L6728A datasheet(23/32 Pages) STMICROELECTRONICS

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L6728A

20 A demonstration board

23/32

11.1

Demonstration board description

11.1.1

Power input (VIN)

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.

If the voltage is between 5 V and 12 V it can supply also the device (through the VCC pin)

and in this case the R16 (0

Ω) resistor must be present.

11.1.2

Output (VOUT)

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

Signal input (VCC)

Using the input voltage VIN to supply the controller no power is required at this input.

However the controller can be supplied separately from the power stage through the VCC

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

mounted

not mounted

3.6 k

11 k

R6, R9

3.6 k

4.7 k

22 k

R8, R13

390

680

1.5 k

2.2 k

39 k

open

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