PRERELEASE
LTM4600
1
4600p
Electrical Specifications Subject to Change
LOAD CURRENT (A)
0
EFFICIENCY (%)
50
60
70
6
10
4600 TA01b
40
30
20
2
4
8
80
90
100
12
0.6V
OUT
1.2V
OUT
1.5V
OUT
2.5V
OUT
3.3V
OUT
10A High Effi ciency
DC/DC µModule
The LTM
®
4600 is a complete 10A, DC/DC step down power
supply. Included in the package are the switching control-
ler, power FETs, inductor, and all support components.
Operating over an input voltage range of 4.5V to 20V, the
LTM4600 supports an output voltage range of 0.6V to 5V,
set by a single resistor. This high effi ciency design delivers
10A continuous current (14A peak), needing no heat sinks
or airfl ow to meet power specifi cations. Only bulk input
and output capacitors are needed to fi nish the design.
The low profi le package (2.8mm) enables utilization of
unused space on the bottom of PC boards for high density
point of load regulation. High switching frequency and an
adaptive on-time current mode architecture enables a very
fast transient response to line and load changes without
sacrifi cing stability. Fault protection features include
integrated overvoltage and short circuit protection with
a defeatable shutdown timer. A built-in soft-start timer is
adjustable with a small capacitor.
The LTM4600 is packaged in a thermally enhanced, compact
(15mm × 15mm) and low profi le (2.8mm) over-molded
Land Grid Array (LGA) package suitable for automated
assembly by standard surface mount equipment. The
LTM4600 is Pb-free and RoHS certifi ed.
Telecom and Networking Equipment
Servers
Industrial Equipment
Point of Load Regulation
Other General Purpose Step Down DC/DC
Complete Switch Mode Power Supply
Wide Input Voltage Range: 4.5V to 20V
10A DC, 14A Peak Output Current
Parallel Two µModulesTM for 20A Output Current
0.6V to 5V Output Voltage
1.5% Regulation
Ultrafast Transient Response
Current Mode Control
Pb-Free (e
4
) RoHS Compliant Package
Up to 92% Effi ciency
Programmable Soft-Start
Output Overvoltage Protection
Optional Short-Circuit Shutdown Timer
Small Footprint, Low Profi le (15mm × 15mm ×
2.8mm) Surface Mount LGA Package
10A µModule Power Supply with 4.5V to 20V Input
APPLICATIO S
U
FEATURES
DESCRIPTIO
U
TYPICAL APPLICATIO
U
, LTC, LT and LTM are registered trademarks of Linear Technology Corporation.
µModule is a trademark of Linear Technology Corporation. All other trademarks are the
property of their respective owners. Protected by U.S. Patents including 5481178,
6100678, 6580258, 5847554, 6304066.
Effi ciency vs Load Current
with 12V
IN
(FCB = 0)
V
IN
C
IN
4600 TA01a
LTM4600
PGND
SGND
V
OUT
V
OSET
V
IN
4.5V TO 20V
V
OUT
1.5V
10A
C
OUT
66.5k
PRERELEASE
LTM4600
2
4600p
RUN/SS
FCB
PGOOD
V
IN
PGND
V
OUT
COMP
SGND
EXTV
CC
V
OSET
F
ADJ
SV
IN
LGA PACKAGE
104-LEAD (15mm
× 15mm × 2.8mm)
TOP VIEW
FCB, EXTV
CC
, PGOOD, RUN/SS, V
OUT
.......... 0.3V to 6V
V
IN
, SV
IN
, F
ADJ
........................................... 0.3V to 20V
V
OSET
, COMP ............................................. 0.3V to 2.7V
Operating Temperature Range (Note 2) ... 40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range ................... 65°C to 150°C
ORDER PART
NUMBER
LGA PART
MARKING
T
JMAX
= 125°C,
JA
= 15°C/W
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
LTM4600EV
LTM4600IV
LTM4600EV
LTM4600IV
(Note 1)
The
denotes the specifi cations which apply over the 40°C to 85°C
temperature range, otherwise specifi cations are at T
A
= 25°C, V
IN
= 12V. External C
IN
= 120µF, C
OUT
= 200µF/Ceramic per typical
application (front page) confi guration.
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U
RATI GS
W
W
W
U
PACKAGE/ORDER I FOR ATIO
U
U
W
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
V
IN(DC)
Input DC Voltage
4.5
20
V
V
OUT(DC)
Output Voltage
V
IN
= 12V, V
OUT
= 1.5V, I
OUT
= 0A
V
IN
= 12V, V
OUT
= 1.5V, I
OUT
= 0A
V
IN
= 5V, V
OUT
= 1.5V, I
OUT
= 0A
FCB = 0
1.478
1.50
1.522
V
Input Specifi cations
V
IN(UVLO)
Under Voltage Lockout Threshold
I
OUT
= 0A
3.4
4
V
I
INRUSH(VIN)
Input Inrush Current at Startup
V
IN
= 5V
V
IN
= 12V
I
OUT
= 0A. V
OUT
= 1.5V, FCB = 0
0.6
0.7
A
A
I
Q(VIN)
Input Supply Bias Current
V
IN
= 12V, V
OUT
= 1.5V, FCB = 5V
V
IN
= 12V, V
OUT
= 1.5V, FCB = 0V
V
IN
= 5V, V
OUT
= 1.5V, FCB = 5V
V
IN
= 5V, V
OUT
= 1.5V, FCB = 0V
Shutdown, RUN = 0, V
IN
= 12V
I
OUT
= 0A, EXTV
CC
Open
1.2
42
1.0
52
15
mA
mA
mA
mA
µA
I
S(VIN)
Input Supply Current
V
IN
= 12V, V
OUT
= 1.5V, I
OUT
= 10A
V
IN
= 12V, V
OUT
= 3.3V, I
OUT
= 10A
V
IN
= 5V, V
OUT
= 1.5V, I
OUT
= 10A
1.52
3.13
3.64
A
A
A
PRERELEASE
LTM4600
3
4600p
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTM4600E is guaranteed to meet performance specifi cations
from 0°C to 85°C. Specifi cations over the 40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTM4600I is guaranteed and tested
over the 40°C to 85°C temperature range.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Output Specifi cations
I
OUTDC
Output Continuous Current Range
(See Output Current Derating Curves for
Different V
IN
, V
OUT
and T
A
)
V
IN
= 12V, V
OUT
= 1.5V
0
10
A
V
OUT
/V
IN
Line
Regulation
Accuracy
I
OUT
= 0A
V
OUT
= 1.5V. FCB = 0V
0.3
%
V
OUT
/I
OUT
Load Regulation Accuracy
V
IN
= 5V
V
IN
= 12V
V
OUT
= 1.5V. FCB = 0V
0A to 10A
±1
±1
%
%
V
OUT(AC)
Output Ripple Voltage
V
IN
= 12V, V
OUT
= 1.5V, FCB = 0V
V
IN
= 5V, V
OUT
= 1.5V, FCB = 0V
I
OUT
= 0A
15
20
25
mV
P-P
mV
P-P
Fs
Output Ripple Voltage Frequency
FCB = 0V, I
OUT
= 5A, V
IN
= 12V, V
OUT
=
1.5V
800
kHz
t
START
Turn-On Time
V
IN
= 12V
V
IN
= 5V
V
OUT
= 1.5V, I
OUT
= 10A
0.5
0.7
ms
ms
V
OUTLS
Voltage Drop for Dynamic Load Step
V
IN
= 12V, V
OUT
= 1.5V
Load Step: 0A to 5A/µs
C
OUT
= 3 · 22µF 6.3V, 470µF 4V Pos Cap,
See Table 2
36
mV
t
SETTLE
Settling Time for Dynamic Load Step
V
IN
= 12V
Load: 10% to 90% to 10% of Full Load
25
µs
I
OUTPK
Output Current Limit
V
IN
= 12V, V
OUT
= 1.5V
V
IN
= 5V, V
OUT
= 1.5V
17
17
A
A
Control Stage
V
OSET
Voltage at V
OSET
Pin
I
OUT
= 0A, V
OUT
= 1.5V
0.594
0.6
0.606
V
V
RUN/SS
RUN ON/OFF Threshold
0.8
1.5
2
V
I
RUN(C)/SS
Soft-Start Charging Current
V
RUN/SS
= 0V
0.5
1.2
3
µA
I
RUN(D)/SS
Soft-Start Discharging Current
V
RUN/SS
= 4V
0.8
1.8
3
µA
V
IN
SV
IN
EXTV
CC
= 0, FCB = 0V
100
mV
I
EXTVCC
Current into EXTV
CC
Pin
FCB = 0V, V
OUT
= 1.5V, I
OUT
= 0A
16
mA
R
FBHI
Resistor Between V
OUT
and FB Pins
100
k
V
FCB
Forced Continuous Threshold
0.57
0.6
0.63
V
I
FCB
Forced Continuous Pin Current
V
FCB
= 0.6V
1
2
µA
PGOOD Output
V
OSETH
PGOOD Upper Threshold
V
OSET
Rising
7.5
10
12.5
%
V
OSETL
PGOOD Lower Threshold
V
OSET
Falling
7.5
10
12.5
%
V
OSET(HYS)
PGOOD Hysteresis
V
OSET
Returning
1
2.5
%
V
PGL
PGOOD Low Voltage
I
PGOOD
= 5mA
0.15
0.4
V
The
denotes the specifi cations which apply over the 40°C to 85°C
temperature range, otherwise specifi cations are at T
A
= 25°C, V
IN
= 12V. Per typical application (front page) confi guration.
ELECTRICAL CHARACTERISTICS
PRERELEASE
LTM4600
4
4600p
LOAD CURRENT (A)
0
EFFICIENCY (%)
50
60
70
6
10
4600 G02
40
30
20
2
4
8
80
90
100
12
0.6V
OUT
1.2V
OUT
1.5V
OUT
2.5V
OUT
3.3V
OUT
Effi ciency vs Load Current
with 5V
IN
(FCB = 0)
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
LOAD CURRENT (A)
0
100
90
80
70
60
50
40
30
6
10
4600 G01
2
4
8
12
EFFICIENCY (%)
0.6V
OUT
1.2V
OUT
1.5V
OUT
2.5V
OUT
Effi ciency vs Load Current
with 12V
IN
(FCB = 0)
Effi ciency vs Load Current
with 18V
IN
(FCB = 0)
LOAD CURRENT (A)
0
EFFICIENCY (%)
6
10
4600 G03
2
4
8
12
80
90
100
70
60
50
40
30
1.5V
OUT
1.8V
OUT
2.5V
OUT
3.3V
OUT
Effi ciency vs Load Current
with Different FCB Settings
LOAD CURRENT (A)
20
50
40
30
90
80
70
60
4600 G04
EFFICIENCY (%)
0.1
10
1
FCB = GND
FCB > 0.7V
1.2V Transient Response
(See Figure 17)
1.5V Transient Response
(See Figure 17)
1.8V Transient Response
(See Figure 17)
2.5V Transient Response
(See Figure 17)
3.3V Transient Response
(See Figure 17)
25µs/DIV
4600 G05
1.2V AT 5A/µs LOAD STEP
C
OUT
= 3 · 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600 G06
1.5V AT 5A/µs LOAD STEP
C
OUT
= 3 · 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600 G07
1.8V AT 5A/µs LOAD STEP
C
OUT
= 3 · 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600 G08
2.5V AT 5A/µs LOAD STEP
C
OUT
= 3 · 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600 G09
3.3V AT 5A/µs LOAD STEP
C
OUT
= 3 · 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
V
OUT
= 50mV/DIV
I
OUT
= 5A/DIV
PRERELEASE
LTM4600
5
4600p
V
IN
(V)
0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
5
15
4600 G17
10
20
V
OUT
(V)
5V
3.3V
2.5V
1.8V
1.5V
1.2V
0.6V
OUTPUT VOLTAGE (V)
0
18
16
14
12
10
8
6
4
2
0
4600 G16
4.0
3.5
3.0
2.5
2.0
1.0
0.5
1.5
OUTPUT CURRENT (A)
OUTPUT VOLTAGE (V)
0
18
16
14
12
10
8
6
4
2
0
4600 G14
6
5
4
3
2
1
CURRENT LIMIT (A)
TYPICAL PERFOR A CE CHARACTERISTICS
U
W
Start-Up, I
OUT
= 0A
(See Figure 17)
Start-Up, I
OUT
= 10A
(Resistive Load) (See Figure 17)
Short-Circuit Protection,
I
OUT
= 0A (See Figure 17)
Short-Circuit Protection,
I
OUT
= 10A (See Figure 17)
200µs/DIV
4600 G10
V
IN
= 12V
V
OUT
= 1.5V
C
OUT
= 200µF
NO EXTERNAL SOFT-START CAPACITOR
V
OUT
(0.5V/DIV)
I
IN
(0.5A/DIV)
200µs/DIV
4600 G11
V
IN
= 12V
V
OUT
= 1.5V
C
OUT
= 200µF
NO EXTERNAL SOFT-START CAPACITOR
V
OUT
(0.5V/DIV)
I
IN
(0.5A/DIV)
20µs/DIV
4600 G12
V
IN
= 12V
V
OUT
= 1.5V
C
OUT
= 2× 200µF/X5R
NO EXTERNAL SOFT-START CAPACITOR
V
OUT
(0.5V/DIV)
I
IN
(0.2A/DIV)
20µs/DIV
4600 G13
V
IN
= 12V
V
OUT
= 1.5V
C
OUT
= 2× 200µF/X5R
NO EXTERNAL SOFT-START CAPACITOR
V
OUT
(0.5V/DIV)
I
IN
(0.5A/DIV)
Current Limit with 12V
IN
Current Limit with 9V
IN
Current Limit with 5V
IN
OUTPUT VOLTAGE (V)
0
18
16
14
12
10
8
6
4
2
0
4600 G15
6
5
4
3
2
1
CURRENT LIMIT (A)
V
IN
to V
OUT
Stepdown Ratio
PRERELEASE
LTM4600
6
4600p
PI FU CTIO S
U
U
U
V
IN
(Bank 1): Power Input Pins. Apply input voltage
between these pins and GND pins. Recommend placing
input decoupling capacitance directly between V
IN
pins
and GND pins.
F
ADJ
(Pin A15): An internal resistor from V
IN
to this pin
sets the one-shot timer current, thereby setting the switch-
ing frequency.
SV
IN
(Pin A17): Supply Pin for Internal PWM Controller.
Leave this pin open or add additional decoupling capaci-
tance.
EXTV
CC
(Pin A19): External 5V supply pin for controller.
If left open, the internal 5V linear regulator will power the
controller and MOSFET drivers. For high input voltage
applications, connecting this pin to an external 5V will
reduce the power loss in the power module. The EXTV
CC
voltage should never be higher than V
IN
.
V
OSET
(Pin A21): The Negative Input of The Error Am-
plifi er. Internally, this pin is connected to V
OUT
with a
100k precision resistor. Different output voltages can be
programmed with additional resistors between the V
OSET
and SGND pins.
COMP (Pin B23): Current Control Threshold and Error
Amplifi er Compensation Point. The current comparator
threshold increases with this control voltage. The voltage
ranges from 0V to 2.4V with 0.8V corresponding to zero
sense voltage (zero current).
SGND (Pin D23): Signal Ground Pin. All small-signal
components should connect to this ground, which in turn
connects to PGND at one point.
RUN/SS (Pin F23): Run and Soft-Start Control. Forcing
this pin below 0.8V will shut down the power supply.
Inside the power module, there is a 1000pF capacitor
which provides approximately 0.7ms soft-start time with
200µF output capacitance. Additional soft-start time can
be achieved by adding additional capacitance between
the RUN/SS and SGND pins. The internal short-circuit
latchoff can be disabled by adding a resistor between this
pin and the V
IN
pin. This resistor must supply a minimum
5µA pull up current.
FCB (Pin G23): Forced Continuous Input. Grounding this
pin enables forced continuous mode operation regardless
of load conditions. Tying this pin above 0.63V enables
discontinuous conduction mode to achieve high effi ciency
operation at light loads. There is an internal 4.75K resistor
between the FCB and SGND pins.
PGOOD (Pin J23): Output Voltage Power Good Indicator.
When the output voltage is within 10% of the nominal
voltage, the PWRGD is open drain output. Otherwise, this
pin is pulled to ground.
PGND (Bank 2): Power ground pins for both input and
output returns.
V
OUT
(Bank 3): Power Output Pins. Apply output load
between these pins and GND pins. Recommend placing
High Frequency output decoupling capacitance directly
between these pins and GND pins.
(See Package Description for Pin Assignment)
E
C
A
RUN/SS
FCB
PGOOD
V
IN
BANK 1
PGND
BANK 2
V
OUT
BANK 3
COMP
SGND
EXTV
CC
V
OSET
F
ADJ
SV
IN
TOP VIEW
3
5
2
4
7
9
6
8
11
13
10
12
15
17
14
16
19
21
18
20
22
94
95
96
97
98
99
100
101
102
103
104
93
82
71
60
49
24
23
22
21
20
19
18
17
16
7
6
5
4
3
2
40
51
62
73
84
85
86
87
88
89
90
91
74
75
76
77
78
79
80
63
64
65
66
67
68
69
52
53
54
55
56
57
58
42
43
44
45
46
47
92
81
70
59
48
11
10
9
13
14
15
26
27
28
29
30
31
33
34
35
36
37
38
41
1
8
12
25
32
39
50
61
72
83
1
23
B
D
F
G
H
J
L
M
N
P
R
S
K
4600 PN01
PRERELEASE
LTM4600
7
4600p
W
U
DECOUPLI G REQUIRE E TS
U
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
C
IN
External Input Capacitor Requirement
(V
IN
= 4.5V to 15V, V
OUT
= 1.5V)
I
OUT
= 10A
20
µF
C
OUT
External Output Capacitor Requirement
(V
IN
= 4.5V to 15V, V
OUT
= 1.5V)
I
OUT
= 10A, Refer to Table 2 in the
Applications Information Section
100
200
µF
SI PLIFIED
W
BLOCK DIAGRA
W
T
A
= 25°C, V
IN
= 12V. Use Figure 1 confi guration.
Figure 1. Simplifi ed LTM4600 Block Diagram
4600 F01
RUN/SS
LTM4600
V
OSET
EXTV
CC
SGND
F
ADJ
FCB
1000pF
Q1
Q2
V
OUT
1.5V/10A MAX
PGND
V
IN
4.5V TO 20V
SV
IN
COMP
PGOOD
R6
66.5k
100k
0.5%
4.75k
1.5
µF
C
IN
15
µF
6.3V
C
OUT
10
INT
COMP
CONTROLLER
PRERELEASE
LTM4600
8
4600p
OPERATIO
U
µModule Description
The LTM4600 is a standalone non-isolated synchronous
switching DC/DC power supply. It can deliver up to 10A of
DC output current with only bulk external input and output
capacitors. This module provides a precisely regulated
output voltage programmable via one external resistor from
0.6V
DC
to 5.0V
DC
, not to exceed 80% of the input voltage.
The input voltage range is 4.5V to 20V. A simplifi ed block
diagram is shown in Figure 1 and the typical application
schematic is shown in Figure 17.
The LTM4600 contains an integrated LTC constant on-time
current-mode regulator, ultra-low R
DS(ON)
FETs with fast
switching speed and integrated Schottky diode. The typical
switching frequency is 800kHz at full load. With current
mode control and internal feedback loop compensation,
the LTM4600 module has suffi cient stability margins and
good transient performance under a wide range of operat-
ing 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
over-current condition while V
FB
drops. Also, the LTM4600
has defeatable short circuit latch off. Internal overvolt-
age and undervoltage comparators pull the open-drain
PGOOD output low if the output feedback voltage exits a
±10% window around the regulation point. Furthermore,
in an overvoltage condition, internal top FET Q1 is turned
off and bottom FET Q2 is turned on and held on until the
overvoltage condition clears.
Pulling the RUN/SS pin low forces the controller into its
shutdown state, turning off both Q1 and Q2. Releasing the
pin allows an internal 1.2µA current source to charge up
the softstart capacitor. When this voltage reaches 1.5V,
the controller turns on and begins switching.
At low load current the module works in continuous cur-
rent mode by default to achieve minimum output voltage
ripple. It can be programmed to operate in discontinuous
current mode for improved light load effi ciency when the
FCB pin is pulled up above 0.8V and no higher than 5V.
The FCB pin has a 4.25k resistor to ground, so a resistor
to V
IN
can set the voltage on the FCB pin.
When EXTV
CC
pin is grounded, an integrated 5V linear
regulator powers the controller and MOSFET gate drivers.
If a minimum 4.7V external bias supply is applied on the
EXTV
CC
pin, the internal regulator is turned off, and an
internal switch connects EXTV
CC
to the gate driver voltage.
This eliminates the linear regulator power loss with high
input voltage, reducing the thermal stress on the controller.
The maximum voltage on EXTV
CC
pin is 6V. The EXTV
CC
voltage should never be higher than the V
IN
voltage. Also
EXTV
CC
must be sequenced after V
IN
.
PRERELEASE
LTM4600
9
4600p
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down when Q
DOWN
is on and Q
UP
is off. If the output
voltage V
O
needs to be margined up/down by ±M%, the
resistor values of R
UP
and R
DOWN
can be calculated from
the following equations:
(
)·
·(
%)
(
)
.
R
R
V
M
R
R
k
V
SET
UP
O
SET
UP
1
100
0 6
+
+
=
R
V
M
R
k
R
V
SET
O
SET
DOWN
·
·( %)
(
)
.
1
100
0 6
+
=
Input Capacitors
The LTM4600 µModule should be connected to a low
ac-impedance AC source. High frequency, low ESR input
capacitors are required to be placed adjacent to the mod-
ule. In Figure 20, the bulk input capacitor C
IN
is selected
for its ability to handle the large RMS current into the
converter. For a buck converter, the switching duty-cycle
can be estimated as:
D
V
V
O
IN
=
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
I
I
D
D
CIN RMS
O MAX
(
)
(
)
%
·
·(
)
=
-
1
In the above equation, % is the estimated effi ciency of
the power module. C1 can be a switcher-rated electrolytic
aluminum capacitor, OS-CON capacitor or high volume
ceramic capacitors. Note the capacitor ripple current
ratings are often based on only 2000 hours of life. This
makes it advisable to properly derate the input capacitor,
or choose a capacitor rated at a higher temperature than
required. Always contact the capacitor manufacturer for
derating requirements.
In Figure 16, the input capacitors are used as high fre-
quency input decoupling capacitors. In a typical 10A
output application, 1-2 pieces of very low ESR X5R or
X7R, 10µF ceramic capacitors are recommended. This
decoupling capacitor should be placed directly adjacent
The typical LTM4600 application circuit is shown in Figure
20. External component selection is primarily determined
by the maximum load current and output voltage.
Output Voltage Programming and Margining
The PWM controller of the LTM4600 has an internal
0.6V±1% reference voltage. As shown in the block diagram,
a 100k/0.5% internal feedback resistor connects V
OUT
and
FB pins. Adding a resistor R
SET
from V
OSET
pin to SGND
pin programs the output voltage:
V
V
k R
R
O
SET
SET
=
+
0 6
100
.
·
Table 1 shows the standard vaules of 1% R
SET
resistor
for typical output voltages:
Table 1.
R
SET
(k)
Open
100
66.5
49.9
43.2
31.6
22.1
13.7
V
O
(V)
0.6
1.2
1.5
1.8
2
2.5
3.3
5
Voltage margining is the dynamic adjustment of the output
voltage to its worst case operating range in production
testing to stress the load circuitry, verify control/protec-
tion functionality of the board and improve the system
reliability. Figure 2 shows how to implement margining
function with the LTM4600. In addition to the feedback
resistor R
SET
, several external components are added.
Turn off both transistor Q
UP
and Q
DOWN
to disable the
margining. When Q
UP
is on and Q
DOWN
is off, the output
voltage is margined up. The output voltage is margined
Figure 2.
PGND
SGND
4600 F02
LTM4600
V
OUT
V
OSET
R
SET
R
UP
Q
UP
100k
2N7002
R
DOWN
Q
DOWN
2N7002
PRERELEASE
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the module input pins in the PCB layout to minimize the
trace inductance and high frequency AC noise.
Output Capacitors
The LTM4600 is designed for low output voltage ripple.
The bulk output capacitors C
OUT
is chosen with low enough
effective series resistance (ESR) to meet the output voltage
ripple and transient requirements. C
OUT
can be low ESR
tantalum capacitor, low ESR polymer capacitor or ceramic
capacitor. The typical capacitance is 200µF if all ceramic
output capacitors are used. The internally optimized loop
compensation provides suffi cient stability margin for all
ceramic capacitors applications. Additional output fi lter-
ing may be required by the system designer, if further
reduction of output ripple or dynamic transient spike is
required. Refer to Table 2 for an output capacitance matrix
for each output voltage Droop, peak to peak deviation and
recovery time during a 5A/µs transient with a specifi c
output capacitance.
Fault Conditions: Current Limit and Over current
Foldback
The LTM4600 has a current mode controller, which inher-
ently 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 over load condi-
tion, the LTM4600 provides foldback current limiting. If the
output voltage falls by more than 50%, then the maximum
output current is progressively lowered to about one sixth
of its full current limit value.
Soft-Start and Latchoff with the RUN/SS pin
The RUN/SS pin provides a means to shut down the
LTM4600 as well as a timer for soft-start and over-cur-
rent latchoff. Pulling the RUN/SS pin below 0.8V puts
the LTM4600 into a low quiescent current shutdown (I
Q
30µA). Releasing the pin allows an internal 1.2µA cur-
rent source to charge up the timing capacitor CSS. Inside
LTM4600, there is an internal 1000pF capacitor from
RUN/SS pin to ground. If RUN/SS pin has an external
capacitor CSS_EXT to ground, the delay before starting
is about:
t
V
A
C
pF
DELAY
SS EXT
=
µ
+
1 5
1 2
1000
.
.
·(
)
_
When the voltage on RUN/SS pin reaches 1.5V, the
LTM4600 internal switches are operating with a clamping
of the maximum output inductor current limited by the
RUN/SS pin total soft-start capacitance. As the RUN/SS pin
voltage rises to 3V, the soft-start clamping of the inductor
current is released.
V
IN
to V
OUT
Stepdown Ratios
There are restrictions in the maximum V
IN
to V
OUT
step
down ratio that can be achieved for a given input voltage.
These contraints are shown in the Typical Performance
Characteristics curves labeled "V
IN
to V
OUT
Stepdown
Ratio". Note that additional thermal de-rating may apply.
See the Thermal Considerations and Output Current De-
Rating sections of this data sheet.
PRERELEASE
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Table 2. Output Voltage Response Verses Component Matrix
TYPICAL MEASURED VALUES
C
OUT1
VENDORS
PART NUMBER
C
OUT2
VENDORS
PART NUMBER
TDK
C4532X5R0J107MZ (100UF,6.3V)
SANYO POS CAP
6TPE330MIL (330µF, 6.3V)
TAIYO YUDEN
JMK432BJ107MU-T ( 100µF, 6.3V)
SANYO POS CAP
2R5TPE470M9 (470µF, 2.5V)
TAIYO YUDEN
JMK316BJ226ML-T501 ( 22µF, 6.3V)
SANYO POS CAP
4TPE470MCL (470µF, 4V)
V
OUT
(V)
C
IN
(CERAMIC)
C
IN
(BULK)
C
OUT1
(CERAMIC)
C
OUT2
(BULK)
C
COMP
C3
V
IN
(V)
DROOP
(mV)
PEAK TO PEAK
(mV)
RECOVERY TIME
(µs)
LOAD STEP
(A/µs)
1.2
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
12
35
68
25
5
1.2
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
5
35
68
25
5
1.5
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
12
36
75
25
5
1.5
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
5
36
75
25
5
1.8
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
12
40
81
30
5
1.8
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
5
40
81
30
5
2.5
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
12
51
102
30
5
2.5
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
5
57
116
30
5
3.3
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
12
64
129
35
5
3.3
2 × 10µF 25V
150µF 35V
3 × 22µF 6.3V
470µF 4V
NONE
100pF
7
82
166
35
5
1.2
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
12
35
70
20
5
1.2
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
5
35
70
20
5
1.5
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
12
37
79
20
5
1.5
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
5
37
79
20
5
1.8
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
12
44
85
20
5
1.8
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 2.5V
NONE
100pF
5
44
88
20
5
2.5
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 4V
NONE
100pF
12
48
103
30
5
2.5
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 4V
NONE
100pF
5
48
103
30
5
3.3
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 4V
NONE
100pF
12
52
106
30
5
3.3
2 × 10µF 25V
150µF 35V
1 × 100µF 6.3V
470µF 4V
NONE
100pF
7
66
132
30
5
1.2
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
12
40
80
20
5
1.2
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
5
40
80
20
5
1.5
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
12
44
89
20
5
1.5
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
5
44
84
20
5
1.8
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
12
44
91
20
5
1.8
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
5
46
91
20
5
2.5
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
12
56
113
30
5
2.5
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
5
56
113
30
5
3.3
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
12
64
126
30
5
3.3
2 × 10µF 25V
150µF 35V
2 × 100µF 6.3V
330µF 6.3V
NONE
100pF
7
64
126
30
5
1.2
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
12
49
98
20
5
1.2
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
5
49
98
20
5
1.5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
12
54
108
20
5
1.5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
5
61
118
20
5
1.8
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
12
62
125
20
5
1.8
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
5
62
128
20
5
2.5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
12
70
159
25
5
2.5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
5
60
115
25
5
3.3
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
12
76
144
25
5
3.3
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
7
100
200
25
5
5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
15
188
375
25
5
5
2 × 10µF 25V
150µF 35V
4 × 100µF 6.3V
NONE
NONE
100pF
20
159
320
25
5
PRERELEASE
LTM4600
12
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After the controller has been started and given adequate
time to charge up the output capacitor, CSS is used as a
short-circuit timer. After the RUN/SS pin charges above 4V,
if the output voltage falls below 75% of its regulated value,
then a short-circuit fault is assumed. A 1.8µA current then
begins discharging CSS. If the fault condition persists until
the RUN/SS pin drops to 3.5V, then the controller turns
off both power MOSFETs, shuting down the converter
permanently. The RUN/SS pin must be actively pulled
down to ground in order to restart operation.
The over-current protection timer requires the soft-start
timing capacitor CSS be made large enough to guarantee
that the output is in regulation by the time CSS has reached
the 4V threshold. In general, this will depends upon the
size of the output capacitance, output voltage and load
current characteristic. A minimum external soft-start
capacitor can be estimated from:
C
pF
C
V
F V
SS EXT
OUT
OUT
S
_
·
(
[ /
])
+
>
1000
10
3
Generally 0.1µF is more than suffi cient.
Since the load current is already limited by the current
mode control and current foldback circuitry during a
shortcircuit, over-current latchoff operation is NOT always
needed or desired, especially the output has large amount
of capacitance or the load draw huge current during start
up. The latchoff feature can be overridden by a pull-up
current greater than 5µA but less than 80µA to the RUN/SS
pin. The additional current prevents the discharge of CSS
during a fault and also shortens the soft-start period. Us-
ing a resistor from RUN/SS pin to V
IN
is a simple solution
V
IN
V
IN
500k
RUN/SS
4600 F04
LTM4600
PGND
SGND
Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up
Resistor to V
IN
Figure 3. RUN/SS Pin Voltage During Startup and
Short-Circuit Protection
V
RUN/SS
3.5V
t
t
75%V
O
SWITCHING
STARTS
SOFT-START
CLAMPING
OF I
L
RELEASED
SHORT-CIRCUIT
LATCHOFF
OUTPUT
OVERLOAD
HAPPENS
SHORT-CIRCUIT
LATCH ARMED
4V
3V
1.5V
4600 F03
V
O
to defeat latchoff. Any pull-up network must be able to
maintain RUN/SS above 4V maximum latchoff threshold
and overcome the 4µA maximum discharge current. Figure
3 shows a conceptual drawing of V
RUN
during startup and
short circuit.
PRERELEASE
LTM4600
13
4600p
Enable
The RUN/SS pin can be driven from logic as shown in
Figure 5. This function allows the LTM4600 to be turned
on or off remotely. The ON signal can also control the
sequence of the output voltage.
Figure 5. Enable Circuit with External Logic
RUN/SS
4600 F05
LTM4600
PGND
2N7002
SGND
ON
Figure 6. Output Voltage Tracking with the LTC2923 Controller
Q1
V
CC
V
IN
V
IN
R
ONB
V
IN
5V
R
TB1
R
TB2
49.9k
1.8V
3.3V
R
TA2
R
TA1
R
ONA
ON
RAMPBUF
TRACK1
TRACK2
FB1
GATE
LTC2923
GND
4600 F06
RAMP
66.5k
1.5V
LTM4600
V
IN
V
OUT
LTM4600
DC/DC
V
IN
V
OUT
V
OSET
V
OSET
FB2
SDO
STATUS
Output Voltage Tracking
For the applications that require output voltage tracking,
several LTM4600 modules can be programmed by the
power supply tracking controller such as the LTC2923.
Figure 6 shows a typical schematic with LTC2923. Coin-
APPLICATIO S I FOR ATIO
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cident, ratiometric and offset tracking for V
O
rising and
falling can be implemented with different sets of resistor
values. See the LTC2923 data sheet for more details.
EXTV
CC
Connection
An internal low dropout regulator produces an internal 5V
supply that powers the control circuitry and FET drivers.
Therefore, if the system does not have a 5V power rail,
the LTM4600 can be directly powered by V
IN
. The gate
driver current through LDO is about 18mA. The internal
LDO power dissipation can be calculated as:
P
LDO_LOSS
= 18mA · (V
IN
5V)
The LTM4600 also provides an external gate driver volt-
age pin EXTV
CC
. If there is a 5V rail in the system, it is
recommended to connect EXTV
CC
pin to the external 5V
rail. Whenever the EXTV
CC
pin is above 4.7V, the internal
5V LDO is shut off and an internal 50mA P-channel switch
connects the EXTV
CC
to internal 5V. Internal 5V is supplied
from EXTV
CC
until this pin drops below 4.5V. Do not apply
more than 6V to the EXTV
CC
pin and ensure that EXTV
CC
< V
IN
. The following list summaries the possible connec-
tions for EXTV
CC
:
1. EXTV
CC
grounded. Internal 5V LDO is always powered
from the internal 5V regulator.
2. EXTV
CC
connected to an external supply. Internal LDO
is shut off. A high effi ciency supply compatible with the
MOSFET gate drive requirements (typically 5V) can im-
prove overall effi ciency. With this connection, it is always
required that the EXTV
CC
voltage can not be higher than
V
IN
pin voltage.
Discontinuous Operation and FCB Pin
The FCB pin determines whether the internal bottom
MOSFET remains on when the inductor current reverses.
There is an internal 4.75k pulling down resistor connecting
this pin to ground. The default light load operation mode
is forced continuous (PWM) current mode. This mode
provides minimum output voltage ripple.
PRERELEASE
LTM4600
14
4600p
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Thermal Considerations and Output Current Derating
The power loss curves in Figures 8 and 13 can be used
in coordination with the load current de-rating curves in
Figures 9 to 12 and Figures 14 to 15 for calculating an
approximate
JA
for the module. Each of the load current
de-rating curves will lower the maximum load current
as a function of the increased ambient temperature to
keep the maximum junction temperature of the power
module at 100°C maximum. This 100°C maximum is to
allow for an increased rise of about 15°C to 20°C inside
the module. This will maintain the maximum operating
temperature to below 125°C. Each of the de-rating curves
and the power loss curve that corresponds to the correct
output voltage can be used to solve for the approximate
JA
of the condition. Each Figure has three curves that are
taken at three different air fl ow conditions. For example
in Figure 9, the 10A load current can be achieved up to
60°C ambient temperature with no air fl ow. If this 60°C
is subtracted from the maximum module temperature
of 100°C, then 40°C is the maximum temperature rise.
Now Figure 8 records the power loss for this 5V to 1.5V
at the 10A output. If we take the 40°C rise and divided it
by the 3 watts of loss, then we get an approximate
JA
of 13.5°C/W with no heatsink. If we take the next air fl ow
curve in Figure 9 at 200LFM of air fl ow, then the maximum
ambient temperature allowed at 10A load current is 65°C.
This calculates to a 35°C rise, and an approximate
JA
of
11.6°C/W with no heatsink. In the next air fl ow curve at
400LFM in Figure 9, the maximum ambient temperature
allowed at 10A load current is 73°C. This calculates to
a 27°C rise, and an approximate
JA
of 9°C/W with no
heatsink. Each of the de-rating curves in Figures 9 to
12 or Figures 14 to 15 can be used with the appropriate
power loss curve in either fi gure 8 or fi gure 13 to derive
an approximate
JA
. Table 3 and 4 provide the approximate
JA
for Figures 9 to 12, and Figures 14 to 15. A complete
explanation of the thermal characteristics is provided in
the thermal application note for the LTM4600.
In the application where the light load effi ciency is im-
portant, tying the FCB pin above 0.6V threshold enables
discontinuous operation where the bottom MOSFET turns
off when inductor current reverses. Therefore, the conduc-
tion loss is minimized and light load effi cient is improved.
The penalty is that the controller may skip cycle and the
output voltage ripple increases at light load.
Paralleling Operation with Load Sharing
Two or more LTM4600 modules can be paralleled to provide
higher than 10A output current. Figure 7 shows the neces-
sary interconnection between two paralleled modules. The
OPTI-LOOPTM current mode control ensures good current
sharing among modules to balance the thermal stress.
The new feedback equation for two or more LTM4600s
in parallel is:
V
V
k
N
R
R
OUT
SET
SET
=
+
0 6
100
.
·
where N is the number of LTM4600s in parallel.
Figure 7. Parallel Two µModules with Load Sharing
V
IN
V
OUT
V
IN
V
OUT
(20A
MAX
)
4600 F07
LTM4600
PGND
SGND
COMP V
OSET
R
SET
V
IN
V
OUT
LTM4600
PGND
SGND
COMP V
OSET
OPTI-LOOP is a trademark of Linear Technology Corporation.
PRERELEASE
LTM4600
15
4600p
AMBIENT TEMPERATURE (
°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600 F12
60
10
9
8
7
6
5
3
4
80
90
100
V
IN
= 12V
V
O
= 1.5V
400 LFM
200 LFM
0 LFM
Figure 12. BGA Heatsink
AMBIENT TEMPERATURE (
°C)
50
55
70
4600 F11
60
65
75
80
85
90
V
IN
= 12V
V
O
= 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
4
Figure 11. No Heatsink
AMBIENT TEMPERATURE (
°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600 F10
60
80
90
100
V
IN
= 5V
V
O
= 1.5V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
Figure 10. BGA Heatsink
APPLICATIO S I FOR ATIO
W
U
U
U
AMBIENT TEMPERATURE (
°C)
50
70
4600 F09
60
80
90
V
IN
= 5V
V
O
= 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
4
Figure 9. No Heatsink
OUTPUT CURRENT (A)
0
8
6
4600 F08
2
4
10
3.5
4.0
4.5
3.0
2.5
2.0
1.5
1.0
0.5
0
POWER LOSS (W)
12V LOSS
5V LOSS
Figure 8. Power Loss vs Load Current
PRERELEASE
LTM4600
16
4600p
APPLICATIO S I FOR ATIO
W
U
U
U
OUTPUT CURRENT (A)
0
8
6
4600 F13
2
4
10
3.5
4.0
5.0
4.5
3.0
2.5
2.0
1.5
1.0
0.5
0
POWER LOSS (W)
12V LOSS
Figure 13. Power Loss vs Load Current
AMBIENT TEMPERATURE (
°C)
40
70
4600 F14
60
50
80
90
V
IN
= 12V
V
O
= 3.3V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
4
5
0
1
2
3
Figure 14. No Heatsink
AMBIENT TEMPERATURE (
°C)
40
50
MAXIMUM LOAD CURRENT (A)
70
4600 F15
60
80
90
100
V
IN
= 12V
V
O
= 3.3V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
Figure 15. BGA Heatsink
PRERELEASE
LTM4600
17
4600p
APPLICATIO S I FOR ATIO
W
U
U
U
Table 4. 3.3V Output
DE-RATING CURVE
V
IN
(V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEATSINK*
JA
(°C/W)
Figure 14
12
Figure 8
0
None
13.5
Figure 14
12
Figure 8
200
None
11.6
Figure 14
12
Figure 8
400
None
10.4
Figure 15
12
Figure 8
0
BGA Heatsink
9.5
Figure 15
12
Figure 8
200
BGA Heatsink
6
Figure 15
12
Figure 8
400
BGA Heatsink
4.77
Table 3. 1.5V Output
DE-RATING CURVE
V
IN
(V)
POWER LOSS CURVE
AIR FLOW (LFM)
HEATSINK*
JA
(°C/W)
Figures 9, 11
5, 12
Figure 8
0
None
13.5
Figures 9, 11
5, 12
Figure 8
200
None
11
Figures 9, 11
5, 12
Figure 8
400
None
9
Figures 10, 12
5, 12
Figure 8
0
BGA Heatsink
9.5
Figures 10, 12
5, 12
Figure 8
200
BGA Heatsink
6.25
Figures 10, 12
5, 12
Figure 8
400
BGA Heatsink
4.5
*Heatsink manufacturer: Wakefi eld Engineering #CiS20069
PRERELEASE
LTM4600
18
4600p
APPLICATIO S I FOR ATIO
W
U
U
U
Figure 16. Recommended PCB Layout
V
IN
PGND
TOP LAYER
V
OUT
4600 F16
LOAD
C
IN
Safety Considerations
The LTM4600 modules do not provide isolation from V
IN
to
V
OUT
. There is no internal fuse. If required, a slow blow fuse
with a rating twice the maximum input current should be
provided to protect each unit from catastrophic failure.
Layout Checklist/Example
The high integration of the LTM4600 makes the PCB board
layout very simple and easy. However, to optimize its electri-
cal and thermal performance, some layout considerations
are still necessary.
· Use large PCB copper areas for high current path, in-
cluding V
IN
, PGND and V
OUT
. It helps to minimize the
PCB conduction loss and thermal stress
· Place high frequency ceramic input and output capaci-
tors next to the V
IN
, PGND and V
OUT
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 via directly on pad
· Use a separated SGND ground copper area for com-
ponents connected to signal pins. Connect the SGND
to PGND underneath the unit
Figure 16 gives a good example of the recommended
layout.
PRERELEASE
LTM4600
19
4600p
TYPICAL APPLICATIO
U
Figure 17. Typical Application, 5V to 20V Input, 0.6V to 5V Output, 10A Max
4600 F20
V
OUT
EXTV
CC
F
ADJ
V
OSET
FCB
COMP
PGOOD
V
OUT
(MULTIPLE PINS)
V
OUT
RUN/SS
SGND
PGND
(MULTIPLE PINS)
C2
22
µF
6.3V
×3
REFER TO
TABLE 2
C
OUT
470
µF
REFER TO
TABLE 2
GND
0.6V TO 5V
C4
OPT
V
IN
5V TO 20V
GND
C
IN
10
µF
2x
C1
150
µF
C3
100pF
R1
66.5k
REFER TO
TABLE 2
V
IN
(MULTIPLE PINS)
LTM4600
SV
IN
+
PRERELEASE
LTM4600
20
4600p
TYPICAL APPLICATIO
U
4600 F17
R4
15.8k
1%
EXTV
CC
RUN
COMP
FCB
V
OUT
V
OUT
= 0.6V · ([100k/N] + R
SET
)/R
SET
WHERE N = 2
C1, C3, C7, C8: TDK C3216X5R1E106MT
C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501
C5, C10: SANYO POS CAP, 4TPE470MCL
PGOOD
FB
SV
IN
PGND
SGND
2.5V AT 20A
4.5V TO 20V
2.5V
2.5V
C7
10
µF
25V
C8
10
µF
25V
C10
470
µF
4V
C9
22
µF
x3
V
IN
LTM4600
F
SET
R1
100k
EXTV
CC
RUN
COMP
FCB
V
OUT
PGOOD
FB
SV
IN
PGND
SGND
C1
10
µF
25V
RUN/SOFT-START
C3
10
µF
25V
C4
220pF
C5
470
µF
4V
C2
22
µF
x3
V
IN
LTM4600
F
SET
TOTAL LOAD
0
INDIVIDUAL SHARE
12
10
8
6
4
2
0
5
10
15
20
4600 F18
25
I
OUT1
I
OUT2
12V
IN
2.5V
OUT
20A
MAX
Current Sharing Between Two
LTM4600 Modules
Parallel Operation and Load Sharing
PRERELEASE
LTM4600
21
4600p
PACKAGE DESCRIPTIO
U
LGA Package
104-Lead (15mm
×
15mm)
(Reference L
T
M DWG # 05-05-1800)
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
2. ALL DIMENSIONS ARE IN MILLIMETERS
LAND DESIGNATION PER JESD MO-222, SPP-010
5. PRIMARY DATUM -Z- IS SEATING PLANE
6. THE TOTAL NUMBER OF PADS: 104
4
3
DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL,
BUT MUST BE LOCATED WITHIN THE ZONE INDICATED.
THE PAD #1 IDENTIFIER IS A MARKED FEATURE OR A
NOTCHED BEVELED PAD
SYMBOL
aaa
bbb
eee
TOLERANCE
0.15
0.10
0.15
2.72 2.92
DETAIL B
DETAIL B
SUBSTRATE
MOLD
CAP
0.27 0.37
2.45 2.55
bbb Z
Z
15
BSC
TOP VIEW
15
BSC
4
PAD 1
CORNER
X
Y
aaa Z
aaa Z
13.97
BSC
12.70
BSC
0.11 0.27
13.93
BSC
35
24
79
68
11
13
10
12
15
17
14
16
19
21
18
20
22
4600 02-18
BOTTOM VIEW
C(0.30)
PAD 1
3
PADS
SEE NOTES
94
95
96
97
98
99
100
101
102
103
104
93
82
71
60
49
24
23
22
21
20
19
18
17
16
7
6
5
4
3
2
40
51
62
73
84
85
86
87
88
89
90
91
74
75
76
77
78
79
80
63
64
65
66
67
68
69
52
53
54
55
56
57
58
42
43
44
45
46
47
92
81
70
59
48
11
10
9
13
14
15
26
27
28
29
30
31
33
34
35
36
37
38
41
1
8
12
25
32
39
50
61
72
83
M
Y
X
eee
1
SUGGESTED SOLDER PAD LAYOUT
TOP VIEW
94
95
96
97
98
99
100
101
102
103
104
93
82
71
60
49
24
23
22
21
20
19
18
17
16
7
6
5
4
3
2
40
51
62
73
84
85
86
87
88
89
90
91
74
75
76
77
78
79
80
63
64
65
66
67
68
69
52
53
54
55
56
57
58
42
43
44
45
46
47
92
81
70
59
48
11
10
9
13
14
15
26
27
28
29
30
31
33
34
35
36
37
38
41
1
8
12
25
32
39
50
61
72
83
0.0000
1.2700
2.5400
0.3175
0.3175
4.4450
5.7150
6.9850
1.4675
5.7158
6.9421
4.4458
6.3500
6.3500
3.8100
3.8100
1.2700
0.3175
0.3175
0.0000
1.2700
3.1758
1.9058
0.6358
0.0000
0.6342
1.9042
3.1742
4.4442
5.7142
6.9865
2.7375
4.0075
5.2775
6.5475
6.9888
1.0900
2.3600
4.4950
5.7650
5.0800
5.0800
2.5400
2.5400
23
A
B
C
D
E
F
G
H
J
L
M
N
P
R
T
K
PRERELEASE
LTM4600
22
4600p
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
A1 -
B1 V
IN
C1 -
D1 V
IN
E1 -
F1 V
IN
G1 PGND
H1 -
A2 -
B2 -
C2 -
D2 -
E2 -
F2 -
G2 -
H2 -
A3 V
IN
B3 -
C3 -
D3 -
E3 -
F3 -
G3 -
H3 -
A4 -
B4 -
C4 -
D4 -
E4 -
F4 -
G4 -
H4 -
A5 V
IN
B5 -
C5 -
D5 -
E5 -
F5 -
G5 -
H5 -
A6 -
B6 -
C6 -
D6 -
E6 -
F6 -
G6 -
H6 -
A7 V
IN
B7 -
C7 -
D7 -
E7 -
F7 -
G7 -
H7 PGND
A8 -
B8 -
C8 -
D8 -
E8 -
F8 -
G8 -
H8 -
A9 V
IN
B9 -
C9 -
D9 -
E9 -
F9 -
G9 -
H9 PGND
A10 -
B10 -
C10 V
IN
D10 -
E10 V
IN
F10 -
G10 -
H10 -
A11 V
IN
B11 -
C11 -
D11 -
E11 -
F11 -
G11 -
H11 PGND
A12 -
B12 -
C12 V
IN
D12 -
E12 V
IN
F12 -
G12 -
H12 -
A13 V
IN
B13 -
C13 -
D13 -
E13 -
F13 -
G13 -
H13 PGND
A14 -
B14 -
C14 V
IN
D14 -
E14 V
IN
F14 -
G14 -
H14 -
A15 FADJ
B15 -
C15 -
D15 -
E15 -
F15 -
G15 -
H15 PGND
A16 -
B16 -
C16 -
D16 -
E16 -
F16 -
G16 -
H16 -
A17 SV
IN
B17 -
C17 -
D17 -
E17 -
F17 -
G17 -
H17 PGND
A18 -
B18 -
C18 -
D18 -
E18 -
F18 -
G18 -
H18 -
A19 EXTV
CC
B19 -
C19 -
D19 -
E19 -
F19 -
G19 -
H19 -
A20 -
B20 -
C20 -
D20 -
E20 -
F20 -
G20 -
H20 -
A21 V
OSET
B21 -
C21 -
D21 -
E21 -
F21 -
G21 -
H21 -
A22 -
B22 -
C22 -
D22 -
E22 -
F22 -
G22 -
H22 -
A23 -
B23 COMP
C23 -
D23 SGND
E23 -
F23 RUN/SS
G23 FCB
H23 -
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
PIN NAME
J1 PGND
K1 -
L1 -
M1 -
N1 -
P1 -
R1 -
T1 -
J2 -
K2 -
L2 PGND
M2 PGND
N2 PGND
P2 V
OUT
R2 V
OUT
T2 V
OUT
J3 -
K3 -
L3 -
M3 -
N3 -
P3 -
R3 -
T3 -
J4 -
K4 -
L4 PGND
M4 PGND
N4 PGND
P4 V
OUT
R4 V
OUT
T4 V
OUT
J5 -
K5 -
L5 -
M5 -
N5 -
P5 -
R5 -
T5 -
J6 -
K6 -
L6 PGND
M6 PGND
N6 PGND
P6 V
OUT
R6 V
OUT
T6 V
OUT
J7 -
K7 PGND
L7 -
M7 -
N7 -
P7 -
R7 -
T7 -
J8 -
K8
L8 PGND
M8 PGND
N8 PGND
P8 V
OUT
R8 V
OUT
T8 V
OUT
J9 -
K9 PGND
L9 -
M9 -
N9 -
P9 -
R9 -
T9 -
J10 -
K10
L10 PGND
M10 PGND
N10 PGND
P10 V
OUT
R10 V
OUT
T10 V
OUT
J11 -
K11 PGND
L11 -
M11 -
N11 -
P11 -
R11 -
T11 -
J12 -
K12 -
L12 PGND
M12 PGND
N12 PGND
P12 V
OUT
R12 V
OUT
T12 V
OUT
J13 -
K13 PGND
L13 -
M13 -
N13 -
P13 -
R13 -
T13 -
J14 -
K14 -
L14 PGND
M14 PGND
N14 PGND
P14 V
OUT
R14 V
OUT
T14 V
OUT
J15 -
K15 PGND
L15 -
M15 -
N15 -
P15 -
R15 -
T15 -
J16 -
K16 -
L16 PGND
M16 PGND
N16 PGND
P16 V
OUT
R16 V
OUT
T16 V
OUT
J17 -
K17 PGND
L17 -
M17 -
N17 -
P17 -
R17 -
T17 -
J18 -
K18 -
L18 PGND
M18 PGND
N18 PGND
P18 V
OUT
R18 V
OUT
T18 V
OUT
J19 -
K19 -
L19 -
M19 -
N19 -
P19 -
R19 -
T19 -
J20 -
K20 -
L20 PGND
M20 PGND
N20 PGND
P20 V
OUT
R20 V
OUT
T20 V
OUT
J21 -
K21 -
L21 -
M21 -
N21 -
P21 -
R21 -
T21 -
J22 -
K22 -
L22 PGND
M22 PGND
N22 PGND
P22 V
OUT
R22 V
OUT
T22 V
OUT
J23 PGOOD
K23 -
L23 -
M23 -
N23 -
P23 -
R23 -
T23 -
PACKAGE DESCRIPTIO
U
Pin Assignment Tables
(Arranged by Pin Number)
PRERELEASE
LTM4600
23
4600p
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.
PACKAGE DESCRIPTIO
U
PIN NAME
G1
PGND
H7
H9
H11
H13
H15
H17
PGND
PGND
PGND
PGND
PGND
PGND
J1
PGND
K7
K9
K11
K13
K15
K17
PGND
PGND
PGND
PGND
PGND
PGND
L2
L4
L6
L8
L10
L12
L14
L16
L18
L20
L22
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
M2
M4
M6
M8
M10
M12
M14
M16
M18
M20
M22
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
N2
N4
N6
N8
N10
N12
N14
N16
N18
N20
N22
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PIN NAME
P2
P4
P6
P8
P10
P12
P14
P16
P18
P20
P22
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
R2
R4
R6
R8
R10
R12
R14
R16
R18
R20
R22
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
T2
T4
T6
T8
T10
T12
T14
T16
T18
T20
T22
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
V
OUT
PIN NAME
A3
A5
A7
A9
A11
A13
V
IN
V
IN
V
IN
V
IN
V
IN
V
IN
B1
V
IN
C10
C12
C14
V
IN
V
IN
V
IN
D1
V
IN
E10
E12
E14
V
IN
V
IN
V
IN
F1
V
IN
PIN NAME
A15
FADJ
A17
SV
IN
A19
EXTV
CC
A21
V
OSET
B23
COMP
D23
SGND
F23
RUN/SS
G23
FCB
J23
PGOOD
Pin Assignment Tables
(Arranged by Pin Number)
PRERELEASE
PRE-RELEASE
LTM4600
24
4600p
© LINEAR TECHNOLOGY CORPORATION 2005
LT 1105 · PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900
FAX: (408) 434-0507
www.linear.com
TYPICAL APPLICATIO
U
1.8V, 10A Regulator
4600 F19
C1, C2: TDK C3216X5R1E106MT
C3: TAIYO YUDEN, JMK316BJ226ML-T501
C4: SANYO POS CAP, 4TPE470MCL
1.8V AT 10A
4.5V AT 20V
R1
100k
EXTV
CC
RUN
COMP
FCB
V
OUT
PGOOD
FB
SV
IN
PGND
SGND
C1
10
µF
25V
C2
10
µF
25V
C5
100pF
C4
470
µF
4V
PGOOD
C3
22
µF
x3
V
IN
LTM4600
F
SET
R2
49.9k
1%
This product contains technology licensed from Silicon Semiconductor Corporation.
®
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