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Application Notes

Increasing the Output Current of the PT4486

with the PT4497 Compatible Current Booster

The PT4497 is a 8.5-A “Current Booster” module

designed specifically for the PT4486 programmable

DC/DC converter. The booster is controlled directly

by the regulator, and effectively adds an additional

output stage that operates in parallel. This allows

the system to run sychronously, providing a low

noise solution. Up to two booster modules can be

connected to a PT4486 converter. Each booster

module increases the available output current by

8.5 A. A combination of one PT4486 converter and

two PT4497 booster modules can supply up to 25.5 A

of output current; enough power to supply a moder-

ately sized rack-mounted system. Figure 1-1 shows

the connection schematic for the regulator and cur-

rent booster combination.

A current booster is not a stand-alone product, and

can only operate with a regulator. It is housed in

the same package as its compatible regulator, and

shares the same mechanical outline. Except for an

increase in output current, the overall performance

of a converter/booster combination is identical to

that of a stand-alone converter.

Figure 1-1; Current Booster Application Schematic

Table 1-1; Booster Pin-Out Information

Pin

Function

Pin Function

Pin Function

20 (–)Vsense

3

Do not connect

21 Do not connect

22 Do not connect

23 Do not connect

6

Do not connect

24 Do not connect

7

Do not connect

25 Do not connect

26 DRV

Notes:

1. Refer to the PT4486 specification table for the

performance of the regulator/booster combination.

2. The pin-out of the current booster modules include a

number pins identified, “Do not connect” (see Table 1-1).

These pins are not connected internally to the module

but must be soldered to a pad to preserve the unit’s

mechanical integrity.

3. A minimum of 33 µF of output capacitance is required

across the output of each PT4497 booster for proper

operation. A value greater than 33 µF will further

reduce transients due to large and/or fast load steps.

4. The converter and all boosters must be located on

the same printed circuit board. A similar footprint

and trace layout for each module will also facilitate

current sharing.

PT4486, PT4497

PT4497

PT4486

1

2

8 - 13

–V

IN

-V

OUT

+V

OUT

20

7

REMOTE SENSE (+)

REMOTE SENSE (-)

VID0

VID1

VID2

VID3

PROGRAMMING PINS

Inhibit

3

C

IN

33µF

Optional

+

C

IN

33µF

Optional

+

LOAD

1

8 - 13

14 - 19

+V

IN

25

VID4

24

23

22

21

14-19

2

4526

20

4526

C

OUT

33µF

Optional

+

C

OUT

33µF

+