LTM4604 Low Voltage, 4A DC/DC µModule Regulator with Tracking

LTM4604 Low Voltage, 4A DC/DC µModule Regulator with Tracking
Features
Complete Standalone Power Supply
n Wide Input Voltage Range: 2.375V to 5.5V
n 4A DC, 5A Peak Output Current
n 0.8V to 5V Output
n Output Voltage Tracking
n±2% Maximum Total DC Output Error
n UltraFastTM Transient Response
n Current Mode Control
n Current Foldback Protection, Parallel/Current Sharing
n Small and Very Low Profile Package:
15mm × 9mm × 2.32mm LGA
n
Applications
Telecom and Networking Equipment
Servers, ATCA Cards
n Industrial Equipment
n
n
Please refer to the LTM4604A for easier PC board layout
and assembly due to increased spacing between land
grid pads.
LTM4604
Low Voltage, 4A DC/DC
µModule Regulator
with Tracking
Description
The LTM®4604 is a complete 4A switch mode step-down
µModule® (micromodule) regulator. 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 LTM4604 supports an output
voltage range of 0.8V to 5V, set by a single resistor. This
high efficiency design delivers up to 4A continuous current (5A peak). Only bulk input and output capacitors are
needed to complete the design.
The low profile package (2.32mm) enables utilization of
unused space on the bottom of PC boards for high density
point of load regulation. High switching frequency and
a current mode architecture enable a very fast transient
response to line and load changes without sacrificing
stability. The device supports output voltage tracking for
supply rail sequencing.
Fault protection features include foldback current protection, thermal shutdown and a programmable soft-start
function. The LTM4604 is offered in a RoHS compliant
15mm × 9mm × 2.32mm LGA package.
L, LT, LTC, LTM, Linear Technology, the Linear logo and µModule are registered trademarks
and LTpowerCAD, LTspice and UltraFast are trademarks of Linear Technology Corporation. All
other trademarks are the property of their respective owners.
Typical Application
Efficiency vs Output Current
3.3V to 2.5V/4A µModule Regulator
100
VIN
3.3V
10µF
6.3V
VIN = 3.3V
VOUT = 2.5V
95
PGOOD
VOUT
2.5V
4A
VOUT
LTM4604
COMP
FB
RUN/SS TRACK
GND
VIN
2.37k
22µF
6.3V
×2
EFFICIENCY (%)
90
VIN
85
80
75
70
4604 TA01a
65
0
1
2
3
OUTPUT CURRENT (A)
4
4604 G02
4604fb
For more information www.linear.com/LTM4604
1
LTM4604
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)
Operating Temperature Range (Note 2)....–40°C to 85°C
Junction Temperature............................................ 125°C
Storage Temperature Range................... –55°C to 125°C
Reflow (Peak Body) Temperature........................... 245°C
pIN CONFIGURATION
A
B
TOP VIEW
TRACK
PGOOD
C
F
D
E
G
VIN
COMP
1
2
SW
3
RUN/
SS
FB
GND
4
5
6
7
8
9
10
11
GND
For easier PC board layout and assembly due to increased spacing between land grid pads, please refer
to the LTM4604A.
VOUT
LGA PACKAGE
66-PIN (15mm × 9mm × 2.32mm)
TJMAX = 125°C, θJA = 25°C/W, θJC(BOT) = 7°C/W,
θJC(TOP) = 50°C/W, WEIGHT = 1.0g
order information
LEAD FREE FINISH
TRAY
PART MARKING*
PACKAGE DESCRIPTION
TEMPERATURE RANGE (NOTE 2)
LTM4604EV#PBF
LTM4604EV#PBF
LTM4604V
15mm × 9mm × 2.32mm LGA
–40°C to 85°C
LTM4604IV#PBF
LTM4604IV#PBF
LTM4604V
15mm × 9mm × 2.32mm LGA
–40°C to 85°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
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
l denotes the specifications which apply over the full operating
temperature range (Note 2), otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
VIN(DC)
VOUT(DC)
PARAMETER
CONDITIONS
Input DC Voltage
Output Voltage, Total Variation CIN = 10µF, COUT = 22µF ×3, RFB = 5.69k (Note 3)
with Line and Load
VIN = 2.375V to 5.5V, IOUT = 0A to 4A, 0°C ≤ TA ≤ 85°C
VIN = 2.375V to 5.5V, IOUT = 0A to 4A
Input Specifications
Undervoltage Lockout
VIN(UVLO)
Threshold
Peak Input Inrush Current at
IINRUSH(VIN)
Start-Up
IQ(VIN NOLOAD)
Input Supply Bias Current
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
TYP
l
MAX
5.5
UNITS
V
l
1.478
1.470
1.5
1.5
1.522
1.522
V
V
1.75
2
2.3
V
0.7
0.7
60
28
100
35
7
A
A
µA
mA
µA
mA
µA
4604fb
2
For more information www.linear.com/LTM4604
LTM4604
Electrical
Characteristics
The
l denotes the specifications which apply over the full operating
temperature range (Note 2), otherwise specifications are at TA = 25°C. VIN = 5V unless otherwise noted. See Figure 15.
SYMBOL
IS(VIN)
PARAMETER
Input Supply Current
Output Specifications
Output Continuous Current
IOUT(DC)
Range
Line Regulation Accuracy
ΔVOUT(LINE)
VOUT
ΔVOUT(LOAD)
Load Regulation Accuracy
VOUT
VOUT(AC)
Output Ripple Voltage
fS
Output Ripple Voltage
Frequency
Turn-On Overshoot
ΔVOUT(START)
tSTART
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/SS
ITRACK
VTRACK(OFFSET)
VTRACK(RANGE)
RFBHI
PGOOD
∆VPGOOD
RPGOOD
RUN/SS 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 (Note 3)
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, COUT = 22µF X5R Ceramic ×3
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
IOUT = 4A, VIN = 5V, VOUT = 1.5V
A
0.2
%
l
l
0.3
0.3
0.6
0.6
%
%
10
12
1.25
l
0.792
0.788
TRACK = 0.4V
0
4.965
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTM4604E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the – 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
4
0.1
0.5
Open-Drain Pull-Down
UNITS
A
A
A
l
COUT = 22µF ×3, VOUT = 1.5V, RUN/SS = 10nF,
IOUT = 0A
VIN = 3.3V
VIN = 5V
COUT = 22µF ×3, 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
COUT = 22µF ×3
VIN = 3.3V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
IOUT = 0A, VOUT = 1.5V, 0°C ≤ TA ≤ 85°C
IOUT = 0A, VOUT = 1.5V
MAX
mVP-P
mVP-P
MHz
20
20
mV
mV
1.5
1.0
ms
ms
25
mV
10
µs
8
8
A
A
0.8
0.8
0.2
0.65
0.2
30
0.808
0.812
4.99
0.8
5.015
V
V
µA
V
µA
mV
V
kΩ
±7.5
90
150
%
Ω
0.8
with statistical process controls. The LTM4604I is guaranteed over the full
–40°C to 85°C operating temperature range.
Note 3: See output current derating curves for different VIN, VOUT and TA.
4604fb
For more information www.linear.com/LTM4604
3
LTM4604
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
70
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
2
3
OUTPUT CURRENT (A)
4
EFFICIENCY (%)
95
EFFICIENCY (%)
100
EFFICIENCY (%)
100
65
0
1
2
VOUT (V)
2.5
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
4604 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
4604 G02
Minimum Input Voltage
at 4A Load
3.0
80
70
4604 G01
3.5
85
20µs/DIV
VIN = 5V
VOUT = 1.5V
COUT = 4 × 22µF, 6.3V CERAMICS
IOUT = 0A to 2A
4604 G05
4604 G06
4604 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
4604 G07
20µs/DIV
VIN = 5V
VOUT = 2.5V
COUT = 3 × 22µF, 6.3V CERAMICS
IOUT = 0A to 2A
4604 G08
20µs/DIV
VIN = 5V
VOUT = 3.3V
COUT = 2 × 22µF, 6.3V CERAMICS
IOUT = 0A to 2A
4604 G09
4604fb
4
For more information www.linear.com/LTM4604
LTM4604
Typical Performance Characteristics
Start-Up
Start-Up
VIN
2V/DIV
VIN
2V/DIV
IIN
1A/DIV
IIN
1A/DIV
4604 G10
200µs/DIV
VIN = 5V
VOUT = 2.5V
COUT = 4 × 22µF
NO LOAD
(0.01µF SOFT-START CAPACITOR)
200µs/DIV
VIN = 5V
VOUT = 2.5V
COUT = 4 × 22µF
4A LOAD
(0.01µF SOFT-START CAPACITOR)
VFB vs Temperature
4604 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
TEMPERATURE (°C)
75
100
7
6
OUTPUT CURRENT (A)
4604 G13
4604 G12
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
1A/DIV
IIN
1A/DIV
VIN = 5V
20µs/DIV
8
4604 G14
VIN = 5V
100µs/DIV
4604 G15
4604fb
For more information www.linear.com/LTM4604
5
LTM4604
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.
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 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 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 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. See 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.
4604fb
6
For more information www.linear.com/LTM4604
LTM4604
Block Diagram
VIN
PGOOD
RSS
1M
RUN/SS
CSSEXT
10µF
6.3V
×2
10µF
6.3V
CSS
1000pF
M1
TRACK
SUPPLY
4.99k
L
CONTROL,
DRIVE
TRACK
5.76k
VIN
2.375V TO 5.5V
C2
470pF
M2
COMP
VOUT
INTERNAL
COMP
R1
4.99k
0.5%
22µF
6.3V
×3
10µF
6.3V
VOUT
1.5V
4A
GND
4604 BD
FB
RFB
5.76k
SW
Figure 1. Simplified LTM4604 Block Diagram
DECOUPLING
REQUIREMENTS A = 25°C. Use Figure 1 Configuration.
T
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
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
4604fb
For more information www.linear.com/LTM4604
7
LTM4604
Operation
Power Module Description
The LTM4604 is a standalone non-isolated switch mode
DC/DC power supply. It can deliver up to 4A of DC output
current with few external input and output capacitors.
This module provides a precise regulated output voltage
programmable via one external resistor from 0.8V DC to
5.0V DC over a 2.375V to 5.5V input voltage. A typical
application schematic is shown in Figure 15.
The LTM4604 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 LTM4604 module has sufficient
stability margins and good transient performance under a
wide range of operating conditions and with a wide range
of output capacitors, even all ceramic output capacitors.
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 LTM4604 is internally compensated to be stable over
a wide operating range. Table 4 provides a guideline for
input and output capacitance for several operating 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.
4604fb
8
For more information www.linear.com/LTM4604
LTM4604
Applications Information
A typical LTM4604 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 LTM4604 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
1.0V
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 LTM4604 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)
h%
• D • (1– D)
The LTM4604 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 LTM4604 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 LTM4604 provides foldback current limiting as
the output voltage falls. The LTM4604 device has overtemperature shutdown protection that inhibits switching
operation around 150°C.
4604fb
For more information www.linear.com/LTM4604
9
LTM4604
Applications Information
Run Enable and Soft-Start
 VIN 
tSOFTSTART = 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.
Output Voltage Tracking
Output voltage tracking can be programmed externally
using the TRACK pin. The output can be tracked up and
down with another regulator. The master regulator’s output
is divided down with an external resistor divider that is the
same as the slave regulator’s feedback divider to implement
coincident tracking. The LTM4604 uses a very accurate
4.99k resistor for the top feedback resistor. Figures 2 and
3 show an example of coincident tracking.
VTRACK =
CIN1
10µF
6.3V
X5R OR X7R
VIN
PGOOD
LTM4604
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
LTM4604
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
4604 F02
Figure 2. Dual Outputs (3.3V and 1.5V) with Tracking
MASTER OUTPUT
OUTPUT VOLTAGE (V)
The RUN/SS pin provides dual functions of enable and
soft-start control. The RUN/SS pin is used to control
turn on of the LTM4604. While this pin is below 0.5V, the
LTM4604 will be in a 7µA low quiescent current state. A
0.8V threshold will enable the LTM4604. This pin can be
used to sequence LTM4604 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:
VIN
5V
SLAVE OUTPUT
TIME
4604 F03
Figure 3. Output Voltage Coincident Tracking
RFB2
•V
4.99k +RFB2 MASTER
4604fb
10
For more information www.linear.com/LTM4604
LTM4604
Applications Information
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
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 ratiometric tracking.
The master and slave regulators require load current for
tracking down.
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 COMP pin is the external compensation pin. The
LTM4604 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.
Parallel Operation
The LTM4604 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
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
1.8
2.0
1.6
1.8
1.4
1.6
WATTS
WATTS
1.4
1.2
1.0
1.0
0.8
0.6
0.8
5V TO 2.5V
POWER LOSS
3.3V TO 2.5V
POWER LOSS
0.4
0.6
0.2
5V TO 1.2V
POWER LOSS
3.3V TO 1.2V
POWER LOSS
0.4
0.2
0
1.2
0
1
3
2
LOAD CURRENT (A)
4
0
0
5
4604 F04
1
2
3
LOAD CURRENT (A)
4
5
4604 F05
Figure 5. 2.5V Power Loss
Figure 4. 1.2V Power Loss
4604fb
For more information www.linear.com/LTM4604
11
LTM4604
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
0
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
75
0LFM
200LFM
400LFM
0.5
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606 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)
4606 F06
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 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
70
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606 F09
4606 F08
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
4.0
4.0
3.5
3.5
3.0
3.0
LOAD CURRENT (A)
LOAD CURRENT (A)
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
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
80 85 90 95 100 105 110
AMBIENT TEMPERATURE (°C)
0
70
4606 F10
Figure 10. 5VIN to 2.5VOUT No Heat Sink
75
80 85 90 95 100 105 110 115
AMBIENT TEMPERATURE (°C)
4606 F11
Figure 11. 5VIN to 2.5VOUT with Heat Sink
4604fb
12
For more information www.linear.com/LTM4604
LTM4604
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
2.0
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)
4606 F13
4606 F12
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
75
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
4604fb
For more information www.linear.com/LTM4604
13
LTM4604
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
qJA (°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
4604fb
14
For more information www.linear.com/LTM4604
LTM4604
Applications Information
Safety Considerations
• Do not put vias directly on the pads unless they are
capped.
The LTM4604 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.
• SW pads can be soldered to board to improve thermal
performance.
Figure 14 gives a good example of the recommended
layout. For easier PC board layout and assembly due
to increased spacing between land grid pads, please
refer to the LTM4604A.
Layout Checklist/Example
The high integration of LTM4604 makes the PCB board
layout very simple and easy. However, to optimize its electrical and thermal performance, some layout considerations
are still necessary.
GND
VOUT
COUT
• 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.
COUT
COUT
•
• Place high frequency ceramic input and output capacitors
next to the VIN, GND and VOUT pins to minimize high
frequency noise.
•
VIN
• 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.
CIN
•
•
•
•
•
•
•
•
•
•
•
• •
•
•
•
•
•
•
•
•
•
SW
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
• •
GND
• •
4604 F14
Figure 14. Recommended PCB Layout
VIN
2.375V TO 5.5V
CIN
10µF
6.3V
X5R OR X7R
OPEN-DRAIN
PULL UP
VIN
PGOOD
LTM4604
COMP
CSSEXT
0.01µF
VOUT
1.5V
4A
VOUT
FB
RUN/SS TRACK
GND
RFB
5.69k
0.5%
COUT
22µF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
4604 F15
Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design
4604fb
For more information www.linear.com/LTM4604
15
LTM4604
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 DEVICES
VIN
VOUT
PGOOD
COUT1
22µF ×3
6.3V
X5R OR X7R
REFER TO
TABLE 4
LTM4604
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
LTM4604
COMP
FB
RUN/SS TRACK
GND
4604 F16
Figure 16. Two LTM4604s in Parallel, 1.5V at 8A Design.
Also See the 8A LTM4608A or Dual 4A per Channel LTM4614
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
LTM4604
COMP
CSSEXT
0.01µF
FB
RUN/SS TRACK
GND
RFB
2.37k
4604 F17
Figure 17. 3.3V to 5V Input, 2.5V at 4A Design
4604fb
16
For more information www.linear.com/LTM4604
For more information www.linear.com/LTM4604
3.810
2.540
1.270
0.4445
0.000
0.4445
1.270
2.540
PACKAGE TOP VIEW
SUGGESTED PCB LAYOUT
TOP VIEW
1.270
5.080
6.350
X
9.00
BSC
Y
DETAIL A
PACKAGE SIDE VIEW
1.90 – 2.10
DETAIL A
MOLD
CAP
Z
0.29 – 0.35
SUBSTRATE
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 A
MARKED FEATURE
4
7
PACKAGE ROW AND COLUMN LABELING MAY VARY
AMONG µModule PRODUCTS. REVIEW EACH PACKAGE
LAYOUT CAREFULLY
SYMBOL TOLERANCE
aaa
0.15
bbb
0.10
!
6. THE TOTAL NUMBER OF PADS: 66
5. PRIMARY DATUM -Z- IS SEATING PLANE
LAND DESIGNATION PER JESD MO-222
3
2. ALL DIMENSIONS ARE IN MILLIMETERS
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
aaa Z
2.19 – 2.45
1.27
BSC
TRAY PIN 1
BEVEL
COMPONENT
PIN “A1”
3
PADS
SEE NOTES
7.620
BSC
0.864 – 0.914
(Reference LTC DWG # 05-08-1807 Rev B)
bbb Z
aaa Z
3.810
4
0.4445
0.000
0.4445
PAD “A1”
CORNER
15.00
BSC
1.270
LGA Package
66-Lead (15mm × 9mm × 2.32mm)
11
10
8
6
5
PACKAGE BOTTOM VIEW
7
12.70
BSC
4
3
LGA 66 0113 REV B
PACKAGE IN TRAY LOADING ORIENTATION
LTMXXXXXX
µModule
9
0.864 – 0.914
2
1
PAD 1
A
B
C
D
E
F
G
7
SEE NOTES
LTM4604
Package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
4604fb
17
6.350
5.080
3.810
2.540
2.540
3.810
LTM4604
Package Description
Pin Assignment Table
(Arranged by Pin Number)
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
4604fb
18
For more information www.linear.com/LTM4604
LTM4604
Revision History
REV
DATE
DESCRIPTION
A
5/10
Updated Front Page Text
1
Updated Absolute Maximum Ratings and Pin Configuration Section
2
B
5/14
PAGE NUMBER
Updated Callouts on Graphs
5
Added text to Layout Checklist/Example Section
15
Updated Figure 16 Title
15
Updated thermal resistance and weight
2
Updated Minimum Input Voltage graph
4
Added output current information to Load Transient Response curves
4
Updated RUN/SS Pin Description
6
Updated Run Enable and Soft-Start section
10
4604fb
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 information
circuits as described
herein will not infringe on existing patent rights.
For more
www.linear.com/LTM4604
19
LTM4604
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
Tracks Both Up and Down; Power Supply Sequencing
LTM4600
10A DC/DC µModule Regulator
Basic 10A DC/DC µModule Regulator
LTM4601
12A DC/DC µModule Regulator with PLL, Output
Tracking/ Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4601-1 Version has no Remote
Sensing
LTM4602
6A DC/DC µModule Regulator
Pin Compatible with the LTM4600
LTM4603
6A DC/DC µModule Regulator with PLL and Output
Tracking/Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote
Sensing, Pin Compatible with the LTM4601
LTM4608A
8A Low Voltage µModule Regulator
2.375V ≤ VIN ≤ 5V, Parallel for Higher Output Current, 9mm × 15mm × 2.82mm
4604fb
20 Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
For more information www.linear.com/LTM4604
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com/LTM4604
LT 0514 REV B • PRINTED IN USA
 LINEAR TECHNOLOGY CORPORATION 2007
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement