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Application Notes

Increasing the Output of the PT7710 Family of

ISRs with a 20-A Compatible Current Booster

The output of PT7710 family of regulators (PT7711–

PT7716) can produce an additional 20-A output using a

compatible current booster module. Two booster modules

are available. They are the PT7744 and PT7745, which

are compatible with regulators that operate off 3.3-V

or 5-V input buses respectively. Refer to Table 2-1 for

regulator/booster compatiblity.

The booster modules are controlled directly by the regu-

lator and effectively add a parallel output stage. They

operate sychronously, to provide a low-noise solution.

Up to two booster modules can be connected to a PT771x

regulator. Each booster added increases the regulator’s

output current by 20A, for up to 60A of output current.

Current boosters are not stand-alone products, and can

only operate with a regulator. They are housed in the same

package as the regulator, and share the same mechanical

outline. Except for an increase in output current, the

overall performance of a regulator/booster combination

is identical to that of a stand-alone regulator. For more

details refer to the applicable regulator specifications.

PT7710 Series, PT7744, PT7745

Figure 1-1; Current Booster Application Schematic

C

IN

+

C

OUT

+

LOAD

V

IN

VID0

VID1

VID2

VID3

V

OUT

GND

GND

STBY*

L

IN

1µH

REMOTE SENSE (–)

REMOTE SENSE (+)

PROGRAMMING PINS

C

IN

+

L

IN

1µH

PT7744/45

Booster

20-25

13-19

27

7-11

V

O

V

IN

GND

Synch In

VID4

C

OUT

+

PT771x

64

321

26

20-25

12

5

13-19

27

7-11

V

O

V

IN

GND

SNS(+)

SNS(-)

Synch

Out

STBY

VID4 - VID0

Table 2-2; Booster Pin-Out Information

Pin Function

Pin Function

Pin Function

1

No Connect

19 GND

2

No Connect

3

No Connect

12 No Connect

4

No Connect

13 GND

5

No Connect

14 GND

6

No Connect

15 GND

16 GND

17 GND

26 No Connect

18 GND

27 Sync In

Notes:

1. Each booster requires the same amount of input and

output capacitance as recommended for a stand-alone

regulator. Consult the individual data sheet of the

applicable regulator, and the related application note

regarding capacitor selection for this product family.

2. The 1-µH filter choke located at the input of each

applications. If specified, each inductor must be sized

to handle 20ADC at full output load.

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

number pins identified, “No Connect” (see Table 2-2).

These pins are not connected internally to the module

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

mechanical integrity.

4. A similar PCB footprint and trace layout between the

regulator and each booster will facilitate current sharing

between all modules.

Table 2-1; Booster Compatibility

P7744 Booster

PT7745 Booster

Regulator

(3.3V Input Bus)

(5V Input Bus)

PT7711

•

PT7712

•

PT7713

•

PT7714

•

PT7715

•

PT7716

•