LTM4602HV
6A, 28VIN High Efficiency
DC/DC µModule
DESCRIPTIO
U
FEATURES
■
■
■
■
■
■
■
■
■
■
■
■
■
■
Complete Switch Mode Power Supply
Wide Input Voltage Range: 4.5V to 28V
6A DC, Typical 8A Peak Output Current
0.6V to 5V Output Voltage
1.5% Output Voltage Regulation
Ultrafast Transient Response
Parallel µModule™ DC/DC Converters
Current Mode Control
Pin Compatible with the LTM4600 and LTM4602
Up to 92% Efficiency
Programmable Soft-Start
Output Overvoltage Protection
Optional Short-Circuit Shutdown Timer
Pb-Free (e4) RoHS Compliant Package with Gold-Pad
Finish
Small Footprint, Low Profile (15mm × 15mm ×
2.8mm) LGA Package
The LTM®4602HV is a complete 6A, 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 LTM4602HV
supports an output voltage range of 0.6V to 5V, set by
a single resistor. This high efficiency design delivers 6A
continuous current (8A peak), needing no heat sinks or
airflow to meet power specifications. Only bulk input and
output capacitors are needed to finish the design.
Telecom and Networking Equipment
Servers
Industrial Equipment
Point of Load Regulation
The LTM4602HV is packaged in a thermally enhanced, compact (15mm × 15mm) and low profile (2.8mm) over-molded
Land Grid Array (LGA) package suitable for automated
assembly by standard surface mount equipment. For the
4.5V to 20V input range version, refer to the LTM4602.
U
APPLICATIO S
■
■
■
■
, 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. Protected by U.S. Patents including 5481178,
6100678, 6580258, 5847554, 6304066.
U
TYPICAL APPLICATIO
The low profile 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
sacrificing 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.
Efficiency vs Load Current with 24VIN (FCB = 0)
90
80
70
6A µModule Power Supply with 4.5V to 28V Input
VIN
4.5V TO 28V
ABS MAX
VIN
CIN
VOUT
2.5V
6A
VOUT
LTM4602HV
VOSET
PGND SGND
COUT
31.6k
EFFICIENCY (%)
■
60
50
40
1.2VOUT
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT
3.3VOUT (1MHz)
30
20
10
4602HV TA01a
0
0
1
2
3
4
LOAD CURRENT (A)
5
6
4602HV G03
4602hvf
1
LTM4602HV
U
W W
W
ABSOLUTE
AXI U RATI GS
U
W
U
PACKAGE/ORDER I FOR ATIO
(Note 1)
TOP VIEW
fADJ
SVIN
EXTVCC
VOSET
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................... –55°C to 125°C
COMP
SGND
RUN/SS
FCB
VIN
PGOOD
PGND
VOUT
LGA PACKAGE
104-LEAD (15mm × 15mm × 2.8mm)
TJMAX = 125°C, θJA = 15°C/W, θJC = 6°C/W,
θJA DERIVED FROM 95mm × 76mm PCB WITH 4 LAYERS
WEIGHT = 1.7g
ORDER PART NUMBER
LGA PART MARKING*
LTM4602HVEV#PBF
LTM4602HVIV#PBF
LTM4602HVV
LTM4602HVV
Consult LTC Marketing for parts specified with wider operating temperature ranges.
*The temperature grade is identified by a label on the shipping container.
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the –40°C to 85°C
temperature range, otherwise specifications are at TA = 25°C, VIN = 12V. External CIN = 120µF, COUT = 200µF/Ceramic per typical
application (front page) configuration.
SYMBOL
VIN(DC)
PARAMETER
Input DC Voltage
CONDITIONS
AbsMax 28V for Tolerance on 24V Inputs
VOUT(DC)
Output Voltage
FCB = 0V
VIN = 5V or 12V, VOUT = 1.5V, IOUT = 0A
MIN
4.5
TYP
●
MAX
28
UNITS
V
●
1.478
1.470
1.50
1.50
1.522
1.530
V
V
3.4
4
V
Input Specifications
VIN(UVLO)
Under Voltage Lockout Threshold
IOUT = 0A
IINRUSH(VIN)
Input Inrush Current at Startup
IOUT = 0A, VOUT = 1.5V, FCB = 0
VIN = 5V
VIN = 12V
VIN = 24V
IOUT = 0A, EXTVCC Open
VIN = 12V, VOUT = 1.5V, FCB = 5V
VIN = 12V, VOUT = 1.5V, FCB = 0V
VIN = 24V, VOUT = 2.5V, FCB = 5V
VIN = 24V, VOUT = 2.5V, FCB = 0V
Shutdown, RUN = 0.8V, VIN = 12V
IQ(VIN)
Input Supply Bias Current
Min On Time
Min Off Time
IS(VIN)
Input Supply Current
VIN = 12V, VOUT = 1.5V, IOUT = 6A
VIN = 12V, VOUT = 3.3V, IOUT = 6A
VIN = 5V, VOUT = 1.5V, IOUT = 6A
VIN = 24V to 3.3V at 6A, EXTVCC = 5V
0.6
0.7
0.8
A
A
A
1.2
42
1.8
36
50
100
mA
mA
mA
mA
µA
ns
100
400
ns
0.88
1.50
2.08
0.98
A
A
A
A
4602hvf
2
LTM4602HV
ELECTRICAL CHARACTERISTICS
The ● denotes the specifications which apply over the –40°C to 85°C
temperature range, otherwise specifications are at TA = 25°C, VIN = 12V. Per typical application (front page) configuration.
SYMBOL
PARAMETER
Output Specifications
IOUTDC
ΔVOUT(LINE)
VOUT
ΔVOUT(0A-6A)
CONDITIONS
MIN
Output Continuous Current Range
VIN = 12V, VOUT = 1.5V
(See Output Current Derating Curves for VIN = 24V, VOUT = 2.5V (Note 3)
Different VIN, VOUT and TA)
Line Regulation Accuracy
VOUT = 1.5V. FCB = 0V, IOUT = 0A,
VIN = 4.5V to 28V
Load Regulation Accuracy
VOUT
VOUT = 1.5V. FCB = 0V, IOUT = 0A to 6A,
VIN = 5V, VIN = 12V (Note 4)
VOUT(AC)
Output Ripple Voltage
VIN = 12V, VOUT = 1.5V, FCB = 0V, IOUT = 0A
fs
Output Ripple Voltage Frequency
tSTART
Turn-On Time
FCB = 0V, IOUT = 6A, VIN = 12V,
VOUT = 1.5V
VOUT = 1.5V, IOUT = 1A
VIN = 12V
VIN = 5V
VOUT = 1.5V, Load Step: 0A/µs to 3A/µs
COUT = 22µF 6.3V, 330µF 4V Pos Cap,
See Table 2
Load: 10% to 90% to 10% of Full Load
ΔVOUTLS
Voltage Drop for Dynamic Load Step
tSETTLE
Settling Time for Dynamic Load Step
VIN = 12V
Output Current Limit
IOUTPK
TYP
0
0
UNITS
6
6
●
0.15
●
±0.25
±0.5
10
Output Voltage in Foldback
VIN = 24V, VOUT = 2.5V
VIN = 12V, VOUT = 1.5V
VIN = 5V, VOUT = 1.5V
MAX
A
A
%
±0.5
±1
15
%
%
mVP-P
800
kHz
0.5
0.7
30
ms
ms
mV
25
µs
9
9
9
A
A
A
Control Stage
VOSET
Voltage at VOSET Pin
VRUN/SS
RUN ON/OFF Threshold
IRUN(C)/SS
Soft-Start Charging Current
IRUN(D)/SS
Soft-Start Discharging Current
VIN – SVIN
IOUT = 0A, VOUT = 1.5V
●
0.591
0.594
0.8
0.6
0.6
1.5
0.609
0.606
2
V
V
V
VRUN/SS = 0V
–0.5
–1.2
–3
µA
VRUN/SS = 4V
0.8
1.8
3
µA
EXTVCC = 0V, FCB = 0V
100
mV
EXTVCC = 5V, FCB = 0V, VOUT = 1.5V,
IOUT = 0A
16
mA
IEXTVCC
Current into EXTVCC Pin
RFBHI
Resistor Between VOUT and FB Pins
VFCB
Forced Continuous Threshold
IFCB
Forced Continuous Pin Current
VFCB = 0.6V
ΔVOSETH
PGOOD Upper Threshold
VOSET Rising
ΔVOSETL
PGOOD Lower Threshold
VOSET Falling
ΔVOSET(HYS)
PGOOD Hysteresis
VOSET Returning
VPGL
PGOOD Low Voltage
IPGOOD = 5mA
100
0.57
kΩ
0.6
0.63
V
–1
–2
µA
7.5
10
12.5
%
–7.5
–10
–12.5
PGOOD Output
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 LTM4602HVE is guaranteed to meet performance
specifications from 0°C to 85°C. Specifications over the –40°C to 85°C
%
2
0.15
%
0.4
V
operating temperature range are assured by design, characterization
and correlation with statistical process controls. The LTM4602HVI 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.
Note 4: Test assumes current derating verses temperature.
4602hvf
3
LTM4602HV
U W
TYPICAL PERFOR A CE CHARACTERISTICS (See Figure 22 for all curves)
Efficiency vs Load Current
with 5VIN (FCB = 0)
Efficiency vs Load Current
with 24VIN (FCB = 0)
Efficiency vs Load Current
with 12VIN (FCB = 0)
90
90
80
80
80
70
70
0.8VOUT
1.2VOUT
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT*
*FOR 5V TO 3.3V CONVERSION,
SEE FREQUENCY ADJUSTMENT
IN APPLICATIONS INFORMATION
50
40
30
20
10
70
60
50
0.8VOUT
1.2VOUT
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT
3.3VOUT (950kHz)
40
30
20
10
0
2
8
4
6
LOAD CURRENT (A)
2
0
4
6
LOAD CURRENT (A)
60
50
40
1.2VOUT
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT
3.3VOUT (1MHz)
30
20
10
0
0
8
0
0
1
2
3
4
LOAD CURRENT (A)
4602HV G02
4602HV G01
Light Load Efficiency vs
Load Current with 12VIN
(FCB > 0.7V, 0.7V
80
80
70
EFFICIENCY (%)
EFFICIENCY (%)
EFFICIENCY (%)
60
EFFICIENCY (%)
100
90
EFFICIENCY (%)
100
60
50
40
30
1.2VOUT
1.5VOUT
1.8VOUT
2.5VOUT
3.3VOUT
20
10
0
0
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9
LOAD CURRENT (A)
70
60
20µs/DIV
1.2V AT 3A/µs LOAD STEP
COUT = 22µF, 6.3V CERAMIC
330µF, 4V SANYO POS CAP
50
40
4602HV G05
30
1
20
0.1
1
LOAD CURRENT (A)
4602HV G15
5
4602HV G04
1.8V Transient Response
1.5V Transient Response
VOUT
50mV/DIV
IOUT
2A/DIV
20µs/DIV
1.5V AT 3A/µs LOAD STEP
COUT = 22µF, 6.3V CERAMIC
330µF, 4V SANYO POS CAP
IOUT
2A/DIV
FCB = GND
4602HV G06
2.5V Transient Response
VOUT
50mV/DIV
VOUT
50mV/DIV
IOUT
2A/DIV
IOUT
2A/DIV
20µs/DIV
1.8V AT 3A/µs LOAD STEP
COUT = 22µF, 6.3V CERAMIC
330µF, 4V SANYO POS CAP
4602HV G07
20µs/DIV
2.5V AT 3A/µs LOAD STEP
COUT = 22µF, 6.3V CERAMIC
330µF, 4V SANYO POS CAP
4602HV G08
4602hvf
4
LTM4602HV
U W
TYPICAL PERFOR A CE CHARACTERISTICS (See Figure 22 for all curves)
VOUT
50mV/DIV
VOUT
0.5V/DIV
VOUT
0.5V/DIV
IOUT
2A/DIV
20µs/DIV
3.3V AT 3A/µs LOAD STEP
COUT = 22µF, 6.3V CERAMIC
330µF, 4V SANYO POS CAP
Start-Up, IOUT = 6A
(Resistive Load)
Start-Up, IOUT = 0A
3.3V Transient Response
4602HV G09
IIN
0.5A/DIV
IIN
0.5A/DIV
4602HV G11
500µs/DIV
VIN = 12V
VOUT = 1.5V
COUT = 1 × 22µF, 6.3V X5R
330µF, 4V SANYO POS CAP
NO EXTERNAL SOFT-START CAPACITOR
4602HV G10
200µs/DIV
VIN = 12V
VOUT = 1.5V
COUT = 1 × 22µF, 6.3V X5R
330µF, 4V SANYO POS CAP
NO EXTERNAL SOFT-START CAPACITOR
Short-Circuit Protection,
IOUT = 0A
Short-Circuit Protection,
IOUT = 6A
VIN to VOUT Stepdown Ratio
5.5
fADJ = OPEN
5.0
VOUT
0.5V/DIV
5V
4.5
VOUT
0.5V/DIV
4.0
3.3V
VOUT (V)
3.5
IIN
0.5A/DIV
IIN
0.5A/DIV
3.0
2.5V
2.5
1.8V
2.0
4602HV G12
20µs/DIV
VIN = 12V
VOUT = 1.5V
COUT = 1 × 22µF, 6.3V X5R
330µF, 4V SANYO POS CAP
NO EXTERNAL SOFT-START CAPACITOR
4602HV G13
20µs/DIV
VIN = 12V
VOUT = 1.5V
COUT = 1 × 22µF, 6.3V X5R
330µF, 4V SANYO POS CAP
NO EXTERNAL SOFT-START CAPACITOR
1.5
1.5V
1.0
1.2V
0.5
0.6V
0
0
5
10
15
VIN (V)
20
25 28
SEE FREQUENCY ADJUSTMENT DISCUSSION
FOR 12VIN TO 5VOUT AND 5VIN TO 3.3VOUT
CONVERSION
4602HV G14
4602hvf
5
LTM4602HV
U
U
U
PI FU CTIO S
(See Package Description for Pin Assignment)
SGND (Pin D23): Signal Ground Pin. All small-signal
components should connect to this ground, which in turn
connects to PGND at one point.
VIN (Bank 1): Power Input Pins. Apply input voltage between these pins and PGND pins. Recommend placing
input decoupling capacitance directly between VIN pins
and PGND pins.
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.
fADJ (Pin A15): A 110k resistor from VIN to this pin sets
the one-shot timer current, thereby setting the switching
frequency. The LTM4602HV 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.
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 efficiency
operation at light loads. There is an internal 10k resistor
between the FCB and SGND pins.
VOSET (Pin A21): The Negative Input of The Error Amplifier.
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.
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.
COMP (Pin B23): Current Control Threshold and Error
Amplifier 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).
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 PGND pins. Recommend placing
High Frequency output decoupling capacitance directly
between these pins and PGND pins.
5
6
7
VOSET
4
EXTVCC
3
SVIN
2
fADJ
TOP VIEW
16
17
18
19
1
VIN
BANK 1
9
10
8
13
14
C
22
E
23
25
26
27
28
29
30
31
33
34
35
36
37
38
24
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
1
3
2
5
4
7
6
9
8
11
10
13
12
15
14
17
16
B
SGND
F
RUN/SS
G
19
18
21
20
J
COMP
D
H
32
VOUT
BANK 3
A
15
12
PGND
BANK 2
20
21
11
K
FCB
PGOOD
L
M
N
P
R
T
23
22
4600hv PN01
4602hvf
6
LTM4602HV
W
W
SI PLIFIED BLOCK DIAGRA
SVIN
RUN/SS
1000pF
CIN
1.5µF
PGOOD
VIN
4.5V TO 28V
ABS MAX
Q1
COMP
INT
COMP
FCB
COUT
VIN
4.75k
110k
VOUT
2.5V
6A MAX
15µF
6.3V
CONTROLLER
fADJ
SGND
PGND
Q2
10Ω
EXTVCC
100k
0.5%
VOSET
RSET
31.6k
4602HV F01
Figure 1. Simplified LTM4602HV Block Diagram
U W
U
DECOUPLI G REQUIRE E TS
TA = 25°C, VIN = 12V. Use Figure 1 configuration.
SYMBOL
PARAMETER
CONDITIONS
MIN
CIN
External Input Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 2.5V)
IOUT = 6A, 2x 10µF 35V Ceramic
Taiyo Yuden GDK316BJ106ML
20
COUT
External Output Capacitor Requirement
(VIN = 4.5V to 28V, VOUT = 2.5V)
IOUT = 6A, Refer to Table 2 in the
Applications Information Section
100
TYP
MAX
UNITS
µF
200
µF
4602hvf
7
LTM4602HV
U
OPERATIO
µModule Description
The LTM4602HV is a standalone non-isolated synchronous
switching DC/DC power supply. It can deliver up to 6A 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 simplified block diagram is shown in Figure 1 and the
typical application schematic is shown in Figure 21.
The LTM4602HV 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 LTM4602HV module has sufficient
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).
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
LTM4602HV has defeatable short circuit latch off. Internal
overvoltage and undervoltage comparators pull the opendrain 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 current mode by default to achieve minimum output voltage
ripple. It can be programmed to operate in discontinuous
current mode for improved light load efficiency when the
FCB pin is pulled up above 0.8V and no higher than 6V.
The FCB pin has a 10k 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 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.
4602hvf
8
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
The typical LTM4602HV 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 LTM4602HV 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:
VO = 0.6V •
100k + RSET
RSET
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/protection functionality of the board and improve the system
reliability. Figure 2 shows how to implement margining
function with the LTM4602HV. 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
VOUT
RDOWN
100k
QDOWN
2N7002
VOSET
PGND
SGND
RSET
RUP
QUP
2N7002
4602HV F02
Figure 2
(RSET RUP )• VO •(1+ M%)
= 0.6V
(RSET RUP ) + 100kΩ
RSET • VO •(1– M%)
= 0.6V
RSET + (100kΩ RDOWN)
Input Capacitors
Table 1 shows the standard values of 1% RSET resistor
for typical output voltages:
LTM4602HV
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:
The LTM4602HV 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 module. 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:
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 •(1− D)
η%
In the above equation, η% is the estimated efficiency 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 frequency
input decoupling capacitors. In a typical 6A 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 module input pins
4602hvf
9
LTM4602HV
U
W
U
U
APPLICATIO S I FOR ATIO
in the PCB layout to minimize the trace inductance and
high frequency AC noise.
Output Capacitors
The LTM4602HV is designed for low output voltage ripple.
The bulk output capacitor 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 sufficient stability
margin for all ceramic capacitors applications. Additional
output filtering 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 3A/µs transient with
a specific output capacitance.
Fault Conditions: Current Limit and Over current
Foldback
The LTM4602HV 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 condition, the LTM4602HV 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
LTM4602HV as well as a timer for soft-start and overcurrent latchoff. Pulling the RUN/SS pin below 0.8V puts
the LTM4602HV 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 LTM4602HV, there is an internal 1000pF capacitor from RUN/SS pin to ground. If RUN/SS pin has an
external capacitor CSS_EXT to ground, the delay before
starting is about:
tDELAY =
1.5V
•(C SS _ EXT + 1000pF )
1.2µA
When the voltage on RUN/SS pin reaches 1.5V, the
LTM4602HV 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 constraints 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 DeRating sections of this data sheet.
4602hvf
10
LTM4602HV
U
W
U
U
APPLICATIO S I FOR ATIO
Table 2. Output Voltage Response Versus Component Matrix (Refer to Figure 17), 0A to 3A Step (Typical Values)
TYPICAL MEASURED VALUES
COUT1 VENDORS
TDK
TAIYO YUDEN
TAIYO YUDEN
VOUT
(V)
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.2
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.5
1.8
1.8
1.8
1.8
1.8
1.8
1.8
1.8
2.5
2.5
2.5
2.5
2.5
2.5
2.5
2.5
3.3
3.3
3.3
3.3
3.3
3.3
3.3
3.3
5
5
CIN
(CERAMIC)
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
1 × 10µF 25V
1 × 10µF 25V
PART NUMBER
C4532X5R0J107MZ (100UF,6.3V)
JMK432BJ107MU-T ( 100µF, 6.3V)
JMK316BJ226ML-T501 ( 22µF, 6.3V)
CIN
(BULK)
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
COUT1
(CERAMIC)
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
3 × 22µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
1 × 100µF 6.3V
2 × 100µF 6.3V
3 × 22µF 6.3V
4 × 100µF 6.3V
1 × 100µF 6.3V
3 × 22µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
2 × 100µF 6.3V
1 × 100µF 6.3V
3 × 22µF 6.3V
4 × 100µF 6.3V
1 × 100µF 6.3V
3 × 22µF 6.3V
2 × 100µF 6.3V
4 × 100µF 6.3V
4 × 100µF 6.3V
4 × 100µF 6.3V
COUT2
(BULK)
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
470µF 2.5V
330µF 6.3V
NONE
470µF 4V
330µF 6.3V
470µF 4V
NONE
470µF 4V
470µF 4V
330µF 6.3V
NONE
330µF 6.3V
470µF 4V
470µF 4V
NONE
470µF 4V
470µF 4V
330µF 6.3V
NONE
NONE
NONE
COUT2 VENDORS
SANYO POS CAP
SANYO POS CAP
SANYO POS CAP
CCOMP
C3
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
NONE
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
100pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
220pF
100pF
100pF
VIN
(V)
5
5
5
5
12
12
12
12
5
5
5
5
12
12
12
12
5
5
5
5
12
12
12
12
5
5
5
5
12
12
12
12
7
7
7
7
12
12
12
12
15
20
DROOP
(mV)
30
30
25
25
30
25
25
25
25
25
25
26
25
25
28
26
25
25
25
29
25
25
25
29
25
25
25
25
25
25
25
27
32
30
30
32
38
30
30
32
80
80
PART NUMBER
6TPE330MIL (330µF, 6.3V)
2R5TPE470M9 (470µF, 2.5V)
4TPE470MCL (470µF, 4V)
PEAK TO PEAK
(mV)
60
60
54
55
60
54
56
55
50
54
59
59
55
54
59
59
54
50
50
60
50
50
50
60
50
50
50
50
50
50
50
54
64
60
60
64
58
60
60
64
160
160
RECOVERY TIME
(µs)
25
20
20
20
25
20
20
20
25
20
20
20
25
20
20
20
30
20
20
20
30
20
20
20
30
30
30
25
30
30
30
25
30
30
35
25
30
35
30
25
25
25
LOAD STEP
(A/µs)
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
3
4602hvf
11
LTM4602HV
U
W
U
U
APPLICATIO S I FOR ATIO
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, shutting 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:
C SS _ EXT + 1000pF > C OUT • VOUT (10–3 [F / VS ])
Generally 0.1µF is more than sufficient.
Since the load current is already limited by the current mode
control and current foldback circuitry during a short circuit,
overcurrent latchoff operation is NOT always needed or
desired, especially if the output has large capacitance or
the load draws high 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. Using a resistor from
RUN/SS pin to VIN is a simple solution 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.
VRUN/SS
4V
3.5V
3V
1.5V
SHORT-CIRCUIT
LATCH ARMED
t
SOFT-START
CLAMPING
OF IL RELEASED
OUTPUT
OVERLOAD
HAPPENS
SHORT-CIRCUIT
LATCHOFF
VO
75%VO
t
SWITCHING
STARTS
4602HV F03
Figure 3. RUN/SS Pin Voltage During Startup and
Short-Circuit Protection
VIN
VIN
500k
LTM4602HV
RUN/SS
PGND SGND
RECOMMENDED VALUES FOR RRUN/SS
VIN
RRUN/SS
4.5V TO 5.5V
10.8V TO 13.8V
24V TO 28V
50k
150k
500k
4602HV F04
Figure 4. Defeat Short-Circuit Latchoff with a Pull-Up
Resistor to VIN
4602hvf
12
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
Enable
EXTVCC Connection
The RUN/SS pin can be driven from logic as shown in
Figure 5. This function allows the LTM4602HV to be
turned on or off remotely. The ON signal can also control
the sequence of the output voltage.
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 LTM4602HV can be directly powered by VIN. The gate
driver current through LDO is about 16mA. The internal
LDO power dissipation can be calculated as:
RUN/SS
PLDO_LOSS = 16mA • (VIN – 5V)
LTM4602HV
ON
PGND SGND
2N7002
4602HV F05
Figure 5. Enable Circuit with External Logic
Output Voltage Tracking
For the applications that require output voltage tracking,
several LTM4602HV modules can be programmed by the
power supply tracking controller such as the LTC2923.
Figure 6 shows a typical schematic with LTC2923. Coincident, 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.
Q1
VIN
5V
3.3V
DC/DC
VIN
VIN
RONB
VCC
RAMP
GATE
ON
RONA
LTM4602HV
VOSET
VOUT
FB1
RAMPBUF
STATUS
VIN
TRACK1
SDO
VIN
FB2
LTM4602HV
VOSET
VOUT
RTB2
TRACK2
RTA2
GND
2. EXTVCC connected to an external supply. Internal LDO
is shut off. A high efficiency supply compatible with the
MOSFET gate drive requirements (typically 5V) can improve overall efficiency. With this connection, it is always
required that the EXTVCC voltage can not be higher than
VIN pin voltage.
Discontinuous Operation and FCB Pin
RTB1
RTA1
1. EXTVCC grounded. Internal 5V LDO is always powered
from the internal 5V regulator.
1.8V
RSET
49.9k
LTC2923
The LTM4602HV 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
connections for EXTVCC:
1.5V
RSET
66.5k
The FCB pin determines whether the internal bottom
MOSFET remains on when the inductor current reverses.
There is an internal 10k 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.
4602HV F06
Figure 6. Output Voltage Tracking with the LTC2923 Controller
4602hvf
13
LTM4602HV
U
W
U
U
APPLICATIO S I FOR ATIO
approximate θJA for the module with various heatsinking methods. Thermal models are derived from several
temperature measurements at the bench, and thermal
modeling analysis. Application Note 103 provides a detailed
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-flow. 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. The θJA values in Tables 3
and 4 can be used to derive the derating curves for other
output voltages.
In the application where the light load efficiency is important, tying the FCB pin above 0.6V threshold enables
discontinuous operation where the bottom MOSFET turns
off when inductor current reverses. Therefore, the conduction loss is minimized and light load efficient 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 LTM4602HV modules can be paralleled to
provide higher than 6A 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 thermal stress. The new feedback equation for two or
more LTM4602HVs in parallel is:
100k
+ RSET
N
VOUT = 0.6 V •
RSET
Safety Considerations
The LTM4602HV 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.
where N is the number of LTM4602HVs in parallel.
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
OPTI-LOOP is a trademark of Linear Technology Corporation.
VPULLUP
100k
PGOOD
VIN
VIN
LTM4602HV
VOUT
VOUT
12A MAX
PGND COMP VOSET SGND
RSET
PGOOD COMP VOSET SGND
VIN
LTM4602HV
VOUT
PGND
4602HV F07
Figure 7. Parallel Two µModules with Load Sharing
4602hvf
14
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
2.0
7
7
6
6
5
5
1.4
12V TO 1.5V
LOSS
1.2
CURRENT (A)
1.0
0.8
5V TO 1.5V
LOSS
0.6
0.4
3
0LFM
200LFM
400LFM
1
0
0.6
1.0
3.1
4.1
2.1
CURRENT (A)
0
6.1
5.1
50
3
60
70
80
90
0LFM
200LFM
400LFM
1
0
4602HV F09
Figure 8. 1.5V Power Loss Curves
vs Load Current
Figure 9. 5V to 1.5V, No Heatsink
6
6
3.5
5
5
CURRENT (A)
4.0
0
50
60
70
80
90
4
3
1
0
50
100
2.5
2.0
1.5
1.0
0LFM
200LFM
400LFM
60
70
80
90
0.5
0
0.5
100
Figure 11. 12V to 1.5V, No Heatsink
6
6
5
5
5
3
2
CURRENT (A)
6
CURRENT (A)
7
4
4
3
2
0LFM
200LFM
400LFM
70
80
90
100
TEMPERATURE (°C)
1
0
50
Figure 14. 5V to 3.3V, No Heatsink
6.1
4
3
2
0LFM
200LFM
400LFM
60
70
80
90
100
TEMPERATURE (°C)
4602HV F14
5.1
Figure 13. 3.3V Power Loss
Figure 12. 12V to 1.5V, BGA Heatsink
7
60
4.1
3.1
CURRENT (A)
4602HV F13
7
50
2.1
4602HV F09
4602HV F11
0
1.0
TEMPERATURE (°C)
TEMPERATURE (°C)
1
5V TO 3.3V LOSS
12V TO 3.3V LOSS
12V TO 3.3V (950kHz) LOSS
3.0
2
0LFM
200LFM
400LFM
100
90
Figure 10. 5V to 1.5V, BGA Heatsink
7
3
80
4602HV F10
7
4
70
TEMPERATURE (°C)
4602HV F08
1
60
50
100
TEMPERATURE (°C)
2
CURRENT (A)
4
2
2
0.2
CURRENT (A)
4
POWER LOSS (W)
POWER LOSS (W)
1.6
CURRENT (A)
1.8
0LFM
200LFM
400LFM
1
0
50
60
70
80
90
100
TEMPERATURE (°C)
4602HV F15
4602HV F16
Figure 15. 5V to 3.3V, BGA Heatsink
Figure 16. 12V to 3.3V (950kHz),
No Heatsink
4602hvf
15
LTM4602HV
U
U
W
U
7
7
6
6
6
5
5
5
4
3
2
CURRENT (A)
7
CURRENT (A)
CURRENT (A)
APPLICATIO S I FOR ATIO
4
3
2
0LFM
200LFM
400LFM
1
0
60
50
0LFM
200LFM
400LFM
0
80
90
100
3
2
1
70
4
0LFM
200LFM
400LFM
1
0
60
50
TEMPERATURE (°C)
70
80
90
100
50
60
TEMPERATURE (°C)
4602HV F16
Figure 17. 12V to 3.3V (950kHz),
BGA Heatsink
70
4602HV F18
Figure 18. 24V to 3.3V, No Heatsink
Table 3. 1.5V Output
80
90
100
TEMPERATURE (°C)
4602HV F19
Figure 19. 24V to 3.3V, BGA Heatsink
Table 4. 3.3V Output
AIR FLOW (LFM)
HEATSINK
θJA (°C/W)
AIR FLOW (LFM)
HEATSINK
θJA (°C/W)
0
None
15.2
0
None
15.2
200
None
14
200
None
14.6
400
None
12
400
None
13.4
0
BGA Heatsink
13.9
0
BGA Heatsink
13.9
200
BGA Heatsink
11.3
200
BGA Heatsink
11.1
400
BGA Heatsink
10.25
400
BGA Heatsink
10.5
Layout Checklist/Example
• Do not put via directly on pad
The high integration of the LTM4602HV makes the PCB
board layout very simple and easy. However, to optimize
its electrical and thermal performance, some layout considerations are still necessary.
• Use a separated SGND ground copper area for components connected to signal pins. Connect the SGND
to PGND underneath the unit
• Use large PCB copper areas for high current path, including VIN, PGND and VOUT. It helps to minimize the
PCB conduction loss and thermal stress
• Place high frequency ceramic input and output capacitors 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
Figure 20 gives a good example of the recommended
layout.
LTM4602 Frequency Adjustment
The LTM4602HV is designed to typically operate at 850kHz
across most input and output conditions. The control architecture 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 operating frequency are set around a programmable constant
on time. This on time is developed by a programmable
4602hvf
16
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
VIN
CIN
PGND
VOUT
4602HV F20
LOAD
TOP LAYER
Figure 20. Recommended PCB Layout
current into an on board 10pF capacitor that establishes
a ramp that is compared to a voltage threshold that is
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, therefore 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 Figure 21. The on time is
equal to tON = (VOUT/ION) • 10pF and tOFF = ts – tON. The
frequency is equal to: Frequency = DC/tON).
t
(DC) DUTY CYCLE = ON
ts
tOFF
tON
Equations for setting frequency: VOUT = 5V
ION = (VIN – 0.7V)/110k; for 12V input, ION = 103µA
frequency = (ION/[2.4V • 10pF]) • (DC) = 1.79MHz;
DC = duty cycle, duty cycle is (VOUT/VIN)
t = tON + tOFF, tON = on-time, tOFF = off-time of the
switching period; t = 1/frequency
tOFF must be greater than 400ns, or t – tON > 400ns.
tON = DC • t
1MHz frequency or 1µs period is chosen.
V
t
DC = ON = OUT
ts
VIN
DC
FREQ =
tON
4602HV F21
PERIOD ts
The LTM4602 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 outputs 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 t = 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.
tON = 0.41 • 1µs ≅ 410ns
tOFF = 1µs – 410ns ≅ 590ns
tON and tOFF are above the minimums with adequate guard
band.
Figure 21
4602hvf
17
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
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 8V to 16V. Higher
input voltages can be used without the 15k on fADJ.
The inductor ripple current gets too high above 16V or
below 8V.
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.
Equations for setting frequency: VOUT = 3.3V
Therefore, at 3.3V output, a 30.1k resistor is recommended
to add from pin fADJ to ground when the input voltage is
between 4.5V to 7V. However, this resistor needs to be
removed to avoid high inductor ripple current when the
input voltage is more than 7V. Similarly, for 5V output, a
15k resistor is recommended to adjust the frequency when
the input voltage is between 8V to 16V. This 15k resistor
is removed when the input voltage becomes higher than
16V. Please refer to the Typical Performance curve VIN to
VOUT Step-Down Ratio.
ION = (VIN – 0.7V)/110k; for 5V input, ION = 39µA
frequency = (ION/[2.4V • 10pF]) • (DC) = 1.07MHz;
DC = duty cycle, duty cycle is (VOUT/VIN)
t = tON + tOFF, tON = on-time, tOFF = off-time of the
switching period; t = 1/frequency
tOFF must be greater than 400ns, or t – tON > 400ns.
tON = DC • t
~450kHz frequency or 2.22µs period is chosen. Frequency
range is about 450kHz to 650kHz from 4.5V to 7V input.
tON = 0.66 • 2.22µs ≅ 1.46µs
tOFF = 2.22µs – 1.46µs ≅ 760ns
tON and tOFF are above the minimums with adequate guard
band.
In 12V to 3.3V and 24V to 3.3V applications, if a 35k
resistor is added from the fADJ pin to ground, then a 2%
efficiency gain will be achieved as shown in the 12V and
24V efficiency graphs shown in the Typical Characteristics. This is due to lowering the transition losses in the
power MOSFETs by reducing the switching frequency
from 1.3mHz to 1mHz.
5V to 3.3V at 5A
R1
30.1k
VIN
4.5V TO 7V
C3
10µF
25V
C1
10µF
25V
VIN
C5
100pF
fADJ
EXTVCC
EFFICIENCY = 92%
VOUT
FCB
VOSET
RSET
22.1k
1%
LTM4602HV
RUN/SOFT-START
VOUT
3.3V AT 5A
RUN/SS
SVIN
PGOOD
COMP
SGND
C2
22µF
+
C4
330µF
6.3V
OPEN DRAIN
PGND
4602HV F23
5V TO 3.3V AT 5A WITH fADJ = 30.1k
LTM4602HV MINIMUM ON-TIME = 100ns
LTM4602HV MINIMUM OFF-TIME = 400ns
C1, C3: TDK C3216X5R1E106MT
C2: TAIYO YUDEN, JMK316BJ226ML
C4: SANYO POS CAP, 6TPE330MIL
4602hvf
18
LTM4602HV
U
U
W
U
APPLICATIO S I FOR ATIO
12V to 5V at 5A
R1
15k
VIN
8V TO 16V
C3
10µF
25V
C1
10µF
25V
VIN
C5
100pF
fADJ
EXTVCC
EFFICIENCY = 90%
VOUT
FCB
VOSET
RSET
13.7k
1%
LTM4602HV
RUN/SS
RUN/SOFT-START
VOUT
5V AT 5A
SVIN
PGOOD
COMP
SGND
C2
22µF
+
C4
330µF
6.3V
OPEN DRAIN
PGND
4602HV F24
12V TO 5V AT 5A WITH fADJ = 15k
LTM4602HV MINIMUM ON-TIME = 100ns
LTM4602HV MINIMUM OFF-TIME = 400ns
VIN
+
5V TO 24V
CIN
150µF
BULK
CIN
10µF
×2
CER
VIN
(MULTIPLE PINS)
GND
EXTVCC
C3
100pF
C1, C3: TDK C3216X5R1E106MT
C2: TAIYO YUDEN, JMK316BJ226ML
C4: SANYO POS CAP, 6TPE330MIL
SVIN
VOUT
(MULTIPLE PINS)
fADJ
VOSET
VOUT
LTM4602HV
COMP
VOUT
COUT1
22µF
6.3V
REFER TO
TABLE 2
+
COUT2
330µF
REFER TO
TABLE 2
FCB
RSET
66.5k
REFER TO
TABLE 1
RUN/SS
PGOOD
C4
OPT
0.6V TO 5V
SGND
REFER TO STEP DOWN
RATIO GRAPH
PGND
(MULTIPLE PINS)
GND
4602HV F22
Figure 22. Typical Application, 5V to 24V Input, 0.6V to 6V Output, 6A Max
4602hvf
19
LTM4602HV
U
TYPICAL APPLICATIO
Parallel Operation and Load Sharing
VIN
4.5V TO 24V
VOUT = 0.6V • ([100k/N] + RSET)/RSET
WHERE N = 2
C8
10µF
35V
VIN
fADJ
EXTVCC
VOUT
FCB
VOSET
RSET
15.8k
1%
LTM4602HV
RUN
C9
22µF
SVIN
+
C10
330µF
4V
PGOOD
COMP
SGND
PGND
VOUT
2.5V
12A
RUN/SOFT-START
C3
10µF
35V
VIN
C4
220pF
fADJ
EXTVCC
VOUT
FCB
C2
22µF
VOSET
LTM4602HV
RUN
+
C5
330µF
4V
R1
100k
SVIN
PGOOD
COMP
SGND
PGND
C3, C8: TAIYO YUDEN, GDK316BJ106ML
C2, C9: TAIYO YUDEN, JMK316BJ226ML-T501
C5, C10: SANYO POS CAP, 4TPE330MI
4602HV TA02
Current Sharing Between Two
LTM4602HV Modules
6
INDIVIDUAL SHARE
12VIN
2.5VOUT
12AMAX
4
IOUT2
IOUT1
2
0
0
6
TOTAL LOAD
12
4602HV TA03
4602hvf
20
5.7150
2.5400
0.3175
0.3175
2.7375
C(0.30)
PAD 1
13.97
BSC
0.11 – 0.27
6.9850
4.4450
1.2700
0.0000
1.4675
4.0075
6.9421
94
83
72
61
50
39
5.7158
102
100
101
80
69
58
47
91
79
68
57
46
38
31
90
37
30
17
18
33
1
1
8
3
5
6
7
4
8
13
10
9
11
6
28
35
55
14
44
13
13.93
BSC
12
10
7
29
36
15
45
56
67
78
89
100
14
11
15
16
30
37
BOTTOM VIEW
9
5
27
34
54
43
66
77
88
99
16
46
57
68
79
90
101
17
17
31
38
18
47
58
69
80
91
102
18
20
48
19
22
49
60
71
70
59
82
93
104
81
92
103
104
93
82
71
60
49
20
24
24
23
22
21
19
21
23
20
21
22
26
53
42
65
76
87
98
12.70
BSC
103
92
81
70
59
48
19
12
4
1.9042
16
3.1742
89
78
67
56
45
99
88
77
66
55
44
36
29
15
11
98
87
76
65
54
43
35
28
14
10
7
5.7142
23
2
3
41
52
40
51
50
86
97
64
85
96
63
61
34
27
13
9
6
4.4442
SUGGESTED SOLDER PAD LAYOUT
TOP VIEW
62
73
72
97
86
75
64
53
42
75
84
83
96
85
74
63
52
41
33
26
4.4950
74
95
2
95
84
73
62
51
40
1.0900
94
39
4.4458
2.3600
3.1758
5.7650
1.9058
5
6.9865
25
32
32
25
12
6.3500
8
5.0800
0.0000
1.2700
5.2775
3.8100
0.6358
0.3175
0.3175
0.0000
4
2.5400
0.6342
1.2700
3
2.5400
2
3.8100
1
5.0800
6.9888
6.3500
6.5475
A
C
E
G
J
L
M
N
P
B
D
F
H
K
LGA104 02-18
eee M X Y
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
4
SYMBOL TOLERANCE
0.15
aaa
0.10
bbb
0.15
eee
6. THE TOTAL NUMBER OF PADS: 104
5. PRIMARY DATUM -Z- IS SEATING PLANE
LAND DESIGNATION PER JESD MO-222, SPP-010
3
2. ALL DIMENSIONS ARE IN MILLIMETERS
DETAIL B
PAD 1
CORNER
R
0.27 – 0.37
SUBSTRATE
4
aaa Z
NOTES:
1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994
DETAIL B
MOLD
CAP
2.72 – 2.92
(Reference LTM DWG # 05-05-1800)
Z
PADS
SEE NOTES
T
3
2.45 – 2.55
bbb Z
LGA Package
104-Lead (15mm × 15mm)
TOP VIEW
15
BSC
X
15
BSC
Y
aaa Z
LTM4602HV
PACKAGE DESCRIPTIO
4602hvf
21
U
LTM4602HV
U
PACKAGE DESCRIPTIO
Pin Assignment Tables
(Arranged by Pin Number)
PIN NAME
A1 A2 A3 VIN
A4 A5 VIN
A6 A7 VIN
A8 A9 VIN
A10 A11 VIN
A12 A13 VIN
A14 A15 fADJ
A16 A17 SVIN
A18 A19 EXTVCC
A20 A21 VOSET
A22 A23 -
PIN NAME
B1 VIN
B2 B3 B4 B5 B6 B7 B8 B9 B10 B11 B12 B13 B14 B15 B16 B17 B18 B19 B20 B21 B22 B23 COMP
PIN NAME
C1 C2 C3 C4 C5 C6 C7 C8 C9 C10 VIN
C11 C12 VIN
C13 C14 VIN
C15 C16 C17 C18 C19 C20 C21 C22 C23 -
PIN NAME
D1 VIN
D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15 D16 D17 D18 D19 D20 D21 D22 D23 SGND
PIN NAME
E1 E2 E3 E4 E5 E6 E7 E8 E9 E10 VIN
E11 E12 VIN
E13 E14 VIN
E15 E16 E17 E18 E19 E20 E21 E22 E23 -
PIN NAME
F1 VIN
F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 RUN/SS
PIN NAME
G1 PGND
G2 G3 G4 G5 G6 G7 G8 G9 G10 G11 G12 G13 G14 G15 G16 G17 G18 G19 G20 G21 G22 G23 FCB
PIN NAME
H1 H2 H3 H4 H5 H6 H7 PGND
H8 H9 PGND
H10 H11 PGND
H12 H13 PGND
H14 H15 PGND
H16 H17 PGND
H18 H19 H20 H21 H22 H23 -
PIN NAME
J1 PGND
J2 J3 J4 J5 J6 J7 J8 J9 J10 J11 J12 J13 J14 J15 J16 J17 J18 J19 J20 J21 J22 J23 PGOOD
PIN NAME
K1 K2 K3 K4 K5 K6 K7 PGND
K8
K9 PGND
K10
K11 PGND
K12 K13 PGND
K14 K15 PGND
K16 K17 PGND
K18 K19 K20 K21 K22 K23 -
PIN NAME
L1 L2 PGND
L3 L4 PGND
L5 L6 PGND
L7 L8 PGND
L9 L10 PGND
L11 L12 PGND
L13 L14 PGND
L15 L16 PGND
L17 L18 PGND
L19 L20 PGND
L21 L22 PGND
L23 -
PIN NAME
M1 M2 PGND
M3 M4 PGND
M5 M6 PGND
M7 M8 PGND
M9 M10 PGND
M11 M12 PGND
M13 M14 PGND
M15 M16 PGND
M17 M18 PGND
M19 M20 PGND
M21 M22 PGND
M23 -
PIN NAME
N1 N2 PGND
N3 N4 PGND
N5 N6 PGND
N7 N8 PGND
N9 N10 PGND
N11 N12 PGND
N13 N14 PGND
N15 N16 PGND
N17 N18 PGND
N19 N20 PGND
N21 N22 PGND
N23 -
PIN NAME
P1 P2 VOUT
P3 P4 VOUT
P5 P6 VOUT
P7 P8 VOUT
P9 P10 VOUT
P11 P12 VOUT
P13 P14 VOUT
P15 P16 VOUT
P17 P18 VOUT
P19 P20 VOUT
P21 P22 VOUT
P23 -
PIN NAME
R1 R2 VOUT
R3 R4 VOUT
R5 R6 VOUT
R7 R8 VOUT
R9 R10 VOUT
R11 R12 VOUT
R13 R14 VOUT
R15 R16 VOUT
R17 R18 VOUT
R19 R20 VOUT
R21 R22 VOUT
R23 -
PIN NAME
T1 T2 VOUT
T3 T4 VOUT
T5 T6 VOUT
T7 T8 VOUT
T9 T10 VOUT
T11 T12 VOUT
T13 T14 VOUT
T15 T16 VOUT
T17 T18 VOUT
T19 T20 VOUT
T21 T22 VOUT
T23 4602hvf
22
LTM4602HV
U
PACKAGE DESCRIPTIO
Pin Assignment Tables
(Arranged by Pin Number)
PIN NAME
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
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
4602hvf
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.
23
LTM4602HV
U
TYPICAL APPLICATIO
1.8V, 5A Regulator
VIN
4.5V TO 24V
C1
10µF
35V
VIN
C5
100pF
fADJ
EXTVCC
VOUT
1.8V AT 6A
VOUT
FCB
VOSET
R1
100k
LTM4602HV
RUN
C3
22µF
+
C4
330µF
4V
SVIN
PGOOD
COMP
SGND
PGND
4602HV TA04
PGOOD
RSET
49.9k
1%
C1: TAIYO YUDEN, GMK316BJ106ML
C3: TAIYO YUDEN, JMK316BJ226ML-T501
C4: SANYO POS CAP, 4TPE330MI
RELATED PARTS
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
10A Basic 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, Fast Transient Response
LTM4603
6A DC/DC µModule with PLL and Output Tracking/
Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote
Sensing, Fast Transient Response
Polyphase is a registered trademark of Linear Technology Corporation.
This product contains technology licensed from Silicon Semiconductor Corporation.
24 Linear Technology Corporation
®
4602hvf
LT 0107 • PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
(408) 432-1900 ● FAX: (408) 434-0507
●
www.linear.com
© LINEAR TECHNOLOGY CORPORATION 2007
工商网监
湘ICP备2023018690号
