PT7720_13 Datasheet, PDF (4/8 Pages) Texas Instruments – High Efficiency

Application Notes
PT7721/22, PT7748
Using the PT7748 17-A Current Booster
with the PT7720 Series Programmable ISRs
The PT7748 is a 17-A “Current Booster” module
for the PT7720 series of regulators. The booster is
controlled directly by the regulator, and effectively
adds a parallel output stage. This allows the system
to run sychronously, providing a low noise solution.
Up to four booster modules can be connected to a
single regulator. Each booster increases the available
output current by 17A. Combinations of a regulator
and booster modules can supply power for virtually
any multi-processor application.
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 PT7720 regulator/booster combination is identi-
cal to that of a stand-alone regulator. Refer to the
appropriate data sheet for the performance speci-
fications.
Notes:
1. Each booster requires the same amount of input and
output capacitance as recommended for a stand-alone
regulator. See the Standard Application schematic and
the respective input/output filter notes in the PT7720
product data sheet.
2. The 1-µH filter choke located at the input of each
regulator and booster module (L_in) is optional for most
applications. If specified, each inductor must be sized
to handle 7ADC at full output load.
3. The pin-out of the current booster modules include a
number pins identified, “No Connect” (see Table 1).
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 1-1; PT7748 Pin-Out Information
Pin Function
1 No Connect
2 No Connect
3 No Connect
4 No Connect
5 No Connect
6 No Connect
7 Vin
8 Vin
9 V_in
Pin Function
10 V_in
11 Vin
12 No Connect
13 GND
14 GND
15 GND
16 GND
17 GND
18 GND
Pin Function
19 GND
20 Vout
21 Vout
22 Vout
23 V_out
24 Vout
25 Vout
26 No Connect
27 Sync In
Figure 1-1; Current Booster Application Schematic
PROGRAMMING PINS
VID0
VID1
VID2
VID3
VID4
V_IN
Lin
1µH
64 321
REMOTE SENSE (+)
26
7 - 11
PT7720
20 - 25
V_OUT
STBY*
GND
+
C_IN
27 13 - 19 5 12
+
C_OUT
REMOTE SENSE (-)
LOAD
GND
27
Lin
1µH
7 - 11
PT7748
+
C_IN
To Additional
Boosters
13 - 19
20 - 25
+
C_OUT
For technical support and more information, see inside back cover or visit www.ti.com