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Application Notes
Increasing the Output Current of the PT4484
with the PT4498 Compatible Current Booster
The PT4498 is a 20-A “Current Booster” module
designed specifically for the PT4484 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 PT4484 converter. Each booster
module increases the available output current by
20A. A combination of one PT4484 converter and
two PT4498 booster modules can supply up to 60A
of output current; enough to supply a large multi-
processor system. Figure 1-1 shows the connection
schematic for the regulator and current 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
1+Vin
10 +Vout
19 –Vout
2–Vin
11 +Vout
20 (–)Vsense
3
Do not connect
12 +Vout
21 Do not connect
4Vr
13 +Vout
22 Do not connect
5Va
14 –Vout
23 Do not connect
6
Do not connect
15 –Vout
24 Do not connect
7
Do not connect
16 –Vout
25 Do not connect
8+Vout
17 –Vout
26 DRV
9+Vout
18 –Vout
Notes:
1. Refer to the PT4484 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 150F of output capacitance is required
across the output of each PT4498 booster for proper
operation. A value greater than 150F 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.
PT4484, PT4498
PT4498
PT4484
1
2
8 - 13
–V
IN
-V
OUT
+V
OUT
20
7
REMOTE SENSE (+)
REMOTE SENSE (-)
VID1
VID2
VID3
PROGRAMMING PINS
Inhibit
3
C
IN
33F
Optional
+
C
IN
33F
Optional
+
LOAD
1
8 - 13
14 - 19
+V
IN
25
VID4
24
23
22
14-19
2
4526
20
4526
C
OUT
150F
Optional
+
C
OUT
150F
Required 3
+