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PDF LTM4615 Data sheet ( Hoja de datos )
| Número de pieza | LTM4615 | |
| Descripción | Triple Output Low Voltage DC/DC uModule Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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LTM4615www.DataSheet4U.com
Triple Output, Low Voltage
DC/DC µModule Regulator
FEATURES
n Dual 4A Output Power Supply with 1.5A VLDO™
n Short-Circuit and Overtemperature Protection
n Power Good Indicators
Switching Regulators Section—Current Mode Control
n Input Voltage Range: 2.375V to 5.5V
n 4A DC Typical, 5A Peak Output Current Each
n 0.8V Up to 5V Output Each, Parallelable
n ±2% Total DC Output Error
n Output Voltage Tracking
n Up to 95% Efficiency
n Programmable Soft-Start
VLDO Section
n VLDO, 1.14V to 3.5V Input Range
n VLDO, 0.4V to 2.6V, 1.5A Output
n VLDO, 40dB Supply Rejection at fSW
n ±1% Total DC Output Error
n Small and Very Low Profile Package:
15mm × 15mm × 2.82mm
APPLICATIONS
n Telecom and Networking Equipment
n Industrial Power Systems
n Low Noise Applications
n FPGA, SERDES Power
L, LT, LTC, LTM, Linear Technology, the Linear logo and μModule are registered trademarks of
Linear Technology Corporation. VLDO is a trademark of Linear Technology Corporation. All other
trademarks are the property of their respective owners. Protected by U.S. Patents including
5481178, 6580258, 6304066, 6127815, 6498466, 6611131, 6724174.
DESCRIPTION
The LTM®4615 is a complete 4A dual output switching mode
DC/DC power supply plus an additional 1.5A VLDO (very
low dropout) linear regulator. Included in the package are
the switching controllers, power FETs, inductors, a 1.5A
regulator and all support components. The dual 4A DC/DC
converters operate over an input voltage range of 2.375V
to 5.5V, and the VLDO operates from a 1.14V to 3.5V input.
The LTM4615 supports output voltages ranging from 0.8V
to 5V for the DC/DC converters, and 0.4V to 2.6V for the
VLDO. The three regulator output voltages are set by a
single resistor for each output. Only bulk input and output
capacitors are needed to complete the design.
The low profile package (2.82mm) enables utilization of
unused space on the bottom of PC boards for high density
point of load regulation. High switching frequency and a
current mode architecture enables a very fast transient
response to line and load changes without sacrificing
stability. The device supports output voltage tracking for
supply rail sequencing.
Additional features include overvoltage protection,
foldback overcurrent protection, thermal shutdown and
programmable soft-start. The power module is offered in
a space saving and thermally enhanced 15mm × 15mm
× 2.82mm LGA package. The LTM4615 is Pb-free and
RoHS compliant.
TYPICAL APPLICATION
VOUT1
1.2V
4A
1.2V at 4A, 1.5V at 4A and 1V at 1A DC/DC μModule® Regulator
PGOOD1
10μF
6.3V
10k
22μF
6.3V
10k VIN
100μF 1.2V
6.3V
10μF
VIN 3V TO 5.5V
VIN1
PGOOD1
VOUT1
FB1
TRACK1
RUN/SS1
LDO_IN
EN3
GND1
LTM4615
GND2
VIN2
PGOOD2
VOUT2
FB2
TRACK2
RUN/SS2
LDO_OUT
FB3
PGOOD3
GND3
PGOOD2
10μF
6.3V
10k
VIN VOUT3
1V AT 1A
PGOOD3
10k
VOUT3
3.32k
5.76k
10μF
6.3V
100μF
6.3V
VOUT2
1.5V
4A
22μF
6.3V
4615 TA01a
Efficiency vs Output Current
91
VIN = 3.3V
89
87 VOUT2
1.5V
85
83
VOUT3
81 1V
(VIN = 1.2V)
79
VOUT1
1.2V
77
75
0 12 34
LOAD CURRENT (A)
4615 TA01b
4615f
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LTM4615www.DataSheet4U.com
TYPICAL PERFORMANCE CHARACTERISTICS
Switching Regulators
Efficiency vs Output Current
VIN = 2.5V
100
Efficiency vs Output Current
VIN = 3.3V
100
95 95
90 90
85 85
80
75
VOUT = 1.8V
70
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
65
01
2
3
OUTPUT CURRENT (A)
4
4615 G01
80
75 VOUT = 2.5V
VOUT = 1.8V
70
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
65
01
2
3
OUTPUT CURRENT (A)
4
4615 G02
Efficiency vs Output Current
VIN = 5V
95
90
85
80
75
70
65
0
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
12
3
OUTPUT CURRENT (A)
4
4615 G03
Minimum Input Voltage
at 4A Load
3.5
VOUT = 3.3V
3.0
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
2.5 VOUT = 1.2V
VOUT = 0.8V
2.0
1.5
Load Transient Response
ILOAD
2A/DIV
VOUT
20mV/DIV
1.0
0.5
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
4615 G04
VIN = 5V
20μs/DIV
VOUT = 1.2V
COUT = 100μF, 6.3V CERAMICS
Load Transient Response
ILOAD
2A/DIV
VOUT
20mV/DIV
4615 G05
VIN = 5V
20μs/DIV
VOUT = 1.5V
COUT = 100μF, 6.3V CERAMICS
4615 G06
Load Transient Response
Load Transient Response
Load Transient Response
ILOAD
2A/DIV
VOUT
20mV/DIV
VIN = 5V
20μs/DIV
VOUT = 1.8V
COUT = 100μF, 6.3V CERAMICS
ILOAD
2A/DIV
VOUT
20mV/DIV
4615 G07
VIN = 5V
20μs/DIV
VOUT = 2.5V
COUT = 100μF, 6.3V CERAMICS
ILOAD
2A/DIV
VOUT
20mV/DIV
4615 G08
VIN = 5V
20μs/DIV
VOUT = 3.3V
COUT = 100μF, 6.3V CERAMICS
4615 G09
4615f
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LTM4615www.DataSheet4U.com
APPLICATIONS INFORMATION
Dual Switching Regulator
The typical LTM4615 application circuit is shown in
Figure 12. External component selection is primarily
determined by the maximum load current and output
voltage. Refer to Table 4 for specific external capacitor
requirements for a particular application.
VIN to VOUT Step-Down Ratios
There are restrictions in the maximum VIN and VOUT step-
down ratio than can be achieved for a given input voltage
on the two switching regulators. The LTM4615 is 100%
duty cycle, but the VIN to VOUT minimum dropout will be
a function the load current. A typical 0.5V minimum is
sufficient.
Output Voltage Programming
Each regulator channel has an internal 0.8V reference
voltage. As shown in the block diagram, a 4.99k internal
feedback resistor connects the VOUT and FB pins together.
The output voltage will default to 0.8V with no feedback
resistor. Adding a resistor RFB from the FB pin to GND
programs the output voltage:
VOUT
=
0.8V
•
4.99k +
RFB
RFB
Table 1. FB Resistor Table vs Various Output Voltages
VOUT 0.8V 1.2V 1.5V 1.8V 2.5V
FB Open 10k 5.76k 3.92k 2.37k
3.3V
1.62k
Input Capacitors
The LTM4615 module should be connected to a low AC
impedance DC source. One 4.7μF ceramic capacitor is
included inside the module for each regulator channel.
Additional input capacitors are needed if a large load step
is required up to the full 4A level and for RMS ripple cur-
rent requirements. A 47μF bulk capacitor can be used for
more input bulk capacitance. This 47μF capacitor is only
needed if the input source impedance is compromised by
long inductive leads or traces.
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. The bulk capacitor can be a switcher-
rated electrolytic aluminum OS-CON capacitor for bulk
input capacitance due to high inductance traces or leads.
If a low inductance plane is used to power the device,
then no input capacitance is required. The internal 4.7μF
ceramics on each channel input are typically rated for 1A of
RMS ripple current up to 85°C operation. The worse-case
ripple current for the 4A maximum current is 2A or less.
An additional 10μF or 22μF ceramic capacitor can be used
to supplement the internal capacitor with an additional 1A
to 2A ripple current rating.
Output Capacitors
The LTM4615 switchers are designed for low output volt-
age ripple on each channel. The bulk output capacitors are
chosen with low enough effective series resistance (ESR)
to meet the output voltage ripple and transient require-
ments. The output capacitors can be a low ESR tantalum
capacitor, low ESR polymer capacitor or ceramic capacitor.
The typical output capacitance range is 66μF to 100μF.
Additional output filtering may be required by the system
designer, if further reduction of output ripple or dynamic
transient spike is required. Table 4 shows a matrix of dif-
ferent output voltages and output capacitors to minimize
the voltage droop and overshoot during a 2A/μs transient.
The table optimizes total equivalent ESR and total bulk
capacitance to maximize transient performance.
4615f
11
11 Page | ||
| Páginas | Total 24 Páginas | |
| PDF Descargar | [ Datasheet LTM4615.PDF ] | |
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