AN3303

Electrical diagram description

Doc ID 18164 Rev 2

13/27

2

Electrical diagram description

The board schematic is shown in Figure 12. Components were dimensioned supposing an

implementation of the SR on a 12 V output converter and using the converter output as

supply bus for the SRK2000. If the board is used with a different supply voltage, some

components should be modified accordingly.

C502 is a bypass capacitor mounted between Vcc and the SGND pin, as close as possible

to the IC pin, in order to obtain a clean supply voltage for the internal circuitry. C503 is

another bypass capacitor from Vcc to PGND working as an energy buffer for the pulsed

gate-drive currents. R503, together with C502 and C503, forms an RC filter and smoothes

eventual disturbances from the 12 V supply. R504 and R505 polarize the EN pin setting the

MOSFET turn-off to -12.5 mV. The EN pin is externally accessible through the board

connector pins #6 and #8 and can be used to force the IC disable.

R506 and R507 connect the power MOSFET drains to DVS1,2 pins and set the turn-on

threshold as previously described.

D503 and D505 bypass R506 and R507 before power MOSFET turn-on. In this case they

are not mounted because the R506 and R507 value is quite low and turn-on delay is

negligible.

C504 and C505 are intended to introduce an additional delay between the signals on the

power MOSFET drain and on the sensing pin itself. In this case they are not mounted

because they are not strictly necessary but their contribution is analyzed in Section 3.

R501A, D501A, Q501A, R502A, D502A, and Q502A are optional and they are present only

in case paralleled power MOSFETs are used (EVLSRK2000-S-40).

Figure 12.

Electrical diagram