LINER LTM4604AIV-PBF Low voltage, 4a dc/dc î¼module with tracking Datasheet

LTM4604A
Low Voltage, 4A DC/DC
µModule with Tracking
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
■
■
DESCRIPTION
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: IQ ≤ 7μA
Overtemperature Protection
Small and Very Low Profile Package:
15mm × 9mm × 2.3mm LGA (0.630mm Pads)
APPLICATIONS
■
■
■
■
■
Telecom and Networking Equipment
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.
The LTM®4604A is a complete 4A switch mode DC/DC
power supply with ±1.75% 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 bulk 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 (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.
Fault protection features include foldback current protection, 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.
TYPICAL APPLICATION
Efficiency vs Output Current
100
3.3V to 2.5V/4A μModule™ Regulator
VIN = 3.3V
VOUT = 2.5V
95
VIN
3.3V
VIN
PGOOD
VOUT
2.5V
4A
VOUT
LTM4604A
COMP
FB
RUN/SS TRACK
GND
VIN
2.37k
EFFICIENCY (%)
90
10μF
6.3V
85
80
75
22μF
6.3V
×2
70
4604A TA01a
65
0
1
2
3
OUTPUT CURRENT (A)
4
4604A TA01b
4604af
1
LTM4604A
ABSOLUTE MAXIMUM RATINGS
PIN CONFIGURATION
(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
A
B
TOP VIEW
TRACK
PGOOD
C
F
D
E
G
VIN
COMP
1
2
RUN/
SS
SW
3
FB
GND
4
5
6
7
8
9
10
11
GND
VOUT
LGA PACKAGE
66-PIN (15mm × 9mm × 2.3mm) 0.630mm PAD
TJMAX = 125°C, θJA = 25°C/W, θJP = 7°C/W, θJC = 50°C/W, WEIGHT = 1.0g
ORDER INFORMATION
LEAD FREE FINISH
TRAY
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE (NOTE 2)
LTM4604AEV#PBF
LTM4604AEV#PBF
LTM4604AV
66-Lead (15mm × 9mm × 2.3mm) LGA
–40°C to 125°C
LTM4604AIV#PBF
LTM4604AIV#PBF
LTM4604AV
66-Lead (15mm × 9mm × 2.3mm) LGA
–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
VIN(DC)
VOUT(DC)
PARAMETER
Input DC Voltage
Output Voltage, Total
Variation with Line and Load
Input Specifications
Undervoltage Lockout
VIN(UVLO)
Threshold
Peak Input Inrush Current at
IINRUSH(VIN)
Start-Up
IQ(VIN NOLOAD)
Input Supply Bias Current
CONDITIONS
●
RFB = 5.69k
VIN = 2.375V to 5.5V, IOUT = 0A to 4A (Note 3)
IOUT = 0A
IOUT = 0A, CIN = 10μF, COUT = 22μF ×3,
RUN/SS = 0.01μF, VOUT = 1.5V
VIN = 3.3V
VIN = 5V
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
●
MIN
2.375
1.482
1.474
TYP
1.5
1.5
MAX
5.5
1.518
1.522
1.75
2
2.3
0.7
0.7
60
28
100
35
7
UNITS
V
V
V
V
A
A
μA
mA
μA
mA
μA
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
IS(VIN)
PARAMETER
Input Supply Current
Output Specifications
IOUT(DC)
Output Continuous Current
Range (Note 3)
Line Regulation Accuracy
ΔVOUT(LINE)
VOUT
ΔVOUT(LOAD)
Load Regulation Accuracy
VOUT
VOUT(AC)
fS
ΔVOUT(START)
tSTART
Output Ripple Voltage
Output Ripple Voltage
Frequency
Turn-On Overshoot
Turn-on Time
ΔVOUT(LS)
Peak Deviation for Dynamic
Load Step
tSETTLE
IOUT(PK)
Settling Time for Dynamic
Load Step
Output Current Limit
Control Section
VFB
Voltage at FB Pin
IFB
VRUN
ITRACK
V TRACK(OFFSET)
V TRACK(RANGE)
RFBHI
PGOOD
ΔVPGOOD
RPGOOD
RUN Pin On/Off Threshold
TRACK Pin Current
Offset Voltage
Tracking Input Range
Resistor Between VOUT and
FB Pins
PGOOD Range
PGOOD Resistance
CONDITIONS
VIN = 2.5V, VOUT = 1.5V, IOUT = 4A
VIN = 3.3V, VOUT = 1.5V, IOUT = 4A
VIN = 5V, VOUT = 1.5V, IOUT = 4A
MIN
TYP
2.9
2.2
1.45
VIN = 3.3V, VOUT = 1.5V
VOUT = 1.5V, VIN from 2.375V to 5.5V, IOUT = 0A
VOUT = 1.5V, 0A to 4A (Note 3)
VIN = 3.3V
VIN = 5V
IOUT = 0A
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
IOUT = 4A, VIN = 5V, VOUT = 1.5V
A
0.2
%
●
●
0.3
0.3
0.6
0.6
%
%
10
12
1.25
●
0.793
0.788
TRACK = 0.4V
0
4.975
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
4
0.1
0.5
Open-Drain Pull-Down
UNITS
A
A
A
●
VOUT = 1.5V, RUN/SS = 10nF,
IOUT = 0A
VIN = 3.3V
VIN = 5V
VOUT = 1.5V, IOUT = 1A Resistive Load, TRACK = VIN
and RUN/SS = Float
VIN = 3.3V
VIN = 5V
Load: 0% to 50% to 0% of Full Load,
COUT = 22μF ×3 Ceramic
VIN = 5V, VOUT = 1.5V
Load: 0% to 50% to 0% of Full Load
VIN = 5V, VOUT = 1.5V
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
IOUT = 0A, VOUT = 1.5V
MAX
mVP-P
mVP-P
MHz
20
20
mV
mV
1.5
1.0
ms
ms
25
mV
10
8
8
μs
A
A
0.8
0.8
0.2
0.65
0.2
30
0.807
0.808
4.99
0.8
5.025
V
V
μA
V
μA
mV
V
kΩ
±7.5
90
150
%
Ω
0.8
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 VIN, VOUT and TA.
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
95
90
90
90
85
80
75
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
EFFICIENCY (%)
95
EFFICIENCY (%)
100
EFFICIENCY (%)
100
70
65
2
3
OUTPUT CURRENT (A)
0
4
1
65
2
3
OUTPUT CURRENT (A)
VOUT (V)
2.5
0
4
4
Load Transient Response
ILOAD
2A/DIV
ILOAD
2A/DIV
2.0
1
2
3
OUTPUT CURRENT (A)
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
3.0
80
70
4604A G01
3.5
85
VOUT
20mV/DIV
VOUT
20mV/DIV
1.5
1.0
VIN = 5V
20μs/DIV
VOUT = 1.2V
COUT = 4 × 22μF, 6.3V CERAMICS
0.5
VIN = 5V
20μs/DIV
VOUT = 1.5V
COUT = 4 × 22μF, 6.3V CERAMICS
4604A G05
4604A G06
0
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
VIN (V)
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
4604A G07
VIN = 5V
20µs/DIV
VOUT = 2.5V
COUT = 3 × 22µF, 6.3V CERAMICS
4604A G08
VIN = 5V
20µs/DIV
VOUT = 3.3V
COUT = 2 × 22µF, 6.3V CERAMICS
4604A G09
4604af
4
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
0.8
0.6
798
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
Short-Circuit Protection
1.5V Short, 4A Load
VOUT
0.5V/DIV
VOUT
0.5V/DIV
IIN
4A/DIV
IIN
1A/DIV
20μs/DIV
8
4604A G13
100μs/DIV
4604A G14
4604af
5
LTM4604A
PIN FUNCTIONS
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.
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.
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.
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.
GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11):
Power Ground Pins for Both Input and Output Returns.
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.
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 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
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. 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.
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.
4604af
6
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
VOUT
L
CONTROL,
DRIVE
5.76k COMP
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
MIN
CIN
External Input Capacitor Requirement
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
IOUT = 4A
10
COUT
External Output Capacitor Requirement IOUT = 4A
(VIN = 2.375V to 5.5V, VOUT = 1.5V)
22
TYP
MAX
UNITS
μF
100
μF
4604af
7
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 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. An excel loop analysis tool is provided for
transient and stability analysis.
The FB pin is used to program the output voltage with a
single resistor connected to ground.
4604af
8
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
In the above equation, η% is the estimated efficiency of
the power module. The bulk capacitor can be a switcherrated 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.
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, 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).
Output Voltage Programming
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 feedback
resistor. Adding a resistor RFB from the FB pin to GND
programs the output voltage:
VOUT = 0.8 V •
4.99k + RFB
RFB
Table 1. FB Resistor vs Output Voltage
VOUT
0.8V
1.2V
1.5V
1.8V
2.5V
3.3V
RFB
Open
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
ICIN(RMS) =
IOUT(MAX)
η%
• D • (1– D)
Output Capacitors
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
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 provided
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.
4604af
9
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 soft-start
control is provided by a 1M pull-up resistor (RSS) and a
1000pF capacitor (CSS) as drawn 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.
The approximate equation for soft-start is:
V
IN
t SOFTSTART = 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 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
TRACK pin to VIN to disable tracking.
pin must go beyond 0.8V to ensure the slave output has
reached its final value. Load current must be present for
proper tracking.
VIN
5V
CIN1
10μF
6.3V
X5R OR X7R
VIN
PGOOD
LTM4604A
COMP
FB
RUN/SS TRACK
GND
CSSEXT
RAMP
CONTROL
OR VIN
CIN2
10μF
6.3V
X5R OR X7R
VIN
PGOOD
LTM4604A
COMP
FB
RUN/SS TRACK
GND
RFB2
•V
4.99k + RFB2 MASTER
V TRACK is the track ramp applied to the slave’s TRACK pin.
V TRACK applies the track reference for the slave output up
to the point of the programmed value at which V TRACK
proceeds beyond the 0.8V reference value. The V TRACK
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
MASTER OUTPUT
OUTPUT VOLTAGE (V)
VTRACK =
RFB3
1.62k
COUT1
22μF
6.3V ×3
X5R OR
X7R
VIN
5V
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 LTM4604A uses a
very accurate 4.99k resistor for the top feedback resistor.
Figure 2 shows an example of coincident tracking.
VMASTER
3.3V
4A
VOUT
SLAVE OUTPUT
TIME
4604A F03
Figure 3. Output Voltage Coincident Tracking
4604af
10
LTM4604A
APPLICATIONS INFORMATION
Ratio metric 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 the tracking to work. Linear Technology Tracker
Cad26 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.
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
Power Good
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.
COMP Pin
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 requirements.
The Linear Technology μModule Power Design Tool can
be provided for other control loop optimizations.
4.99k
+ RFB
= 0.8 V • N
RFB
N is the number of paralleled modules.
Thermal Considerations and Output Current Derating
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.
2.0
2.0
1.8
1.8
1.6
1.6
1.4
1.4
1.2
1.2
WATTS
WATTS
Parallel Operation
1.0
0.8
1.0
0.8
0.6
0.6
5V TO 1.2V
POWER LOSS
3.3V TO 1.2V
POWER LOSS
0.4
0.2
0
0
1
3
2
LOAD CURRENT (A)
4
0.2
0
5
4604A F04
Figure 4. 1.2V Power Loss
5V TO 2.5V
POWER LOSS
3.3V TO 2.5V
POWER LOSS
0.4
0
1
2
3
LOAD CURRENT (A)
4
5
4604A F05
Figure 5. 2.5V Power Loss
4604af
11
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 95 100 105 110 115
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)
4606A F08
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
0
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F09
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
4604af
12
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
2.5
2.0
1.5
1.0
1.0
0LFM
200LFM
400LFM
0.5
0
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
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
4606A F11
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)
4606A F12
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
0
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606A F13
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
4604af
13
LTM4604A
APPLICATIONS INFORMATION
Table 2. 1.2V Output
DERATING CURVE
VIN (V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEAT SINK
θJA (°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
4604af
14
LTM4604A
APPLICATIONS INFORMATION
Safety Considerations
The LTM4604A modules do not provide 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
VOUT
1.5V
4A
VOUT
LTM4604A
COUT
COMP
FB
RUN/SS TRACK
CSSEXT
0.01μF
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
4604af
15
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
PGOOD
VOUT
COUT1
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
LTM4604A
COMP
FB
RUN/SS TRACK
CSSEXT
0.01μF
GND
RFB
2.87k
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
4604af
16
LTM4604A
TYPICAL APPLICATIONS
VIN
3.3V TO 5V
CIN
10μF
6.3V
X5R OR X7R
50k
VIN
OPEN-DRAIN
PULL UP
PGOOD
VOUT
2.5V
4A
VOUT
LTM4604A
COMP
FB
RUN/SS TRACK
CSSEXT
0.01μF
GND
RFB
2.37k
COUT
22μF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
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
2.19 – 2.45
G
aaa Z
F
E
D
C
B
PAD 1
A
1
PAD “A1”
CORNER
2
4
3
4
5
15.00
BSC
12.70
BSC
MOLD
CAP
6
SUBSTRATE
7
0.290 – 0.350
8
1.90 – 2.10
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
6.350
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
5.080
2. ALL DIMENSIONS ARE IN MILLIMETERS
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
SYMBOL TOLERANCE
aaa
0.15
bbb
0.10
eee
0.05
COMPONENT
PIN “A1”
LTMXXXXXX
μModule
TRAY PIN 1
BEVEL
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
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
A1
GND
B1
VIN
C1
VIN
D1
RUN/SS E1
TRACK
F1
PGOOD
G1
A2
GND
B2
–
C2
–
D2
–
E2
–
F2
–
G2
COMP
FB
A3
GND
B3
SW
C3
VIN
D3
–
E3
–
F3
GND
G3
GND
A4
GND
B4
SW
C4
VIN
D4
–
E4
GND
F4
GND
G4
GND
A5
GND
B5
–
C5
VIN
D5
–
E5
GND
F5
GND
G5
GND
A6
GND
B6
GND
C6
VIN
D6
–
E6
VIN
F6
VOUT
G6
VOUT
A7
GND
B7
GND
C7
VIN
D7
VIN
E7
VIN
F7
VOUT
G7
VOUT
A8
GND
B8
GND
C8
GND
D8
VOUT
E8
VOUT
F8
VOUT
G8
VOUT
A9
GND
B9
GND
C9
GND
D9
VOUT
E9
VOUT
F9
VOUT
G9
VOUT
A10 GND
B10 GND
C10 GND
D10 VOUT
E10 VOUT
F10 VOUT
G10 VOUT
A11 GND
B11 GND
C11 GND
D11 VOUT
E11 VOUT
F11 VOUT
G11 VOUT
4604af
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 its circuits as described herein will not infringe on existing patent rights.
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
LTM4600HV
10A DC/DC μModule
Tracks Both Up and Down; Power Supply Sequencing
4.5V ≤ VIN ≤ 28V; 0.6V ≤ VOUT ≤ 5V; 15mm × 15mm × 2.8mm
LTM4601/LTM4601A 12A DC/DC μModule with PLL, Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1/LTM4601A-1 Version
has no Remote Sensing
LTM4601AHVMP
12A Military Grade μModule
4.5V ≤ VIN ≤ 28V; 0.6V ≤ VOUT ≤ 5V; 15mm × 15mm × 2.8mm,
–55°C to 125°C
LTM4602
6A DC/DC μModule
Pin Compatible with the LTM4600
LTM4603
6A DC/DC μModule with PLL and Output Tracking/ Synchronizable, PolyPhase Operation, LTM4603-1 Version has
Margining and Remote Sensing
no Remote Sensing, Pin Compatible with the LTM4601
LTM4605
5A Buck-Boost μModule
4.5V ≤ VIN ≤ 20V; 0.8V ≤ VOUT ≤ 16V; 15mm × 15mm × 2.8mm LGA
LTM4607
5A Buck-Boost μModule
4.5V ≤ VIN ≤ 36V; 0.8V ≤ VOUT ≤ 24V; 15mm × 15mm × 2.8mm LGA
LTM4608A
8A Low Voltage μModule
2.4V ≤ VIN ≤ 5.5V, Parallel for Higher Output Current,
9mm × 15mm × 2.8mm LGA
LTM4616
Dual 8A DC/DC μModule
Dual 8A or Single 16A; 2.375V ≤ VIN ≤ 5.5V; 15mm × 15mm × 2.5mm LGA
LTM8020
0.2A DC/DC μModule
4V ≤ VIN ≤ 36V; 1.25V ≤ VOUT ≤ 5V; 6.25mm × 6.25mm × 2.3mm LGA
LTM8021
0.5A DC/DC μModule
3.6V ≤ VIN ≤ 36V; 0.8V ≤ VOUT ≤ 5V; 6.25mm × 11.25mm × 2.8mm LGA
LTM8022
1A DC/DC μModule
3.6V ≤ VIN ≤ 36V; 0.8V ≤ VOUT ≤ 10V; 11.25mm × 9mm × 2.8mm LGA
LTM8023
2A DC/DC μModule
3.6V ≤ VIN ≤ 36V; 0.8V ≤ VOUT ≤ 10V; 11.25mm × 9mm × 2.8mm LGA
4604af
20 Linear Technology Corporation
LT 0808 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2008
Similar pages