LTM4604A [Linear]
Low Voltage, 4A DC/DC μModule with Tracking; 低电压， 4A DC / DC微型模块与跟踪
| 型号： | LTM4604A |
| 厂家： | 
Linear |
| 描述： | Low Voltage, 4A DC/DC μModule with Tracking |
| 文件： | 总20页 (文件大小：358K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
LTM4604A
Low Voltage, 4A DC/DC
µModule with Tracking
FEATURES
DESCRIPTION
The LTM®4604A is a complete 4A switch mode DC/DC
power supply with 1.75% total output voltage error.
Includedinthepackagearetheswitchingcontroller,power
FETs,inductorandallsupportcomponents.Operatingover
an input voltage range of 2.375V to 5.5V, the LTM4604A
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 capaci-
tors are needed to complete the design.
■
Complete Standalone Power Supply
■
1.75% Total DC Output Error (–40°C to 125°C)
■
Wide Input Voltage Range: 2.375V to 5.5V
■
4A DC, 5A Peak Output Current
■
0.8V to 5V Output
■
Output Voltage Tracking
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 0.630mm LGA pads with 1.27mm pitch simplify
PCB layout by providing standard trace routing and via
placement. (The LTM4604A has smaller pads than the
LTM4604.) 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.
■
■
■
Q
■
■
Small and Very Low Profile Package:
15mm × 9mm × 2.3mm LGA (0.630mm Pads)
APPLICATIONS
■
Telecom and Networking Equipment
Fault protection features include foldback current protec-
tion, thermal shutdown and a programmable soft-start
function. The LTM4604A is offered in a small thermally
enhanced 15mm × 9mm × 2.3mm LGA package and is
Pb free and RoHS compliant.
■
Servers
■
Storage Cards
ATCA Cards
Industrial Equipment
■
■
, 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.
TYPICAL APPLICATION
Efficiency vs Output Current
100
3.3V to 2.5V/4A μModule™ Regulator
V
V
= 3.3V
IN
OUT
= 2.5V
95
90
V
IN
3.3V
10μF
6.3V
85
80
75
V
IN
V
2.5V
4A
OUT
PGOOD
LTM4604A
COMP
V
OUT
22μF
6.3V
FB
V
IN
RUN/SS TRACK
GND
×2
70
65
2.37k
4604A TA01a
1
2
4
0
3
OUTPUT CURRENT (A)
4604A TA01b
4604af
1
LTM4604A
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(Note 1)
V , PGOOD ................................................. –0.3V to 6V
IN
TOP VIEW
TRACK
COMP, RUN/SS, FB, TRACK..........................–0.3V to V
PGOOD
IN
A
B
C
D
E
F
G
SW, V ........................................–0.3V to (V + 0.3V)
OUT
IN
V
IN
Internal Operating Temperature Range
COMP
FB
1
2
RUN/
SS
(Note 2) ............................................. –40°C to 125°C
Storage Temperature Range................... –55°C to 125°C
SW
3
GND
4
5
6
7
8
9
10
11
GND
V
OUT
LGA PACKAGE
66-PIN (15mm × 9mm × 2.3mm) 0.630mm PAD
T
JMAX
= 125°C, θ = 25°C/W, θ = 7°C/W, θ = 50°C/W, WEIGHT = 1.0g
JA
JP
JC
ORDER INFORMATION
LEAD FREE FINISH
LTM4604AEV#PBF
LTM4604AIV#PBF
TRAY
PART MARKING*
LTM4604AV
PACKAGE DESCRIPTION
TEMPERATURE RANGE (NOTE 2)
–40°C to 125°C
LTM4604AEV#PBF
LTM4604AIV#PBF
66-Lead (15mm × 9mm × 2.3mm) LGA
66-Lead (15mm × 9mm × 2.3mm) LGA
LTM4604AV
–40°C to 125°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://www.linear.com/packaging/
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full internal
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
1.482
1.474
5.5
1.518
1.522
V
V
V
IN(DC)
R
= 5.69k
1.5
1.5
OUT(DC)
FB
V
= 2.375V to 5.5V, I
= 0A
= 0A to 4A (Note 3)
IN
OUT
Input Specifications
V
Undervoltage Lockout
Threshold
Peak Input Inrush Current at
Start-Up
I
I
1.75
2
2.3
V
IN(UVLO)
OUT
OUT
I
= 0A, C = 10μF, C
= 22μF ×3,
= 1.5V
INRUSH(VIN)
IN
OUT
RUN/SS = 0.01μF, V
OUT
V
V
= 3.3V
= 5V
0.7
0.7
A
A
IN
IN
I
Input Supply Bias Current
V
= 3.3V, No Switching
60
28
100
35
7
μA
mA
μA
mA
μA
Q(VIN NOLOAD)
IN
IN
IN
IN
V
V
V
= 3.3V, V
= 1.5V, Switching Continuous
OUT
= 5V, No Switching
= 5V, V = 1.5V, Switching Continuous
OUT
Shutdown, RUN = 0, V = 5V
IN
4604af
2
LTM4604A
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full internal
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
V
V
= 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)
IN
IN
IN
OUT
OUT
OUT
OUT
= 5V, V
= 1.5V, I
= 4A
OUT
OUT
Output Specifications
I
Output Continuous Current
Range (Note 3)
Line Regulation Accuracy
V
V
= 3.3V, V = 1.5V
OUT
4
A
OUT(DC)
IN
●
ΔV
= 1.5V, V from 2.375V to 5.5V, I
= 0A
0.1
0.2
%
OUT(LINE)
OUT
IN
OUT
V
OUT
ΔV
Load Regulation Accuracy
V
= 1.5V, 0A to 4A (Note 3)
= 3.3V
= 5V
OUT(LOAD)
OUT
●
●
V
V
0.3
0.3
0.6
0.6
%
%
IN
IN
V
OUT
V
Output Ripple Voltage
I
I
= 0A
OUT(AC)
OUT
V
V
= 3.3V, V
= 1.5V
10
12
1.25
mV
mV
MHz
IN
IN
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
V
= 1.5V, RUN/SS = 10nF,
OUT(START)
OUT
OUT
IN
IN
I
= 0A
V
V
= 3.3V
= 5V
20
20
mV
mV
t
Turn-on Time
V
= 1.5V, I
= 1A Resistive Load, TRACK = V
OUT IN
START
OUT
and RUN/SS = Float
V
V
= 3.3V
= 5V
1.5
1.0
ms
ms
IN
IN
ΔV
Peak Deviation for Dynamic
Load Step
Load: 0% to 50% to 0% of Full Load,
= 22μF ×3 Ceramic
IN
OUT(LS)
C
OUT
V
= 5V, V
= 1.5V
OUT
25
10
8
8
mV
μs
A
A
t
I
Settling Time for Dynamic
Load Step
Output Current Limit
Load: 0% to 50% to 0% of Full Load
IN
SETTLE
OUT(PK)
V
= 5V, V
= 1.5V
OUT
V
V
= 3.3V, V
= 1.5V
IN
IN
OUT
= 5V, V
= 1.5V
= 1.5V
OUT
OUT
Control Section
V
Voltage at FB Pin
I
= 0A, V
0.793
0.788
0.8
0.8
0.807
0.808
V
V
FB
OUT
●
I
V
I
V
V
R
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
TRACK
TRACK = 0.4V
30
TRACK(OFFSET)
TRACK(RANGE)
FBHI
Tracking Input Range
0
0.8
5.025
Resistor Between V
FB Pins
and
4.975
4.99
kΩ
OUT
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 LTM4604AE is guaranteed to meet performance specifications
over the 0°C to 125°C internal operating temperature range. Specifications
over the full –40°C to 125°C internal operating temperature range are assured
by design, characterization and correlation with statistical process controls.
The LTM4604AI is guaranteed to meet specifications over the full internal
operating temperature range. Note that the maximum ambient temperature
is determined by specific operating conditions in conjunction with board
layout, the rated package thermal resistance and other environmental factors.
Note 3: See output current derating curves for different V , V
and T .
A
IN OUT
4604af
3
LTM4604A
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Output Current
VIN = 2.5V
Efficiency vs Output Current
VIN = 3.3V
Efficiency vs Output Current
VIN = 5V
95
90
100
95
100
95
90
90
85
80
85
80
75
85
80
75
70
65
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
0
1
2
3
4
1
2
4
1
2
4
0
3
0
3
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
OUTPUT CURRENT (A)
4604A G03
4604A G02
4604A G01
Minimum Input Voltage
at 4A Load
Load Transient Response
Load Transient Response
3.5
3.0
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
= 3.3V
= 2.5V
= 1.8V
= 1.5V
= 1.2V
= 0.8V
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
4604A G06
V
V
C
= 5V
20μs/DIV
IN
4604A 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
IN
(V)
4604A 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
4604A G07
4604A G09
4604A G08
V
V
C
= 5V
20µs/DIV
V
V
C
= 5V
OUT
OUT
20µs/DIV
= 2 × 22µF, 6.3V CERAMICS
V
V
C
= 5V
20µs/DIV
IN
IN
IN
= 1.8V
= 3.3V
= 2.5V
OUT
OUT
OUT
OUT
= 3 × 22µF, 6.3V CERAMICS
= 3 × 22µF, 6.3V CERAMICS
4604af
4
LTM4604A
TYPICAL PERFORMANCE CHARACTERISTICS
Start-Up
Start-Up
V
V
OUT
OUT
1V/DIV
1V/DIV
I
IN
I
IN
1A/DIV
1A/DIV
4604A G10
4604A 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
OUT
= 1.5V
0.4
0.2
0
V
V
V
= 5V
= 3.3V
= 2.5V
IN
IN
IN
4
5
7
3
8
–50 –25
0
25
50
75
100 125
6
TEMPERATURE (°C)
OUTPUT CURRENT (A)
4604A G12
4604A G15
Short-Circuit Protection
1.5V Short, No Load
Short-Circuit Protection
1.5V Short, 4A Load
V
V
OUT
0.5V/DIV
OUT
0.5V/DIV
I
I
IN
IN
1A/DIV
4A/DIV
4604A G13
4604A G14
20μs/DIV
100μs/DIV
4604af
5
LTM4604A
PIN FUNCTIONS
V
(B1, C1, C3-C7, D7, E6 and E7): Power Input Pins.
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
(D8-D11, E8-E11, F6-F11, G6-G11): Power Output
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.
OUT
Pins. Apply output load between these pins and GND
pins. Recommend placing output decoupling capaci-
tance directly between these pins and GND pins. Review
Table 4.
GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11):
PGOOD(F1):Output Voltage Power Good Indicator. Open-
drain logic output that is pulled to ground when the output
voltage is not within 7.5% of the regulation point.
Power Ground Pins for Both Input and Output Returns.
TRACK(E1):Output Voltage Tracking Pin. When the module
is configured as a master output, then a soft-start capaci-
tor is placed on the RUN/SS pin to ground to control the
masterramprate. Slaveoperationisperformedbyputting
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 Information
section for soft-start information. The shut down pin
should be pull low with a falling edge of ≤ 1μs to ensure
the device does not transition slowly through the internal
under voltage lockout threshold.
the TRACK pin to V . Load current must be present for
IN
tracking. See Applications Information section.
FB (G2): The Negative Input of the Error Amplifier. Inter-
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.
nally, this pin is connected to V
with a 4.99k precision
OUT
resistor. Different output voltages can be programmed
4604af
6
LTM4604A
BLOCK DIAGRAM
PGOOD
V
V
IN
V
IN
2.375V TO 5.5V
10μF
6.3V
×2
10μF
6.3V
R
SS
RUN/SS
1M
C
SS
C
SSEXT
1000pF
M1
M2
TRACK
COMP
OUT
L
V
1.5V
4A
OUT
4.99k
CONTROL,
DRIVE
TRACK
SUPPLY
22μF
6.3V
×3
R1
4.99k
C2
470pF
10μF
6.3V
5.76k
INTERNAL
COMP
GND
4604A BD
FB
SW
R
FB
5.76k
Figure 1. Simplified LTM4604A Block Diagram
DECOUPLING REQUIREMENTS T = 25°C. Use Figure 1 Configuration.
A
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
C
External Input Capacitor Requirement
IN
I
= 4A
10
μF
IN
OUT
(V = 2.375V to 5.5V, V
= 1.5V)
OUT
C
External Output Capacitor Requirement
(V = 2.375V to 5.5V, V = 1.5V)
I
= 4A
22
100
μF
OUT
OUT
IN
OUT
4604af
7
LTM4604A
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 LTM4604A 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 LTM4604A has an integrated constant frequency
current mode regulator with built-in power MOSFETs with
fast switching speed. The typical switching frequency is
1.25MHz.Withcurrentmodecontrolandinternalfeedback
loop compensation, the LTM4604A module has sufficient
stability margins and good transient performance under a
widerangeofoperatingconditionsandwithawiderangeof
output capacitors, even all ceramic output capacitors.
The TRACK pin is used for power supply tracking. See the
Applications Information section.
The LTM4604A is internally compensated to be stable
over a wide operating range. Table 4 provides a guideline
for input and output capacitance for several operating
conditions. 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-
4604af
8
LTM4604A
APPLICATIONS INFORMATION
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
A typical LTM4604A application circuit is shown in
Figure 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 LTM4604A 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
The PWM controller has an internal 0.8V reference volt-
age. As shown in the Block Diagram, a 4.99k 0.5% internal
The LTM4604A 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
capacitancetomaximizetransientperformance.TheLinear
Technology μModule Power Design Tool can be provided
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 LTM4604A 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 LTM4604A 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 LTM4604A provides foldback current limiting as
the output voltage falls. The LTM4604A device has over-
temperature shutdown protection that inhibits switching
VOUT
D =
V
IN
operation around 150°C.
4604af
9
LTM4604A
APPLICATIONS INFORMATION
Run Enable and Soft-Start
pin must go beyond 0.8V to ensure the slave output has
reached its final value. Load current must be present for
proper tracking.
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 LTM4604A. While this pin is below 0.5V, the
LTM4604A will be in a 7μA low quiescent current state.
A 0.8V threshold will enable the LTM4604A. This pin can
be used to sequence LTM4604A devices. The soft-start
V
IN
5V
C
10μF
6.3V
IN1
X5R OR X7R
control is provided by a 1M pull-up resistor (R ) and a
SS
V
IN
V
3.3V
4A
MASTER
1000pF capacitor (C ) as drawn in the Block Diagram.
SS
PGOOD
LTM4604A
COMP
V
OUT
An external 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:
C
OUT1
22μF
FB
6.3V ×3
X5R OR
X7R
RAMP
RUN/SS TRACK
GND
CONTROL
R
FB3
OR V
C
IN
1.62k
SSEXT
ꢀ
ꢂ
ꢁ
ꢃ
ꢅ
ꢄ
V
IN
tSOFTSTART = ln
•R
CSS +CSSEXT
SS
(
)
V – 1.8V
IN
V
IN
5V
where R and C are shown in the Block Diagram of
SS
SS
C
10μF
6.3V
IN2
Figure 1, 1.8V is the soft-start upper range, and C
SSEXT
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
X5R OR X7R
V
IN
V
1.5V
4A
SLAVE
PGOOD
LTM4604A
COMP
V
OUT
C
OUT2
22μF
FB
6.3V ×3
X5R OR
X7R
RUN/SS TRACK
GND
R
TRACK pin to V to disable tracking.
FB
IN
R
FB2
5.76k
5.76k
Output Voltage Tracking
R
FB1
4.99k
4604A F02
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 LTM4604A uses a
very accurate 4.99k resistor for the top feedback resistor.
Figure 2 shows an example of coincident tracking.
Figure 2. Dual Outputs (3.3V and 1.5V) with Tracking
MASTER OUTPUT
SLAVE OUTPUT
RFB2
VTRACK
=
• VMASTER
4.99k +RFB2
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
TIME
4604A F03
Figure 3. Output Voltage Coincident Tracking
4604af
10
LTM4604A
APPLICATIONS INFORMATION
Ratio metric modes of tracking can be achieved by select-
ing different resistor values to change the output tracking
ratio. The master output must be greater than the slave
output for the tracking to work. Linear Technology Tracker
Cad26 can be used to implement different tracking sce-
narios. 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 LTM4604A device is an inherently current mode
controlled device. Parallel modules will have very good
current sharing. This will balance the thermals on the
design.Figure 16showsaschematicoftheparalleldesign.
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
alreadybeeninternallycompensatedforalloutputvoltages.
Table 4 is provided for most application requirements.
The Linear Technology μModule Power Design Tool can
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
5V TO 2.5V
0.4
0.4
POWER LOSS
POWER LOSS
3.3V TO 1.2V
POWER LOSS
3.3V TO 2.5V
0.2
0.2
0
POWER LOSS
0
0
3
4
5
2
3
4
1
2
0
5
1
LOAD CURRENT (A)
LOAD CURRENT (A)
4604A F04
4604A F05
Figure 4. 1.2V Power Loss
Figure 5. 2.5V Power Loss
4604af
11
LTM4604A
APPLICATIONS INFORMATION
4.0
3.5
3.0
2.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.0
1.5
1.0
0LFM
200LFM
400LFM
0LFM
200LFM
400LFM
0.5
0
90 95
70 75 80 85
100 105 110 115
90 95
70 75 80 85
100 105 110 115
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606A F06
4606A 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
0LFM
0.5
0.5
200LFM
200LFM
400LFM
400LFM
0
0
90 95
100 105 110 115
90 95
70 75 80 85
70 75 80 85
100 105 110 115
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606A F09
4606A F08
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
4604af
12
LTM4604A
APPLICATIONS INFORMATION
4.0
3.5
3.0
2.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2.0
1.5
1.0
0LFM
0LFM
200LFM
400LFM
0.5
200LFM
400LFM
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)
4606A F10
4606A F11
Figure 10. 5VIN to 2.5VOUT No Heat Sink
Figure 11. 5VIN to 2.5VOUT 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
100 105 110 115
90 95
70 75 80 85
70 75 80 85
100 105 110 115
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4606A F13
4606A F12
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
4604af
13
LTM4604A
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)
25
IN
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
3.3, 5
0
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
45
46
41
43
43
50
60
60
45
55
55
50
56
56
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
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
10
56μF Aluminum 100μF 6.3V
2.5
3.3
5
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
56μF Aluminum 100μF 6.3V
2.5
3.3
5
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
56μF Aluminum 100μF 6.3V
2.5
3.3
5
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
56μF Aluminum 100μF 6.3V
2.5
3.3
5
56μF Aluminum
56μF Aluminum
22μF ×3
22μF ×3
4604af
14
LTM4604A
APPLICATIONS INFORMATION
Safety Considerations
• Place high frequency ceramic input and output capaci-
tors next to the V , GND and V
pins to minimize
IN
OUT
The LTM4604A modules do not provide isolation from
high frequency noise.
V to V . There is no internal fuse. If required, a slow
IN
OUT
• Place a dedicated power ground layer underneath the
unit.
blow fuse with a rating twice the maximum input current
needs to be provided to protect each unit from catastrophic
failure.
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
Layout Checklist/Example
The high integration of LTM4604A makes the PCB board
layout very simple and easy. However, to optimize its
electrical and thermal performance, some layout consid-
erations are still necessary.
• Do not put vias directly on the pads unless they are
capped.
• SW pads can be soldered to board to improve thermal
performance.
• Use large PCB copper areas for high current path,
Figure 14 gives a good example of the recommended
layout.
including V , GND and V . It helps to minimize the
IN
OUT
PCB conduction loss and thermal stress.
V
IN
V
OUT
GND
2.375V TO 5.5V
C
10μF
6.3V
IN
C
OUT
C
OUT
C
OUT
X5R OR X7R
V
IN
V
1.5V
4A
OUT
OPEN-DRAIN
PGOOD
LTM4604A
COMP
V
OUT
PULL UP
C
OUT
FB
22μF ×3
6.3V
RUN/SS TRACK
GND
X5R OR X7R
R
FB
C
SSEXT
5.69k
0.01μF
4604A F15
Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design
V
IN
C
IN
GND
4604A F14
Figure 14. Recommended PCB Layout
4604af
15
LTM4604A
TYPICAL APPLICATIONS
V
IN
2.375V TO 5V
C
10μF
6.3V
IN1
X5R OR X7R
V
= 0.8V × ((4.99k/N) + R )/R
FB FB
OUT
WHERE N IS THE NUMBER OF PARALLEL MODULES
V
IN
OPEN-DRAIN PULL UP
PGOOD
LTM4604A
COMP
V
OUT
C
OUT1
22μF ×3
6.3V
FB
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
10μF
6.3V
IN2
X5R OR X7R
V
IN
PGOOD
LTM4604A
COMP
V
OUT
C
OUT2
22μF ×3
6.3V
FB
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
4604A F16
Figure 16. Two LTM4604As in Parallel, 1.5V at 8A Design
4604af
16
LTM4604A
TYPICAL APPLICATIONS
V
IN
3.3V TO 5V
C
10μF
6.3V
IN
50k
X5R OR X7R
V
IN
V
2.5V
4A
OUT
OPEN-DRAIN
PULL UP
PGOOD
LTM4604A
COMP
V
OUT
C
OUT
22μF ×3
FB
6.3V
X5R OR X7R
REFER TO
TABLE 4
RUN/SS TRACK
GND
R
FB
C
SSEXT
2.37k
0.01μF
4604A F17
Figure 17. 3.3V to 5V Input, 2.5V at 4A Design
4604af
17
LTM4604A
PACKAGE DESCRIPTION
LGA Package
66-Lead (15mm × 9mm × 2.32mm)
(Reference LTC DWG # 05-08-1820 Rev Ø)
DETAIL A
G
2.19 – 2.45
PAD 1
F
E
D
C
B
A
aaa
Z
1
PAD “A1”
CORNER
2
4
3
4
5
12.70
BSC
6
15.00
BSC
MOLD
SUBSTRATE
CAP
7
0.290 – 0.350
8
1.90 – 2.10
DETAIL B
9
10
11
0.630 0.025 SQ. 68x
PADS
1.27
BSC
X
Y
SEE NOTES
9.00
BSC
eee
S X Y
7.620
BSC
3
DETAIL B
PACKAGE TOP VIEW
PACKAGE BOTTOM VIEW
DETAIL A
6.350
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
5.080
3.810
2.540
1.270
0.000
1.270
2. ALL DIMENSIONS ARE IN MILLIMETERS
3
4
LAND DESIGNATION PER JESD MO-222
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
0.315
0.315
LTMXXXXXX
μModule
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. THE TOTAL NUMBER OF PADS: 66
COMPONENT
PIN “A1”
2.540
3.810
5.080
6.350
SYMBOL TOLERANCE
TRAY PIN 1
BEVEL
aaa
bbb
eee
0.15
0.10
0.05
PACKAGE IN TRAY LOADING ORIENTATION
LGA 66 0108 REV Ø
SUGGESTED PCB LAYOUT
TOP VIEW
4604af
18
LTM4604A
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
4604af
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However,noresponsibilityisassumedforitsuse.LinearTechnologyCorporationmakesnorepresenta-
t ion t h a t t he in ter c onne c t ion o f i t s cir cui t s a s de s cr ib e d her ein w ill no t in fr inge on ex is t ing p a ten t r igh t s.
19
LTM4604A
PACKAGE PHOTOGRAPH
RELATED PARTS
PART NUMBER
DESCRIPTION
COMMENTS
LTC2900
Quad Supply Monitor with Adjustable Reset Timer Monitors Four Supplies; Adjustable Reset Timer
LTC2923
Power Supply Tracking Controller
10A DC/DC μModule
Tracks Both Up and Down; Power Supply Sequencing
4.5V ≤ V ≤ 28V; 0.6V ≤ V ≤ 5V; 15mm × 15mm × 2.8mm
LTM4600HV
IN
OUT
LTM4601/LTM4601A 12A DC/DC μModule with PLL, Output Tracking/
Synchronizable, PolyPhase Operation, LTM4601-1/LTM4601A-1 Version
has no Remote Sensing
Margining and Remote Sensing
LTM4601AHVMP
12A Military Grade μModule
4.5V ≤ V ≤ 28V; 0.6V ≤ V
≤ 5V; 15mm × 15mm × 2.8mm,
OUT
IN
–55°C to 125°C
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
Margining and Remote Sensing
5A Buck-Boost μModule
5A Buck-Boost μModule
8A Low Voltage μModule
no Remote Sensing, Pin Compatible with the LTM4601
LTM4605
LTM4607
LTM4608A
4.5V ≤ V ≤ 20V; 0.8V ≤ V
≤ 16V; 15mm × 15mm × 2.8mm LGA
≤ 24V; 15mm × 15mm × 2.8mm LGA
IN
OUT
OUT
4.5V ≤ V ≤ 36V; 0.8V ≤ V
IN
2.4V ≤ V ≤ 5.5V, Parallel for Higher Output Current,
IN
9mm × 15mm × 2.8mm LGA
LTM4616
LTM8020
LTM8021
LTM8022
LTM8023
Dual 8A DC/DC μModule
0.2A DC/DC μModule
0.5A DC/DC μModule
1A DC/DC μModule
2A DC/DC μModule
Dual 8A or Single 16A; 2.375V ≤ V ≤ 5.5V; 15mm × 15mm × 2.5mm LGA
IN
4V ≤ V ≤ 36V; 1.25V ≤ V
≤ 5V; 6.25mm × 6.25mm × 2.3mm LGA
≤ 5V; 6.25mm × 11.25mm × 2.8mm LGA
≤ 10V; 11.25mm × 9mm × 2.8mm LGA
≤ 10V; 11.25mm × 9mm × 2.8mm LGA
IN
OUT
3.6V ≤ V ≤ 36V; 0.8V ≤ V
IN
OUT
OUT
OUT
3.6V ≤ V ≤ 36V; 0.8V ≤ V
IN
3.6V ≤ V ≤ 36V; 0.8V ≤ V
IN
4604af
LT 0808 • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
20
●
●
© LINEAR TECHNOLOGY CORPORATION 2008
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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