LTM4600HV
1
4600hvfd
LOAD CURRENT (A)
0
EFFICIENCY (%)
6
4600HV TA01b
24 8
10
80
90
100
70
60
50
40
30
1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
10A, 28VIN High Effi ciency
DC/DC µModule
The LTM
®
4600HV is a complete 10A, DC/DC step down
power supply with up to 28V input operation. Included
in the package are the switching controller, power FETs,
inductor, and all support components. Operating over
an input voltage range of 4.5V to 28V, the LTM4600HV
supports an output voltage range of 0.6V to 5V, set by a
single resistor. This high effi ciency design delivers 10A
continuous current (12A 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 LTM4600HV is packaged in a thermally enhanced,
compact (15mm × 15mm) and low profi le (2.8mm) over-
molded Land Grid Array (LGA) package suitable for auto-
mated assembly by standard surface mount equipment.
The LTM4600HV is Pb-free and RoHS compliant.
n Telecom and Networking Equipment
n Military and Avionics Systems
n Industrial Equipment
n Point of Load Regulation
n Servers
n Complete Switch Mode Power Supply
n Wide Input Voltage Range: 4.5V to 28V
n 10A DC, 12A Peak Output Current
n Parallel Two μModule™ DC/DC Converters for 20A
Output Current
n 0.6V to 5V Output Voltage
n 1.5% Output Voltage Regulation
n Ultrafast Transient Response
n Current Mode Control
n –55°C to 125°C Operating Temperature Range
(LTM4600HVMPV)
n Pb-Free (e4) RoHS Compliant Package Gold-Pad
Finish
n Up to 92% Effi ciency
n Programmable Soft-Start
n Output Overvoltage Protection
n Optional Short-Circuit Shutdown Timer
n Small Footprint, Low Profi le (15mm × 15mm ×
2.8mm) LGA Package
10A μModule Power Supply with 4.5V to 28V Input
Effi ciency vs Load Current with 24VIN (FCB = 0)
VIN
CIN
4600hv TA01a
LTM4600HV
PGND SGND
VOUT
VOSET
VIN
4.5V TO 28V
ABSMAX
VOUT
2.5V*
10A
COUT
31.6k
*REVIEW DE-RATING CURVE AT
THE HIGHER INPUT VOLTAGE
L, LT, LTC 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.
TYPICAL APPLICATION
FEATURES
APPLICATIONS
DESCRIPTION
LTM4600HV
2
4600hvfd
FCB, EXTVCC, PGOOD, RUN/SS, VOUT .......... –0.3V to 6V
VIN, SVIN, fADJ ............................................ –0.3V to 28V
VOSET
, COMP ............................................. –0.3V to 2.7V
Operating Temperature Range (Note 2)
E and I Grades ..................................... –40°C to 85°C
MP Grade ........................................... –55°C to 125°C
Junction Temperature ........................................... 125°C
Storage Temperature Range ................... –55°C to 125°C
(Note 1)
The
l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. External CIN = 120μF, COUT = 200μF/Ceramic per typical
application (front page) confi guration.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN(DC) Input DC Voltage AbsMax 28V for Tolerance on 24V Inputs l4.5 28 V
VOUT(DC) Output Voltage FCB = 0V
V
IN = 5V or 12V, VOUT = 1.5V, IOUT = 0A
l
1.478
1.470
1.50
1.50
1.522
1.530
V
V
Input Specifi cations
VIN(UVLO) Under Voltage Lockout Threshold IOUT = 0A 3.4 4 V
IINRUSH(VIN) Input Inrush Current at Startup IOUT = 0A, VOUT = 1.5V, FCB = 0
V
IN = 5V
V
IN = 12V
V
IN = 24V
0.6
0.7
0.8
A
A
A
IQ(VIN) Input Supply Bias Current IOUT = 0A, EXTVCC Open
V
IN = 12V, VOUT = 1.5V, FCB = 5V
V
IN = 12V, VOUT = 1.5V, FCB = 0V
V
IN = 24V, VOUT = 2.5V, FCB = 5V
V
IN = 24V, VOUT = 2.5V, FCB = 0V
Shutdown, RUN = 0.8V, VIN = 12V
1.2
42
1.8
36
35 75
mA
mA
mA
mA
μA
Min On Time 100 ns
Min Off Time 400 ns
IS(VIN) Input Supply Current VIN = 12V, VOUT = 1.5V, IOUT = 10A
V
IN = 12V, VOUT = 3.3V, IOUT = 10A
V
IN = 5V, VOUT = 1.5V, IOUT = 10A
V
IN = 24V to 3.3V at 10A, EXTVCC = 5V
1.52
3.13
3.64
1.6
A
A
A
A
RUN/SS
FCB
PGOOD
VIN
PGND
VOUT
COMP
SGND
EXTVCC
VOSET
fADJ
SVIN
LGA PACKAGE
104-LEAD
(
15mm × 15mm × 2.8mm
)
TOP VIEW
TJMAX = 125°C, θJA = 15°C/W, θJC = 6°C/W,
θJA DERIVED FROM 95mm × 76mm PCB WITH 4 LAYERS, WEIGHT = 1.7g
LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE
LTM4600HVEV#PBF
LTM4600HVIV#PBF
LTM4600HVMPV#PBF
LTM4600HVEV#TRPBF
LTM4600HVIV#TRPBF
LTM4600HVMPV#TRPBF
LTM4600HVEV
LTM4600HVIV
LTM4600HVMPV
104-Lead (15mm × 15mm × 2.8mm)
104-Lead (15mm × 15mm × 2.8mm)
104-Lead (15mm × 15mm × 2.8mm)
–40°C to 85°C
–40°C to 85°C
–55°C to 125°C
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
Consult LTC Marketing for information on non-standard lead based fi nish parts.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
For more information on tape and reel specifi cations, go to: http://www.linear.com/tapeandreel/
PIN CONFIGURATION ABSOLUTE MAXIMUM RATINGS
ORDER INFORMATION
ELECTRICAL CHARACTERISTICS
LTM4600HV
3
4600hvfd
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Output Specifi cations
IOUTDC Output Continuous Current Range
(See Output Current Derating Curves for
Different VIN, VOUT and TA)
VIN = 12V, VOUT = 1.5V
VIN = 24V, VOUT = 2.5V (Note 3)
0
0
10
10
A
A
ΔVOUT(LINE)
VOUT
Line Regulation Accuracy VOUT = 1.5V. FCB = 0V, IOUT = 0A,
VIN = 4.5V to 28V
l0.15 0.3 %
ΔVOUT(LOAD)
VOUT
Load Regulation Accuracy VOUT = 1.5V. FCB = 0V, IOUT = 0A to 10A
V
IN = 5V
V
IN = 12V (Notes 4, 5) l
±1
±1.5
%
%
VOUT(AC) Output Ripple Voltage VIN = 12V, VOUT = 1.5V, FCB = 0V, IOUT = 0A 10 15 mVP-P
fs Output Ripple Voltage Frequency FCB = 0V, IOUT = 5A, VIN = 12V, VOUT = 1.5V 850 kHz
tSTART Turn-On Time VOUT = 1.5V, IOUT = 1A
V
IN = 12V
V
IN = 5V
0.5
0.7
ms
ms
ΔVOUTLS Voltage Drop for Dynamic Load Step VOUT = 1.5V, Load Step: 0A/μs to 5A/μs
COUT = 3 • 22μF 6.3V, 470μF 4V POSCAP,
See Table 2
36 mV
tSETTLE Settling Time for Dynamic Load Step VIN = 12V Load: 10% to 90% to 10% of Full Load 25 μs
IOUTPK Output Current Limit Output Voltage in Foldback
V
IN = 24V, VOUT = 2.5V
V
IN = 12V, VOUT = 1.5V
V
IN = 5V, VOUT = 1.5V
17
17
17
A
A
A
Control Stage
VOSET Voltage at VOSET Pin IOUT = 0A, VOUT = 1.5V l0.591
0.594
0.6
0.6
0.609
0.606
V
V
VRUN/SS RUN ON/OFF Threshold 0.8 1.5 2 V
IRUN(C)/SS Soft-Start Charging Current VRUN/SS = 0V –0.5 –1.2 –3 μA
IRUN(D)/SS Soft-Start Discharging Current VRUN/SS = 4V 0.8 1.8 3 μA
VIN – SVIN EXTVCC = 0V, FCB = 0V 100 mV
IEXTVCC Current into EXTVCC Pin EXTVCC = 5V, FCB = 0V, VOUT = 1.5V, IOUT = 0A 16 mA
RFBHI Resistor Between VOUT and VOSET Pins 100 kΩ
VFCB Forced Continuous Threshold 0.57 0.6 0.63 V
IFCB Forced Continuous Pin Current VFCB = 0.6V –1 –2 μA
PGOOD Output
ΔVOSETH PGOOD Upper Threshold VOSET Rising 7.5 10 12.5 %
ΔVOSETL PGOOD Lower Threshold VOSET Falling –7.5 –10 –12.5 %
ΔVOSET(HYS) PGOOD Hysteresis VOSET Returning 2 %
VPGL PGOOD Low Voltage IPGOOD = 5mA 0.15 0.4 V
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at TA = 25°C, VIN = 12V. External CIN = 120μF, COUT = 200μF/Ceramic per typical
application (front page) confi guration.
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 LTM4600HVE 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 LTM46000HVMP
is guaranteed and tested over the –55°C to 125°C temperature range.
For output current derating at high temperature, please refer to Thermal
Considerations and Output Current Derating discussion.
Note 3: Refer to current de-rating curves and thermal application note.
Note 4: Test assumes current derating versus temperature.
Note 5: Guaranteed by correlation.
ELECTRICAL CHARACTERISTICS
LTM4600HV
4
4600hvfd
Effi ciency vs Load Current
w
ith 5VIN (FCB = 0)
Effi ciency vs Load Current
with 12V
IN (
FCB = 0
)
Effi ciency vs Load Current
with 24VIN (FCB = 0)
Effi ciency vs Load Current
with Different FCB Settin
g
s 1.2V Transient Response 1.5V Transient Response
1.8V Transient Res
p
onse 2.5V Transient Res
p
onse 3.3V Transient Res
p
onse
25μs/DIV
4600hv G05
1.2V AT 5A/μs LOAD STEP
COUT = 3 • 22μF 6.3V CERAMICS
470μF 4V SANYO POSCAP
C3 = 100pF
25μs/DIV
4600hv G06
1.5V AT 5A/μs LOAD STEP
COUT = 3 • 22μF 6.3V CERAMICS
470μF 4V SANYO POSCAP
C3 = 100pF
25μs/DIV
4600hv G07
1.8V AT 5A/μs LOAD STEP
COUT = 3 • 22μF 6.3V CERAMICS
470μF 4V SANYO POSCAP
C3 = 100pF
25μs/DIV
4600hv G08
2.5V AT 5A/μs LOAD STEP
COUT = 3 • 22μF 6.3V CERAMICS
470μF 4V SANYO POSCAP
C3 = 100pF
25μs/DIV
4600hv G09
3.3V AT 5A/μs LOAD STEP
COUT = 3 • 22μF 6.3V CERAMICS
470μF 4V SANYO POSCAP
C3 = 100pF
VOUT = 50mV/DIV
IOUT = 5A/DIV
(See Figure 21 for all curves)
TYPICAL PERFORMANCE CHARACTERISTICS
LOAD CURRENT (A)
0
100
90
80
70
60
50
40
30 6
4600hv G01
24 810
EFFICIENCY (%)
0.6VOUT
1.2VOUT
1.5VOUT
2.5VOUT
LOAD CURRENT (A)
0
EFFICIENCY (%)
50
60
70
6
4600hv G02
40
30 24 8
80
90
100
10
0.6VOUT
1.2VOUT
1.5VOUT
2.5VOUT
3.3VOUT
LOAD CURRENT (A)
0
EFFICIENCY (%)
6
4600hv G03
24 8
10
80
90
100
70
60
50
40
30
1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
LOAD CURRENT (A)
20
50
40
30
90
80
70
60
4600hv G04
EFFICIENCY (%)
0.1 10
1
FCB = GND
FCB > 0.7V
VIN = 12V
VOUT = 1.5V
LTM4600HV
5
4600hvfd
Start-Up, IOUT = 0A
Start-Up, IOUT = 10A
(
Resistive Load
)
Short-Circuit Protection,
I
OUT
= 0A
Short-Circuit Protection,
I
OUT
= 10A
200μs/DIV
4600hv G10
VIN = 12V
VOUT = 1.5V
COUT = 200μF
NO EXTERNAL SOFT-START CAPACITOR
VOUT
(0.5V/DIV)
IIN
(0.5A/DIV)
200μs/DIV
4600hv G11
VIN = 12V
VOUT = 1.5V
COUT = 200μF
NO EXTERNAL SOFT-START CAPACITOR
VOUT
(0.5V/DIV)
IIN
(0.5A/DIV)
20μs/DIV
4600hv G12
VIN = 12V
VOUT = 1.5V
COUT = 2× 200μF/X5R
NO EXTERNAL SOFT-START CAPACITOR
VOUT
(0.5V/DIV)
IIN
(0.2A/DIV)
20μs/DIV
4600hv G13
VIN = 12V
VOUT = 1.5V
COUT = 2× 200μF/X5R
NO EXTERNAL SOFT-START CAPACITOR
VOUT
(0.5V/DIV)
IIN
(0.5A/DIV)
V
IN
to V
OUT
Ste
p
down Ratio
(See Figure 21 for all curves)
V
OSET
vs Tem
p
erature Start-U
p
Waveform, T
A
= –55°C
TYPICAL PERFORMANCE CHARACTERISTICS
VIN (V)
0
5.5
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0515
4600HV G14
10 2420
VOUT (V)
5V
3.3V
fADJ = OPEN
2.5V
1.8V
1.5V
1.2V
0.6V
SEE FREQUENCY ADJUSTMENT DISCUSSION
FOR 12VIN TO 5VOUT AND 5VIN TO 3.3VOUT
CONVERSION
TEMPERATURE (°C)
–55
0.590
VOSET(V)
0.595
0.600
0.605
0.610
–25 5 35 65
4600HV G15
95 125
VIN = 12V
VOUT = 1.5V
IOUT = 10A
400μs/DIV 4600HV G16
12V
I
npu
t
L
oa
d
R
egu
l
a
ti
on vs
Tem
p
erature
LOAD CURRENT
0
–0.45
LOAD REGULATION %
–0.40
–0.35
–0.10
–0.15
–0.20
–0.25
–0.30
–0.05
0.00
5
4600HV G17
10
25°C
100°C
–45°C
LTM4600HV
6
4600hvfd
VIN (Bank 1): Power Input Pins. Apply input voltage
between these pins and GND pins. Recommend placing
input decoupling capacitance directly between VIN pins
and GND pins.
fADJ (Pin A15): A 110k resistor from VIN to this pin sets
the one-shot timer current, thereby setting the switching
frequency. The LTM4600HV switching frequency is typically
850kHz. An external resistor to ground can be selected to
reduce the one-shot timer current, thus lower the switching
frequency to accommodate a higher duty cycle step down
requirement. See the applications section.
SVIN (Pin A17): Supply Pin for Internal PWM Controller. Leave
this pin open or add additional decoupling capacitance.
EXTVCC (Pin A19): External 5V supply pin for controller. If
left open or grounded, 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
EXTVCC voltage should never be higher than VIN.
VOSET (Pin A21): The Negative Input of The Error Amplifi er.
Internally, this pin is connected to VOUT with a 100k precision
resistor. Different output voltages can be programmed with
additional resistors between the VOSET 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 VIN 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 PGOOD is open drain output. Otherwise, this
pin is pulled to ground.
PGND (Bank 2): Power ground pins for both input and
output returns.
VOUT (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)
PIN FUNCTIONS
E
C
A
RUN/SS
FCB
PGOOD
VIN
BANK 1
PGND
BANK 2
VOUT
BANK 3
COMP
SGND
EXTVCC
VOSET
fADJ
SVIN
TOP VIEW
35
24
79
68
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
1918171676543
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
11109
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
123
B
D
F
G
H
J
L
M
N
P
R
T
K
4600hv PN01
LTM4600HV
7
4600hvfd
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
CIN External Input Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 2.5V)
IOUT = 10A, 2x 10μF 35V Ceramic
Taiyo Yuden GDK316BJ106ML
20 μF
COUT External Output Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 2.5V)
IOUT = 10A, Refer to Table 2 in the
Applications Information Section
100 200 μF
T
A = 25°C, VIN = 12V. Use Figure 1 confi guration.
Figure 1. Simplifi ed LTM4600HV Block Diagram
SIMPLIFIED BLOCK DIAGRAM
4600hv F01
RUN/SS LTM4600HV
VOSET
EXTVCC
SGND
fADJ
FCB
1000pF
Q1
Q2
VOUT, 2.5V/10A MAX
PGND
VIN, 4.5V TO 28V ABS MAX
SVIN
COMP
PGOOD
R6
31.6k
100k
0.5%
4.75k
1.5μFCIN
15μF
6.3V
COUT
10Ω
INT
COMP
CONTROLLER
DECOUPLING REQUIREMENTS
LTM4600HV
8
4600hvfd
μModule Description
The LTM4600HV 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
0.6VDC to 5.0VDC. The input voltage range is 4.5V to 28V.
A simplifi ed block diagram is shown in Figure 1 and the
typical application schematic is shown in Figure 21.
The LTM4600HV contains an integrated LTC constant
on-time current-mode regulator, ultra-low RDS(ON) FETs
with fast switching speed and integrated Schottky diode.
The typical switching frequency is 850kHz at full load.
With current mode control and internal feedback loop
compensation, the LTM4600HV module has suffi cient
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
(X5R or X7R for extended temperature range).
Current mode control provides cycle-by-cycle fast current
limit. In addition, foldback current limiting is provided in
an over-current condition while VOSET drops. Also, the
LTM4600HV has defeatable short circuit latch off. Internal
overvoltage 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 6V.
The FCB pin has a 4.75k resistor to ground, so a resistor
to VIN can set the voltage on the FCB pin.
When EXTVCC pin is grounded or open, an integrated 5V
linear regulator powers the controller and MOSFET gate
drivers. If a minimum 4.7V external bias supply is ap-
plied on the EXTVCC pin, the internal regulator is turned
off, and an internal switch connects EXTVCC 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 EXTVCC pin is
6V. The EXTVCC voltage should never be higher than the
VIN voltage. Also EXTVCC must be sequenced after VIN.
Recommended for 24V operation to lower temperature
in the μModule.
OPERATION
LTM4600HV
9
4600hvfd
voltage is margined up. The output voltage is margined
down when QDOWN is on and QUP is off. If the output
voltage VO needs to be margined up/down by ±M%, the
resistor values of RUP and RDOWN can be calculated from
the following equations:
(RSET RUP)•V
O•(1+M%)
(RSET RUP)+100k
=0.6V
RSET •V
O•(1–M%)
RSET +(100kRDOWN)=0.6V
Input Capacitors
The LTM4600HV μModule should be connected to a low
ac-impedance DC source. High frequency, low ESR input
capacitors are required to be placed adjacent to the mod-
ule. In Figure 21, the bulk input capacitor CIN 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=VO
VIN
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
ICIN(RMS) =IO(MAX)
%•D•(1D)
In the above equation, η% 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 over temperature.
In Figure 21, 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 (for extended temperature range), 10μF ceramic
capacitors are recommended. This decoupling capacitor
The typical LTM4600HV application circuit is shown in
Figure 21. External component selection is primarily
determined by the maximum load current and output
voltage.
Output Voltage Programming and Margining
The PWM controller of the LTM4600HV has an internal
0.6V±1% reference voltage. As shown in the block dia-
gram, a 100k/0.5% internal feedback resistor connects
VOUT and VOSET pins. Adding a resistor RSET from VOSET
pin to SGND pin programs the output voltage:
VO=0.6V • 100k +RSET
RSET
Table 1 shows the standard values of 1% RSET resistor
for typical output voltages:
Table 1.
RSET
(kΩ)Open 100 66.5 49.9 43.2 31.6 22.1 13.7
VO
(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 LTM4600HV. In addition to the feedback
resistor RSET
, several external components are added.
Turn off both transistor QUP and QDOWN to disable the
margining. When QUP is on and QDOWN is off, the output
Figure 2. LTM4600HV Margining Implementation
PGND SGND
4600hv F02
LTM4600HV VOUT
VOSET
RSET RUP
QUP
100k
2N7002
RDOWN
QDOWN
2N7002
APPLICATIONS INFORMATION
LTM4600HV
10
4600hvfd
should be placed directly adjacent the module input pins
in the PCB layout to minimize the trace inductance and
high frequency AC noise.
Output Capacitors
The LTM4600HV is designed for low output voltage ripple.
The bulk output capacitors COUT is chosen with low enough
effective series resistance (ESR) to meet the output voltage
ripple and transient requirements. COUT can be low ESR
tantalum capacitor, low ESR polymer capacitor or ceramic
capacitor (X5R or X7R). 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 ltering 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 capaci-
tance 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 LTM4600HV has a current mode controller, 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 over load condi-
tion, the LTM4600HV 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
LTM4600HV as well as a timer for soft-start and over-
current latchoff. Pulling the RUN/SS pin below 0.8V puts
the LTM4600HV into a low quiescent current shutdown
(IQ ≤ 75μA). Releasing the pin allows an internal 1.2μA
current source to charge up the timing capacitor CSS.
Inside LTM4600HV, there is an internal 1000pF capaci-
tor from RUN/SS pin to ground. If RUN/SS pin has an
external capacitor CSS_EXT to ground, the delay before
starting is about:
tDELAY =1.5V
1.2μA•(CSS_EXT +1000pF)
When the voltage on RUN/SS pin reaches 1.5V, the LT-
M4600HV 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.
VIN to VOUT Stepdown Ratios
There are restrictions in the maximum VIN to VOUT step
down ratio that can be achieved for a given input voltage.
These contraints are shown in the Typical Performance
Characteristics curves labeled “VIN to VOUT Stepdown
Ratio”. Note that additional thermal de-rating may apply.
See the Thermal Considerations and Output Current De-
Rating sections of this data sheet.
APPLICATIONS INFORMATION
LTM4600HV
11
4600hvfd
Table 2. Output Voltage Response Versus Component Matrix *(Refer to Figure 21)
TYPICAL MEASURED VALUES
COUT1 VENDORS PART NUMBER COUT2 VENDORS PART NUMBER
TDK C4532X5R0J107MZ (100μF,6.3V) SANYO POSCAP 6TPE330MIL (330μF, 6.3V)
TAIYO YUDEN JMK432BJ107MU-T ( 100μF, 6.3V) SANYO POSCAP 2R5TPE470M9 (470μF, 2.5V)
TAIYO YUDEN JMK316BJ226ML-T501 ( 22μF, 6.3V) SANYO POSCAP 4TPE470MCL (470μF, 4V)
TAIYO YUDEN JMK316BJ226ML-T501 ( 22μF, 6.3V) SANYO POSCAP 6TPD470M (470μF, 6.3V)
VOUT
(V)
CIN
(CERAMIC)
CIN
(BULK)
COUT1
(CERAMIC)
COUT2
(BULK)
CCOMP C3 VIN
(V)
DROOP
(mV)
PEAK TO PEAK
(mV)
RECOVERY TIME
(μs)
LOAD STEP
(A/μs)
1.2 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 5 35 68 25 5
1.2 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 5 35 70 20 5
1.2 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 5 40 80 20 5
1.2 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 5 49 98 20 5
1.2 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 12 35 68 25 5
1.2 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 12 35 70 20 5
1.2 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 12 40 80 20 5
1.2 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 12 49 98 20 5
1.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 5 36 75 25 5
1.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 5 37 79 20 5
1.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 5 44 84 20 5
1.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 5 61 118 20 5
1.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 12 36 75 25 5
1.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 12 37 79 20 5
1.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 12 44 89 20 5
1.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 12 54 108 20 5
1.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 5 40 81 30 5
1.8 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 5 44 88 20 5
1.8 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 5 46 91 20 5
1.8 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 5 62 128 20 5
1.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 12 40 81 30 5
1.8 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 2.5V NONE 100pF 12 44 85 20 5
1.8 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 12 44 91 20 5
1.8 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 12 62 125 20 5
2.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 4V NONE 100pF 5 48 103 30 5
2.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 5 56 113 30 5
2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 5 57 116 30 5
2.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 5 60 115 25 5
2.5 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 4V NONE 100pF 12 48 103 30 5
2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 12 51 102 30 5
2.5 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 12 56 113 30 5
2.5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 12 70 159 25 5
2.5 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 6.3V NONE 100pF 24 56 112 30 5
2.8 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 6.3V NONE 100pF 24 50 100 30 5
3.3 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 7 64 126 30 5
3.3 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 4V NONE 100pF 7 66 132 30 5
3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 7 82 166 35 5
3.3 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 7 100 200 25 5
3.3 2 × 10μF 35V 150μF 35V 1 × 100μF 6.3V 470μF 4V NONE 100pF 12 52 106 30 5
3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 4V NONE 100pF 12 64 129 35 5
3.3 2 × 10μF 35V 150μF 35V 2 × 100μF 6.3V 330μF 6.3V NONE 100pF 12 64 126 30 5
3.3 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 12 76 144 25 5
3.3 2 × 10μF 35V 150μF 35V 3 × 22μF 6.3V 470μF 6.3V NONE 100pF 24 74 149 30 5
5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 15 188 375 25 5
5 2 × 10μF 35V 150μF 35V 4 × 100μF 6.3V NONE NONE 100pF 20 159 320 25 5
*X7R is recommended for extended temperature range.
APPLICATIONS INFORMATION
LTM4600HV
12
4600hvfd
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 depend upon the size
of the output capacitance, output voltage and load current
characteristic. A minimum external soft-start capacitor
can be estimated from:
CSS_EXT +1000pF >COUT •V
OUT(10–3[F / VS])
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 VIN is a simple solution
VIN
VIN
RRUN/SS
RUN/SS
4600hv F04
LTM4600HV
PGND SGND
VIN
4.5V TO 5.5V
10.8V TO 13.8V
24V TO 28V
RRUN/SS
50k
150k
500k
RECOMMENDED VALUES FOR RUN/SS
Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up
Resistor to VIN
Figure 3. RUN/SS Pin Voltage During Startup and
Short-Circuit Protection
VRUN/SS
3.5V
t
t
75%VO
SWITCHING
STARTS
SOFT-START
CLAMPING
OF IL RELEASED
SHORT-CIRCUIT
LATCHOFF
OUTPUT
OVERLOAD
HAPPENS
SHORT-CIRCUIT
LATCH ARMED
4V
3V
1.5V
4600hv F03
VO
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 VRUN during startup and
short circuit.
APPLICATIONS INFORMATION
LTM4600HV
13
4600hvfd
Enable
The RUN/SS pin can be driven from logic as shown in Figure
5. This function allows the LTM4600HV 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
4600hv F05
LTM4600HV
PGND
2N7002
SGND
ON
Figure 6. Output Voltage Tracking with the LTC2923 Controller
Q1
VCC
VIN
VIN
RONB
VIN
5V
RTB1
RTB2
49.9k
1.8V
3.3V
RTA2
RTA1
RONA
ON
RAMPBUF
TRACK1
TRACK2
FB1
GATE
LTC2923
GND
4600hv F06
RAMP
66.5k
1.5V
LTM4600HV
VIN
VOUT
LTM4600HV
DC/DC
VIN
VOUT
VOSET
VOSET
FB2
SDO
STATUS
Output Voltage Tracking
For the applications that require output voltage tracking,
several LTM4600HV modules can be programmed by the
power supply tracking controller such as the LTC2923.
Figure 6 shows a typical schematic with LTC2923. Coin-
cident, ratiometric and offset tracking for VO rising and
falling can be implemented with different sets of resistor
values. See the LTC2923 data sheet for more details.
EXTVCC 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 LTM4600HV can be directly powered by VIN. The gate
driver current through LDO is about 18mA. The internal
LDO power dissipation can be calculated as:
PLDO_LOSS = 18mA • (VIN – 5V)
The LTM4600HV also provides an external gate driver
voltage pin EXTVCC. If there is a 5V rail in the system, it
is recommended to connect EXTVCC pin to the external 5V
rail. Whenever the EXTVCC pin is above 4.7V, the internal
5V LDO is shut off and an internal 50mA P-channel switch
connects the EXTVCC to internal 5V. Internal 5V is supplied
from EXTVCC until this pin drops below 4.5V. Do not apply
more than 6V to the EXTVCC pin and ensure that EXTVCC
< VIN. The following list summaries the possible connec-
tions for EXTVCC:
1. EXTVCC grounded. Internal 5V LDO is always powered
from the internal 5V regulator.
2. EXTVCC 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 EXTVCC voltage can not be higher than
VIN pin voltage.
3. EXTVCC is recommended for VIN > 20V
Discontinuous Operation and FCB Pin
The FCB pin determines whether the internal bottom
MOSFET remains on when the current reverses. There is
an internal 4.75k pull-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.
APPLICATIONS INFORMATION
LTM4600HV
14
4600hvfd
explanation of the analysis for the thermal models, and the
derating curves. Tables 3 and 4 provide a summary of the
equivalent θJA for the noted conditions. These equivalent
θJA parameters are correlated to the measure values, and
improved with air-fl ow. The case temperature is maintained
at 100°C or below for the derating curves. This allows for
4W maximum power dissipation in the total module with
top and bottom heatsinking, and 2W power dissipation
through the top of the module with an approximate θJC
between 6°C/W to 9°C/W. This equates to a total of 124°C
at the junction of the device.
Safety Considerations
The LTM4600HV modules do not provide isolation from
VIN to VOUT
. There is no internal fuse. If required, a slow
blow fuse with a rating twice the maximum input current
should be provided to protect each unit from catastrophic
failure.
Layout Checklist/Example
The high integration of the LTM4600HV makes the PCB
board layout very simple and easy. However, to optimize
its electrical and thermal performance, some layout con-
siderations are still necessary.
• Use large PCB copper areas for high current path, in-
cluding VIN, PGND and VOUT
. It helps to minimize the
PCB conduction loss and thermal stress
• Place high frequency ceramic input and output capaci-
tors next to the VIN, PGND and VOUT pins to minimize
high frequency noise
• Place a dedicated power ground layer underneath
the unit
• To minimize the via conduction loss and reduce module
thermal stress, use multiple vias for interconnection
between top layer and other power layers
• Do not put vias directly on pad unless they are capped.
• Use a separated SGND ground copper area for com-
ponents connected to signal pins. Connect the SGND
to PGND underneath the unit
Figure 20 gives a good example of the recommended
layout.
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 ciency 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 LTM4600HV modules can be paralleled to
provide higher than 10A output current. Figure 7 shows
the necessary interconnection between two paralleled
modules. The OPTI-LOOP™ current mode control ensures
good current sharing among modules to balance the ther-
mal stress. The new feedback equation for two or more
LTM4600HVs in parallel is:
VOUT =0.6V •
100k
N+RSET
RSET
where N is the number of LTM4600HVs in parallel.
Figure 7. Parallel Two μModules with Load Sharing
VIN VOUT
VIN VOUT
(20AMAX)
4600hv F07
LTM4600HV
PGND SGNDCOMP VOSET
RSET
VIN VOUT
LTM4600HV
PGND
SGNDCOMP VOSET
OPTI-LOOP is a trademark of Linear Technology Corporation.
Thermal Considerations and Output Current Derating
The power loss curves in Figures 8 and 15 can be used
in coordination with the load current derating curves in
Figures 9 to 14, and Figures 16 to 19 for calculating an
approximate θJA for the module with various heatsink-
ing methods. Thermal models are derived from several
temperature measurements at the bench, and thermal
modeling analysis. Application Note 103 provides a detailed
APPLICATIONS INFORMATION
LTM4600HV
15
4600hvfd
Figure 12. BGA HeatsinkFigure 11. No Heatsink
Figure 10. BGA Heatsink
Figure 9. No HeatsinkFigure 8. 1.5V Power Loss Curves
vs Load Current
Figure 14. BGA Heatsink
Figure 13. No Heatsink
Figure 15. 3.3V Power Loss
Curves vs Load Current
Figure 16. No Heatsink
APPLICATIONS INFORMATION
OUTPUT CURRENT (A)
086
4600hv F08
24 10
3.5
4.0
4.5
3.0
2.5
2.0
1.5
1.0
0.5
0
POWER LOSS (W)
5V LOSS
12V LOSS
18V LOSS
VOUT = 1.5V
AMBIENT TEMPERATURE (°C)
50 70
4600hv F09
60 80 90
VIN = 5V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
4
AMBIENT TEMPERATURE (°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600hv F10
60 80 90 100
VIN = 5V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
AMBIENT TEMPERATURE (°C)
50 55 70
4600hv F11
60 65 75 80 85 90
VIN = 12V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
4
AMBIENT TEMPERATURE (°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600hv F12
60
10
9
8
7
6
5
3
4
80 90 100
VIN = 12V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
AMBIENT TEMPERATURE (°C)
40 50 70
4600hv F13
60 80 90
VIN = 18V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
0
1
2
3
4
AMBIENT TEMPERATURE (°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600hv F14
60
10
8
6
4
0
2
80 90 100
VIN = 18V
VOUT = 1.5V
400 LFM
200 LFM
0 LFM
OUTPUT CURRENT (A)
086
4600hv F15
24 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
24V LOSS
AMBIENT TEMPERATURE (°C)
40 70
4600hv F16
6050 80 90
VIN = 12V
VOUT = 3.3V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
4
5
0
1
2
3
LTM4600HV
16
4600hvfd
Figure 17. BGA Heatsink Figure 19. BGA HeatsinkFigure 18. No Heatsink
Table 4. 3.3V Output
DERATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W)
Figures 16, 18 12, 24 Figure 15 0 None 15.2
Figures 16, 18 12, 24 Figure 15 200 None 14.6
Figures 16, 18 12, 24 Figure 15 400 None 13.4
Figures 17, 19 12, 24 Figure 15 0 BGA Heatsink 13.9
Figures 17, 19 12, 24 Figure 15 200 BGA Heatsink 11.1
Figures 17, 19 12, 24 Figure 15 400 BGA Heatsink 10.5
Table 3. 1.5V Output
DERATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W)
Figures 9, 11, 13 5, 12, 18 Figure 8 0 None 15.2
Figures 9, 11, 13 5, 12, 18 Figure 8 200 None 14
Figures 9, 11, 13 5, 12, 18 Figure 8 400 None 12
Figures 10, 12, 14 5, 12, 18 Figure 8 0 BGA Heatsink 13.9
Figures 10, 12, 14 5, 12, 18 Figure 8 200 BGA Heatsink 11.3
Figures 10, 12, 14 5, 12, 18 Figure 8 400 BGA Heatsink 10.25
APPLICATIONS INFORMATION
AMBIENT TEMPERATURE (°C)
40 50
MAXIMUM LOAD CURRENT (A)
70
4600hv F17
60 80 90 100
VIN = 12V
VOUT = 3.3V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
AMBIENT TEMPERATURE (°C)
50 70
4600hv F18.eps
60 80 90
VIN = 24V
VOUT = 3.3V TEMPERATURE
DE-RATING
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
8
6
4
0
2
AMBIENT TEMPERATURE (°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600hv F19.eps
60 80 90
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
VIN = 24V
VOUT = 3.3V TEMPERATURE
DE-RATING
LTM4600HV
17
4600hvfd
Figure 20. Recommended PCB Layout
VIN
PGND
TOP LAYER
VOUT
4600hv F20
LOAD
CIN
LTM4600HV Frequency Adjustment
The LTM4600HV is designed to typically operate at 850kHz
across most input and output conditions. The control ar-
chitecture is constant on time valley mode current control.
The fADJ pin is typically left open or decoupled with an
optional 1000pF capacitor. The switching frequency has
been optimized to maintain constant output ripple over the
operating conditions. The equations for setting the operat-
ing frequency are set around a programmable constant on
time. This on time is developed by a programmable current
into an on board 10pF capacitor that establishes a ramp
that is compared to a voltage threshold equal to the output
voltage up to a 2.4V clamp. This ION current is equal to:
ION = (VIN – 0.7V)/110k, with the 110k onboard resistor
from VIN to fADJ. The on time is equal to tON = (VOUT/ION)
• 10pF and tOFF = ts – tON. The frequency is equal to: Freq.
= DC/tON. The ION current is proportional to VIN, and the
regulator duty cycle is inversely proportional to VIN, there-
fore the step-down regulator will remain relatively constant
frequency as the duty cycle adjustment takes place with
lowering VIN. The on time is proportional to VOUT up to a
2.4V clamp. This will hold frequency relatively constant
with different output voltages up to 2.4V. The regulator
switching period is comprised of the on time and off time
as depicted in the following waveform. The on time is
equal to tON = (VOUT/ION) • 10pF and tOFF = ts – tON. The
frequency is equal to: Frequency = DC/tON).
The LTM4600HV has a minimum (tON) on time of 100
nanoseconds and a minimum (tOFF) off time of 400
nanoseconds. The 2.4V clamp on the ramp threshold as
a function of VOUT will cause the switching frequency to
increase by the ratio of VOUT/2.4V for 3.3V and 5V outputs.
This is due to the fact the on time will not increase as VOUT
increases past 2.4V. Therefore, if the nominal switching
frequency is 850kHz, then the switching frequency will
increase to ~1.2MHz for 3.3V, and ~1.7MHz for 5V out-
puts due to Frequency = (DC/tON) When the switching
frequency increases to 1.2MHz, then the time period tS is
reduced to ~833 nanoseconds and at 1.7MHz the switching
period reduces to ~588 nanoseconds. When higher duty
cycle conversions like 5V to 3.3V and 12V to 5V need to
be accommodated, then the switching frequency can be
lowered to alleviate the violation of the 400ns minimum
off time. Since the total switching period is tS = tON + tOFF
,
tOFF will be below the 400ns minimum off time. A resistor
from the fADJ pin to ground can shunt current away from
the on time generator, thus allowing for a longer on time
and a lower switching frequency. 12V to 5V and 5V to
3.3V derivations are explained in the data sheet to lower
switching frequency and accommodate these step-down
conversions.
Equations for setting frequency for 12V to 5V:
I
ON = (VIN – 0.7V)/110k; ION = 103μA
frequency = (ION/[2.4V • 10pF]) • DC = 1.79MHz;
DC = duty cycle, duty cycle is (VOUT/VIN)
t
S = tON + tOFF
, tON = on-time, tOFF = off-time of the
switching period; tS = 1/frequency
tOFF must be greater than 400ns, or tS – tON > 400ns.
t
ON = DC • tS
1MHz frequency or 1μs period is chosen for 12V to 5V.
tOFF
PERIOD ts
tON
4602 F25
(DC) DUTY CYCLE = tON
ts
DC = =
tON
ts
FREQ = DC
tON
VOUT
VIN
APPLICATIONS INFORMATION
LTM4600HV
18
4600hvfd
t
ON = 0.41 • 1μs ≅ 410ns
t
OFF = 1μs – 410ns ≅ 590ns
tON and tOFF are above the minimums with adequate guard
band.
Using the frequency = (ION/[2.4V • 10pF]) • DC, solve for
ION = (1MHz • 2.4V • 10pF) • (1/0.41) ≅ 58μA. ION current
calculated from 12V input was 103μA, so a resistor from
fADJ to ground = (0.7V/15k) = 46μA. 103μA – 46μA =
57μA, sets the adequate ION current for proper frequency
range for the higher duty cycle conversion of 12V to
5V. Input voltage range is limited to 9V to 16V. Higher
input voltages can be used without the 15k on fADJ. The
inductor ripple current gets too high above 16V, and the
400ns minimum off-time is limited below 9V.
Equations for setting frequency for 5V to 3.3V:
I
ON = (VIN – 0.7V)/110k; ION = 39μA
frequency = (ION/[2.4V • 10pF]) • DC = 1.07MHz;
DC = duty cycle, duty cycle is (VOUT/VIN)
t
S = tON + tOFF
, tON = on-time, tOFF = off-time of the
switching period; tS = 1/frequency
tOFF must be greater than 400ns, or tS – tON > 400ns.
t
ON = DC • tS
~450kHz frequency or 2.22μs period is chosen for 5V to
3.3V. Frequency range is about 450kHz to 650kHz from
4.5V to 7V input.
t
ON = 0.66 • 2.22μs ≅ 1.46μs
t
OFF = 2.22μs – 1.46μs ≅ 760ns
tON and tOFF are above the minimums with adequate guard
band.
Using the frequency = (ION/[2.4V • 10pF]) • DC, solve for
ION = (450kHz • 2.4V • 10pF) • (1/0.66) ≅ 16μA. ION current
calculated from 5V input was 39μA, so a resistor from fADJ
to ground = (0.7V/30.1k) = 23μA. 39μA – 23μA = 16μA,
sets the adequate ION current for proper frequency range
for the higher duty cycle conversion of 5V to 3.3V. Input
voltage range is limited to 4.5V to 7V. Higher input voltages
can be used without the 30.1k on fADJ. The inductor ripple
current gets too high above 7V, and the 400ns minimum
off-time is limited below 4.5V.
5V to 3.3V at 8A
APPLICATIONS INFORMATION
4600 F22
R2
22.1k
1%
R1
30.1k
EXTVCC
RUN/SS
COMP
FCB
VOUT
5V TO 3.3V AT 8A WITH fADJ = 30.1k
LTM4600HV MINIMUM ON-TIME = 100ns
LTM4600HV MINIMUM OFF-TIME = 400ns
C1, C3: TDK C3216X5R1E106MT
C2: TAIYO YUDEN, JMK316BJ226ML
C4: SANYO POSCAP, 6TPE330MIL
PGOOD
VOSET
SVIN
PGNDSGND
4.5V TO 7V
3.3V AT 8A
C1
10μF
25V
C3
10μF
25V
C4
330μF
6.3V
C2
22μF
C5
100pF
VIN
LTM4600HV
fADJ
RUN/SOFT-START
OPEN DRAIN
EFFICIENCY = 94%
+
LTM4600HV
19
4600hvfd
Figure 21. Typical Application, 5V to 24V Input, 0.6V to 5V Output, 10A Max
VIN to VOUT Stepdown Ratio for
12V to 5V and 5V to 3.3V
12V to 5V at 8A
APPLICATIONS INFORMATION
4600 F23
R2
13.7k
1%
R1
15k
EXTVCC
RUN/SS
COMP
FCB
VOUT
12V TO 5V AT 8A WITH fADJ = 15k
LTM4600HV MINIMUM ON-TIME = 100ns
LTM4600HV MINIMUM OFF-TIME = 400ns
C1, C3: TDK C3216X5R1E106MT
C2: TAIYO YUDEN, JMK316BJ226ML
C4: SANYO POSCAP, 6TPE330MIL
PGOOD
VOSET
SVIN
PGNDSGND
9V TO 16V
5V AT 8A EFFICIENCY = 94%
C1
10μF
25V
C3
10μF
25V
C4
330μF
6.3V
C2
22μF
C5
100pF
VIN
LTM4600HV
fADJ
RUN/SOFT-START
OPEN DRAIN
+
VIN (V)
4600 F24
1357911131517
3.3V: fADJ = 30.1k
5V: fADJ = 15k
5V AT 8A
3.3V AT 8A
VOUT (V)
5.0
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0
4600HV F21
VOUT
EXTVCC
fADJ
VOSET
FCB
COMP
PGOOD
VOUT
(MULTIPLE PINS)
VOUT
RUN/SS
SGND
PGND
(MULTIPLE PINS)
COUT1
22μF
6.3V
×3
REFER TO
TABLE 2
COUT2
470μF
REFER TO
TABLE 2
GND
0.6V TO 5V
REFER TO STEP DOWN
RATIO GRAPH
C4
OPT
VIN
5V TO 24V
GND
CIN (CER)
10μF
2x
CIN (BULK)
150μF
C3
100pF
R1
66.5k
REFER TO
TABLE 1
VIN
(MULTIPLE PINS)
LTM4600HV
SVIN
+
+
TYPICAL APPLICATION
LTM4600HV
20
4600hvfd
P
ara
ll
e
l
O
pera
ti
on an
d
L
oa
d
Sh
ar
i
ng
4600hv TA02
R4
15.8k
1%
EXTVCC
RUN
COMP
FCB
VOUT
VOUT = 0.6V • ([100k/N] + RSET)/RSET
WHERE N = 2
C1, C3, C7, C8: TAIYO YUDEN, GDK316BJ106ML
C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501
C5, C10: SANYO POSCAP, 4TPE470MCL
PGOOD
VOSET
SVIN
PGNDSGND
2.5V AT 20A
4.5V TO 24V
2.5V
C7
10μF
35V
C8
10μF
35V
C10
470μF
4V
C9
22μF
x3
VIN
LTM4600HV
fADJ
R1
100k
EXTVCC
RUN
COMP
FCB
VOUT
PGOOD
VOSET
SVIN
PGNDSGND
C1
10μF
35V
RUN/SOFT-START
C3
10μF
35V
C4
220pF
C5
470μF
4V
C2
22μF
x3
VIN
LTM4600HV
fADJ
+
+
TOTAL LOAD
0
INDIVIDUAL SHARE
12
10
8
6
4
2
0
510 15
4600hv TA03
20
IOUT1
IOUT2
12VIN
2.5VOUT
20AMAX
Current Sharing Between Two
LTM4600HV Modules
TYPICAL APPLICATION
LTM4600HV
21
4600hvfd
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
4PAD 1
CORNER
XY
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
1918171676543
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
11109
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
MYXeee
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
1817
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
GH
J
L
M
N
P
R
T
K
LGA Package
104-Lead (15mm × 15mm)
(Reference LTM DWG # 05-05-1800)
PACKAGE DESCRIPTION
LTM4600HV
22
4600hvfd
PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME PIN NAME
A1 - B1 VIN C1 - D1 VIN E1 - F1 VIN G1 PGND H1 -
A2 - B2 - C2 - D2 - E2 - F2 - G2 - H2 -
A3 VIN B3 - C3 - D3 - E3 - F3 - G3 - H3 -
A4 - B4 - C4 - D4 - E4 - F4 - G4 - H4 -
A5 VIN B5 - C5 - D5 - E5 - F5 - G5 - H5 -
A6 - B6 - C6 - D6 - E6 - F6 - G6 - H6 -
A7 VIN B7 - C7 - D7 - E7 - F7 - G7 - H7 PGND
A8 - B8 - C8 - D8 - E8 - F8 - G8 - H8 -
A9 VIN B9 - C9 - D9 - E9 - F9 - G9 - H9 PGND
A10 - B10 - C10 VIN D10 - E10 VIN F10 - G10 - H10 -
A11 VIN B11 - C11 - D11 - E11 - F11 - G11 - H11 PGND
A12 - B12 - C12 VIN D12 - E12 VIN F12 - G12 - H12 -
A13 VIN B13 - C13 - D13 - E13 - F13 - G13 - H13 PGND
A14 - B14 - C14 VIN D14 - E14 VIN F14 - G14 - H14 -
A15 fADJ B15 - C15 - D15 - E15 - F15 - G15 - H15 PGND
A16 - B16 - C16 - D16 - E16 - F16 - G16 - H16 -
A17 SVIN B17 - C17 - D17 - E17 - F17 - G17 - H17 PGND
A18 - B18 - C18 - D18 - E18 - F18 - G18 - H18 -
A19 EXTVCC B19 - C19 - D19 - E19 - F19 - G19 - H19 -
A20 - B20 - C20 - D20 - E20 - F20 - G20 - H20 -
A21 VOSET 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 VOUT R2 VOUT T2 VOUT
J3 - K3 - L3 - M3 - N3 - P3 - R3 - T3 -
J4 - K4 - L4 PGND M4 PGND N4 PGND P4 VOUT R4 VOUT T4 VOUT
J5 - K5 - L5 - M5 - N5 - P5 - R5 - T5 -
J6 - K6 - L6 PGND M6 PGND N6 PGND P6 VOUT R6 VOUT T6 VOUT
J7 - K7 PGND L7 - M7 - N7 - P7 - R7 - T7 -
J8 - K8 L8 PGND M8 PGND N8 PGND P8 VOUT R8 VOUT T8 VOUT
J9 - K9 PGND L9 - M9 - N9 - P9 - R9 - T9 -
J10 - K10 L10 PGND M10 PGND N10 PGND P10 VOUT R10 VOUT T10 VOUT
J11 - K11 PGND L11 - M11 - N11 - P11 - R11 - T11 -
J12 - K12 - L12 PGND M12 PGND N12 PGND P12 VOUT R12 VOUT T12 VOUT
J13 - K13 PGND L13 - M13 - N13 - P13 - R13 - T13 -
J14 - K14 - L14 PGND M14 PGND N14 PGND P14 VOUT R14 VOUT T14 VOUT
J15 - K15 PGND L15 - M15 - N15 - P15 - R15 - T15 -
J16 - K16 - L16 PGND M16 PGND N16 PGND P16 VOUT R16 VOUT T16 VOUT
J17 - K17 PGND L17 - M17 - N17 - P17 - R17 - T17 -
J18 - K18 - L18 PGND M18 PGND N18 PGND P18 VOUT R18 VOUT T18 VOUT
J19 - K19 - L19 - M19 - N19 - P19 - R19 - T19 -
J20 - K20 - L20 PGND M20 PGND N20 PGND P20 VOUT R20 VOUT T20 VOUT
J21 - K21 - L21 - M21 - N21 - P21 - R21 - T21 -
J22 - K22 - L22 PGND M22 PGND N22 PGND P22 VOUT R22 VOUT T22 VOUT
J23 PGOOD K23 - L23 - M23 - N23 - P23 - R23 - T23 -
Pin Assignment Tables
(Arranged by Pin Number)
PACKAGE DESCRIPTION
LTM4600HV
23
4600hvfd
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 representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
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
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
R2
R4
R6
R8
R10
R12
R14
R16
R18
R20
R22
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
T2
T4
T6
T8
T10
T12
T14
T16
T18
T20
T22
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
VOUT
PIN NAME
A3
A5
A7
A9
A11
A13
VIN
VIN
VIN
VIN
VIN
VIN
B1 VIN
C10
C12
C14
VIN
VIN
VIN
D1 VIN
E10
E12
E14
VIN
VIN
VIN
F1 VIN
PIN NAME
A15 fADJ
A17 SVIN
A19 EXTVCC
A21 VOSET
B23 COMP
D23 SGND
F23 RUN/SS
G23 FCB
J23 PGOOD
Pin Assignment Tables
(Arranged by Pin Number)
PACKAGE DESCRIPTION
LTM4600HV
24
4600hvfd
© LINEAR TECHNOLOGY CORPORATION 2005
LT 0807 REV D • PRINTED IN USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com
1
.
8V
,
10A
R
egu
l
a
t
or
4600hv TA04
C1, C2: TAIYO YUDEN, GDK316BJ106ML
C3: TAIYO YUDEN, JMK316BJ226ML-T501
C4: SANYO POSCAP, 4TPE470MCL
1.8V AT 10A
4.5V TO 22V
R1
100k
EXTVCC
RUN
COMP
FCB
VOUT
PGOOD
VOSET
SVIN
PGNDSGND
C1
10μF
35V
C2
10μF
35V
C5
100pF
C4
470μF
4V
PGOOD
C3
22μF
x3
VIN
LTM4600HV
fADJ
R2
49.9k
1%
+
This product contains technology licensed from Silicon Semiconductor Corporation. ®
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
LT3825/LT3837 Synchronous Isolated Flyback Controllers No Optocoupler Required; 3.3V, 12A Output; Simple Design
LTM4600 10A DC/DC μModule Basic 10A DC/DC μModule
LTM4601 12A DC/DC μModule with PLL, Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation to 48A, LTM4601-1 Version has no
Remote Sensing
LTM4602 6A DC/DC μModule Pin Compatible with the LTM4600
LTM4603 6A DC/DC μModule with PLL and Outpupt Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation to 48A, LTM4601-1 Version has no
Remote Sensing, Pin Compatible with the LTM4601
TYPICAL APPLICATION
RELATED PARTS
