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PDF LTM4601-1 Data sheet ( Hoja de datos )
| Número de pieza | LTM4601-1 | |
| Descripción | step-down switch mode DC/DC power supply | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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FEATURES
■ Complete Switch Mode Power Supply
■ Wide Input Voltage Range: 4.5V to 20V
■ 12A DC Typical, 14A Peak Output Current
■ 0.6V to 5V Output Voltage
■ Output Voltage Tracking and Margining
■ Parallel Multiple µModules for Current Sharing
■ Differential Remote Sensing for Precision
Regulation (LTM4601 Only)
■ PLL Frequency Synchronization
■ ±1.5% Regulation
■ Current Foldback Protection (Disabled at Start-Up)
■ Pb-Free (e4) RoHS Compliant Package with Gold
Finish Pads
■ Ultrafast Transient Response
■ Current Mode Control
■ Up to 95% Efficiency at 5VIN, 3.3VOUT
■ Programmable Soft-Start
■ Output Overvoltage Protection
■ Small Footprint, Low Profile (15mm × 15mm ×
2.8mm) Surface Mount LGA Package
U
APPLICATIO S
■ Telecom and Networking Equipment
■ Servers
■ Industrial Equipment
■ Point of Load Regulation
LTM4601/LTM4601-1
12A DC/DC µModules
with PLL, Output Tracking
and Margining
DESCRIPTIO
The LTM®4601 is a complete 12A step-down switch mode
DC/DC power supply with onboard switching controller,
MOSFETs, inductor and all support components. The
µModuleTM is housed in a small surface mount 15mm
×15mm × 2.8mm LGA package. Operating over an input
voltage range of 4.5 to 20V, the LTM4601 supports an
output voltage range of 0.6V to 5V as well as output voltage
tracking and margining. The high efficiency design delivers
12A continuous current (14A peak). Only bulk input and
output capacitors are needed to complete the design.
The low profile (2.8mm) and light weight (1.7g) pack-
age easily mounts in unused space on the back side of
PC boards for high density point of load regulation. The
µModule can be synchronized with an external clock for
reducing undesirable frequency harmonics and allows
PolyPhase® operation for high load currents.
A high switching frequency and adaptive on-time current
mode architecture deliver a very fast transient response
to line and load changes without sacrificing stability. An
onboard differential remote sense amplifier can be used
to accurately regulate an output voltage independent of
load current. The onboard remote sense amplifier is not
available in the LTM4601-1.
, LTC, LT and PolyPhase are registered trademarks of Linear Technology Corporation.
µModule is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
Protected by U.S. Patents, including 5481178, 5847554, 6580258, 6304066, 6476589,
6774611, 6677210
TYPICAL APPLICATIO
1.5V/12A Power Supply with 4.5V to 20V Input
VIN
4.5V TO 20V
CIN
CLOCK SYNC
TRACK/SS CONTROL
VIN
PGOOD
PLLIN TRACK/SS
VOUT
ON/OFF
R1
392k
RUN
COMP
INTVCC
DRVCC
MPGM
LTM4601
SGND PGND
VFB
MARG0
MARG1
VOUT_LCL
DIFFVOUT
VOSNS+
VOSNS–
fSET
5% MARGIN
100pF
MARGIN
CONTROL
RSET
40.2k
4601 TA01a
VOUT
1.5V
12A
COUT
Efficiency and Power Loss
vs Load Current
95
EFFICIENCY
90
5VIN
85
12VIN
80
75
12VIN
70
5VIN
65
60
POWER LOSS
55
4.0
3.5
3.0
2.5
2.0
1.5
1.0
50
0
0.5
2 4 6 8 10 12 14
OUTPUT CURRENT (A)
4601 TA01b
4601f
1
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www.DataSheet4U.com
LTM4601/LTM4601-1
TYPICAL PERFOR A CE CHARACTERISTICS (See Figure 18 for all curves)
Efficiency vs Load Current
with 5VIN
100
95
90
85
80
75
0.6VOUT
70 1.2VOUT
1.5VOUT
65 2.5VOUT
3.3VOUT
60
0 5 10
OUTPUT CURRENT (A)
1.2V Transient Response
15
4601 G01
Efficiency vs Load Current
with 12VIN
100
95
90
85
80
75
70
65
60
55
50
0
0.6VOUT
1.2VOUT
1.5VOUT
2.5VOUT
3.3VOUT
5VOUT
5 10
OUTPUT CURRENT (A)
1.5V Transient Response
15
4601 G02
Efficiency vs Load Current
with 20VIN
100
95
90
85
80
75
1.2VOUT
70 1.5VOUT
2.5VOUT
65 3.3VOUT
5.0VOUT
60
0 5 10 15
OUTPUT CURRENT (A)
4601 G03
1.8V Transient Response
VOUT
50mV/DIV
IOUT
5A/DIV
20µs/DIV
1.2V AT 6A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POSCAP
C3 = 100pF
VOUT
50mV/DIV
IOUT
5A/DIV
4601 G04
20µs/DIV
1.5V AT 6A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POSCAP
C3 = 100pF
VOUT
50mV/DIV
IOUT
5A/DIV
4601 G05
20µs/DIV
1.8V AT 6A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POSCAP
C3 = 100pF
4601 G06
2.5V Transient Response
VOUT
50mV/DIV
IOUT
5A/DIV
20µs/DIV
2.5V AT 6A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POSCAP
C3 = 100pF
4601 G07
3.3V Transient Response
VOUT
50mV/DIV
IOUT
5A/DIV
20µs/DIV
3.3V AT 6A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POSCAP
C3 = 100pF
4601 G08
4601f
5
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www.DataSheet4U.com
LTM4601/LTM4601-1
APPLICATIO S I FOR ATIO
For a buck converter, the switching duty-cycle can be
estimated as:
D = VOUT
VIN
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
( )ICIN(RMS)
=
IOUT(MAX)
η%
•
D • 1– D
In the above equation, η% is the estimated efficiency of
the power module. CIN can be a switcher-rated electrolytic
aluminum capacitor, OS-CON capacitor or high volume
ceramic capacitor. Note the capacitor ripple current rat-
ings are often based on temperature and hours of life. This
makes it advisable to properly derate the input capacitor,
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 12A output application, three 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 LTM4601 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 figure provides a
ratio of RMS ripple current to DC load current as 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 LTM4601 design provides 24A 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 24A equals ~6A of input RMS ripple
current for the external input capacitors.
Output Capacitors
The LTM4601 is designed for low output voltage ripple.
The bulk output capacitors defined as COUT are chosen
with low enough effective series resistance (ESR) to meet
the output voltage ripple and transient requirements. COUT
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 filtering 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 5A/µs transient. The table
optimizes total equivalent ESR and total bulk capacitance
to maximize transient performance.
0.6
0.5
1-PHASE
0.4
2-PHASE
3-PHASE
4-PHASE
0.3 6-PHASE
12-PHASE
0.2
0.1
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
DUTY FACTOR (VOUT/VIN)
4601 F02
Figure 2. Normalized Input RMS Ripple Current
vs Duty Factor for One to Six Modules (Phases)
4601f
11
11 Page | ||
| Páginas | Total 28 Páginas | |
| PDF Descargar | [ Datasheet LTM4601-1.PDF ] | |
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