PRERELEASE
LTM4600HV
1
4600hvp
Electrical Specifications Subject to Change
, 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.
LOAD CURRENT (A)
0
EFFICIENCY (%)
6
4600HV TA01b
24 8
10
80
90
100
70
60
50
40
30
1.5VOUT
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.
■ 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 28V
■ 10A DC, 12A Peak Output Current
■ Parallel Two µModules™ for 20A Output Current
■ 0.6V to 5V Output Voltage
■ 1.5% Regulation of Output Voltage
■ Ultrafast Transient Response
■ Current Mode Control
■ Up to 92% Effi ciency
■ Programmable Soft-Start
■ Output Overvoltage Protection
■ Optional Short-Circuit Shutdown Timer
■ Pb-Free (e4) RoHS Compliant Package
■ Small Footprint, Low Profi le (15mm × 15mm ×
2.8mm) LGA Package
10A µModule Power Supply with 4.5V to 28V Input
APPLICATIO S
U
FEATURES DESCRIPTIO
U
TYPICAL APPLICATIO
U
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
66.5k
*REVIEW DE-RATING CURVE AT
THE HIGHER INPUT VOLTAGE
PRERELEASE
LTM4600HV
2
4600hvp
RUN/SS
FCB
PGOOD
VIN
PGND
VOUT
COMP
SGND
EXTVCC
VOSET
FADJ
SVIN
LGA PACKAGE
104-LEAD (15mm × 15mm × 2.8mm)
TOP VIEW
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) ... –40°C to 85°C
Junction Temperature ........................................... 125°C
Storage Temperature Range ................... –65°C to 150°C
ORDER PART
NUMBER
LGA PART
MARKING
TJMAX = 125°C, θJA = 15°C/W
Consult LTC Marketing for parts specifi ed with wider operating temperature ranges.
LTM4600HVEV
LTM4600HVIV
LTM4600HVEV
LTM4600HVIV
(Note 1)
The ● denotes the specifi cations which apply over the –40°C to 85°C
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.
ELECTRICAL CHARACTERISTICS
ABSOLUTE AXI U RATI GS
W
WW
U
PACKAGE/ORDER I FOR ATIO
UUW
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
VIN(DC) Input DC Voltage AbsMax 28V for Tolerance on 24V Inputs ●4.5 28 V
VOUT(DC) Output Voltage
V
IN = 12V, VOUT = 1.5V, IOUT = 0A
V
IN = 12V, VOUT = 1.5V, IOUT = 10A
V
IN = 5V, VOUT = 1.5V, IOUT = 0A
FCB = 0 ●1.478 1.50 1.522 V
Input Specifi cations
VIN(UVLO) Under Voltage Lockout Threshold IOUT = 0A 3.4 4 V
IINRUSH(VIN) Input Inrush Current at Startup
V
IN = 5V
V
IN = 12V
V
IN = 24V
IOUT = 0A. VOUT = 1.5V, FCB = 0
0.6
0.7
A
A
A
IQ(VIN) Input Supply Bias Current
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, VIN = 12V
Shutdown, RUN = 0, VIN = 28V
IOUT = 0A, EXTVCC Open
1.2
42
1.8
36
15
40
mA
mA
mA
mA
µA
µA
Min On Time 50 100 ns
Min Off Time 250 400 ns
IS(VIN) Input Supply Current
V
IN = 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
0.8
A
A
A
A
PRERELEASE
LTM4600HV
3
4600hvp
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
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 LTM4600HVI is
guaranteed and tested over the –40°C to 85°C temperature range.
Note 3: Refer to current de-rating curves and thermal application note.
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 = 1.5V (Note 3)
0
TBD
10
10
A
A
ΔVOUT/ΔVIN Line Regulation Accuracy
I
OUT = 0A
VOUT = 1.5V. FCB = 0V
●0.15 0.3 %
ΔVOUT/ΔIOUT Load Regulation Accuracy
V
IN = 5V
V
IN = 12V
VOUT = 1.5V. FCB = 0V
0A to 10A
●
±1
±1
%
%
VOUT(AC) Output Ripple Voltage
V
IN = 24V, VOUT = 1.5V, FCB = 0V
V
IN = 12V, VOUT = 1.5V, FCB = 0V
V
IN = 5V, VOUT = 1.5V, FCB = 0V
IOUT = 0A
●
25
20
15
mVP-P
mVP-P
mVP-P
Fs Output Ripple Voltage Frequency FCB = 0V, IOUT = 5A, VIN = 12V, VOUT =
1.5V
800 kHz
tSTART Turn-On Time
V
IN = 12V
V
IN = 5V
VOUT = 1.5V, IOUT = 10A
0.5
0.7
ms
ms
ΔVOUTLS Voltage Drop for Dynamic Load Step
VIN = 12V, VOUT = 1.5V
Load Step: 0A to 5A/µs
COUT = 3 • 22µF 6.3V, 470µF 4V Pos Cap,
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
V
IN = 24V, VOUT = 1.5V
V
IN = 12V, VOUT = 1.5V
V
IN = 5V, VOUT = 1.5V
Output Voltage in Foldback
17
17
17
A
A
A
Control Stage
VOSET Voltage at VOSET Pin IOUT = 0A, VOUT = 1.5V ●0.594 0.6 0.606 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 = 0, FCB = 0V 100 mV
IEXTVCC Current into EXTVCC Pin FCB = 0V, VOUT = 1.5V, IOUT = 0A 16 mA
RFBHI Resistor Between VOUT and FB 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 1 2.5 %
VPGL PGOOD Low Voltage IPGOOD = 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 TA = 25°C, VIN = 12V. Per typical application (front page) confi guration.
ELECTRICAL CHARACTERISTICS
PRERELEASE
LTM4600HV
4
4600hvp
LOAD CURRENT (A)
0
EFFICIENCY (%)
50
60
70
610
4600hv G02
40
30
20 24 8
80
90
100
12
0.6VOUT
1.2VOUT
1.5VOUT
2.5VOUT
3.3VOUT
Effi ciency vs Load Current
w
ith 5VIN (FCB = 0)
TYPICAL PERFOR A CE CHARACTERISTICS
UW
LOAD CURRENT (A)
0
100
90
80
70
60
50
40
30 610
4600hv G01
24 812
EFFICIENCY (%)
0.6VOUT
1.2VOUT
1.5VOUT
2.5VOUT
Effi ciency vs Load Current
with 12V
IN (
FCB = 0
)
Effi ciency vs Load Current
with 24VIN (FCB = 0)
LOAD CURRENT (A)
0
EFFICIENCY (%)
6
4600hv G03
24 8
10
80
90
100
70
60
50
40
30
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT
5VOUT
Effi ciency vs Load Current
with Different FCB Settin
g
s
LOAD CURRENT (A)
20
50
40
30
90
80
70
60
4600hv G04
EFFICIENCY (%)
0.1 10
1
FCB = GND
VOUT > 0.7V
1.2V Transient Response
(See Figure 21)
1.5V Transient Response
(See Figure 21)
1.8V Transient Response
(
See Fi
g
ure 21
)
2.5V Transient Response
(
See Fi
g
ure 21
)
3.3V Transient Response
(
See Fi
g
ure 21
)
25µs/DIV
4600hv G05
1.2V AT 5A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600hv G06
1.5V AT 5A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600hv G07
1.8V AT 5A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600hv G08
2.5V AT 5A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
25µs/DIV
4600hv G09
3.3V AT 5A/µs LOAD STEP
COUT = 3 • 22µF 6.3V CERAMICS
470µF 4V SANYO POS CAP
C3 = 100pF
VOUT = 50mV/DIV
IOUT = 5A/DIV
PRERELEASE
LTM4600HV
5
4600hvp
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 G17
10 2420
VOUT (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
4600hv G16
4.03.53.02.52.01.00.5 1.5
OUTPUT CURRENT (A)
OUTPUT VOLTAGE (V)
0
18
16
14
12
10
8
6
4
2
0
4600hv G14
654321
CURRENT LIMIT (A)
TYPICAL PERFOR A CE CHARACTERISTICS
UW
Start-Up, IOUT = 0A
(See Figure 21)
Start-Up, IOUT = 10A
(
Resistive Load
)
(
See Fi
g
ure 21
)
Short-Circuit Protection,
I
OUT
= 0A
(
See Fi
g
ure 21
)
Short-Circuit Protection,
I
OUT
= 10A
(
See Fi
g
ure 21
)
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)
Current Limit with 12V
IN
Current Limit with 9V
IN
Current Limit with 5VIN
OUTPUT VOLTAGE (V)
0
18
16
14
12
10
8
6
4
2
0
4600hv G15
654321
CURRENT LIMIT (A)
V
IN
to V
OUT
Ste
p
down Ratio
PRERELEASE
LTM4600HV
6
4600hvp
PI FU CTIO S
UUU
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): An internal resistor from VIN to this pin
sets the one-shot timer current, thereby setting the switch-
ing frequency.
SVIN (Pin A17): Supply Pin for Internal PWM Controller.
Leave this pin open or add additional decoupling capaci-
tance.
EXTVCC (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 EXTVCC
voltage should never be higher than VIN.
VOSET (Pin A21): The Negative Input of The Error Am-
plifi 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 PWRGD 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)
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
S
K
4600hv PN01
PRERELEASE
LTM4600HV
7
4600hvp
WU
DECOUPLI G REQUIRE E TS
U
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
CIN External Input Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 1.5V)
IOUT = 10A, 2x 10µF 35V Ceramic 20 µF
COUT External Output Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 1.5V)
IOUT = 10A, Refer to Table 2 in the
Applications Information Section
100 200 µF
SI PLIFIED
W
BLOCK DIAGRA
W
T
A = 25°C, VIN = 12V. Use Figure 1 confi guration.
Figure 1. Simplifi ed LTM4600HV Block Diagram
4600hv F01
RUN/SS LTM4600HV
VOSET
EXTVCC
SGND
FADJ
FCB
1000pF
Q1
Q2
VOUT, 1.5V/10A MAX
PGND
VIN, 4.5V TO 28V ABS MAX
SVIN
COMP
PGOOD
R6
66.5k
100k
0.5%
4.75k
1.5µFCIN
15µF
6.3V
COUT
10Ω
INT
COMP
CONTROLLER
PRERELEASE
LTM4600HV
8
4600hvp
OPERATIO
U
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 800kHz 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.
Current mode control provides cycle-by-cycle fast current
limit. In addition, foldback current limiting is provided
in an over-current condition while VFB 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 5V.
The FCB pin has a 4.25k resistor to ground, so a resistor
to VIN can set the voltage on the FCB pin.
When EXTVCC 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
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.
PRERELEASE
LTM4600HV
9
4600hvp
APPLICATIO S I FOR ATIO
WUUU
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:
()••(%)
() .
RR V M
RR k V
SET UP O
SET UP
1
100 06
+
+Ω
=
RV M
RkR V
SET O
SET DOWN
••(–%)
()
.
1
100 06
+Ω =
Input Capacitors
The LTM4600HV 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 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:
DV
V
O
IN
=
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
IIDD
CIN RMS OMAX
() ()
%••( )=−
η1
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.
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 LTM4600HV 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 LTM4600HV has an internal
0.6V±1% reference voltage. As shown in the block diagram,
a 100k/0.5% internal feedback resistor connects VOUT and
FB pins. Adding a resistor RSET from VOSET pin to SGND
pin programs the output voltage:
VV
kR
R
OSET
SET
=+
06 100
.•
Table 1 shows the standard vaules 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.
PGND SGND
4600hv F02
LTM4600HV VOUT
VOSET
RSET RUP
QUP
100k
2N7002
RDOWN
QDOWN
2N7002
PRERELEASE
LTM4600HV
10
4600hvp
APPLICATIO S I FOR ATIO
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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 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. 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 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 ≤ 40µA). 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:
tV
ACpF
DELAY SS EXT
=µ+
15
12 1000
.
.•( )
_
When the voltage on RUN/SS pin reaches 1.5V, the
LTM4600HV internal switches are operating with a clamp-
ing 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.
PRERELEASE
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11
4600hvp
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Table 2. Output Voltage Response Versus Component Matrix
TYPICAL MEASURED VALUES
COUT1 VENDORS PART NUMBER COUT2 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)
TAIYO YUDEN JMK316BJ226ML-T501 ( 22µF, 6.3V) SANYO POS CAP 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 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
52 × 10µF 25V 150µF 35V 4 × 100µF 6.3V NONE NONE 100pF 15 188 375 25 5
52 × 10µF 25V 150µF 35V 4 × 100µF 6.3V NONE NONE 100pF 20 159 320 25 5
1.5 2 × 10µF 25V 150µF 35V 3 × 22µF 6.3V 470µF 6.3V NONE 100pF 24 45 89 25 5
2.8 2 × 10µF 25V 150µF 35V 3 × 22µF 6.3V 470µF 6.3V NONE 100pF 24 50 100 30 5
2.5 2 × 10µF 25V 150µF 35V 3 × 22µF 6.3V 470µF 6.3V NONE 100pF 24 56 112 30 5
3.3 2 × 10µF 25V 150µF 35V 3 × 22µF 6.3V 470µF 6.3V NONE 100pF 24 74 149 30 5
PRERELEASE
LTM4600HV
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:
CpFCVFV
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 VIN is a simple solution
VIN
VIN
500k
RUN/SS
4600hv F04
LTM4600HV
PGND SGND
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.
PRERELEASE
LTM4600HV
13
4600hvp
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
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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 in-
ternal 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
connections 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 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
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14
4600hvp
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Thermal Considerations and Output Current Derating
The power loss curves in Figures 8 and 15 can be used
in coordination with the load current de-rating curves in
Figures 9 to 14 and Figures 16 to 19 for calculating an
approximate θJA 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
θJA 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 θJA
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 θJA 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 θJA of 9°C/W with no
heatsink. Each of the de-rating curves in Figures 9 to
14 or Figures 16 to 19 can be used with the appropriate
power loss curve in either fi gure 8 or fi gure 15 to derive an
approximate θJA. Tables 3 and 4 provide the approximate
θJA for Figures 9 to 14, and Figures 16 to 19. 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 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 en-
sures good current sharing among modules to balance
the thermal stress. The new feedback equation for two or
more LTM4600HVs in parallel is:
VV
k
NR
R
OUT
SET
SET
=
+
06
100
.•
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.
PRERELEASE
LTM4600HV
15
4600hvp
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
VO = 1.5V
400 LFM
200 LFM
0 LFM
Figure 12. BGA Heatsink
AMBIENT TEMPERATURE (°C)
50 55 70
4600hv F11
60 65 75 80 85 90
VIN = 12V
VO = 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
4600hv F10
60 80 90 100
VIN = 5V
VO = 1.5V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
Figure 10. BGA Heatsink
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AMBIENT TEMPERATURE (°C)
50 70
4600hv F09
60 80 90
VIN = 5V
VO = 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)
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
24V LOSS
Figure 8. 1.5V Power Loss Curves
vs Load Current
AMBIENT TEMPERATURE (°C)
50
MAXIMUM LOAD CURRENT (A)
70
4600hv F14
60
10
8
6
4
0
2
80 90 100
VIN = 24V
VO = 1.5V
400 LFM
200 LFM
0 LFM
Figure 14. BGA Heatsink
AMBIENT TEMPERATURE (°C)
40 50 70
4600hv F13
60 80 90
VIN = 24V
VO = 1.5V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
5
0
1
2
3
4
Figure 13. No Heatsink
PRERELEASE
LTM4600HV
16
4600hvp
Figure 17. BGA HeatsinkFigure 16. No Heatsink
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
Figure 19. BGA Heatsink
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
Figure 18. No Heatsink
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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
Figure 15. 3.3V Power Loss Curves vs Load Current
AMBIENT TEMPERATURE (°C)
40 70
4600hv F16
6050 80 90
VIN = 12V
VO = 3.3V
400 LFM
200 LFM
0 LFM
MAXIMUM LOAD CURRENT (A)
10
9
8
7
6
4
5
0
1
2
3
AMBIENT TEMPERATURE (°C)
40 50
MAXIMUM LOAD CURRENT (A)
70
4600hv F17
60 80 90 100
VIN = 12V
VO = 3.3V
400 LFM
200 LFM
0 LFM
10
9
8
7
6
5
4
PRERELEASE
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17
4600hvp
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Table 4. 3.3V Output
DE-RATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W)
Figures 16, 18 12, 24 Figure 15 0 None 13.5
Figures 16, 18 12, 24 Figure 15 200 None 11.6
Figures 16, 18 12, 24 Figure 15 400 None 10.4
Figures 16, 18 12, 24 Figure 15 0 BGA Heatsink 9.5
Figures 16, 18 12, 24 Figure 15 200 BGA Heatsink 6
Figures 16, 18 12, 24 Figure 15 400 BGA Heatsink 4.77
Table 3. 1.5V Output
DE-RATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEATSINK θJA (°C/W)
Figures 9, 11, 13 5, 12, 24 Figure 8 0 None 13.5
Figures 9, 11, 13 5, 12, 24 Figure 8 200 None 11
Figures 9, 11, 13 5, 12, 24 Figure 8 400 None 9
Figures 10, 12, 14 5, 12, 24 Figure 8 0 BGA Heatsink 9.5
Figures 10, 12, 14 5, 12, 24 Figure 8 200 BGA Heatsink 6.25
Figures 10, 12, 14 5, 12, 24 Figure 8 400 BGA Heatsink 4.5
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Figure 20. Recommended PCB Layout
VIN
PGND
TOP LAYER
VOUT
SGND
4600hv F20
LOAD
CIN
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 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 20 gives a good example of the recommended
layout.
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LTM4600HV
19
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Figure 21. Typical Application, 5V to 24V Input, 0.6V to 5V Output, 10A Max
4600hv F21
VOUT
EXTVCC
FADJ
VOSET
FCB
COMP
PGOOD
VOUT
(MULTIPLE PINS)
RUN/SS
SGND
PGND
(MULTIPLE PINS)
C2
22µF
6.3V
×3
REFER TO
TABLE 2
COUT
470µF
REFER TO
TABLE 2
0.6V TO 5V
C4
OPT
5V TO 24V
CIN
10µF
2x
C1
150µF
C3
100pF
R1
66.5k
REFER TO
TABLE 2
VIN
(MULTIPLE PINS)
LTM4600HV
SVIN
+
TYPICAL APPLICATIO
U
PRERELEASE
LTM4600HV
20
4600hvp
P
ara
ll
e
l
O
pera
ti
on an
d
L
oa
d
Sh
ar
i
ng
4600hv F22
R4
15.8k
1%
EXTVCC
RUN
COMP
FCB
VOUT
VOUT = 0.6V • ([100k/N] + RSET)/RSET
WHERE N = 2
C1, C3, C7, C8: TBD
C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501
C5, C10: SANYO POS CAP, 4TPE470MCL
PGOOD
FB
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
FSET
R1
100k
EXTVCC
RUN
COMP
FCB
VOUT
PGOOD
FB
SVIN
PGNDSGND
C1
10µF
35V
RUN/SOFT-START
C3
10µF
35V
C4
220pF
C5
470µF
4V
C2
22µF
x3
VIN
LTM4600HV
FSET
TOTAL LOAD
0
INDIVIDUAL SHARE
12
10
8
6
4
2
0
510 15 20
4600hv F23
25
IOUT1
IOUT2
12VIN
2.5VOUT
20AMAX
Current Sharing Between Two
LTM4600HV Modules
TYPICAL APPLICATIO
U
PRERELEASE
LTM4600HV
21
4600hvp
PACKAGE DESCRIPTIO
U
LGA Package
104-Lead (15mm × 15mm)
(Reference LTM 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
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
PRERELEASE
LTM4600HV
22
4600hvp
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 -
PACKAGE DESCRIPTIO
U
Pin Assignment Tables
(Arranged by Pin Number)
PRERELEASE
LTM4600HV
23
4600hvp
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
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)
PRERELEASE
PRERELEASE
LTM4600HV
24
4600hvp
© 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
R
egu
l
a
t
or
4600hv F24
C1, C2: TBD
C3: TAIYO YUDEN, JMK316BJ226ML-T501
C4: SANYO POS CAP, 4TPE470MCL
1.8V AT 10A
4.5V TO 24V
R1
100k
EXTVCC
RUN
COMP
FCB
VOUT
PGOOD
FB
SVIN
PGNDSGND
C1
10µF
35V
C2
10µF
35V
C5
100pF
C4
470µF
4V
PGOOD
C3
22µF
x3
VIN
LTM4600HV
FSET
R2
49.9k
1%
This product contains technology licensed from Silicon Semiconductor Corporation. ®
