Datasheet

LTC3728
14
3728fg
OPERATION
A fi nal question: If 2-phase operation offers such an ad-
vantage over single-phase operation for dual switching
regulators, why hasn’t it been done before? The answer
is that, while simple in concept, it is hard to implement.
Constant-frequency current mode switching regulators
require an oscillator derived slope compensation signal
to allow stable operation of each regulator at over 50%
duty cycle. This signal is relatively easy to derive in
single-phase dual switching regulators, but required the
development of a new and proprietary technique to allow
2-phase operation. In addition, isolation between the two
channels becomes more critical with 2-phase operation
because switch transitions in one channel could potentially
disrupt the operation of the other channel.
These 2-phase parts are proof that these hurdles have
been surmounted. They offer unique advantages for the
ever-expanding number of high effi ciency power supplies
required in portable electronics.
INPUT VOLTAGE (V)
0
INPUT RMS CURRENT (A)
3.0
2.5
2.0
1.5
1.0
0.5
0
10 20 30 40
3728 F04
SINGLE PHASE
DUAL CONTROLLER
2-PHASE
DUAL CONTROLLER
V
O1
= 5V/3A
V
O2
= 3.3V/3A
Figure 4. RMS Input Current Comparison
(Refer to Functional Diagram)