFM1C331

30.1 k

3.3 nF

150 pF

3.3 nF