LTM4604IV-PBF [Linear]
Low Voltage, 4A DC/DC μModuleTM with Tracking; 低电压， 4A DC / DC μModuleTM与跟踪
| 型号： | LTM4604IV-PBF |
| 厂家： | 
Linear |
| 描述： | Low Voltage, 4A DC/DC μModuleTM with Tracking |
| 文件： | 总20页 (文件大小：302K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTM4604
Low Voltage, 4A DC/DC
µModuleTM with Tracking
FEATURES
DESCRIPTION
TheLTM®4604isacomplete4AswitchmodeDC/DCpower
supply. Included in the package are the switching control-
ler, power FETs, inductor and all support components.
Operating over an input voltage range of 2.375V to 5.5V,
the LTM4604 supports an output voltage range of 0.8V
to 5V, set by a single resistor. This high efficiency design
delivers up to 4A continuous current (5A peak). Only bulk
output capacitors are needed to complete the design.
■
Complete Standalone Power Supply
■
Wide Input Voltage Range: 2.375V to 5.5V
■
4A DC, 5A Peak Output Current
■
0.8V to 5V Output
■
Output Voltage Tracking
■
2% Total DC Error
UltraFastTM Transient Response
■
■
Power Good Indicator
Current Mode Control
Current Foldback Protection, Parallel/Current Sharing
Up to 95% Efficiency
Programmable Soft-Start
Micropower Shutdown: I ≤ 7μA
Overtemperature Protection
■
The low profile package (2.3mm) 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 enable a very fast transient
response to line and load changes without sacrificing
stability. The device supports output voltage tracking for
supply rail sequencing.
■
■
■
■
Q
■
■
Small and Very Low Profile Package:
15mm × 9mm × 2.3mm LGA
Fault protection features include foldback current protec-
tion, thermal shutdown and a programmable soft-start
function. The LTM4604 is offered in a space saving and
thermally enhanced 15mm × 9mm × 2.3mm LGA package
and is Pb free and RoHS compliant.
APPLICATIONS
■
Telecom and Networking Equipment
■
Servers
■
Storage Cards
ATCA Cards
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
μModule and UltraFast are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
■
■
Industrial Equipment
TYPICAL APPLICATION
Efficiency vs Output Current
3.3V to 2.5V/4A μModule Regulator
100
V
V
= 3.3V
IN
OUT
V
IN
= 2.5V
95
90
3.3V
10μF
6.3V
V
85
80
75
IN
V
2.5V
4A
OUT
PGOOD
LTM4604
COMP
V
OUT
FB
22μF
6.3V
V
RUN/SS TRACK
GND
IN
×2
2.37k
70
65
4604 TA01a
1
2
4
0
3
OUTPUT CURRENT (A)
4604f
1
LTM4604
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
V , PGOOD ................................................. –0.3V to 6V
TOP VIEW
TRACK
IN
PGOOD
COMP, RUN/SS, FB, TRACK.........................–0.3V to V
IN
A
B
C
D
E
F
G
SW, V ........................................–0.3V to (V + 0.3V)
OUT
IN
V
IN
Operating Temperature Range (Note 2) ... –40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range................... –55°C to 125°C
COMP
FB
1
2
RUN/
SS
SW
3
GND
4
5
6
7
8
9
10
11
GND
V
OUT
LGA PACKAGE
66-PIN (15mm 9mm 2.3mm)
= 125°C, θ = 25°C/W, WEIGHT = 0.86g
T
JMAX
JA
ORDER INFORMATION
LEAD FREE FINISH
TRAY
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE
LTM4604EV#PBF
LTM4604IV#PBF
LTM4604EV#PBF
LTM4604IV#PBF
LTM4604V
LTM4604V
15mm × 9mm × 2.3mm LGA
15mm × 9mm × 2.3mm LGA
–40°C to 85°C
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Consult LTC Marketing for information on non-standard lead based finish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://linear.com/packaging/
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
●
●
V
V
Input DC Voltage
Output Voltage, Total Variation
with Line and Load
2.375
5.5
V
IN(DC)
C
= 10μF × 1, C
IN
IN
= 22μF ×3, R = 5.69k 0.5%
OUT(DC)
IN
V
V
OUT FB
= 2.375V to 5.5V, I
= 2.375V to 5.5V, I
= 0A to 4A, 0°C ≤ T ≤ 85°C
1.478
1.470
1.5
1.5
1.522
1.522
V
V
OUT
OUT
A
= 0A to 4A
Input Specifications
V
Undervoltage Lockout
Threshold
Peak Input Inrush Current at
Start-Up
I
I
= 0A
1.75
2
2.3
V
IN(UVLO)
OUT
I
I
= 0A, C = 10μF, C
RUN/SS = 0.01μF, V
= 22μF ×3,
INRUSH(VIN)
OUT
IN
OUT
= 1.5V
OUT
V
IN
V
IN
= 3.3V
= 5V
= 3.3V, V
= 3.3V, V
= 5V, V
= 5V, V
0.7
0.7
60
28
100
35
7
A
A
Input Supply Bias Current
V
= 1.5V, No Switching
μA
mA
μA
Q(VIN NOLOAD)
IN
IN
IN
IN
OUT
OUT
OUT
OUT
V
V
V
= 1.5V, Switching Continuous
= 1.5V, No Switching
= 1.5V, Switching Continuous
mA
μA
Shutdown, RUN = 0, V = 5V
IN
4604f
2
LTM4604
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
I
Input Supply Current
V
IN
V
IN
V
IN
= 2.5V, V
= 3.3V, V
= 1.5V, I
= 1.5V, I
= 4A
= 4A
2.9
2.2
1.45
A
A
A
S(VIN)
OUT
OUT
OUT
OUT
= 5V, V
= 1.5V, I
= 4A
OUT
OUT
Output Specifications
I
Output Continuous Current
Range (See Output Current
Derating Curves for Different
V
IN
= 3.3V, V = 1.5V
OUT
4
A
OUT(DC)
V , V
and T )
A
IN OUT
●
ΔV
ΔV
Line Regulation Accuracy
V
V
= 1.5V, V from 2.375V to 5.5V, I
= 0A
0.1
0.2
%
OUT(LINE)
OUT
IN
OUT
V
OUT
Load Regulation Accuracy
= 1.5V, 0A to 4A
= 3.3V
= 5V
OUT(LOAD)
OUT
●
●
V
IN
V
IN
0.3
0.3
0.6
0.6
%
%
V
OUT
V
Output Ripple Voltage
I
I
= 0A, C
= 22μF/X5R/Ceramic ×3
OUT
OUT(AC)
OUT
V
IN
V
IN
= 3.3V, V
= 1.5V
10
12
1.25
mV
mV
MHz
OUT
P-P
P-P
= 5V, V
= 4A, V = 5V, V = 1.5V
OUT
= 1.5V
OUT
f
Output Ripple Voltage
Frequency
S
OUT
IN
ΔV
Turn-On Overshoot
C
= 22μF ×3, V
= 0A
= 1.5V, RUN/SS = 10nF,
OUT(START)
OUT
OUT
IN
IN
OUT
I
V
V
= 3.3V
20
20
mV
mV
= 5V
t
Turn-on Time
C
= 22μF ×3, V
= 1.5V, I
= 1A Resistive Load,
OUT
START
OUT
OUT
TRACK = V and RUN/SS = Float
IN
= 3.3V
= 5V
V
V
1.5
1.0
ms
ms
IN
IN
ΔV
OUT(LS)
Peak Deviation for Dynamic
Load Step
Load: 0% to 50% to 0% of Full Load,
= 22μF ×3 Ceramic
C
OUT
V
= 5V, V
= 1.5V
25
10
mV
μs
IN
OUT
t
I
Settling Time for Dynamic
Load Step
Output Current Limit
Load: 0% to 50% to 0% of Full Load
= 5V, V = 1.5V
SETTLE
V
IN
OUT
C
= 22μF ×3
OUT(PK)
OUT
V
IN
V
IN
= 3.3V, V
= 1.5V
OUT
8
8
A
A
= 5V, V
= 1.5V
OUT
Control Section
V
FB
Voltage at FB Pin
I
I
= 0A, V
= 0A, V
= 1.5V, 0°C ≤ T ≤ 85°C
0.792
0.788
0.8
0.8
0.808
0.812
V
V
OUT
OUT
OUT
OUT
A
●
= 1.5V
I
V
0.2
0.65
0.2
μA
V
μA
mV
V
FB
RUN Pin On/Off Threshold
TRACK Pin Current
Offset Voltage
0.5
0.8
RUN
I
TRACK
V
V
TRACK = 0.4V
30
TRACK(OFFSET)
TRACK(RANGE)
Tracking Input Range
0
0.8
R
Resistor Between V
and
OUT
4.975
4.99
5.025
kΩ
FBHI
FB Pins
PGOOD
ΔV
R
PGOOD Range
PGOOD Resistance
7.5
90
%
Ω
PGOOD
PGOOD
Open-Drain Pull-Down
150
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM4604E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTM4604I is guaranteed over the full
–40°C to 85°C temperature range.
4604f
3
LTM4604
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Output Current
Efficiency vs Output Current
VIN = 3.3V
Efficiency vs Output Current
VIN = 5V
V
IN = 2.5V
100
95
95
90
100
95
90
90
85
80
85
80
75
70
65
85
80
75
V
V
V
V
V
V
= 3.3V
= 2.5V
= 1.8V
= 1.5V
= 1.2V
= 0.8V
OUT
OUT
OUT
OUT
OUT
OUT
75
70
65
V
V
V
V
V
= 2.5V
= 1.8V
= 1.5V
= 1.2V
= 0.8V
OUT
OUT
OUT
OUT
OUT
V
= 1.8V
= 1.5V
= 1.2V
= 0.8V
OUT
OUT
OUT
OUT
V
70
65
V
V
1
2
4
0
1
2
3
4
0
3
1
2
4
0
3
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
Minimum Input Voltage
at 4A Load
Load Transient Response
Load Transient Response
3.5
3.0
V
V
V
V
V
V
= 3.3V
= 2.5V
= 1.8V
= 1.5V
= 1.2V
= 0.8V
OUT
OUT
OUT
OUT
OUT
OUT
I
I
LOAD
LOAD
2.5
2A/DIV
2A/DIV
V
OUT
2.0
1.5
1.0
0.5
V
OUT
20mV/DIV
20mV/DIV
4604 G06
V
V
C
= 5V
20μs/DIV
IN
4604 G05
V
V
C
= 5V
20μs/DIV
IN
= 1.5V
OUT
OUT
= 1.2V
OUT
OUT
= 4 × 22μF, 6.3V CERAMICS
= 4 × 22μF, 6.3V CERAMICS
0
0
1.5
2.5
2
3
3.5
4
4.5
5
5.5
0.5
1
V
(V)
IN
4604 G04
Load Transient Response
Load Transient Response
Load Transient Response
I
I
LOAD
LOAD
2A/DIV
2A/DIV
I
LOAD
2A/DIV
V
OUT
V
V
OUT
20mV/DIV
OUT
20mV/DIV
20mV/DIV
4604 G07
4604 G08
4604 G09
V
V
C
= 5V
20μs/DIV
V
V
C
= 5V
20 s/DIV
V
V
C
= 5V
OUT
OUT
20μs/DIV
= 2 × 22μF, 6.3V CERAMICS
IN
IN
IN
= 1.8V
= 2.5V
= 3.3V
OUT
OUT
OUT
OUT
= 3 × 22μF, 6.3V CERAMICS
= 3 22 F, 6.3V CERAMICS
4604f
4
LTM4604
TYPICAL PERFORMANCE CHARACTERISTICS
Start-Up
Start-Up
V
V
OUT
OUT
1V/DIV
1V/DIV
I
IN
I
IN
1A/DIV
1A/DIV
4604 G10
4604 G11
V
V
C
= 5V
200μs/DIV
V
V
C
= 5V
200μs/DIV
IN
IN
= 2.5V
= 2.5V
OUT
OUT
OUT
OUT
= 4 × 22μF
= 4 × 22μF
NO LOAD
4A LOAD
(0.01μF SOFT-START CAPACITOR)
(0.01μF SOFT-START CAPACITOR)
VFB vs Temperature
Current Limit Foldback
806
804
1.6
1.4
1.2
1.0
802
800
0.8
0.6
798
796
794
V
= 1.5V
0.4
0.2
0
OUT
V
V
V
= 5V
= 3.3V
= 2.5V
IN
IN
IN
-50
-25
0
25
50
75
100
4
5
7
3
8
6
Temperature (C)
OUTPUT CURRENT (A)
4604 G12
Short-Circuit Protection
1.5V Short, No Load
Short-Circuit Protection
1.5V Short, 4A Load
V
V
OUT
OUT
0.5V/DIV
0.5V/DIV
I
I
IN
IN
1A/DIV
4A/DIV
4604 G14
4604 G13
100μs/DIV
20μs/DIV
4604f
5
LTM4604
PIN FUNCTIONS
V
(B1, C1, C3-C7, D7, E6 and E7): Power Input Pins.
resistor. Different output voltages can be programmed
with an additional resistor between FB and GND pins.
Two power modules can current share when this pin is
connected in parallel with the adjacent module’s FB pin.
See Applications Information section.
IN
Apply input voltage between these pins and GND pins.
Recommendplacinginputdecouplingcapacitancedirectly
between V pins and GND pins.
IN
V
OUT
(D8-D11, E8-E11, F6-F11, G6-G11): Power Output
Pins. Apply output load between these pins and GND pins.
Recommendplacingoutputdecouplingcapacitancedirectly
between these pins and GND pins. Review Table 4.
COMP(G1):CurrentControlThresholdandErrorAmplifier
Compensation Point. The current comparator threshold
increases with this control voltage. Two power modules
can current share when this pin is connected in parallel
with the adjacent module’s COMP pin.
GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11):
Power Ground Pins for Both Input and Output Returns.
PGOOD(F1):OutputVoltagePowerGoodIndicator.Open-
drain logic output that is pulled to ground when the output
voltage is not within 7.5% of the regulation point.
TRACK(E1):OutputVoltageTrackingPin.Whenthemodule
is configured as a master output, then a soft-start capaci-
tor is placed on the RUN/SS pin to ground to control the
master ramp rate. Slave operation is performed by putting
a resistor divider from the master output to ground, and
connecting the center point of the divider to this pin on
the slave regulator. If tracking is not desired, then connect
RUN/SS (D1): Run Control and Soft-Start Pin. A voltage
above 0.8V will turn on the module, and below 0.5V will
turn off the module. This pin has a 1M resistor to V and
IN
a 1000pF capacitor to GND. See Application Infomation
the TRACK pin to V . Load current must be present for
section for soft-start information.
IN
tracking. See Applications Information section.
SW (B3 and B4): Switching Node of the circuit is used for
testing purposes. This can be connected to copper on the
board to improve thermal performance. Make sure not to
connect it to other output pins.
FB (G2): The Negative Input of the Error Amplifier. Inter-
nally, this pin is connected to V
with a 4.99k precision
OUT
TOP VIEW
TRACK
PGOOD
A
B
C
D
E
F
G
V
IN
COMP
FB
1
2
RUN/
SS
SW
3
GND
4
5
6
7
8
9
10
11
GND
V
OUT
4604f
6
LTM4604
BLOCK DIAGRAM
V
V
PGOOD
IN
V
IN
2.375V TO 5.5V
10μF
6.3V
×2
10μF
R
SS
6.3V
1M
RUN/SS
C
SS
C
SSEXT
1000pF
M1
M2
L
V
1.5V
4A
OUT
OUT
CONTROL,
DRIVE
4.99k
TRACK
COMP
TRACK
SUPPLY
22μF
6.3V
×3
R1
4.99k
0.5%
C2
470pF
10μF
6.3V
5.76k
INTERNAL
COMP
GND
4604 BD
FB
SW
R
FB
5.76k
Figure 1. Simplified LTM4604 Block Diagram
DECOUPLING REQUIREMENTS T = 25°C. Use Figure 1 Configuration.
A
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
C
External Input Capacitor Requirement
I
= 4A
10
μF
IN
OUT
(V = 2.375V to 5.5V, V
= 1.5V)
IN
OUT
C
External Output Capacitor Requirement
(V = 2.375V to 5.5V, V = 1.5V)
I
= 4A
22
100
μF
OUT
OUT
IN
OUT
4604f
7
LTM4604
OPERATION
Power Module Description
drainPGOODoutputlowiftheoutputfeedbackvoltageexits
a 7.5%windowaroundtheregulationpoint.Furthermore,
in an overvoltage condition, internal top FET M1 is turned
off and bottom FET M2 is turned on and held on until the
overvoltage condition clears.
The LTM4604 is a standalone non-isolated switch mode
DC/DC power supply. It can deliver up to 4A of DC output
current with few external input and output capacitors.
This module provides a precise regulated output voltage
programmable via one external resistor from 0.8V DC to
5.0V DC over a 2.375V to 5.5V input voltage. A typical
application schematic is shown in Figure 15.
PullingtheRUNpinbelow0.5Vforcesthecontrollerintoits
shutdown state, turning off both M1 and M2. At low load
current, the module works in continuous current mode by
default to achieve minimum output voltage ripple.
The LTM4604 has an integrated constant frequency cur-
rent mode regulator with built-in power MOSFETs with
fast switching speed. The typical switching frequency is
1.25MHz.Withcurrentmodecontrolandinternalfeedback
loop compensation, the LTM4604 module has sufficient
stability margins and good transient performance under a
wide range of operating conditions and with a wide range
of output capacitors, even all ceramic output capacitors.
The TRACK pin is used for power supply tracking. See the
Applications Information section.
The LTM4604 is internally compensated to be stable over
a wide operating range. Table 4 provides a guideline for
input and output capacitance for several operating condi-
tions. An excel loop analysis tool is provided for transient
and stability analysis.
Currentmodecontrolprovidescycle-by-cyclefastcurrent
limit. In addition, foldback current limiting is provided
The FB pin is used to program the output voltage with a
single resistor connected to ground.
in an overcurrent condition while V
drops. Internal
OUT
overvoltage and undervoltage comparators pull the open-
4604f
8
LTM4604
APPLICATIONS INFORMATION
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
AtypicalLTM4604applicationcircuitisshowninFigure 15.
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.
IOUT(MAX)
ICIN(RMS)
=
• D • 1–D
(
)
η%
In the above equation, η% is the estimated efficiency of
the power module. The bulk capacitor can be a switcher-
rated electrolytic aluminum capacitor, 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 two
internal 10μF ceramics are typically rated for 2A to 3A of
RMS ripple current. The worst-case ripple current for the
4A maximum current is 2A or less.
V to V
Step-Down Ratios
IN
OUT
There are restrictions in the maximum V and V
down ratio that can be achieved for a given input voltage.
The LTM4604 is 100% duty cycle, but the V to V
minimum dropout is a function of the load current. A typi-
cal 0.5V minimum is sufficient (see Typical Performance
Characteristics).
step-
IN
OUT
IN
OUT
Output Voltage Programming
Output Capacitors
ThePWMcontrollerhasaninternal0.8Vreferencevoltage.
As shown in the Block Diagram, a 4.99k, 0.5% internal
The LTM4604 is designed for low output voltage ripple.
The bulk output capacitors defined as C
with low enough effective series resistance (ESR) to meet
theoutputvoltagerippleandtransientrequirements. C
feedback resistor connects the V
and FB pins together.
OUT
are chosen
OUT
The output voltage will default to 0.8V with no feedback
resistor. Adding a resistor R from the FB pin to GND
FB
OUT
programs the output voltage:
can be a low ESR tantalum capacitor, a low ESR polymer
capacitor or an X5R/X7R ceramic capacitor. The typical
output capacitance range is 22μF 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 different
output voltages and output capacitors to minimize the
voltage droop and overshoot during a 2A/μs transient.
The table optimizes the total equivalent ESR and total
bulk capacitance to maximize transient performance. The
Linear Technology μModule Power Design Tool can be for
further optimization.
4.99k +RFB
VOUT = 0.8V •
RFB
Table 1. FB Resistor vs Output Voltage
V
0.8V
1.2V
10k
1.5V
1.8V
2.5V
3.3V
OUT
R
Open
5.76k
4.02k
2.37k
1.62k
FB
Input Capacitors
The LTM4604 module should be connected to a low ac-
impedance DC source. Two 10μF ceramic capacitors are
included inside the module. Additional input capacitors
are only needed if a large load step is required up to a
full 4A level. An input 47μF bulk capacitor is only needed
if the input source impedance is compromised by long
inductive leads or traces.
Fault Conditions: Current Limit and Overcurrent
Foldback
The LTM4604 has current mode control, which inher-
ently limits the cycle-by-cycle inductor current not only
in steady-state operation, but also in transient.
For a buck converter, the switching duty cycle can be
estimated as:
To further limit current in the event of an overload condi-
tion, the LTM4604 provides foldback current limiting as
the output voltage falls. The LTM4604 device has over-
temperature shutdown protection that inhibits switching
VOUT
D =
V
IN
operation around 150°C.
4604f
9
LTM4604
APPLICATIONS INFORMATION
Run Enable and Soft-Start
V
IN
5V
C
10μF
6.3V
IN1
The RUN/SS pin provides dual functions of enable and
soft-start control. The RUN/SS pin is used to control
turn on of the LTM4604. While this pin is below 0.5V, the
LTM4604 will be in a 7μA low quiescent current state. A
0.8V threshold will enable the LTM4604. This pin can be
usedtosequenceLTM4604devices. Thesoft-startcontrol
X5R OR X7R
V
IN
V
3.3V
4A
MASTER
PGOOD
LTM4604
COMP
V
OUT
FB
C
OUT1
22μF
6.3V ×3
X5R OR
X7R
RAMP
RUN/SS TRACK
GND
is provided by a 1M pull-up resistor (R ) and a 1000pF
SS
CONTROL
R
FB3
OR V
C
IN
1.62k
capacitor(C )asdrawnintheBlockDiagram.Anexternal
SSEXT
SS
capacitor can be applied to the RUN/SS pin to increase the
soft-start time. A typical value is 0.01μF. The approximate
equation for soft-start is:
V
IN
5V
⎛
⎞
⎟
V
IN
C
10μF
6.3V
IN2
tSOFTSTART = ln
•RSS CSS + CSSEXT
(
)
⎜
V – 1.8V
⎝
⎠
IN
X5R OR X7R
V
IN
where R and C are shown in the Block Diagram of
V
1.5V
4A
SS
SS
SLAVE
PGOOD
LTM4604
COMP
V
OUT
FB
Figure 1, 1.8V is the soft-start upper range, and C
SSEXT
C
OUT2
is the additional capacitance for further soft-start contol.
The soft-start function can also be used to control the
output ramp-up time, so that another regulator can be
easily tracked. An independent ramp control signal can
be applied to the master ramp, otherwise, connect the
22μF
6.3V ×3
X5R OR
X7R
RUN/SS TRACK
GND
R
FB
R
FB2
5.76k
5.76k
R
FB1
4.99k
4604 F02
TRACK pin to V to disable tracking.
IN
Figure 2
Output Voltage Tracking
Output voltage tracking can be programmed externally
using the TRACK pin. The output can be tracked up and
down with another regulator. The master regulator’s
output is divided down with an external resistor divider
that is the same as the slave regulator’s feedback divider
to implement coincident tracking. The LTM4604 uses a
very accurate 4.99k resistor for the top feedback resistor.
Figure 2 shows an example of coincident tracking.
MASTER OUTPUT
SLAVE OUTPUT
RFB2
4.99k +RFB2
VTRACK
=
• VMASTER
TIME
4604 F03
Figure 3
V
V
is the track ramp applied to the slave’s TRACK pin.
applies the track reference for the slave output up
TRACK
TRACK
to the point of the programmed value at which V
proceeds beyond the 0.8V reference value. The V
TRACK
TRACK
pin must go beyond 0.8V to ensure the slave output has
reached its final value. Load current must be present for
proper tracking.
4604f
10
LTM4604
APPLICATIONS INFORMATION
Ratiometricmodesoftrackingcanbeachievedbyselecting
differentresistorvaluestochangetheoutputtrackingratio.
The master output must be greater than the slave output
for the tracking to work. Linear Technology Tracker Cad26
canbeusedtoimplementdifferenttrackingscenarios.The
Master and Slave data inputs can be used to implement
the correct resistor values for coincident or ratio tracking.
The master and slave regulators require load current for
tracking down.
Parallel Operation
The LTM4604 device is an inherently current mode con-
trolleddevice.Parallelmoduleswillhaveverygoodcurrent
sharing. This will balance the thermals on the design.
Figure 16 shows a schematic of the parallel design. The
voltage feedback changes with the variable N as more
modules are paralleled. The equation:
4.99k
+RFB
N
VOUT = 0.8V •
Power Good
RFB
The PGOOD pin is an open-drain pin that can be used to
monitor valid output voltage regulation. This pin monitors
a 7.5% window around the regulation point.
N is the number of paralleled modules.
Thermal Considerations and Output Current Derating
COMP Pin
The power loss curves in Figures 4 and 5 can be used
in coordination with the load derating curves in Figures
The pin is the external compensation pin. The module
has already been internally compensated for all output
voltages. Table 4 is provided for most application require-
ments. A spice model will be provided for other control
loop optimizations.
6 through 13 for calculating an approximate θ for the
JA
module with and without heat sinking methods with vari-
ous airflow conditions. Thermal models are derived from
several temperature measurements at the bench, and are
correlated with thermal analysis software. Tables 2 and
3 provide a summary of the equivalent θ for the noted
JA
conditions.Theseequivalentθ parametersarecorrelated
JA
to the measured values and improve with air flow. The
maximum junction temperature is monitored while the
derating curves are derived.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
5V TO 1.2V
POWER LOSS
5V TO 2.5V
POWER LOSS
0.4
0.4
3.3V TO 1.2V
POWER LOSS
3.3V TO 2.5V
POWER LOSS
0.2
0
0.2
0
0
3
4
5
0
2
3
4
5
1
2
1
LOAD CURRENT (A)
LOAD CURRENT (A)
4604 F04
4604 F05
Figure 4. 1.2V Power Loss
Figure 5. 2.5V Power Loss
4604f
11
LTM4604
APPLICATIONS INFORMATION
4.0
3.5
3.0
2.5
2.0
1.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1.0
0LFM
200LFM
400LFM
0LFM
200LFM
400LFM
0.5
0
90 95
90 95
100 105 110 115
70 75 80 85
100 105 110 115
70 75 80 85
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606 F06
4606 F07
Figure 6. 5VIN to 1.2VOUT No Heat Sink
Figure 7. 5VIN to 1.2VOUT with Heat Sink
4.0
3.5
3.0
2.5
2.0
1.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
1.0
0LFM
200LFM
400LFM
0LFM
200LFM
400LFM
0.5
0
0.5
0
90 95
90 95
100 105 110 115
70 75 80 85
100 105 110 115
70 75 80 85
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606 F08
4606 F09
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
4.0
3.5
3.0
2.5
2.0
1.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
1.0
0LFM
0LFM
0.5
0.5
200LFM
200LFM
400LFM
400LFM
0
0
90 95
70 75 80 85
100 105 110
90 95
70 75 80 85
100 105 110 115
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606 F10
4606 F11
Figure 10. 5VIN to 2.5VOUT No Heat Sink
Figure 11. 5VIN to 2.5VOUT with Heat Sink
4604f
12
LTM4604
APPLICATIONS INFORMATION
4.0
3.5
3.0
2.5
2.0
1.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
1.0
0LFM
200LFM
400LFM
0LFM
200LFM
400LFM
0.5
0
90 95
90 95
100 105 110 115
70 75 80 85
100 105 110 115
70 75 80 85
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606 F12
4606 F13
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
4604f
13
LTM4604
APPLICATIONS INFORMATION
Table 2. 1.2V Output
DERATING CURVE
Figures 6, 8
Figures 6, 8
Figures 6, 8
Figures 7, 9
Figures 7, 9
Figures 7, 9
V
(V)
POWER LOSS CURVE
Figure 4
AIR FLOW (LFM)
HEAT SINK
None
θ
JA
(°C/W)
IN
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
0
25
Figure 4
200
400
0
None
22.5
21
Figure 4
None
Figure 4
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
21
Figure 4
200
400
20
Figure 4
18
Table 3. 2.5V Output
DERATING CURVE
Figures 10, 12
V
(V)
POWER LOSS CURVE
Figure 5
AIR FLOW (LFM)
HEAT SINK
None
θ
JA
(°C/W)
25
IN
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
0
Figures 10, 12
Figure 5
200
400
0
None
21
Figures 10, 12
Figure 5
None
21
Figures 11, 13
Figure 5
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
21
Figures 11, 13
Figure 5
200
400
18
Figures 11, 13
Figure 5
16
Table 4. Output Voltage Response Versus Component Matrix (Refer to Figure 17), 0A to 2A Load Step Typical Measured Values
C
C
DROOP
(mV)
PEAK-TO- RECOVERY LOAD STEP
R
FB
IN
OUT
(CERAMIC)
V
(V) (CERAMIC)
C
(Bulk)
C
V (V)
IN
PEAK(mV)
(μs)
10
10
10
10
10
10
10
10
10
12
12
12
15
15
15
(A/μs)
(kΩ)
OUT
IN
COMP
1.2
1.2
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
10μF
56μF Aluminum 100μF 6.3V
None
None
None
None
None
None
None
None
None
None
None
None
None
None
None
2.5
21
23
24
19
21
21
25
30
30
22
25
25
22
25
25
43
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
10
56μF Aluminum
56μF Aluminum
22μF ×4
22μF ×4
3.3
5
45
10
1.2
1.5
1.5
1.5
1.8
1.8
1.8
2.5
2.5
2.5
3.3
3.3
3.3
46
10
56μF Aluminum 100μF 6.3V
2.5
3.3
5
41
5.76
5.76
5.76
4.02
4.02
4.02
2.37
2.37
2.37
1.62
1.62
1.62
56μF Aluminum
56μF Aluminum
22μF ×4
22μF ×4
43
43
56μF Aluminum 100μF 6.3V
2.5
3.3
5
50
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
60
60
56μF Aluminum 100μF 6.3V
2.5
3.3
5
45
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
55
55
56μF Aluminum 100μF 6.3V
2.5
3.3
5
50
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
56
56
4604f
14
LTM4604
APPLICATIONS INFORMATION
Safety Considerations
• Do not put vias directly on the pads unless they are
capped.
TheLTM4604modulesdonotprovideisolationfromV to
IN
V
.Thereisnointernalfuse.Ifrequired,aslowblowfuse
• SW pads can be soldered to board to improve thermal
performance.
OUT
with a rating twice the maximum input current needs to be
provided to protect each unit from catastrophic failure.
Figure14 gives a good example of the recommended
layout.
Layout Checklist/Example
GND
V
OUT
The high integration of LTM4604 makes the PCB board
layoutverysimpleandeasy.However,tooptimizeitselectri-
cal and thermal performance, some layout considerations
are still necessary.
C
C
C
OUT
OUT
OUT
• Use large PCB copper areas for high current path,
including V , GND and V . It helps to minimize the
IN
OUT
•
•
•
•
•
•
•
•
PCB conduction loss and thermal stress.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
• Placehighfrequencyceramicinputandoutputcapacitors
•
•
next to the V , GND and V
pins to minimize high
•
• •
•
•
•
•
IN
OUT
V
IN
•
frequency noise.
• •
•
•
•
•
•
•
•
SW
•
• Place a dedicated power ground layer underneath the
unit.
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
C
IN
GND
•
•
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
4604 F14
Figure 14. Recommended PCB Layout
V
IN
2.375V TO 5.5V
C
IN
10μF
6.3V
X5R OR X7R
V
IN
V
1.5V
4A
OUT
OPEN-DRAIN
PGOOD
LTM4604
COMP
V
OUT
FB
PULL UP
C
OUT
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
R
5.69k
0.5%
FB
C
SSEXT
0.01μF
4604 F15
Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design
4604f
15
LTM4604
TYPICAL APPLICATIONS
V
IN
2.375V TO 5V
C
IN1
10μF
6.3V
X5R OR X7R
V
= 0.8V × ((4.99k/N) + R )/R
FB FB
OUT
WHERE N IS THE NUMBER OF PARALLEL DEVICES
V
IN
OPEN-DRAIN PULL UP
PGOOD
LTM4604
COMP
V
OUT
FB
C
OUT1
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
R
FB
C
SSEXT
2.87k
0.01μF
V
1.5V
8A
OUT
C
IN2
10μF
6.3V
X5R OR X7R
V
IN
PGOOD
LTM4604
COMP
V
OUT
FB
C
OUT2
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
4604 F16
Figure 16. Two LTM4604s in Parallel, 1.5V at 8A Design
4604f
16
LTM4604
TYPICAL APPLICATIONS
V
IN
3.3V TO 5V
C
IN
50k
10μF
6.3V
X5R OR X7R
V
IN
V
2.5V
4A
OUT
OPEN-DRAIN
PULL UP
PGOOD
LTM4604
COMP
V
OUT
FB
C
OUT
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
R
FB
C
SSEXT
2.37k
0.01μF
4604 F17
Figure 17. 3.3V to 5V Input, 2.5V at 4A Design
4604f
17
LTM4604
PACKAGE DESCRIPTION
Z
b b b
Z
6 . 3 5 0
5 . 0 8 0
3 . 8 1 0
2 . 5 4 0
1 . 2 7 0
0 . 4 4 4 5
0 . 0 0 0
0 . 4 4 4 5
1 . 2 7 0
2 . 5 4 0
3 . 8 1 0
5 . 0 8 0
6 . 3 5 0
a a a
Z
4604f
18
LTM4604
PACKAGE DESCRIPTION
Pin Assignment Table
(Arranged by Pin Number)
PIN NAME
A1 GND
A2 GND
A3 GND
A4 GND
A5 GND
A6 GND
A7 GND
A8 GND
A9 GND
A10 GND
A11 GND
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
B1
B2
V
–
C1
C2
C3
C4
C5
C6
C7
V
–
V
V
V
V
V
D1 RUN/SS E1 TRACK
F1 PGOOD G1 COMP
IN
IN
D2
D3
D4
D5
D6
–
–
–
–
–
E2
E3
–
–
F2
–
G2 FB
B3 SW
B4 SW
F3 GND
F4 GND
F5 GND
F6 VOUT
F7 VOUT
F8 VOUT
F9 VOUT
F10 VOUT
F11 VOUT
G3 GND
G4 GND
G5 GND
G6 VOUT
G7 VOUT
G8 VOUT
G9 VOUT
G10 VOUT
G11 VOUT
IN
IN
IN
IN
IN
E4 GND
E5 GND
B5
–
B6 GND
B7 GND
B8 GND
B9 GND
B10 GND
B11 GND
E6
E7
V
V
IN
IN
D7 VIN
C8 GND
C9 GND
C10 GND
C11 GND
D8 VOUT
D9 VOUT
D10 VOUT
D11 VOUT
E8 VOUT
E9 VOUT
E10 VOUT
E11 VOUT
4604f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTM4604
RELATED PARTS
PART NUMBER
LTC2900
DESCRIPTION
COMMENTS
Quad Supply Monitor with Adjustable Reset Timer
Power Supply Tracking Controller
10A DC/DC μModule
Monitors Four Supplies; Adjustable Reset Timer
Tracks Both Up and Down; Power Supply Sequencing
Basic 10A DC/DC μModule
LTC2923
LTM4600
LTM4601
12A DC/DC μModule with PLL, Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1 Version has no Remote
Sensing
LTM4602
LTM4603
6A DC/DC μModule
Pin Compatible with the LTM4600
6A DC/DC μModule with PLL and Output Tracking/ Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote
Margining and Remote Sensing
Sensing, Pin Compatible with the LTM4601
LTM4608
8A Low Voltage μModule
2.375V ≤ V ≤ 5V, Parallel for Higher Output Current, 9mm × 15mm × 2.8mm
IN
4604f
LT 0807 • PRINTED IN USA
20 LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
●
●
© LINEAR TECHNOLOGY CORPORATION 2007
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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