L6728A

20 A demonstration board

23/32

11.1

Demonstration board description

11.1.1

This is the input voltage for the power conversion. The high-side drain is connected to this

input. This voltage can range from 1.5 V to 12 V bus.

and in this case the R16 (0

Ω) resistor must be present.

11.1.2

Different output voltage rails have been tested. For each rail a few component need to be

changed: these components are used to program the desiderated output voltage and to

compensate the system. The over-current-protection limit is set to ~27 A but it can be

changed by replacing the resistors R18.

Note:

All the previous resistors are SMD 0603 package, 1/16W, 1% tolerance.

11.1.3

input and, in this case, the R16 (0

Ω) resistor must be unsoldered.

11.1.4

Test points

Several test points are provided to have easy access at all important signal characterizing

the device:

–

COMP: the output of the error amplifier;

–

FB: the inverting input of the error amplifier;

–

PGOOD: signaling the regular functioning (active high);

–

VGDHS: the bootstrap diode anode;

–

PHASE: Phase node;

–

LGATE: Low-side gate pin of the device;

–

HGATE: High-side gate pin of the device.

Table 7.

Rail dependent components

Ref.

8 V rail

5 V rail

3.3 V rail

2.5 V rail

1.25 V rail

0.8 V rail

Q9

mounted

not mounted

R7

3.6 k

Ω

3.6 k

Ω

3.6 k

Ω

3.6 k

Ω

11 k

Ω

11 k

Ω

R6, R9

3.6 k

Ω

3.6 k

Ω

4.7 k

Ω

4.7 k

Ω

22 k

Ω

22 k

Ω

R8, R13

390

Ω

680

Ω

1.5 k

Ω

2.2 k

Ω

39 k

Ω

open