LTC3736EUF-2#TRPBF Linear Technology, LTC3736EUF-2#TRPBF Datasheet - Page 13

• Manufacturer Part Number: LTC3736EUF-2#TRPBF
• Description: IC CTRLR SW SYNC DUAL 2PH 24QFN
• Manufacturer: Linear Technology
• Series: PolyPhase®r
• Type: Step-Down (Buck)r

Specifications of LTC3736EUF-2#TRPBF

• Internal Switch(s): No
• Synchronous Rectifier: Yes
• Number Of Outputs: 2
• Voltage - Output: 0.6 ~ 9.8 V
• Current - Output: 1A
• Frequency - Switching: 550kHz ~ 750kHz
• Voltage - Input: 2.75 ~ 9.8 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 24-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Power - Output: -

OPERATION
Figure 2 shows example waveforms for a single-phase
dual controller versus a 2-phase LTC3736-2 system. In this
case, 2.5V and 1.8V outputs, each drawing a load current
of 2A, are derived from a 7V (e.g., a 2-cell Li-Ion battery)
input supply. In this example, 2-phase operation would
reduce the RMS input capacitor current from 1.79A
to 0.91A
itself, remember that power losses are proportional to
I
a factor of 3.86.
The reduced input ripple current also means that less
power is lost in the input power path, which could include
batteries, switches, trace/connector resistances, and
SW1 (V)
SW2 (V)
RMS
I
I
I
L1
L2
IN
2
, meaning that actual power wasted is reduced by
Figure 2. Example Waveforms for a Single-Phase
RMS
Dual Controller vs the 2-Phase LTC3736-2
Dual Controller
Single-Phase
. While this is an impressive reduction by
(Refer to Functional Diagram)
Dual Controller
2-Phase
RMS
37362 F02
protection circuitry. Improvements in both conducted
and radiated EMI also directly accrue as a result of the
reduced RMS input current and voltage. Signifi cant cost
and board footprint savings are also realized by being able
to use smaller, less expensive, lower RMS current-rated
input capacitors.
Of course, the improvement afforded by 2-phase operation
is a function of the relative duty cycles of the two control-
lers, which in turn are dependent upon the input supply
voltage. Figure 3 depicts how the RMS input current varies
for single-phase and 2-phase dual controllers with 2.5V
and 1.8V outputs over a wide input voltage range.
It can be readily seen that the advantages of 2-phase op-
eration are not limited to a narrow operating range, but in
fact extend over a wide region. A good rule of thumb for
most applications is that 2-phase operation will reduce the
input capacitor requirement to that for just one channel
operating at maximum current and 50% duty cycle.
Figure 3. RMS Input Current Comparison
1.2
2.0
1.8
1.6
1.4
1.0
0.8
0.6
0.4
0.2
0
2
V
V
OUT1
OUT2
3
= 2.5V/2A
= 1.8V/2A
4
INPUT VOLTAGE (V)
DUAL CONTROLER
SINGLE-PHASE
5
6
DUAL CONTROLER
7
2-PHASE
LTC3736-2
8
9
37362 F03
10
13
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