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LTM4604A
Low Voltage, 4A DC/DC
µModule Regulator with Tracking
Description
Features
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Complete Standalone Power Supply
±1.75% Max 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: IQ ≤ 7µA
Overtemperature Protection
9mm × 15mm × 2.32mm LGA and
9mm × 15mm × 3.42mm BGA Packages
Applications
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Telecom and Networking Equipment
Servers
Storage Cards
ATCA Cards
Industrial Equipment
L, LT, LTC, LTM, Linear Technology, LTspice, µModule and the Linear logo are registered
trademarks and UltraFast and LTpowerCAD are trademarks of Linear Technology Corporation.
All other trademarks are the property of their respective owners.
The LTM®4604A is a complete 4A switch mode step-down
µModule® (micromodule) regulator with ±1.75% maximum
total output voltage error. Included in the package are the
switching controller, power FETs, inductor and all support
components. Operating over 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 input and output capacitors are needed
to complete the design.
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 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.
Fault protection features include foldback current protection, thermal shutdown and a programmable soft-start
function. The LTM4604A is offered with SnPb (BGA) or
RoHS-compliant terminal finish.
Typical Application
Efficiency vs Output Current
100
3.3V to 2.5V/4A µModule Regulator
VIN
3.3V
90
VIN
PGOOD
VOUT
2.5V
4A
VOUT
LTM4604A
COMP
FB
RUN/SS TRACK
GND
VIN
2.37k
22µF
6.3V
×2
EFFICIENCY (%)
10µF
6.3V
VIN = 3.3V
VOUT = 2.5V
95
85
80
75
70
65
4604A TA01a
0
1
2
3
OUTPUT CURRENT (A)
4
4604A TA01b
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1
LTM4604A
Absolute Maximum Ratings
(Note 1)
VIN, PGOOD.................................................. –0.3V to 6V
COMP, RUN/SS, FB, TRACK......................... –0.3V to VIN
SW, VOUT....................................... –0.3V to (VIN + 0.3V)
Internal Operating Temperature Range
(Note 2)................................................... –40°C to 125°C
Storage Temperature Range................... –55°C to 125°C
Peak Solder Reflow Body Temperature.................. 245°C
Pin Configuration
A
B
TOP VIEW
TRACK
PGOOD
C
F
D
E
A
G
VIN
SW
3
PGOOD
C
F
D
E
G
VIN
1
2
B
TOP VIEW
TRACK
RUN/
SS
COMP
1
FB
2
COMP
RUN/
SS
SW
3
GND
4
4
5
5
6
6
7
7
8
8
9
9
10
10
11
FB
GND
11
GND
GND
VOUT
BGA PACKAGE
66-PIN (15mm × 9mm × 3.42mm)
VOUT
LGA PACKAGE
66-PIN (15mm × 9mm × 2.32mm) 0.630mm PAD
TJMAX = 125°C, θJA = 25°C/W, θJC(BOTTOM) = 7°C/W, θJC(TOP) = 50°C/W, WEIGHT = 1.1g
TJMAX = 125°C, θJA = 25°C/W, θJC(BOTTOM) = 7°C/W, θJC(TOP) = 50°C/W, WEIGHT = 1.0g
Order Information
PART NUMBER
PAD OR BALL FINISH
PART MARKING*
DEVICE
FINISH CODE
PACKAGE
TYPE
MSL
RATING
TEMPERATURE RANGE
(SEE NOTE 2)
LTM4604AEV#PBF
Au (RoHS)
LTM4604AV
e4
LGA
3
–40°C to 125°C
LTM4604AIV#PBF
Au (RoHS)
LTM4604AV
e4
LGA
3
–40°C to 125°C
LTM4604AEY#PBF
SAC305 (RoHS)
LTM4604AY
e1
BGA
3
–40°C to 125°C
LTM4604AIY#PBF
SAC305 (RoHS)
LTM4604AY
e1
BGA
3
–40°C to 125°C
LTM4604AIY
SnPb (63/37)
LTM4604AY
e0
BGA
3
–40°C to 125°C
Consult Marketing for parts specified with wider operating temperature
ranges. *Device temperature grade is indicated by a label on the shipping
container. Pad or ball finish code is per IPC/JEDEC J-STD-609.
• Recommended LGA and BGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/umodule/pcbassembly
• Terminal Finish Part Markings:
www.linear.com/leadfree
• LGA and BGA Package and Tray Drawings:
http://www.linear.com/packaging
2
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LTM4604A
Electrical
Characteristics
The l denotes the specifications which apply over the specified internal
operating temperature range (Note 2), otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
PARAMETER
VIN(DC)
Input DC Voltage
CONDITIONS
l
2.375
MIN
VOUT(DC)
Output Voltage, Total Variation CIN = 10µF, COUT = 22µF × 3, RFB = 5.69k
with Line and Load
VIN = 2.375V to 5.5V, IOUT = 0A to 4A (Note 3)
l
1.482
1.474
1.75
TYP
MAX
UNITS
5.5
V
1.5
1.5
1.518
1.522
V
V
2
2.3
V
Input Specifications
VIN(UVLO)
Undervoltage Lockout
Threshold
IOUT = 0A
IINRUSH(VIN)
Peak Input Inrush Current at
Start-Up
IOUT = 0A, CIN = 10µF, COUT = 22µF × 3,
RUN/SS = 0.01µF, VOUT = 1.5V
VIN = 3.3V
VIN = 5V
0.7
0.7
A
A
IQ(VIN NOLOAD)
Input Supply Bias Current
VIN = 3.3V, No Switching
VIN = 3.3V, VOUT = 1.5V, Switching Continuous
VIN = 5V, No Switching
VIN = 5V, VOUT = 1.5V, Switching Continuous
Shutdown, RUN = 0, VIN = 5V
60
28
100
35
7
µA
mA
µA
mA
µA
IS(VIN)
Input Supply Current
VIN = 2.5V, VOUT = 1.5V, IOUT = 4A
VIN = 3.3V, VOUT = 1.5V, IOUT = 4A
VIN = 5V, VOUT = 1.5V, IOUT = 4A
2.9
2.2
1.45
A
A
A
Output Specifications
IOUT(DC)
Output Continuous Current
Range
VIN = 3.3V, VOUT = 1.5V (Note 3)
ΔVOUT(LINE)
Line Regulation Accuracy
VOUT = 1.5V, VIN from 2.375V to 5.5V, IOUT = 0A
l
Load Regulation Accuracy
VOUT = 1.5V, 0A to 4A (Note 3)
VIN = 3.3V
VIN = 5V
l
l
4
A
0.1
0.2
%
0.3
0.3
0.6
0.6
%
%
VOUT
ΔVOUT(LOAD)
VOUT
VOUT(AC)
Output Ripple Voltage
IOUT = 0A
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
fS
Output Ripple Voltage
Frequency
IOUT = 4A, VIN = 5V, VOUT = 1.5V
ΔVOUT(START)
Turn-On Overshoot
10
12
mVP-P
mVP-P
1.25
MHz
VOUT = 1.5V, RUN/SS = 10nF, COUT = 22µF × 3,
IOUT = 0A
VIN = 3.3V
VIN = 5V
20
20
mV
mV
COUT = 22µF × 3, VOUT = 1.5V, IOUT = 1A Resistive Load,
TRACK = VIN and RUN/SS = Float
VIN = 3.3V
VIN = 5V
1.5
1.0
ms
ms
Peak Deviation for Dynamic
Load Step
Load: 0% to 50% to 0% of Full Load,
COUT = 22µF ×3 Ceramic
VIN = 5V, VOUT = 1.5V
25
mV
tSETTLE
Settling Time for Dynamic
Load Step
Load: 0% to 50% to 0% of Full Load
VIN = 5V, VOUT = 1.5V
10
µs
IOUT(PK)
Output Current Limit
8
8
A
A
tSTART
ΔVOUT(LS)
Turn-on Time
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
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3
LTM4604A
Electrical
Characteristics
The l denotes the specifications which apply over the specified internal
operating temperature range (Note 2), otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
PARAMETER
CONDITIONS
Voltage at FB Pin
IOUT = 0A, VOUT = 1.5V
MIN
TYP
MAX
UNITS
0.793
0.788
0.8
0.8
0.807
0.808
V
V
0.5
0.65
Control Section
VFB
l
0.2
IFB
VRUN/SS
RUN/SS Pin On/Off Threshold
ITRACK
TRACK Pin Current
VTRACK(OFFSET)
Offset Voltage
VTRACK(RANGE)
Tracking Input Range
RFBHI
Resistor Between VOUT and
FB Pins
µA
0.8
0.2
TRACK = 0.4V
µA
30
0
4.965
mV
0.8
4.99
V
5.015
V
kΩ
PGOOD
∆VPGOOD
PGOOD Range
RPGOOD
PGOOD Resistance
±7.5
Open-Drain Pull-Down
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 LTM4604A is tested under pulsed load conditions such that
TJ ≈ TA. The LTM4604AE is guaranteed to meet performance specifications
over the 0°C to 125°C internal operating temperature range. Specifications
over the –40°C to 125°C internal operating temperature range are assured
4
90
%
150
Ω
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 consistent with these specifications 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 VIN, VOUT and TA.
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LTM4604A
Typical Performance Characteristics
Efficiency vs Output Current
VIN = 3.3V
95
95
95
90
90
90
85
80
65
0
1
85
80
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
75
VOUT = 1.8V
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
70
70
2
3
OUTPUT CURRENT (A)
4
EFFICIENCY (%)
100
75
65
0
1
3.0
2.5
80
2
4
3
OUTPUT CURRENT (A)
65
VOUT
20mV/DIV
1.0
20µs/DIV
VIN = 5V
VOUT = 1.2V
COUT = 4 × 22µF, 6.3V CERAMICS
IOUT = 0A TO 2A
0.5
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
4
ILOAD
2A/DIV
VOUT
20mV/DIV
1.5
1
2
3
OUTPUT CURRENT (A)
Load Transient Response
ILOAD
2A/DIV
2.0
0
4604A G03
Load Transient Response
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
VOUT = 3.3V
VOUT = 2.5V
VOUT = 1.8V
VOUT = 1.5V
VOUT = 1.2V
VOUT = 0.8V
75
4604A G02
Minimum Input Voltage
at 4A Load
3.5
85
70
4604A G01
VOUT (V)
Efficiency vs Output Current
VIN = 5V
100
EFFICIENCY (%)
EFFICIENCY (%)
Efficiency vs Output Current
VIN = 2.5V
20µs/DIV
VIN = 5V
VOUT = 1.5V
COUT = 4 × 22µF, 6.3V CERAMICS
IOUT = 0A TO 2A
4604A G05
4604A G06
4604A G04
Load Transient Response
Load Transient Response
Load Transient Response
ILOAD
2A/DIV
ILOAD
2A/DIV
VOUT
20mV/DIV
ILOAD
2A/DIV
VOUT
20mV/DIV
VOUT
20mV/DIV
20µs/DIV
VIN = 5V
VOUT = 1.8V
COUT = 3 × 22µF, 6.3V CERAMICS
IOUT = 0A TO 2A
4604A G07
20µs/DIV
VIN = 5V
VOUT = 2.5V
COUT = 3 × 22µF, 6.3V CERAMICS
IOUT = 0A TO 2A
4604A G08
20µs/DIV
VIN = 5V
VOUT = 3.3V
COUT = 2 × 22µF, 6.3V CERAMICS
IOUT = 0A TO 2A
4604A G09
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5
LTM4604A
Typical Performance Characteristics
Start-Up
Start-Up
VOUT
1V/DIV
VOUT
1V/DIV
IIN
1A/DIV
IIN
1A/DIV
VIN = 5V
200µs/DIV
VOUT = 2.5V
COUT = 4 × 22µF
NO LOAD
(0.01µF SOFT-START CAPACITOR)
4604A G10
VIN = 5V
200µs/DIV
VOUT = 2.5V
COUT = 4 × 22µF
4A LOAD
(0.01µF SOFT-START CAPACITOR)
VFB vs Temperature
4604A G11
Current Limit Foldback
806
1.6
1.4
804
1.2
1.0
VOUT (V)
VFB (mV)
802
800
798
0.8
0.6
VOUT = 1.5V
VIN = 5V
0.2
VIN = 3.3V
VIN = 2.5V
0
4
5
3
0.4
796
794
–50
–25
0
25
50
75
TEMPERATURE (°C)
100
125
7
6
OUTPUT CURRENT (A)
4604A G12
4604A G15
Short-Circuit Protection
1.5V Short, No Load
6
Short-Circuit Protection
1.5V Short, 4A Load
VOUT
0.5V/DIV
VOUT
0.5V/DIV
IIN
1A/DIV
IIN
1A/DIV
VIN = 5V
20µs/DIV
8
4604A G13
VIN = 5V
100µs/DIV
4604A G14
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LTM4604A
Pin Functions
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY.
VIN (B1, C1, C3-C7, D7, E6 and E7): Power Input Pins.
Apply input voltage between these pins and GND pins.
Recommend placing input decoupling capacitance directly
between VIN pins and GND pins.
VOUT (D8-D11, E8-E11, F6-F11, G6-G11): Power Output
Pins. Apply output load between these pins and GND
pins. Recommend placing output decoupling capacitance
directly between these pins and GND pins. Review Table 4.
GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11):
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 capacitor 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
the TRACK pin to VIN. Load current must be present for
tracking. See the Applications Information section.
FB (G2): The Negative Input of the Error Amplifier. Internally, this pin is connected to VOUT with a 4.99k precision
resistor. Different output voltages can be programmed
with an externally connected 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 the Applications Information section.
COMP (G1): Current Control Threshold and Error Amplifier
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.
PGOOD (F1): Output Voltage Power Good Indicator. Opendrain logic output that is pulled to ground when the output
voltage is not within ±7.5% of the regulation point.
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 VIN and
a 1000pF capacitor to GND. The voltage on the RUN/SS
pin clamps the control loop’s current comparator threshold. A RUN/SS pin voltage of 2.375V upon completion of
soft-start guarantees the regulator can deliver full output
current. To tun off the module while VIN remains active, the
RUN/SS pin should be pulled low with a falling edge ≤ 1µs
to ensure the device does not transition slowly through
the internal undervoltage lockout threshold. See the
Applications Information section for soft-start information.
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.
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7
LTM4604A
Block Diagram
PGOOD
VIN
RSS
1M
RUN/SS
CSSEXT
TRACK
SUPPLY
4.99k
10µF
6.3V
×2
10µF
6.3V
VIN
2.375V TO 5.5V
CSS
1000pF
M1
TRACK
CONTROL,
DRIVE
5.76k COMP
VOUT
0.47µH
C2
470pF
M2
R1
4.99k
22µF
6.3V
×3
10µF
6.3V
INTERNAL
COMP
VOUT
1.5V
4A
GND
4604A BD
FB
RFB
5.76k
SW
Figure 1. Simplified LTM4604A Block Diagram
Decoupling
Requirements TA = 25°C. Use Figure 1 Configuration.
SYMBOL
PARAMETER
CONDITIONS
CIN
External Input Capacitor Requirement
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
IOUT = 4A
10
µF
COUT
External Output Capacitor Requirement
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
IOUT = 4A
66
µF
8
MIN
TYP
MAX
UNITS
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LTM4604A
Operation
Power Module Description
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.
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. With current mode control and internal feedback
loop compensation, the LTM4604A 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.
Current mode control provides cycle-by-cycle fast current
limit. In addition, foldback current limiting is provided in
an overcurrent condition while VOUT drops. Internal overvoltage and undervoltage comparators pull the open-drain
PGOOD output low if the output feedback voltage exits a
±7.5% window around the regulation point. 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.
Pulling the RUN/SS pin below 0.5V forces the controller
into its 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 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. The LTpowerCAD™ GUI is available for transient
and stability analysis.
The FB pin is used to program the output voltage with a
single external resistor connected to ground.
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9
LTM4604A
Applications Information
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.
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
VIN to VOUT Step-Down Ratios
There are restrictions in the maximum VIN and VOUT stepdown ratio that can be achieved for a given input voltage.
The LTM4604A is 100% duty cycle capable, but the VIN
to VOUT minimum dropout is a function of the load current. A typical 0.5V minimum is sufficient (see Typical
Performance Characteristics).
In the above equation, η% is the estimated efficiency of
the power module. The bulk capacitor can be a switcherrated aluminum electrolytic capacitor, OS-CON or
polymer capacitor. 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.
Output Voltage Programming
Output Capacitors
The PWM controller has an internal 0.8V reference voltage.
As shown in the Block Diagram, a 4.99k 0.5% internal
feedback resistor connects the VOUT and FB pins together.
The output voltage will default to 0.8V with no externally
applied 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 vs Output Voltage
VOUT
0.8V
1V
1.2V
1.5V
1.8V
2.5V
3.3V
RFB
Open
20k
10k
5.76k
4.02k
2.37k
1.62k
Input Capacitors
The LTM4604A module should be connected to a low acimpedance 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.
For a buck converter, the switching duty cycle can be
estimated as:
D=
VOUT
VIN
10
ICIN(RMS) =
IOUT(MAX)
η%
• D • (1– D)
The LTM4604A 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 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
spikes 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
LTpowerCAD GUI is available for further optimization.
Fault Conditions: Current Limit and Overcurrent
Foldback
The LTM4604A has current mode control, which inherently limits the cycle-by-cycle inductor current not only
in steady-state operation, but also in transient.
To further limit current in the event of an overload condition, the LTM4604A provides foldback current limiting as
the output voltage falls. The LTM4604A device has overtemperature shutdown protection that inhibits switching
operation around 150°C.
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LTM4604A
Applications Information
Run Enable and Soft-Start
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 voltage on the
RUN/SS pin clamps the control loop’s current comparator
threshold. A RUN/SS pin voltage of 2.375V upon completion
of soft-start guarantees the regulator can deliver full output
current. The soft-start control is provided by a 1M pull-up
resistor (RSS) and a 1000pF capacitor (CSS) as shown in
the Block Diagram. An external capacitor can be applied
to the RUN/SS pin to increase the soft-start time. A typical
value is 0.01µF. Soft-start time is approximately given by:
tSOFTSTART


VIN
= ln 
• RSS (CSS + CSSEXT )
 VIN – 1.8V 
where RSS and CSS are shown in the Block Diagram of
Figure 1, 1.8V is the soft-start upper range, and CSSEXT is
the additional capacitance for further soft-start control. 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 TRACK pin to
VIN to disable tracking. To turn off the module while VIN
remains active, the RUN/SS pin should be pulled low with
a falling edge ≤1µs to ensure the device does not transition
slowly through the internal undervoltage lockout threshold.
VTRACK is the track ramp applied to the slave’s TRACK pin.
VTRACK applies the track reference for the slave output up
to the point of the programmed value at which VTRACK
proceeds beyond the 0.8V reference value. The VTRACK
VIN
5V
CIN1
10µF
6.3V
X5R OR X7R
VIN
PGOOD
LTM4604A
COMP
FB
RUN/SS TRACK
GND
CSSEXT
VMASTER
3.3V
4A
VOUT
RAMP
CONTROL
OR VIN
RFB3
1.62k
COUT1
22µF
6.3V ×3
X5R OR
X7R
VIN
5V
CIN2
10µF
6.3V
X5R OR X7R
VIN
PGOOD
LTM4604A
COMP
FB
RUN/SS TRACK
GND
VSLAVE
1.5V
4A
VOUT
RFB2
5.76k
RFB
5.76k
COUT2
22µF
6.3V ×3
X5R OR
X7R
RFB1
4.99k
4604A F02
Figure 2. Dual Outputs (3.3V and 1.5V) with Tracking
Output Voltage Tracking
VTRACK
RFB2
=
•V
4.99k + RFB2 MASTER
MASTER OUTPUT
OUTPUT VOLTAGE (V)
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.
Figures 2 and 3 show an example of coincident tracking.
SLAVE OUTPUT
TIME
4604A F03
Figure 3. Output Voltage Coincident Tracking
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11
LTM4604A
Applications Information
pin must go beyond 0.8V to ensure the slave output has
reached its final value. Load current must be present for
proper tracking.
Ratiometric modes of tracking can be achieved by selecting
different resistor values to change the output tracking ratio.
The master output must be greater than the slave output
for ratiometric tracking to work. LTspice® can be used to
implement different tracking scenarios. 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 16 shows a schematic of the parallel design.
The voltage feedback changes with the variable N as more
modules are paralleled. The equation:
VOUT
4.99k
+ RFB
= 0.8V • N
RFB
Power Good
N is the number of paralleled modules.
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.
Thermal Considerations and Output Current Derating
COMP Pin
2.0
2.0
1.8
1.8
1.6
1.6
1.4
1.4
1.2
1.2
WATTS
WATTS
The COMP pin is the external compensation pin. The
LTM4604A has already been internally compensated for
all output voltages. Table 4 is provided for most application requirements. The LTpowerCAD GUI is available for
other control loop optimizations.
The power loss curves in Figures 4 and 5 can be used
in coordination with the load derating curves in Figures
6 through 13 for calculating an approximate θJA for the
module with and without heat sinking methods with various 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 θJA for the noted
conditions. These equivalent θJA parameters are correlated
to the measured values and improve with air flow. The
maximum junction temperature is monitored while the
derating curves are derived.
1.0
0.8
0.6
0.8
0.6
5V TO 1.2V
POWER LOSS
3.3V TO 1.2V
POWER LOSS
0.4
0.2
0
1.0
0
1
3
2
LOAD CURRENT (A)
4
5V TO 2.5V
POWER LOSS
3.3V TO 2.5V
POWER LOSS
0.4
0.2
5
0
0
4604A F04
Figure 4. 1.2V Power Loss
12
1
2
3
LOAD CURRENT (A)
4
5
4604A F05
Figure 5. 2.5V Power Loss
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LTM4604A
4.0
4.0
3.5
3.5
3.0
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
Applications Information
2.5
2.0
1.5
1.0
0
70
75
2.0
1.5
1.0
0LFM
200LFM
400LFM
0.5
2.5
0LFM
200LFM
400LFM
0.5
0
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F07
Figure 6. 5VIN to 1.2VOUT No Heat Sink
Figure 7. 5VIN to 1.2VOUT with Heat Sink
4.0
4.0
3.5
3.5
3.0
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
4606A F06
2.5
2.0
1.5
2.0
1.5
1.0
1.0
0LFM
200LFM
400LFM
0.5
0
2.5
70
75
0LFM
200LFM
400LFM
0.5
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
0
70
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F09
4606A F08
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
75
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
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13
LTM4604A
4.0
4.0
3.5
3.5
3.0
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
Applications Information
2.5
2.0
1.5
1.0
2.0
1.5
1.0
0LFM
200LFM
400LFM
0.5
0
2.5
70
75
0LFM
200LFM
400LFM
0.5
0
80 85 90 95 100 105 110
AMBIENT TEMPERATURE (°C)
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F10
4606A F11
Figure 11. 5VIN to 2.5VOUT with Heat Sink
4.0
4.0
3.5
3.5
3.0
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
Figure 10. 5VIN to 2.5VOUT No Heat Sink
2.5
2.0
1.5
2.0
1.5
1.0
1.0
0LFM
200LFM
400LFM
0.5
0
2.5
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
0
70
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F13
4606A F12
14
0LFM
200LFM
400LFM
0.5
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
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LTM4604A
Applications Information
Table 2. 1.2V Output
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
qJA (°C/W)
Figures 6, 8
3.3, 5
Figure 4
0
None
25
Figures 6, 8
3.3, 5
Figure 4
200
None
22.5
Figures 6, 8
3.3, 5
Figure 4
400
None
21
Figures 7, 9
3.3, 5
Figure 4
0
BGA Heat Sink
21
Figures 7, 9
3.3, 5
Figure 4
200
BGA Heat Sink
20
Figures 7, 9
3.3, 5
Figure 4
400
BGA Heat Sink
18
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA (°C/W)
Figures 10, 12
3.3, 5
Figure 5
0
None
25
Table 3. 2.5V Output
Figures 10, 12
3.3, 5
Figure 5
200
None
21
Figures 10, 12
3.3, 5
Figure 5
400
None
21
Figures 11, 13
3.3, 5
Figure 5
0
BGA Heat Sink
21
Figures 11, 13
3.3, 5
Figure 5
200
BGA Heat Sink
18
Figures 11, 13
3.3, 5
Figure 5
400
BGA Heat Sink
16
Table 4. Output Voltage Response Versus Component Matrix (Refer to Figure 17), 0A to 2A Load Step Typical Measured Values
CIN
VOUT (V) (CERAMIC)
CIN (BULK)
COUT
(CERAMIC)
CCOMP
VIN (V)
DROOP
(mV)
PEAK-TOPEAK(mV)
RECOVERY LOAD STEP
(µs)
(A/µs)
RFB
(kΩ)
1.2
10µF
56µF Aluminum
100µF 6.3V
None
2.5
21
43
10
2
10
1.2
10µF
56µF Aluminum
22µF ×4
None
3.3
23
45
10
2
10
1.2
10µF
56µF Aluminum
22µF ×4
None
5
24
46
10
2
10
1.5
10µF
56µF Aluminum
100µF 6.3V
None
2.5
19
41
10
2
5.76
1.5
10µF
56µF Aluminum
22µF ×4
None
3.3
21
43
10
2
5.76
1.5
10µF
56µF Aluminum
22µF ×4
None
5
21
43
10
2
5.76
1.8
10µF
56µF Aluminum
100µF 6.3V
None
2.5
25
50
10
2
4.02
1.8
10µF
56µF Aluminum
22µF ×3
None
3.3
30
60
10
2
4.02
1.8
10µF
56µF Aluminum
22µF ×3
None
5
30
60
10
2
4.02
2.5
10µF
56µF Aluminum
100µF 6.3V
None
2.5
22
45
12
2
2.37
2.5
10µF
56µF Aluminum
22µF ×3
None
3.3
25
55
12
2
2.37
2.5
10µF
56µF Aluminum
22µF ×3
None
5
25
55
12
2
2.37
3.3
10µF
56µF Aluminum
100µF 6.3V
None
2.5
22
50
15
2
1.62
3.3
10µF
56µF Aluminum
22µF ×3
None
3.3
25
56
15
2
1.62
3.3
10µF
56µF Aluminum
22µF ×3
None
5
25
56
15
2
1.62
4604afc
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15
LTM4604A
Applications Information
Safety Considerations
The LTM4604A µModule regulator does not provide
galvanic isolation from VIN to VOUT. There is no internal
fuse. If required, a slow blow fuse with a rating twice the
maximum input current needs to be provided to protect
each unit from catastrophic failure.
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 considerations are still necessary.
• Use large PCB copper areas for high current path,
including VIN, GND and VOUT. It helps to minimize the
PCB conduction loss and thermal stress.
GND
• Place high frequency ceramic input and output capacitors
next to the VIN, GND and VOUT pins to minimize high
frequency noise.
• Place a dedicated power ground layer underneath the
unit.
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers.
• Do not put vias directly on the pads unless they are
capped.
• SW pads can be soldered to board to improve thermal
performance.
Figure 14 gives a good example of the recommended layout.
VIN
2.375V TO 5.5V
VOUT
CIN
10µF
6.3V
X5R OR X7R
COUT
COUT
OPEN-DRAIN
PULL UP
VIN
PGOOD
LTM4604A
COMP
COUT
CSSEXT
0.01µF
VOUT
1.5V
4A
VOUT
FB
RUN/SS TRACK
GND
RFB
5.69k
COUT
22µF ×3
6.3V
X5R OR X7R
4604A F15
Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design
VIN
CIN
GND
4604A F14
Figure 14. Recommended PCB Layout (LGA Shown,
for BGA Use Circle Pads)
16
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LTM4604A
Typical Applications
VIN
2.375V TO 5V
CIN1
10µF
6.3V
X5R OR X7R
OPEN-DRAIN PULL UP
VOUT = 0.8V × ((4.99k/N) + RFB)/RFB
WHERE N IS THE NUMBER OF PARALLEL MODULES
VIN
VOUT
PGOOD
COUT1
22µF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
LTM4604A
FB
COMP
RUN/SS TRACK
CSSEXT
0.01µF
RFB
2.87k
GND
VOUT
1.5V
8A
CIN2
10µF
6.3V
X5R OR X7R
VIN
PGOOD
VOUT
COUT2
22µF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
LTM4604A
COMP
FB
RUN/SS TRACK
GND
4604A F16
Figure 16. Two LTM4604As in Parallel, 1.5V at 8A Design
VIN
3.3V TO 5V
CIN
10µF
6.3V
X5R OR X7R
50k
VIN
OPEN-DRAIN
PULL UP
PGOOD
VOUT
2.5V
4A
VOUT
COUT
22µF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
LTM4604A
COMP
CSSEXT
0.01µF
FB
RUN/SS TRACK
GND
RFB
2.37k
4604A F17
Figure 17. 3.3V to 5V Input, 2.5V at 4A Design
4604afc
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17
LTM4604A
Package Description
BGA Package
66-Lead (15mm × 9mm × 3.42mm)
(Reference LTC DWG # 05-08-1954 Rev Ø)
A
aaa Z
E
Y
X
Z
A1
SEE NOTES
DETAIL A
A2
7
G
SEE NOTES
PIN 1
3
ccc Z
1
PIN “A1”
CORNER
2
4
b
b1
MOLD
CAP
3
4
SUBSTRATE
F
6
Z
// bbb Z
D
5
H1
H2
7
DETAIL B
8
Øb (66 PLACES)
9
e
ddd M Z X Y
eee M Z
10
11
aaa Z
G
PACKAGE TOP VIEW
5.080
3.810
0.000
1.270
2.540
3.810
5.080
6.350
SUGGESTED PCB LAYOUT
TOP VIEW
D
C
B
A
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
DIMENSIONS
6.350
0.630 ±0.025 Ø 66x
E
2. ALL DIMENSIONS ARE IN MILLIMETERS
3.810
2.540
1.270
0.3175
0.3175
1.270
2.540
3.810
0.000
DETAIL A
F
PACKAGE BOTTOM VIEW
DETAIL B
PACKAGE SIDE VIEW
SYMBOL
A
A1
A2
b
b1
D
E
e
F
G
H1
H2
aaa
bbb
ccc
ddd
eee
MIN
3.22
0.50
2.72
0.60
0.60
0.27
2.45
NOM
3.42
0.60
2.82
0.75
0.63
15.00
9.00
1.27
12.70
7.62
0.32
2.50
MAX
3.62
0.70
2.92
0.90
0.66
0.37
2.55
0.15
0.10
0.20
0.30
0.15
TOTAL NUMBER OF BALLS: 66
NOTES
3
BALL DESIGNATION PER JESD MS-028 AND JEP95
4
DETAILS OF PIN #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PIN #1 IDENTIFIER MAY BE EITHER A MOLD OR
MARKED FEATURE
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. SOLDER BALL COMPOSITION CAN BE 96.5% Sn/3.0% Ag/0.5% Cu
OR Sn Pb EUTECTIC
7
!
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
LTMXXXXXX
µModule
COMPONENT
PIN “A1”
TRAY PIN 1
BEVEL
PACKAGE IN TRAY LOADING ORIENTATION
BGA 66 0813 REV Ø
18
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LTM4604A
Package Description
LGA Package
66-Lead (15mm × 9mm × 2.32mm)
(Reference LTC DWG # 05-08-1820 Rev A)
SEE NOTES
DETAIL A
2.19 – 2.45
G
aaa Z
7
F
E
D
C
B
A
PAD 1
1
PAD “A1”
CORNER
2
4
3
4
5
15.00
BSC
MOLD
CAP
12.70
BSC
SUBSTRATE
6
7
0.290 – 0.350
1.90 – 2.10
8
9
Z
// bbb Z
DETAIL B
10
11
0.630 ±0.025 SQ. 68x
X
aaa Z
9.00
BSC
eee S X Y
Y
7.620
BSC
DETAIL B
PADS
SEE NOTES
3
PACKAGE BOTTOM VIEW
3.810
2.540
1.270
0.000
1.270
2.540
3.810
0.315
0.315
PACKAGE TOP VIEW
1.27
BSC
DETAIL A
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
6.350
2. ALL DIMENSIONS ARE IN MILLIMETERS
5.080
3.810
3
LAND DESIGNATION PER JESD MO-222
4
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
2.540
1.270
0.000
1.270
2.540
3.810
5.080
6.350
0.315
0.315
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. THE TOTAL NUMBER OF PADS: 66
7
!
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
SYMBOL TOLERANCE
aaa
0.15
bbb
0.10
eee
0.05
COMPONENT
PIN “A1”
TRAY PIN 1
BEVEL
LTMXXXXXX
µModule
PACKAGE IN TRAY LOADING ORIENTATION
LGA 66 0113 REV A
SUGGESTED PCB LAYOUT
TOP VIEW
4604afc
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19
LTM4604A
Package Description
Pin Assignment Table
(Arranged by Pin Number)
20
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
A1
GND
B1
VIN
C1
VIN
D1
RUN/SS
A2
GND
B2
–
C2
–
D2
–
A3
GND
B3
SW
C3
VIN
D3
–
A4
GND
B4
SW
C4
VIN
D4
–
A5
GND
B5
–
C5
VIN
D5
–
A6
GND
B6
GND
C6
VIN
D6
–
A7
GND
B7
GND
C7
VIN
D7
VIN
A8
GND
B8
GND
C8
GND
D8
VOUT
A9
GND
B9
GND
C9
GND
D9
VOUT
A10
GND
B10
GND
C10
GND
D10
VOUT
A11
GND
B11
GND
C11
GND
D11
VOUT
PIN ID
FUNCTION
PIN ID
FUNCTION
PIN ID
FUNCTION
E1
TRACK
F1
PGOOD
G1
COMP
E2
–
F2
–
G2
FB
E3
–
F3
GND
G3
GND
E4
GND
F4
GND
G4
GND
E5
GND
F5
GND
G5
GND
E6
VIN
F6
VOUT
G6
VOUT
E7
VIN
F7
VOUT
G7
VOUT
E8
VOUT
F8
VOUT
G8
VOUT
E9
VOUT
F9
VOUT
G9
VOUT
E10
VOUT
F10
VOUT
G10
VOUT
E11
VOUT
F11
VOUT
G11
VOUT
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LTM4604A
Revision History
REV
DATE
DESCRIPTION
A
12/13
Added BGA package option
B
5/14
C
9/14
PAGE NUMBER
Throughout
Updated Minimum Input Voltage graph
5
Added output current information to Load Transient Response curves
5
Updated RUN/SS pin description
7
Updated Run Enable and Soft-Start section
11
Add SnPb BGA package option
1, 2
Update Block Diagram
8
Update Block Diagram
8
4604afc
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 representation that the interconnection
of itsinformation
circuits as described
herein will not infringe on existing patent rights.
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21
LTM4604A
Package Photograph
4604A BGA Package
4604A LGA Package
Related Parts
PART NUMBER
DESCRIPTION
COMMENTS
LTM4624
Wider VIN range than LTM4604A, 0.5cm2 solution
size (dual sided PCB)
2.375V ≤ VIN ≤ 14V, low VIN requires auxiliary VBIAS, 0.6V ≤ VOUT ≤ 5.5V,
6.25mm x 6.25mm x 5.01mm BGA
LTM4615
Triple output, 4A, 4A, 1.5A
2.375 ≤ VIN ≤ 5.5V, auxiliary VBIAS not required
LTM4644
Wider VIN range (up to 14V), Quad output, 4A each
2.375V ≤ VIN ≤ 14V, low VIN requires auxiliary VBIAS, 0.6V ≤ VOUT ≤ 5.5V,
current share to 16A, 9mm x 15mm x 5.01mm BGA
LTM4619
Wider VIN range (up to 26V), Dual output, 4A each
4.5V ≤ VIN ≤ 26.5V, 0.8V ≤ VOUT ≤ 5V, 15mm x 15mm x 2.82mm LGA
LTM8027
Wider VIN range (up to 60V) and VOUT range
4.5V ≤ VIN ≤ 60V, 2.5V ≤ VOUT ≤ 24V, 15mm x 15mm x 4.32mm LGA &
15mm x 15mm x 4.92mm BGA
LTM4608A
More current (8A)
2.7V ≤ VIN ≤ 5.5V, 8A, 9mm x 15mm x 2.82mm LGA
Design Resources
SUBJECT
DESCRIPTION
µModule Design and Manufacturing Resources
Design:
• Selector Guides
• Demo Boards and Gerber Files
• Free Simulation Tools
µModule Regulator Products Search
1. Sort table of products by parameters and download the result as a spread sheet.
Manufacturing:
• Quick Start Guide
• PCB Design, Assembly and Manufacturing Guidelines
• Package and Board Level Reliability
2. Search using the Quick Power Search parametric table.
TechClip Videos
Quick videos detailing how to bench test electrical and thermal performance of µModule products.
Digital Power System Management
Linear Technology’s family of digital power supply management ICs are highly integrated solutions that
offer essential functions, including power supply monitoring, supervision, margining and sequencing,
and feature EEPROM for storing user configurations and fault logging.
22 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTM4604A
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTM4604A
4604afc
LT 0914 REV C • PRINTED IN USA
© LINEAR TECHNOLOGY CORPORATION 2008
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