LTM4645
25A DC/DC Step-Down
µModule Regulator
FeaTures
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DescripTion
The
LTM
®
4645
is a 25A output switching mode step-down
DC/DC µModule
®
(power module) regulator. Included in
the package are the switching controller, power FETs, in-
ductor and all supporting components. Operating over an
input voltage range of 4.7V to 15V, the LTM4645 supports
an output voltage range of 0.6V to 1.8V, set by a single
external resistor. Only a few input and output capacitors
are needed.
Its high efficiency design delivers about 86% efficiency
from 12V input to 1.0V output with 25A continuous load
current. 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 frequency synchronization, programmable
multiphase operation, N+1 phase redundancy, and output
voltage tracking for supply rail sequencing.
Fault protection features include overvoltage and overcur-
rent protection. The power module is offered in a space
saving 9mm
×
15mm
×
3.51mm BGA package. The
LTM4645 is available with SnPb (BGA) or RoHS compli-
ant terminal finish.
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4.7V to 15V Input Voltage Range
0.6V to 1.8V Output Voltage Range
25A DC Output Current
±1.2% Total DC Output Voltage Error (–40°C to 125°C)
High Reliability N + 1 Phase Redundancy Supported
Internal or External Control Loop Compensation
Differential Remote Sense Amplifier for Precision
Regulation
Current Mode Control/Fast Transient Response
Multiphase Current Sharing Up to 150A
Built-In Temperature Monitoring
Selectable Pulse-Skipping, Burst Mode
®
Operation
Soft-Start/Voltage Tracking
Frequency Synchronization
Output Overvoltage Protection
Output Overcurrent Foldback Protection
9mm
×
15mm
×
3.51mm BGA Package
applicaTions
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Telecom, Networking and Industrial Equipment
Point of Load Regulation
L,
LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, µModule, LTpowerCAD
and PolyPhase are registered trademarks of Analog Devices, Inc. All other trademarks are the
property of their respective owners.
Typical applicaTion
12V
IN
, 1V
OUT
, 25A DC/DC µModule Regulator
1µF
2.2
V
IN
6V TO 15V
V
IN
HIZB
FREQ
COMPa
COMPb
TRACK/SS
0.1µF
LTM4645
V
OUT
V
OSNS+
V
FB
V
OSNS–
SGND GND
4645 TA01a
Efficiency vs Output Current
at 1V Output
100
95
90
EFFICIENCY (%)
85
80
75
70
65
60
0
5
10
15
5V INPUT
12V INPUT
20
25
4645 TA01b
4.7µF
6.3V
DRV
CC
INTV
CC
SV
IN
22µF
25V
×2
43.2k
47pF
90.9k
V
OUT
1V
25A
100µF
6.3V
×4
PINS NOT USED IN THIS CIRCUIT:
CLKOUT, MODE/PLLIN, PGOOD,
PHASMD, PWM, RUN, SW, TEMP
+
, TEMP
–
LOAD CURRENT (A)
4645f
For more information
www.linear.com/LTM4645
1
LTM4645
absoluTe MaxiMuM raTings
(Note 1)
pin conFiguraTion
1
A
DRV
CC
TEST2
B
C
GND
HIZB
GND
V
IN
2
TOP VIEW
3
4
5
6
7
GND GND RUN GND
PWM
TEST1
MODE/PLLIN
INTV
CC
PHASMD
SV
IN
FREQ
V
FB
SGND
TEST3
V
OSNS+
PGOOD
COMPa
COMPb
CLKOUT
V
IN
, SV
IN
, HIZB .......................................... –0.3V to 16V
V
OUT
, ......................................................... –0.3V to 3.5V
INTV
CC
, DRV
CC
, PGOOD, RUN ..................... –0.3V to 6V
MODE/PLLIN, TRACK/SS, V
OSNS+
, V
OSNS –
,
CLKOUT, COMPa, COMPb, V
FB
, PHASMD,
FREQ .................................................... –0.3V to INTV
CC
Operating Junction Temperature (Note 2) .. –40 to 125°C
Storage Temperature Range ...................... –55 to 125°C
Peak Solder Reflow Body Temperature ................. 250°C
TEMP
+
, TEMP
–
.......................................... –0.3V to 0.8V
D
TEMP
–
E
TRACK/SS
SW
+
TEMP F
V
OSNS–
G
H
J
K
L
GND
V
OUT
GND
BGA PACKAGE
77-LEAD (9mm
×
15mm
×
3.51mm)
T
J(MAX)
= 125°C,
θ
JA
= 9.5°C/W,
θ
JCbottom
= 4°C/W,
θ
JCtop
= 6.7°C/W,
θ
JB
= 4.5°C/W
θ
JA
DERIVED FROM 95mm
×
76mm PCB WITH SIX LAYERS; WEIGHT = 1.3g
θ
VALUES DETERMINED PER JESD51-12
orDer inForMaTion
PART NUMBER
LTM4645EY#PBF
LTM4645IY#PBF
LTM4645IY
PAD OR BALL FINISH
SAC305 (RoHS)
SAC305 (RoHS)
SnPb (63/37)
http://www.linear.com/product/LTM4645#orderinfo
PART MARKING*
DEVICE
LTM4645Y
LTM4645Y
LTM4645Y
FINISH CODE
e1
e1
e0
PACKAGE
TYPE
BGA
BGA
BGA
MSL
RATING
3
3
3
TEMPERATURE RANGE
(Note 2)
–40°C to 125°C
–40°C to 125°C
–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.
•
Terminal Finish Part Marking:
www.linear.com/leadfree
•
Recommended LGA and BGA PCB Assembly and Manufacturing
Procedures:
www.linear.com/umodule/pcbassembly
•
LGA and BGA Package and Tray Drawings:
www.linear.com/packaging
4645f
2
For more information
www.linear.com/LTM4645
LTM4645
The
l
denotes the specifications which apply over the specified internal
operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, per the typical application.
SYMBOL
V
IN
V
OUT(RANGE)
V
OUT(DC)
PARAMETER
Input DC Voltage
Output Voltage Range
Output Voltage, Total Variation
with Line and Load
Input Supply Bias Current
V
IN
= 4.7V to 15V
C
IN
= 22µF
×
4, C
OUT
= 100µF Ceramic, 470µF POSCAP,
R
FB
= 60.4k, MODE = GND,V
IN
= 4.7V to 15V, I
OUT
= 0A to 25A
V
IN
= 12V, V
OUT
= 1.2V, Burst Mode Operation, I
OUT
= 0A
V
IN
= 12V, V
OUT
= 1.2V, Pulse-Skipping Mode, I
OUT
= 0A
V
IN
= 12V, V
OUT
= 1.2V, Switching Continuous, I
OUT
= 0A
Shutdown, RUN = 0, V
IN
= 12V
V
IN
= 12V, V
OUT
= 1.2V, I
OUT
= 25A
V
IN
= 12V, V
OUT
= 1.2V (Note 4)
V
OUT
= 1.2V, V
IN
from 4.7V to 15V, I
OUT
= 0A
V
OUT
= 1.2V, I
OUT
= 0A to 25A, V
IN
= 12V (Note 4)
C
OUT
= 100µF Ceramic
×
6,
V
IN
= 12V, V
OUT
= 1.2V, I
OUT
= 0A
C
OUT
= 100µF Ceramic
×
6,
V
IN
= 12V, V
OUT
= 1.2V, I
OUT
= 0A
C
OUT
= 100µF Ceramic
×
6
V
IN
= 12V, V
OUT
= 1.2V, No Load, TRACK/SS = 0.01µF
Load: 0% to 50% to 0% of Full Load,
C
OUT
= 100µF Ceramic
×
6, V
IN
= 12V, V
OUT
= 1.2V
Load: 0% to 50% to 0% of Full Load,
C
OUT
= 100µF Ceramic × 6, V
IN
= 12V, V
OUT
= 1.2V
V
IN
= 12V, V
OUT
= 1.2V
I
OUT
= 0A, V
OUT
= 1.2V
(Note 7)
TRACK/SS = 0V
(Note 3)
60.05
V
RUN
Rising
V
INTVCC
Falling
V
HIZB
Rising
1.2
l
l
l
elecTrical characTerisTics
CONDITIONS
l
l
l
MIN
4.7
0.6
1.186
TYP
MAX
15
1.8
UNITS
V
V
V
mA
mA
mA
µA
A
1.200
11
25
170
90
3.0
1.214
Input Specifications
I
Q(VIN)
I
S(VIN)
I
OUT(DC)
∆V
OUT(LINE)
/V
OUT
V
OUT(AC)
∆V
OUT(START)
t
START
∆V
OUTLS
t
SETTLE
I
OUTPK
V
FB
I
FB
I
TRACK/SS
t
ON(MIN)
R
FBHI
V
RUN
V
RUNHYS
UVLO
UVLO
HYS
V
HIZB
V
HIZBHYS
Input Supply Current
Output Continuous Current
Range
Line Regulation Accuracy
Output Ripple Voltage
Turn-On Overshoot
Turn-On Time
Peak Deviation for Dynamic
Load
Settling Time for Dynamic
Load Step
Output Current Limit
Voltage at V
FB
Pin
Current at V
FB
Pin
Track Pin Soft-Start Pull-Up
Current
Minimum On-Time
Resistor Between V
OUT_LCL
and V
FB
Pins
RUN Pin On Threshold
RUN Pin On Hysteresis
Undervoltage Lockout
UVLO Hysteresis
HIZB Pin On Threshold
HIZB Pin On Hysteresis
Output Specifications
0
0.005
0.1
15
20
5
36
15
35
594
600
–30
1.25
90
60.40
1.35
180
4
400
2.3
800
60.75
1.45
606
–100
nA
µA
ns
kΩ
V
mV
V
mV
V
mV
25
0.05
0.3
A
%/V
%
mV
mV
ms
mV
µs
A
∆V
OUT(LOAD)
/ V
OUT
Load Regulation Accuracy
Control Specifications
4645f
For more information
www.linear.com/LTM4645
3
LTM4645
The
l
denotes the specifications which apply over the specified internal
operating temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 12V, per the typical application.
SYMBOL
PGOOD
R
PGOOD
V
PGOOD
V
PGL
V
INTVCC
V
INTVCC
Load Reg
f
SYNC
f
SW
I
FREQ
R
MODE_PLLIN
V
IH_MODE_PLLIN
V
IL_MODE_PLLIN
θ
CLKOUT
PGOOD Pull-Down Resistance
PGOOD Trip Level
V
FB
With Respect to Set Output
V
FB
Ramping Negative
V
FB
Ramping Positive
I
PGOOD
= 2mA
V
IN
≥ 12V
I
CC
= 0mA to 10mA
300
R
FREQ
= 47.5kΩ
V
FREQ
= 0.8V
2.0
1.2
V
PHSMD
= 0V
V
PHSMD
= 1/4 INTV
CC
V
PHSMD
= Float
V
PHSMD
= 3/4 INTV
CC
V
PHSMD
= INTV
CC
90
90
120
60
180
540
600
20
250
5.3
90
–7.5
7.5
0.1
5.5
0.5
1000
660
0.3
5.7
200
Ω
%
%
V
V
%
kHz
kHz
µA
kΩ
V
V
Deg
Deg
Deg
Deg
Deg
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
elecTrical characTerisTics
PGOOD Voltage Low
Internal V
CC
Voltage
INTV
CC
Load Regulation
SYNC Capture Range
Switching Frequency
FREQ Pin Current
Mode_PLLIN Input Resistance
Clock Input Level High
Clock Input Level Low
CLKOUT to SW Phase Delay
INTV
CC
Linear Regulator
Oscillator and Phase-Locked Loop
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 LTM4645 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTM4645E is guaranteed to meet performance specifications
over the 0°C to 125°C internal operating temperature range. Specifications
over the full –40°C to 125°C internal operating temperature range are
assured by design, characterization and correlation with statistical process
controls. The LTM4645I is guaranteed to meet specifications over the
full –40°C to 125°C 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:
The minimum on-time condition is specified for a peak-to-peak
inductor ripple current of ~40% of I
MAX
Load. (See the Applications
Information section)
Note 4:
See output current derating curves for different V
IN
, V
OUT
and T
A
.
Note 5:
Limit current into the RUN pin to less than 2mA.
Note 6:
Guaranteed by design.
Note 7:
100% tested at wafer level.
4645f
4
For more information
www.linear.com/LTM4645
LTM4645
Typical perForMance characTerisTics
Efficiency vs Output Current,
V
IN
= 5V
100
95
90
EFFICIENCY (%)
EFFICIENCY (%)
85
80
75
70
65
0
5
10
0.9V
OUT
500kHz
1V
OUT
600kHz
1.2V
OUT
700kHz
1.5V
OUT
800kHz
1.8V
OUT
900kHz
15
20
25
4645 G01
Efficiency vs Output Current,
V
IN
= 12V
100
95
90
EFFICIENCY (%)
85
80
75
70
65
0
5
10
0.9V
OUT
500kHz
1V
OUT
600kHz
1.2V
OUT
700kHz
1.5V
OUT
800kHz
1.8V
OUT
900kHz
15
20
25
4645 G02
100
90
80
70
60
50
40
30
20
10
CCM, Burst Mode and Pulse-
Skipping Mode Efficiency
V
IN
= 12V, V
OUT
= 1.2V, 750kHz
0
0.01
CCM
Burst Mode OPERATION
PULSE-SKIPPING MODE
0.1
1
10
LOAD CURRENT (A)
100
4645 G03
LOAD CURRENT (A)
LOAD CURRENT (A)
0.9V Output Load Step Transient
Response
V
OUT
50mV/DIV
AC-
COUPLED
V
OUT
50mV/DIV
AC-
COUPLED
1V Output Load Step Transient
Response
V
OUT
50mV/DIV
AC-
COUPLED
1.2V Output Load Step Transient
Response
LOAD STEP
5A/DIV
50µs/DIV
V
IN
= 12V, V
OUT
= 0.9V, F
S
= 500kHz
C
OUT
= 6 × 100µF CERAMIC
C
FF
= 33pF
0A TO 6.25A LOAD STEP 10A/µs
,
4645 G04
LOAD STEP
5A/DIV
50µs/DIV
V
IN
= 12V, V
OUT
= 1V, F
S
= 600kHz
C
OUT
= 6 × 100µF CERAMIC
C
FF
= 33pF
0A TO 6.25A LOAD STEP 10A/µs
,
4645 G05
LOAD STEP
5A/DIV
50µs/DIV
V
IN
= 12V, V
OUT
= 1.2V, F
S
= 700kHz
C
OUT
= 6 × 100µF CERAMIC
C
FF
= 33pF
0A TO 6.25A LOAD STEP 10A/µs
,
4645 G06
1.5V Output Load Step Transient
Response
V
OUT
50mV/DIV
AC-
COUPLED
V
OUT
50mV/DIV
AC-
COUPLED
1.8V Output Load Step Transient
Response
LOAD STEP
5A/DIV
50µs/DIV
V
IN
= 12V, V
OUT
= 1.5V, F
S
= 800kHz
C
OUT
= 6 × 100µF CERAMIC
C
FF
= 33pF
0A TO 6.25A LOAD STEP 10A/µs
,
4645 G07
LOAD STEP
5A/DIV
50µs/DIV
V
IN
= 12V, V
OUT
= 1.8V, F
S
= 900kHz
C
OUT
= 6 × 100µF CERAMIC
C
FF
= 33pF
0A TO 6.25A LOAD STEP 10A/µs
,
4645 G08
4645f
For more information
www.linear.com/LTM4645
5
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