FEATURES
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LTM4608A
Low V
IN
, 8A DC/DC µModule
Regulator with Tracking, Margining,
and Frequency Synchronization
DESCRIPTION
The
LTM
®
4608A
is a complete 8A 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 2.7V to 5.5V, the LTM4608A sup-
ports an output voltage range of 0.6V to 5V, set by a single
external resistor. This high efficiency design delivers up
to 8A continuous current (10A peak). Only bulk input and
output capacitors are needed to complete the design.
The low profile package (2.82mm) enables utilization
of unused space on the back side of PC boards for high
density point-of-load regulation. The 0.630mm LGA pads
with 1.27mm pitch simplify PCB layout by providing stan-
dard trace routing and via placement. The high switching
frequency and current mode architecture enable a very
fast transient response to line and load changes without
sacrificing stability. The device supports frequency syn-
chronization, programmable multiphase and/or spread
spectrum operation, output voltage tracking for supply
rail sequencing and voltage margining.
Fault protection features include overvoltage protec-
tion, overcurrent protection and thermal shutdown. The
LTM4608A is offered in 9mm × 15mm × 2.82mm LGA and
9mm × 15mm × 3.42mm BGA packages. The LTM4608A is
available with SnPb (BGA) or RoHS compliant terminal finish.
Complete Standalone Power Supply
±1.75%
Total DC Output Error (–55°C to 125°C)
2.7V to 5.5V Input Voltage Range
8A DC, 10A Peak Output Current
0.6V Up to 5V Output
Output Voltage Tracking and Margining
Power Good Tracks Margining
Multiphase Operation
Parallel Current Sharing
Onboard Frequency Synchronization
Spread Spectrum Frequency Modulation
Overcurrent/Thermal Shutdown Protection
Current Mode Control/Fast Transient Response
Selectable Burst Mode
®
Operation
Up to 95% Efficiency
Output Overvoltage Protection
9mm × 15mm × 2.82mm LGA and
9mm × 15mm × 3.42mm BGA Packages
APPLICATIONS
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Telecom, Networking and Industrial Equipment
Storage Systems
Point of Load Regulation
L,
LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, µModule and PolyPhase
are registered trademarks and LTpowerCAD is a trademark of Linear Technology Corporation.
All other trademarks are the property of their respective owners. Protected by U.S. Patents
including 5481178, 6580258, 6304066, 6127815, 6498466, 6611131.
TYPICAL APPLICATION
2.7V to 5.5V Input to 1.8V Output DC/DC µModule
®
Regulator
CLKIN
V
IN
2.7V TO 5.5V
10µF
CLKIN
V
OUT
1.8V
100µF
4.87k
PGOOD
Efficiency vs Load Current
100
95
V
IN
= 3.3V
EFFICIENCY (%)
90
V
IN
= 5V
85
80
75
4608A TA01a
V
OUT
= 1.8V
V
IN
SV
IN
SW
RUN
TRACK
V
OUT
FB
I
TH
I
THM
MGN
LTM4608A
PLLLPF
PGOOD
CLKOUT GND SGND
70
0
2
4
6
LOAD CURRENT (A)
8
10
4608A TA01b
4608afe
For more information
www.linear.com/LTM4608A
1
LTM4608A
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V
IN
, SV
IN
...................................................... –0.3V to 6V
CLKOUT ....................................................... –0.3V to 2V
PGOOD, PLLLPF, CLKIN, PHMODE, MODE . –0.3V to V
IN
I
TH
, I
THM
, RUN, FB, TRACK,MGN, BSEL...... –0.3V to V
IN
V
OUT
, SW ...................................... –0.3V to (V
IN
+ 0.3V)
Internal Operating Temperature Range
(Note 2).................................................. –55°C to 125°C
Storage Temperature Range .................. –55°C to 125°C
Peak Solder Reflow Body Temperature ................. 245°C
PIN CONFIGURATION
1
2
CLKIN
PHMODE
MODE
PGOOD
BSEL
MGN
3
4
5
6
7
8
9
10
11
GND
V
OUT
FB
A
GND
B
TOP VIEW
C
D
E
V
IN
F
G
GND
RUN
SGND
SW
CLKOUT
PLLLPF
SV
IN
I
THM
TRACK
I
TH
CLKIN
PHMODE
MODE
A
1
2
3
4
5
FB
GND
B
TOP VIEW
C
D
E
V
IN
F
G
GND
RUN
SGND
SW
CLKOUT
PLLLPF
SV
IN
I
THM
TRACK
I
TH
PGOOD 6
BSEL
7
MGN
8
9
10
11
GND
V
OUT
BGA PACKAGE
68-LEAD (15mm
×
9mm
×
3.42mm)
T
JMAX
= 125°C,
θ
JA
= 25°C/W,
θ
JCbottom
= 7°C/W,
θ
JCtop
= 50°C/W, WEIGHT = 1.1g
LGA PACKAGE
68-LEAD (15mm
×
9mm
×
2.82mm)
T
JMAX
= 125°C,
θ
JA
= 25°C/W,
θ
JCbottom
= 7°C/W,
θ
JCtop
= 50°C/W, WEIGHT = 1.0g
ORDER INFORMATION
PART MARKING*
PART NUMBER
LTM4608AEV#PBF
LTM4608AIV#PBF
LTM4608AMPV#PBF
LTM4608AEY#PBF
LTM4608AIY#PBF
LTM4608AMPY#PBF
LTM4608AMPY
SnPb (63/37)
SAC305 (RoHS)
Au (RoHS)
PAD OR BALL FINISH
DEVICE
LTM4608AV
LTM4608AV
LTM4608AMPV
LTM4608AY
LTM4608AY
LTM4608AY
LTM4608AY
e0
e1
BGA
3
–55°C to 125°C
e4
LGA
3
FINISH CODE
PACKAGE
TYPE
MSL
RATING
TEMPERATURE RANGE
(SEE NOTE 2)
–40°C to 125°C
–55°C to 125°C
–40°C to 125°C
• Consult Marketing for parts specified with wider operating temperature
ranges. *Pad or ball finish code is per IPC/JEDEC J-STD-609.
• Device temperature grade is indicated by a label on the shipping
container.
• 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
4608afe
2
For more information
www.linear.com/LTM4608A
LTM4608A
ELECTRICAL CHARACTERISTICS
SYMBOL
V
IN(DC)
V
OUT(DC)
PARAMETER
Input DC Voltage
Output Voltage, Total Variation
with Line and Load
C
IN
= 10µF × 1, C
OUT
= 100µF Ceramic,
100µF POSCAP, R
FB
= 6.65k, MODE = 0V
V
IN
= 2.7V to 5.5V, I
OUT
= I
OUT(DC)MIN
to
I
OUT(DC)MAX
(Note 3)
SV
IN
Rising
SV
IN
Falling
V
IN
= 3.3V, No Switching, MODE = V
IN
V
IN
= 3.3V, No Switching, MODE = 0V
V
IN
= 3.3V, V
OUT
= 1.5V, Switching Continuous
V
IN
= 5V, No Switching, MODE = V
IN
V
IN
= 5V, No Switching, MODE = 0V
V
IN
= 5V, V
OUT
= 1.5V, Switching Continuous
Shutdown, RUN = 0, V
IN
= 5V
I
S(VIN)
Input Supply Current
V
IN
= 3.3V, V
OUT
= 1.5V, I
OUT
= 8A
V
IN
= 5V, V
OUT
= 1.5V, I
OUT
= 8A
The
l
denotes the specifications which apply over the specified internal
operating temperature range (Note 2), otherwise specifications are at T
A
= 25°C. V
IN
= 5V unless otherwise noted. See Figure 1.
CONDITIONS
l
MIN
2.7
TYP
MAX
5.5
UNITS
V
l
1.472
1.464
2.05
1.85
1.49
1.49
2.2
2.0
400
1.15
55
450
1.3
75
1
4.5
2.93
1.508
1.516
2.35
2.15
V
V
V
V
µA
mA
mA
µA
mA
mA
µA
A
A
Input Specifications
V
IN(UVLO)
I
Q(VIN)
Undervoltage Lockout Threshold
Input Supply Bias Current
Output Specifications
I
OUT(DC)
Output Continuous Current Range V
OUT
= 1.5V
(Note 3)
V
IN
= 3.3V, 5.5V
V
IN
= 2.7V
Line Regulation Accuracy
Load Regulation Accuracy
V
OUT
= 1.5V, V
IN
from 2.7V to 5.5V, I
OUT
= 0A
V
OUT
= 1.5V (Note 3)
V
IN
= 3.3V, 5.5V, I
LOAD
= 0A to 8A
V
IN
= 2.7V, I
LOAD
= 0A to 5A
I
OUT
= 0A, C
OUT
= 100µF X5R Ceramic, V
IN
= 5V,
V
OUT
= 1.5V
I
OUT
= 8A, V
IN
= 5V, V
OUT
= 1.5V
C
OUT
= 100µF, V
OUT
= 1.5V, I
OUT
= 0A
V
IN
= 3.3V
V
IN
= 5V
C
OUT
= 100µF, V
OUT
= 1.5V, V
IN
= 5V,
I
OUT
= 1A Resistive Load, Track = V
IN
,
1.25
0.75
10
10
100
15
l
0
0
0.1
8
5
0.25
A
A
%/V
∆V
OUT(LINE)
V
OUT
∆V
OUT(LOAD)
V
OUT
V
OUT(AC)
f
S
f
SYNC
∆V
OUT(START)
l
l
0.3
0.3
10
1.5
0.75
0.75
%
%
mV
P-P
Output Ripple Voltage
Switching Frequency
SYNC Capture Range
Turn-On Overshoot
1.75
2.25
MHz
MHz
mV
mV
µs
mV
t
START
∆V
OUT(LS)
Turn-On Time
Peak Deviation for Dynamic Load Load: 0% to 50% to 0% of Full Load,
C
OUT
= 100µF Ceramic, 100µF POSCAP,
V
IN
= 5V, V
OUT
= 1.5V
Settling Time for Dynamic Load
Step
Output Current Limit
Load: 0% to 50% to 0% of Full Load, V
IN
= 5V,
V
OUT
= 1.5V, C
OUT
= 100µF
C
OUT
= 100µF
V
IN
= 2.7V, V
OUT
= 1.5V
V
IN
= 3.3V, V
OUT
= 1.5V
V
IN
= 5V, V
OUT
= 1.5V
t
SETTLE
I
OUT(PK)
10
µs
8
11
13
A
A
A
4608afe
For more information
www.linear.com/LTM4608A
3
LTM4608A
ELECTRICAL CHARACTERISTICS
SYMBOL
Control Section
V
FB
SS Delay
I
FB
V
RUN
TRACK
RUN Pin On/Off Threshold
Tracking Threshold (Rising)
Tracking Threshold (Falling)
Tracking Disable Threshold
Resistor Between V
OUT
and FB
Pins
PGOOD Range
Output Voltage Margining
Percentage
MGN = V
IN
, BSEL = 0V
MGN = V
IN
, BSEL = V
IN
MGN = V
IN
, BSEL = Float
MGN = 0V, BSEL = 0V
MGN = 0V, BSEL = V
IN
MGN = 0V, BSEL = Float
4
9
14
–4
–9
–14
RUN Rising
RUN Falling
RUN = V
IN
RUN = 0V
9.95
1.4
1.3
Voltage at FB Pin
Internal Soft-Start Delay
I
OUT
= 0A, V
OUT
= 1.5V, V
IN
= 2.7V to 5.5V
l
The
l
denotes the specifications which apply over the specified internal
operating temperature range (Note 2), otherwise specifications are at T
A
= 25°C. V
IN
= 5V unless otherwise noted. See Figure 1.
PARAMETER
CONDITIONS
MIN
0.590
0.587
TYP
0.596
0.596
90
0.2
1.55
1.4
0.57
0.18
V
IN
– 0.5
10
±10
5
10
15
–5
–10
–15
6
11
16
–6
–11
–16
10.05
1.7
1.5
MAX
0.602
0.606
UNITS
V
V
µs
µA
V
V
V
V
V
kΩ
%
%
%
%
%
%
%
R
FBHI
∆V
PGOOD
%Margining
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 LTM4608A is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTM4608AE is guaranteed to meet specifications from
0°C to 125°C internal temperature. Specifications over the –40°C to
125°C internal operating temperature range are assured by design,
characterization and correlation with statistical process controls.
The LTM4608AI is guaranteed over the –40°C to 125°C internal operating
temperature range and the LTM4608AMP is tested and guaranteed over
the full –55°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 impedance and other environmental
factors.
Note 3:
See output current derating curves for different V
IN
, V
OUT
and T
A
.
4608afe
4
For more information
www.linear.com/LTM4608A
LTM4608A
TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Load Current
100
95
EFFICIENCY (%)
90
85
80
75
70
CONTINUOUS MODE
100
95
EFFICIENCY (%)
EFFICIENCY (%)
90
85
80
75
70
3.3V
IN
1.2V
OUT
3.3V
IN
1.5V
OUT
3.3V
IN
1.8V
OUT
3.3V
IN
2.5V
OUT
0
2
4
LOAD CURRENT
6
8
4608A G02
Efficiency vs Load Current
CONTINUOUS MODE
100
95
90
85
80
75
70
Efficiency vs Load Current
CONTINUOUS MODE
5V
IN
1.2V
OUT
5V
IN
1.5V
OUT
5V
IN
1.8V
OUT
5V
IN
2.5V
OUT
5V
IN
3.3V
OUT
0
2
4
LOAD CURRENT
6
8
4608A G01
2.7V
IN
1.0V
OUT
2.7V
IN
1.5V
OUT
2.7V
IN
1.8V
OUT
0
1
4
3
2
5
LOAD CURRENT (A)
6
7
4608A G03
Burst Mode Efficiency with
5V Input
100
90
EFFICIENCY (%)
80
V
OUT
(V)
70
60
50
40
V
OUT
= 1.5V
V
OUT
= 2.5V
V
OUT
= 3.3V
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1
LOAD CURRENT (A)
4608A G04
V
IN
to V
OUT
Step-Down Ratio
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
2
I
OUT
= 8A
V
OUT
= 1.2V
V
OUT
= 1.5V
3
4
V
IN
(V)
4608A G05
V
IN
to V
OUT
Step-Down Ratio
4.0
3.5
3.0
2.5
V
OUT
(V)
2.0
1.5
1.0
0.5
6
0
2
I
OUT
= 6A
V
OUT
= 1.2V
V
OUT
= 1.5V
3
4
V
IN
(V)
4608A G06
V
OUT
= 1.8V
V
OUT
= 2.5V
V
OUT
= 3.3V
5
V
OUT
= 1.8V
V
OUT
= 2.5V
V
OUT
= 3.3V
5
6
1.6
1.4
SUPPLY CURRENT (mA)
1.2
1
0.8
0.6
0.4
0.2
0
Supply Current vs V
IN
I
LOAD
1A/DIV
V
O
= 1.2V PULSE-SKIPPING MODE
V
IN
2V/DIV
V
OUT
20mV/DIV
AC COUPLED
V
O
= 1.2V BURST MODE
Load Transient Response
Load Transient Response
I
LOAD
2A/DIV
V
OUT
20mV/DIV
AC COUPLED
2.5
3
3.5
4
4.5
INPUT VOLTAGE (V)
5
5.5
4608A G07
4608A G08
V
IN
= 5V
20µs/DIV
V
OUT
= 3.3V, R
FB
= 2.21k
2A/µs STEP
C
OUT
= 100µF X5R
C1 = 100pF C3 = 22pF FROM FIGURE 18
,
4608A G09
V
IN
= 5V
20µs/DIV
V
OUT
= 2.5V, R
FB
= 3.09k
2.5A/µs STEP
C
OUT
= 100µF X5R
C1 = 120pF C3 = 47pF FROM FIGURE 18
,
4608afe
For more information
www.linear.com/LTM4608A
5
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