LTM4603IV-1#PBF Linear Technology, LTM4603IV-1#PBF Datasheet - Page 11

• Manufacturer Part Number: LTM4603IV-1#PBF
• Description: IC DC/DC UMODULE 6A 118-LGA
• Manufacturer: Linear Technology
• Series: µModuler
• Type: Point of Load (POL) Non-Isolatedr

Specifications of LTM4603IV-1#PBF

• Design Resources: LTM4603-1 Spice Model
• Output: 0.6 ~ 5 V
• Number Of Outputs: 1
• Power (watts): 30W
• Mounting Type: Surface Mount
• Voltage - Input: 4.5 ~ 20V
• Package / Case: 118-LGA
• 1st Output: 0.6 ~ 5 VDC @ 6A
• Size / Dimension: 0.59" L x 0.59" W x 0.11" H (15mm x 15mm x 2.8mm)
• Power (watts) - Rated: 30W
• Operating Temperature: -40°C ~ 85°C
• Efficiency: 93%
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• 3rd Output: -
• 2nd Output: -

or choose a capacitor rated at a higher temperature than
required. Always contact the capacitor manufacturer for
derating requirements.
In Figure 18, the 10μF ceramic capacitors are together
used as a high frequency input decoupling capacitor. In a
typical 6A output application, two very low ESR, X5R or
X7R, 10μF ceramic capacitors are recommended. These
decoupling capacitors should be placed directly adjacent
to the module input pins in the PCB layout to minimize
the trace inductance and high frequency AC noise. Each
10μF ceramic is typically good for 2A to 3A of RMS ripple
current. Refer to your ceramics capacitor catalog for the
RMS current ratings.
Multiphase operation with multiple LTM4603 devices in
parallel will lower the effective input RMS ripple current due
to the interleaving operation of the regulators. Application
Note 77 provides a detailed explanation. Refer to Figure 2
for the input capacitor ripple current requirement as a
function of the number of phases. The fi gure provides a
ratio of RMS ripple current to DC load current as a function
of duty cycle and the number of paralleled phases. Pick
the corresponding duty cycle and the number of phases
to arrive at the correct ripple current value. For example,
the 2-phase parallel LTM4603 design provides 10A at 2.5V
output from a 12V input. The duty cycle is DC = 2.5V/12V
= 0.21. The 2-phase curve has a ratio of ~0.25 for a duty
cycle of 0.21. This 0.25 ratio of RMS ripple current to a
DC load current of 10A equals ~2.5A of input RMS ripple
current for the external input capacitors.
APPLICATIONS INFORMATION
Figure 2. Normalized Input RMS Ripple Current
vs Duty Factor for One to Six Modules (Phases)
0.6
0.5
0.4
0.3
0.2
0.1
0
0.1
0.2
0.3
DUTY FACTOR (V
0.4
1-PHASE
2-PHASE
3-PHASE
4-PHASE
6-PHASE
0.5
OUT
0.6
/V
IN
0.7
)
0.8
4603 F02
0.9
Output Capacitors
The LTM4603 is designed for low output voltage ripple.
The bulk output capacitors defi ned as C
with low enough effective series resistance (ESR) to meet
the output voltage ripple and transient requirements. C
can be a low ESR tantalum capacitor, a low ESR polymer
capacitor or a ceramic capacitor. The typical capacitance is
200μF if all ceramic output capacitors are used. Additional
output fi ltering may be required by the system designer,
if further reduction of output ripple or dynamic transient
spike is required. Table 2 shows a matrix of different output
voltages and output capacitors to minimize the voltage
droop and overshoot during a 2.5A/μs transient. The table
optimizes total equivalent ESR and total bulk capacitance
to maximize transient performance.
Multiphase operation with multiple LTM4603 devices in
parallel will lower the effective output ripple current due
to the interleaving operation of the regulators. For ex-
ample, each LTM4603’s inductor current of a 12V to 2.5V
multiphase design can be read from the “Inductor Ripple
Current vs Duty Cycle” graph (Figure 3). The large ripple
current at low duty cycle and high output voltage can be
reduced by adding an external resistor from f
which increases the frequency. If we choose the duty cycle
of DC = 2.5V/12V = 0.21, the inductor ripple current for
2.5V output at 21% duty cycle is ~3A in Figure 3.
5
4
3
2
1
0
0
Figure 3. Inductor Ripple Current vs Duty Cycle
20
DUTY CYCLE (V
LTM4603/LTM4603-1
40
OUT
/V
IN
60
)
4603 F03
80
OUT
2.5V OUTPUT
5V OUTPUT
1.8V OUTPUT
1.5V OUTPUT
1.2V OUTPUT
3.3V OUTPUT WITH
82.5k ADDED FROM
V
5V OUTPUT WITH
150k ADDED FROM
f
SET
SET
OUT
are chosen
TO GND
TO f
to ground
SET
11
4603fa
OUT