LTC3785EUF#PBF [Linear]
暂无描述;
Linear 
LTM4609
36V , 34V High Efficiency
IN
OUT
Buck-Boost DC/DC
µModule Regulator
Features
Description
n
Single Inductor Architecture Allows V Above,
The LTM®4609 is a high efficiency switching mode buck-
boost power supply. Included in the package are the
switchingcontroller,powerFETsandsupportcomponents.
Operating over an input voltage range of 4.5V to 36V, the
LTM4609 supports an output voltage range of 0.8V to
34V, set by a resistor. This high efficiency design delivers
up to 4A continuous current in boost mode (10A in buck
mode). Only the inductor, sense resistor, bulk input and
output capacitors are needed to finish the design.
IN
Below or Equal to V
OUT
n
n
n
n
n
n
n
n
n
n
n
Wide V Range: 4.5V to 36V
IN
OUT
Wide V
OUT
Range: 0.8V to 34V
I
: 4A DC (10A DC in Buck Mode)
Up to 98% Efficiency
Current Mode Control
Power Good Output Signal
Phase-Lockable Fixed Frequency: 200kHz to 400kHz
Ultrafast Transient Response
Current Foldback Protection
Output Overvoltage Protection
Thelowprofilepackageenablesutilizationofunusedspace
on the bottom of PC boards for high density point of load
regulation. The high switching frequency and current
mode architecture enable a very fast transient response
to line and load changes without sacrificing stability. The
LTM4609 can be frequency synchronized with an external
clock to reduce undesirable frequency harmonics.
RoHS Compliant with Pb-Free Finish:
Gold Finish LGA (e4) or SAC 305 BGA (e1)
Small Surface Mount Footprint, Low Profile
(15mm × 15mm × 2.82mm) LGA and
(15mm × 15mm × 3.42mm) BGA Packages
n
Faultprotectionfeaturesincludeovervoltageandfoldback
current protection. The DC/DC µModule® regulator is
offered in small thermally enhanced 15mm × 15mm ×
2.82mm LGA and 15mm × 15mm × 3.42mm BGA pack-
ages. TheLTM4609isRoHScompliantwithPb-freefinish.
L, LT, LTC, LTM, Linear Technology, the Linear logo, µModule, Burst Mode and PolyPhase are
applications
n
Telecom, Servers and Networking Equipment
n
Industrial and Automotive Equipment
n
High Power Battery-Operated Devices
registered trademarks and No R
is a trademark of Linear Technology Corporation. All other
SENSE
trademarks are the property of their respective owners.
typical application
Efficiency and Power Loss
vs Input Voltage
30V/2A Buck-Boost DC/DC µModule Regulator with 6.5V to 36V Input
V
IN
99
98
97
96
95
94
93
92
91
6
5
4
3
2
1
0
CLOCK SYNC
6.5V TO 36V
10µF
50V
V
30V
2A
OUT
V
PLLIN
IN
V
OUT
+
10µF
50V
330µF
50V
FCB
ON/OFF
RUN
LTM4609
5.6µH
SW1
SW2
R
SENSE
+
SENSE
R2
0.1µF
15mΩ
×2
–
SS
SENSE
EFFICIENCY
POWER LOSS
SGND
V
FB
PGND
2.74k
24
(V)
28
36
8
12
16
20
V
32
IN
4609 TA01a
4609 TA01b
4609fc
1
LTM4609
absolute MaxiMuM ratings
(Note 1)
V ............................................................. –0.3V to 36V
OUT
PLLFLTR.................................................... –0.3V to 2.7V
Operating Temperature Range (Note 2)
E- and I-grades....................................–40°C to 85°C
MP-grade........................................... –55°C to 125°C
Junction Temperature ........................................... 125°C
Storage Temperature Range...................–55°C to 125°C
Solder Temperature (Note 3)................................. 245°C
IN
V
............................................................. 0.8V to 36V
INTV , EXTV , RUN, SS, PGOOD.............. –0.3V to 7V
CC
CC
SW1, SW2 (Note 7) ...................................... –5V to 36V
V , COMP................................................ –0.3V to 2.4V
FB
FCB, STBYMD....................................... –0.3V to INTV
CC
PLLIN........................................................ –0.3V to 5.5V
(See Table 6 Pin Assignment)
pin conFiguration
TOP VIEW
TOP VIEW
SW2
SW2
(BANK 2)
(BANK 2)
M
L
M
L
SW1
(BANK 4)
V
SW1
(BANK 4)
V
IN
(BANK 1)
IN
(BANK 1)
K
J
K
J
H
G
F
H
G
F
V
V
OUT
(BANK 5)
OUT
(BANK 5)
R
R
SENSE
(BANK 3)
SENSE
(BANK 3)
INTV
EXTV
INTV
EXTV
CC
CC
CC
CC
E
E
D
C
B
A
D
C
B
A
PGND
PGND
(BANK 6)
(BANK 6)
COMP
PLLFLTR
PLLIN
COMP
PLLFLTR
PLLIN
PGOOD
PGOOD
V
FB
V
FB
–
–
SENSE SS SGND RUN FCB
SENSE SS SGND RUN FCB
1
2
3
4
5
6
7
8
9
10
11
12
1
2
3
4
5
6
7
8
9
10
11
12
+
+
SENSE
STBYMD
SENSE
STBYMD
LGA PACKAGE
141-LEAD (15mm × 15mm × 2.82mm)
BGA PACKAGE
141-LEAD (15mm × 15mm × 3.42mm)
T
= 125°C, θ = 4°C/W, WEIGHT = 1.5g
T
JMAX
= 125°C, θ = 4°C/W, WEIGHT = 1.7g
JMAX
JCbottom
JCbottom
orDer inForMation
LEAD FREE FINISH
LTM4609EV#PBF
LTM4609IV#PBF
LTM4609MPV#PBF
LTM4609EY#PBF
LTM4609IY#PBF
LTM4609MPY#PBF
PART MARKING*
LTM4609V
LTM4609V
LTM4609V
LTM4609Y
LTM4609Y
LTM4609Y
PACKAGE DESCRIPTION
TEMPERATURE RANGE (NOTE 2)
–40°C to 85°C
141-Lead (15mm × 15mm × 2.82mm) LGA
141-Lead (15mm × 15mm × 2.82mm) LGA
141-Lead (15mm × 15mm × 2.82mm) LGA
141-Lead (15mm × 15mm × 3.42mm) BGA
141-Lead (15mm × 15mm × 3.42mm) BGA
141-Lead (15mm × 15mm × 3.42mm) BGA
–40°C to 85°C
–55°C to 125°C
–40°C to 85°C
–40°C to 85°C
–55°C to 125°C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
For more information on lead free part marking, go to: http://www.linear.com/leadfree/
This product is only offered in trays. For more information go to: http://www.linear.com/packaging/
4609fc
2
LTM4609
electrical characteristics
The l denotes the specifications which apply over the specified operating
temperature range (Note 2), otherwise specifications are at TA = 25°C, VIN = 12V, per typical application (front page) configuration.
SYMBOL
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
Input Specifications
l
V
V
Input DC Voltage
Undervoltage Lockout Threshold
4.5
36
4
4.5
V
V
V
IN(DC)
l
l
V
IN
V
IN
Falling (–40°C to 85°C)
Falling (–55°C to 125°C)
3.4
3.4
IN(UVLO)
I
Input Supply Bias Current
Normal
Q(VIN)
2.8
1.6
35
mA
mA
µA
Standby
V
RUN
V
RUN
= 0V, V
= 0V, V
> 2V
= Open
STBYMD
STBYMD
Shutdown Supply Current
60
Output Specifications
I
Output Continuous Current Range
(See Output Current Derating Curves
V
IN
V
IN
= 32V, V = 12V
OUT
10
4
A
A
OUTDC
= 6V, V
= 12V
OUT
for Different V , V
and T )
A
IN OUT
Reference Voltage Line Regulation
Accuracy
V
= 4.5V to 36V, V
= 1.2V (Note 4)
COMP
0.002
0.02
%/V
ΔV /V
FB FB(NOM)
IN
l
l
Load Regulation Accuracy
V
V
= 1.2V to 0.7V
= 1.2V to 1.8V (Note 4)
0.15
–0.15
0.5
–0.5
%
%
ΔV /V
FB FB(LOAD)
COMP
COMP
Switch Section
M1 t
M1 t
M3 t
M3 t
Turn-On Time (Note 5)
Turn-Off Time
Drain to Source Voltage V = 12V,
50
40
25
20
20
20
50
50
50
50
220
220
10
14
14
14
ns
ns
r
f
r
f
DS
Bias Current I = 10mA
SW
Drain to Source Voltage V = 12V,
DS
Bias Current I = 10mA
SW
Turn-On Time
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Turn-Off Time
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
M2, M4 t
Turn-On Time
Drain to Source Voltage V = 12V,
ns
r
f
DS
Bias Current I = 10mA
SW
M2, M4 t
Turn-Off Time
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
t
1d
t
2d
t
3d
t
4d
M1 Off to M2 On Delay (Note 5)
M2 Off to M1 On Delay
M3 Off to M4 On Delay
M4 Off to M3 On Delay
M2 Off to M4 On Delay
M4 Off to M2 On Delay
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Mode Transition 1
Mode Transition 2
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
Drain to Source Voltage V = 12V,
ns
DS
Bias Current I = 10mA
SW
M1 R
M2 R
M3 R
M4 R
Static Drain-to-Source
On-Resistance
Static Drain-to-Source
On-Resistance
Static Drain-to-Source
On-Resistance
Static Drain-to-Source
On-Resistance
Bias Current I = 3A
mΩ
mΩ
mΩ
mΩ
DS(ON)
DS(ON)
DS(ON)
DS(ON)
SW
Bias Current I = 3A
20
20
20
SW
Bias Current I = 3A
SW
Bias Current I = 3A
SW
Oscillator and Phase-Locked Loop
f
f
Nominal Frequency
Lowest Frequency
V
V
= 1.2V
= 0V
260
170
300
200
330
220
kHz
kHz
NOM
LOW
PLLFLTR
PLLFLTR
4609fc
3
LTM4609
electrical characteristics The l denotes the specifications which apply over the specified operating
temperature range (Note 2), otherwise specifications are at TA = 25°C, VIN = 12V, per typical application (front page) configuration.
SYMBOL
PARAMETER
Highest Frequency
PLLIN Input Resistance
Phase Detector Output Current
CONDITIONS
MIN
340
TYP
400
50
–15
15
MAX
440
UNITS
kHz
f
V
= 2.4V
PLLFLTR
HIGH
R
kΩ
µA
µA
PLLIN
I
f
f
< f
> f
PLLFLTR
PLLIN
PLLIN
OSC
OSC
Control Section
l
l
V
FB
Feedback Reference Voltage
V
V
= 1.2V(–40°C to 85°C)
= 1.2V (–55°C to 125°C)
0.792
0.785
0.8
0.8
0.808
0.815
V
V
COMP
COMP
V
RUN Pin ON/OFF Threshold
Soft-Start Charging Current
Start-Up Threshold
Keep-Active Power On Threshold
Forced Continuous Threshold
Forced Continuous Pin Current
1
1
0.4
1.6
1.7
0.7
1.25
0.8
–0.2
5.3
2.2
V
µA
V
V
V
RUN
I
V
V
V
= 2.2V
RUN
SS
V
V
V
Rising
Rising, V
STBYMD(START)
STBYMD(KA)
FCB
STBYMD
STBYMD
= 0V
RUN
0.76
–0.3
0.84
–0.1
5.5
I
V
= 0.85V
FCB
µA
V
FCB
V
Burst Inhibit (Constant Frequency)
Threshold
Measured at FCB Pin
BURST
DF
DF
Maximum Duty Factor
Maximum Duty Factor
Minimum On-Time for Synchronous Switch M1 (Note 6)
Switch in Buck Operation
% Switch M4 On
% Switch M1 On
99
99
200
%
%
ns
(BOOST, MAX)
(BUCK, MAX)
t
250
ON(MIN, BUCK)
RFBHI
Internal V Regulator
Resistor Between V
and V Pins
99.5
5.7
100
100.5
kΩ
OUT
FB
CC
l
l
INTV
Internal V Voltage
V
I
> 7V, V = 5V
EXTVCC
6
6.3
2
V
%
CC
CC
IN
Internal V Load Regulation
= 0mA to 20mA, V
= 5V
0.3
5.6
300
60
ΔV /V
CC
CC
CC
EXTVCC
LDO LDO
V
EXTV Switchover Voltage
I
= 20mA, V
Rising
5.4
V
mV
mV
EXTVCC
CC
EXTVCC
EXTVCC
EXTV Switchover Hysteresis
ΔV
ΔV
CC
EXTVCC(HYS)
EXTV Switch Drop Voltage
I
CC
= 20mA, V
= 6V
150
CC
EXTVCC
Current Sensing Section
l
l
V
Maximum Current Sense Threshold Boost Mode
Buck Mode
160
–130
190
–150
mV
mV
SENSE(MAX)
–95
V
I
Minimum Current Sense Threshold Discontinuous Mode
–6
–380
mV
µA
SENSE(MIN, BUCK)
SENSE
–
+
Sense Pins Total Source Current
V
= V
= 0V
SENSE
SENSE
PGOOD
PGOOD Upper Threshold
PGOOD Lower Threshold
PGOOD Hysteresis
V
V
V
Rising
Falling
5.5
7.5
–7.5
2.5
10
%
%
%
V
ΔV
ΔV
ΔV
FB
FBH
–5.5
–10
FB
FBL
Returning
FB
FB(HYS)
V
PGL
PGOOD Low Voltage
PGOOD Leakage Current
I
= 2mA
= 5V
0.2
0.3
1
PGOOD
I
V
µA
PGOOD
PGOOD
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.
Thermal Considerations and Output Current Derating discussion. High
junction temperatures degrade operating lifetimes; operating lifetime is
derated for junction temperatures greater than 125°C.
Note 3: See Application Note 100.
Note 2: The LTM4609 is tested under pulsed load conditions such that
Note 4: The LTM4609 is tested in a feedback loop that servos V
to a
COMP
T ≈ T . The LTM4609E is guaranteed to meet performance specifications
J
A
specified voltage and measures the resultant V
.
FB
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls. The LTM4609I is guaranteed over
the –40°C to 85°C operating temperature range. The LTM4609MP is
guaranteed and tested over the –55°C to 125°C operating temperature
range. For output current derating at high temperature, please refer to
Note 5: Turn-on and turn-off time are measured using 10% and 90%
levels. Transition delay time is measured using 50% levels.
Note 6: 100% test at wafer level only.
Note 7: Absolute Maximum Rating of –5V on SW1 and SW2 is under
transient condition only.
4609fc
4
LTM4609
typical perForMance characteristics (Refer to Figure 18)
Efficiency vs Load Current
6VIN to 12VOUT
Efficiency vs Load Current
12VIN to 12VOUT
Efficiency vs Load Current
32VIN to 12VOUT
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
100
90
80
70
60
50
40
30
20
10
0
BURST
DCM
BURST
DCM
SKIP CYCLE
DCM
CCM
CCM
CCM
0.01
0.1
1
10
0.01
0.1
1
10
0.01
0.1
1
10
100
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
4609 G01
4609 G02
4609 G03
Efficiency vs Load Current
5.6µH Inductor
Efficiency vs Load Current
8µH Inductor
Efficiency vs Load Current
3.3µH Inductor
100
99
98
97
96
95
94
93
92
91
90
100
99
98
97
96
95
94
93
100
95
90
85
80
75
70
28V to 20V
30V to 30V
12V TO 5V
IN
OUT
OUT
OUT
IN
OUT
OUT
OUT
IN
OUT
OUT
OUT
32V to 20V
32V to 30V
24V TO 5V
IN
IN
IN
36V to 20V
IN
36V to 30V
IN
32V TO 5V
IN
0
1
2
3
4
5
6
7
8
3
6
0
1
2
4
5
0
4
5
6
7
8
9
10
1
2
3
LOAD CURRENT (A)
LOAD CURRENT (A)
LOAD CURRENT (A)
4609 G05
4609 G06
4609 G04
Efficiency vs Load Current
3.3µH Inductor
Transient Response from
12VIN to 12VOUT
Transient Response from
6VIN to 12VOUT
100
95
90
85
80
75
70
I
I
OUT
OUT
2A/DIV
2A/DIV
V
V
OUT
OUT
200mV/DIV
200mV/DIV
4609 G09
4609 G08
200µs/DIV
200µs/DIV
LOAD STEP: 0A TO 3A AT CCM
LOAD STEP: 0A TO 3A AT CCM
5V to 16V
IN
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
OUT
OUT
OUT
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
5V to 24V
IN
5V to 30V
IN
2x 15mΩ SENSING RESISTORS
2x 15mΩ SENSING RESISTORS
0
0.5
1
1.5
2
2.5
3
LOAD CURRENT (A)
4609 G07
4609fc
5
LTM4609
typical perForMance characteristics
Transient Response from
32VIN to 12VOUT
Start-Up with 6VIN to 12VOUT at
IOUT = 4A
Start-Up with 32VIN to 12VOUT at
IOUT = 5A
I
I
L
L
5A/DIV
5A/DIV
I
OUT
2A/DIV
I
I
IN
IN
2A/DIV
5A/DIV
V
OUT
V
100mV/DIV
V
OUT
OUT
10V/DIV
10V/DIV
4609 G12
4609 G10
4609 G11
10ms/DIV
0.1µF SOFT-START CAP
200µs/DIV
50ms/DIV
0.1µF SOFT-START CAP
LOAD STEP: 0A TO 5A AT CCM
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
2x 12mΩ SENSING RESISTORS
2x 12mΩ SENSING RESISTORS
2x 12mΩ SENSING RESISTORS
Short Circuit with 32VIN to 12VOUT
at IOUT = 5A
Short Circuit with 12VIN to 34VOUT
at IOUT = 2A
Short Circuit with 6VIN to 12VOUT
at IOUT = 4A
V
OUT
10V/DIV
V
OUT
5V/DIV
I
IN
2A/DIV
V
OUT
5V/DIV
I
IN
I
IN
5A/DIV
5A/DIV
4609 G14
4607 G15
4609 G13
50µs/DIV
20µs/DIV
50µs/DIV
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
2x 12mΩ SENSING RESISTORS
OUTPUT CAPS: 2x 10µF 50V CERAMIC CAPS AND
2x 47µF 50V ELECTROLYTIC CAPS
2x 15mΩ SENSING RESISTORS
OUTPUT CAPS: 4x 22µF CERAMIC CAPS AND
2x 180µF ELECTROLYTIC CAPS
2x 12mΩ SENSING RESISTORS
4609fc
6
LTM4609
pin Functions
V (Bank 1): Power Input Pins. Apply input voltage be-
STBYMD(PinA10):LDOControlPin.Determineswhether
theinternalLDOremainsactivewhenthecontrollerisshut
down. See Operations section for details. If the STBYMD
pin is pulled to ground, the SS pin is internally pulled to
ground to disable start-up and thereby providing a single
control pin for turning off the controller. An internal de-
coupling capacitor is tied to this pin.
IN
tween these pins and PGND pins. Recommend placing
input decoupling capacitance directly between V pins
IN
and PGND pins.
V
(Bank 5): Power Output Pins. Apply output load
OUT
between these pins and PGND pins. Recommend placing
outputdecouplingcapacitancedirectlybetweenthesepins
and PGND pins.
V
(Pin B6): The Negative Input of the Error Amplifier.
FB
Internally, this pin is connected to V
with a 100k preci-
OUT
PGND (Bank 6): Power Ground Pins for Both Input and
Output Returns.
sionresistor.Differentoutputvoltagescanbeprogrammed
with an additional resistor between V and SGND pins.
FB
SW1, SW2 (Bank 4, Bank 2): Switch Nodes. The power
inductor is connected between SW1 and SW2.
See the Applications Information section.
FCB(PinA9):ForcedContinuousControlInput.Thevoltage
applied to this pin sets the operating mode of the module.
When the applied voltage is less than 0.8V, the forced
continuous current mode is active in boost operation and
the skip cycle mode is active in buck operation. When the
R
(Bank3):SensingResistorPin. Thesensingresis-
SENSE
tor is connected from this pin to PGND.
+
SENSE (Pin A4): Positive Input to the Current Sense and
Reverse Current Detect Comparators.
pinistiedtoINTV ,theconstantfrequencydiscontinuous
CC
–
SENSE (Pin A5): Negative Input to the Current Sense and
current mode is active in buck or boost operation. See the
Reverse Current Detect Comparators.
Applications Information section.
EXTV (PinF6):ExternalV Input.WhenEXTV exceeds
CC
CC
CC
SGND (Pin A7): Signal Ground Pin. This pin connects to
5.7V, an internal switch connects this pin to INTV and
CC
PGND at output capacitor point.
shutsdowntheinternalregulatorsothatthecontrollerand
COMP (Pin B7): 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.
gate drive power is drawn from EXTV . Do not exceed
CC
7V at this pin and ensure that EXTV < V
CC
IN
INTV (Pin F5): Internal 6V Regulator Output. This pin
CC
is for additional decoupling of the 6V internal regulator.
PGOOD (Pin B5): Output Voltage Power Good Indicator.
Open drain logic output that is pulled to ground when the
output voltage is not within 7.5% of the regulation point.
Do not source more than 40mA from INTV .
CC
PLLIN (Pin B9): External Clock Synchronization Input
to the Phase Detector. This pin is internally terminated
to SGND with a 50k resistor. The phase-locked loop will
force the rising bottom gate signal of the controller to be
synchronized with the rising edge of PLLIN signal.
RUN (Pin A8): Run Control Pin. A voltage below 1.6V will
turn off the module. There is a 100k resistor between the
RUN pin and SGND in the module. Do not apply more than
6V to this pin. See the Applications Information section.
PLLFLTR (Pin B8): The lowpass filter of the phase-locked
loop is tied to this pin. This pin can also be used to set the
frequency of the internal oscillator with an AC or DC volt-
age. See the Applications Information section for details.
SS (Pin A6): Soft-Start Pin. Soft-start reduces the input
surgecurrentfromthepowersourcebygraduallyincreas-
ing the controller’s current limit.
4609fc
7
LTM4609
siMpliFieD block DiagraM
V
IN
4.5V TO 36V
EXTV
CC
C1
C
IN
M1
M2
SW2
INTV
CC
PGOOD
RUN
L
SW1
ON/OFF
V
OUT
100k
12V
4A
STBYMD
COMP
CO1
M3
M4
C
OUT
0.1µF
100k
R
FB
V
FB
7.15k
CONTROLLER
R
SENSE
INT
COMP
+
SS
SENSE
SS
0.1µF
PLLIN
PLLFLTR
INT
FILTER
R
SENSE
–
SENSE
INT
FILTER
PGND
FCB
1000pF
SGND
TO PGND PLANE AS
SHOWN IN FIGURE 15
4609 BD
Figure 1. Simplified LTM4609 Block Diagram
Decoupling requireMents
TA = 25°C. Use Figure 1 configuration.
CONDITIONS
SYMBOL
PARAMETER
MIN
TYP
MAX
UNITS
C
External Input Capacitor Requirement
IN
I
= 4A
10
µF
IN
OUT
(V = 4.5V to 36V, V
= 12V)
OUT
C
External Output Capacitor Requirement
(V = 4.5V to 36V, V = 12V)
I
= 4A
200
300
µF
OUT
OUT
IN
OUT
4609fc
8
LTM4609
operation
Power Module Description
input clock signal from the PLLIN pin. The typical switch-
ing frequency is 400kHz.
The LTM4609 is a non-isolated buck-boost DC/DC power
supply.Itcandeliverawiderangeoutputvoltagefrom0.8V
to 34V over a wide input range from 4.5V to 36V, by only
adding the sensing resistor, inductor and some external
inputandoutputcapacitors.Itprovidespreciselyregulated
output voltage programmable via one external resistor.
The typical application schematic is shown in Figure 18.
The Burst Mode® and skip-cycle mode operations can be
enabledatlightloadstoimproveefficiency,whiletheforced
continuousmodeanddiscontinuousmodeoperationsare
usedforconstantfrequencyapplications.Foldbackcurrent
limiting is activated in an overcurrent condition as V
FB
drops. Internal overvoltage and undervoltage compara-
tors pull the open-drain PGOOD output low if the output
feedback voltage exits the 7.5% window around the
regulation point. Pulling the RUN pin below 1.6V forces
the controller into its shutdown state.
The LTM4609 has an integrated current mode buck-boost
controller, ultralowR
FETswithfastswitchingspeed
DS(ON)
andintegratedSchottkydiodes.Withcurrentmodecontrol
and internal feedback loop compensation, the LTM4609
modulehassufficientstabilitymarginsandgoodtransient
performance under a wide range of operating conditions
and with a wide range of output capacitors. The operating
frequency of the LTM4609 can be adjusted from 200kHz
to 400kHz by setting the voltage on the PLLFLTR pin.
Alternatively, its frequency can be synchronized by the
IfanexternalbiassupplyisappliedontheEXTV pin,then
CC
an efficiency improvement will occur due to the reduced
powerlossintheinternallinearregulator.Thisisespecially
true at the higher end of the input voltage range.
applications inForMation
The typical LTM4609 application circuit is shown in Fig-
ure 18. External component selection is primarily deter-
mined by the maximum load current and output voltage.
RefertoTable3forspecificexternalcapacitorrequirements
for a particular application.
Operation Frequency Selection
The LTM4609 uses current mode control architecture at
constant switching frequency, which is determined by the
internal oscillator’s capacitor. This internal capacitor is
charged by a fixed current plus an additional current that
is proportional to the voltage applied to the PLLFLTR pin.
The PLLFLTR pin can be grounded to lower the frequency
to 200kHz or tied to 2.4V to yield approximately 400kHz.
When PLLFLTR is left open, the PLLFLTR pin goes low,
forcing the oscillator to its minimum frequency.
Output Voltage Programming
ThePWMcontrollerhasaninternal0.8Vreferencevoltage.
As shown in the Block Diagram, a 100k internal feedback
resistor connects V
and V pins together. Adding a
FB
OUT
FB
resistor R from the V pin to the SGND pin programs
FB
A graph for the voltage applied to the PLLFLTR pin vs
frequency is given in Figure 2. As the operating frequency
increases, the gate charge losses will be higher, thus the
efficiency is lower. The maximum switching frequency is
approximately 400kHz.
the output voltage:
100k + RFB
VOUT = 0.8V •
RFB
Table 1. RFB Resistor (0.5%) vs Output Voltage
V
0.8V 1.5V 2.5V
Open 115k 47.5k 32.4k 19.1k 15.4k
10V 12V 15V 16V 20V 24V
8.66k 7.15k 5.62k 5.23k 4.12k 3.4k 2.74k 2.37k
3.3V
5V
6V
8V
11k 9.76k
30V 34V
9V
OUT
FREꢀUENCY SYNCHRONIꢁATION
R
FB
The LTM4609 can also be synchronized to an external
source via the PLLIN pin instead of adjusting the voltage
on the PLLFLTR pin directly. The power module has a
V
OUT
R
FB
4609fc
9
LTM4609
applications inForMation
phase-locked loop comprised of an internal voltage con-
trolled oscillator and a phase detector. This allows turning
on the internal top MOSFET for locking to the rising edge
of the external clock. A pulse detection circuit is used to
detect a clock on the PLLIN pin to turn on the phase-lock
loop. The input pulse width of the clock has to be at least
400ns, and 2V in amplitude. The synchronized frequency
rangesfrom200kHzto400kHz,correspondingtoaDCvolt-
age input from 0V to 2.4V at PLLFLTR. During the start-up
of the regulator, the phase-lock loop function is disabled.
load current is lower than the preset minimum output
current level. The MOSFETs will turn on for several cycles,
followed by a variable “sleep” interval depending upon the
load current. During buck operation, skip-cycle mode sets
a minimum positive inductor current level. In this mode,
some cycles will be skipped when the output load current
drops below 1% of the maximum designed load in order
to maintain the output voltage.
When the FCB pin voltage is tied to the INTV pin, the
CC
controllerentersconstantfrequencydiscontinuouscurrent
mode (DCM). For boost operation, if the output voltage is
highenough,thecontrollercanenterthecontinuouscurrent
buck mode for one cycle to discharge inductor current.
In the following cycle, the controller will resume DCM
boost operation. For buck operation, constant frequency
discontinuous current mode is turned on if the preset
minimum negative inductor current level is reached. At
very light loads, this constant frequency operation is not
as efficient as Burst Mode operation or skip-cycle, but
does provide low noise, constant frequency operation.
450
400
350
300
250
200
150
100
50
0
0
0.5
1.0
1.5
2.0
2.5
PLLFLTR PIN VOLTAGE (V)
Input Capacitors
4609 F02
Figure 2. Frequency vs PLLFLTR Pin Voltage
In boost mode, since the input current is continuous, only
minimuminputcapacitorsarerequired.However,theinput
current is discontinuous in buck mode. So the selection
Low Current Operation
of input capacitor C is driven by the need of filtering the
To improve efficiency at low output current operation,
LTM4609 provides three modes for both buck and boost
operations by accepting a logic input on the FCB pin. Table
2 shows the different operation modes.
IN
input square wave current.
For a buck converter, the switching duty-cycle can be
estimated as:
Table 2. Different Operating Modes (VINTVCC = 6V)
VOUT
D=
FCB PIN
0V to 0.75V
0.85V to
BUCK
BOOST
V
IN
Force Continuous Mode
Skip-Cycle Mode
Force Continuous Mode
Burst Mode Operation
Without considering the inductor current ripple, the RMS
current of the input capacitor can be estimated as:
V
– 1V
INTVCC
>5.3V
DCM with Constant Freq DCM with Constant Freq
IOUT(MAX)
ICIN(RMS)
=
• D•(1− D)
When the FCB pin voltage is lower than 0.8V, the controller
behavesasacontinuous,PWMcurrentmodesynchronous
switching regulator. When the FCB pin voltage is below
η
In the above equation, η is the estimated efficiency of the
power module. C can be a switcher-rated electrolytic
V
– 1V, but greater than 0.85V, where V
is 6V,
IN
INTVCC
INTVCC
aluminum capacitor, OS-CON capacitor or high volume
ceramic capacitors. Note the capacitor ripple current
ratings are often based on temperature and hours of life.
thecontrollerentersBurstModeoperationinboostopera-
tion or enters skip-cycle mode in buck operation. During
boost operation, Burst Mode operation is activated if the
4609fc
10
LTM4609
applications inForMation
Thismakesitadvisabletoproperlyderatetheinputcapaci-
tor, or choose a capacitor rated at a higher temperature
than required. Always contact the capacitor manufacturer
for derating requirements.
ripple ΔI is typically set to 20% to 40% of the maximum
L
inductor current. In the inductor design, the worst cases
in continuous mode are considered as follows:
V2 • V
− V
IN
(
)
IN
OUT(MAX)
LBOOST
≥
V2OUT(MAX) • ƒ •IOUT(MAX) •Ripple%
Output Capacitors
In boost mode, the discontinuous current shifts from the
input to the output, so the output capacitor C
must be
VOUT • V
− V
OUT
OUT
(
)
IN(MAX)
LBUCK
where:
≥
capable of reducing the output voltage ripple.
V
IN(MAX) • ƒ •IOUT(MAX) •Ripple%
For boost and buck modes, the steady ripple due to charg-
ing and discharging the bulk capacitance is given by:
ƒ is operating frequency, Hz
IOUT(MAX) • V
− V
IN(MIN)
(
)
OUT
VRIPPLE,BOOST
=
Ripple% is allowable inductor current ripple, %
COUT • VOUT • ƒ
V
V
V
I
is maximum output voltage, V
OUT(MAX)
VOUT • V
8 •L •COUT • VIN(MAX) • ƒ2
− V
OUT
(
)
IN(MAX)
is maximum input voltage, V
VRIPPLE,BUCK
=
IN(MAX)
is output voltage, V
OUT
is maximum output load current, A
The steady ripple due to the voltage drop across the ESR
(effective series resistance) is given by:
OUT(MAX)
The inductor should have low DC resistance to reduce the
I R losses, and must be able to handle the peak inductor
current without saturation. To minimize radiated noise,
use a toroid, pot core or shielded bobbin inductor. Please
refer to Table 3 for the recommended inductors for dif-
ferent cases.
2
VESR,BUCK = ΔIL(MAX) •ESR
VESR,BOOST = IL(MAX) •ESR
The LTM4609 is designed for low output voltage ripple.
The bulk output capacitors defined as C
are chosen
OUT
R
Selection and Maximum Output Current
SENSE
withlowenoughESRtomeettheoutputvoltagerippleand
transient requirements. C can be the low ESR tantalum
R
is chosen based on the required inductor current.
OUT
SENSE
capacitor, the low ESR polymer capacitor or the ceramic
capacitor. Multiple capacitors can be placed in parallel to
meettheESRandRMScurrenthandlingrequirements.The
typicalcapacitanceis300µF.Additionaloutputfilteringmay
be required by the system designer, if further reduction of
outputrippleordynamictransientspikeisrequired.Table3
shows a matrix of different output voltages and output
capacitors to minimize the voltage droop and overshoot
at a current transient.
Since the maximum inductor valley current at buck mode
is much lower than the inductor peak current at boost
mode, different sensing resistors are suggested to use
in buck and boost modes.
The current comparator threshold sets the peak of the
inductorcurrentinboostmodeandthemaximuminductor
valley current in buck mode. In boost mode, the allowed
maximum average load current is:
160mV ΔIL
V
IN
VOUT
IOUT(MAX,BOOST)
=
−
•
Inductor Selection
R
2
SENSE
The inductor is chiefly decided by the required ripple cur-
rent and the operating frequency. The inductor current
where ΔI is peak-to-peak inductor ripple current.
L
4609fc
11
LTM4609
applications inForMation
In buck mode, the allowed maximum average load cur-
rent is:
Run Enable
The RUN pin is used to enable the power module. The pin
can be driven with a logic input, not to exceed 6V.
ΔIL
2
130mV
RSENSE
IOUT(MAX,BUCK)
=
+
The RUN pin can also be used as an undervoltage lockout
(UVLO) function by connecting a resistor from the input
supply to the RUN pin. The equation:
The maximum current sensing R
mode is:
value for the boost
SENSE
R1+ R2
V _UVLO=
•1.6V
RSENSE(MAX,BOOST)
=
R2
2•160mV • V
IN
Power Good
2•IOUT(MAX,BOOST) • VOUT + ΔIL • V
IN
The PGOOD pin is an open drain pin that can be used to
monitor valid output voltage regulation. This pin monitors
a 7.5% window around the regulation point.
The maximum current sensing R
mode is:
value for the buck
SENSE
2•130mV
2•IOUT(MAX,BUCK) – ΔIL
RSENSE(MAX,BUCK)
=
COMP Pin
This pin is the external compensation pin. The module
has already been internally compensated for most output
voltages. A spice model is available for other control loop
optimization.
A 20% to 30% margin on the calculated sensing resistor
is usually recommended. Please refer to Table 3 for the
recommendedsensingresistorsfordifferentapplications.
Fault Conditions: Current Limit and Overcurrent
Foldback
Soft-Start
The SS pin provides a means to soft-start the regulator.
A capacitor on this pin will program the ramp rate of the
output voltage. A 1.7µA current source will charge up the
external soft-start capacitor. This will control the ramp of
the internal reference and the output voltage. The total
soft-start time can be calculated as:
LTM4609 has a current mode controller, which inherently
limitsthecycle-by-cycleinductorcurrentnotonlyinsteady
state operation, but also in transient. Refer to Table 3.
To further limit current in the event of an overload condi-
tion,theLTM4609providesfoldbackcurrentlimiting.Ifthe
output voltage falls by more than 70%, then the maximum
output current is progressively lowered to about 30% of
its full current limit value for boost mode and about 40%
for buck mode.
2.4V •CSS
1.7µA
tSOFTSTART
=
When the RUN pin falls below 1.6V, then soft-start pin
is reset to allow for proper soft-start control when the
regulator is enabled again. Current foldback and force
continuous mode are disabled during the soft-start pro-
cess. The soft-start function can also be used to control
the output ramp up time, so that another regulator can be
easily tracked. Do not apply more than 6V to the SS pin.
Standby Mode (STBYMD)
Thestandbymode(STBYMD)pinprovidesseveralchoices
for start-up and standby operational modes. If the pin is
pulled to ground, the SS pin is internally pulled to ground,
preventing start-up and thereby providing a single control
4609fc
12
LTM4609
applications inForMation
pin for turning off the controller. If the pin is left open or
decoupledwithacapacitortoground,theSSpinisinternally
providedwithastartingcurrent,permittingexternalcontrol
for turning on the controller. If the pin is connected to a
Thermal Considerations and Output Current Derating
In different applications, LTM4609 operates in a variety
of thermal environments. The maximum output current is
limited by the environmental thermal condition. Sufficient
cooling should be provided to ensure reliable operation.
When the cooling is limited, proper output current de-
rating is necessary, considering ambient temperature,
airflow, input/output condition, and the need for increased
reliability.
voltage greater than 1.25V, the internal regulator (INTV )
CC
will be on even when the controller is shut down (RUN
pin voltage <1.6V). In this mode, the onboard 6V output
linear regulator can provide power to keep-alive functions
such as a keyboard controller.
INTV and EXTV
The power loss curves in Figures 5 and 6 can be used
in coordination with the load current derating curves in
CC
CC
An internal P-channel low dropout regulator produces 6V
Figures 7 to 14 for calculating an approximate θ for
JA
at the INTV pin from the V supply pin. INTV powers
CC
IN
CC
the module. Column designation delineates between no
heat sink, and a BGA heat sink. Each of the load current
derating 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 115°C allowing a safe margin for the maximum operat-
ing temperature below 125°C. Each of the derating curves
and the power loss curve that corresponds to the correct
output voltage can be used to solve for the approximate
the control chip and internal circuitry within the module.
TheLTM4609alsoprovidestheexternalsupplyvoltagepin
EXTV . When the voltage applied to EXTV rises above
CC
CC
5.7V, the internal regulator is turned off and an internal
switch connects the EXTV pin to the INTV pin thereby
CC
CC
supplyinginternalpower.Theswitchremainsclosedaslong
as the voltage applied to EXTV remains above 5.5V. This
CC
allows the MOSFET driver and control power to be derived
from the output when (5.7V < V
< 7V) and from the
θ ofthecondition.Acompleteexplanationofthethermal
OUT
JA
internalregulatorwhentheoutputisoutofregulation(start-
characteristics is provided in the thermal application note
up, short-circuit). If more current is required through the
for the LTM4609.
EXTV switchthanisspecified,anexternalSchottkydiode
CC
can be interposed between the EXTV and INTV pins.
CC
CC
DESIGN EXAMPLES
Ensure that EXTV ≤ V .
CC
IN
Buck Mode Operation
The following list summarizes the three possible connec-
tions for EXTV :
CC
As a design example, use input voltage V = 12V to 36V,
IN
V
OUT
= 12V and ƒ = 400kHz.
1. EXTV left open (or grounded). This will cause INTV
CC
CC
to be powered from the internal 6V regulator at the cost
Set the PLLFLTR pin at 2.4V or more for 400kHz frequency
and connect FCB to ground for continuous current mode
operation.Ifadividerisusedtosetthefrequencyasshown
in Figure 16, the bottom resistor R3 is recommended not
to exceed 1kΩ.
of a small efficiency penalty.
2. EXTV connected directly to V
(5.7V < V
< 7V).
CC
OUT
OUT
This is the normal connection for a 6V regulator and
provides the highest efficiency.
To set the output voltage at 12V, the resistor R from V
3. EXTV connected to an external supply. If an external
FB
FB
CC
pin to ground should be chosen as:
supply is available in the 5.5V to 7V range, it may be
used to power EXTV provided it is compatible with
CC
0.8V •100k
RFB =
≈ 7.15k
the MOSFET gate drive requirements.
VOUT − 0.8V
4609fc
13
LTM4609
applications inForMation
To choose a proper inductor, we need to know the current
ripple at different input voltages. The inductor should
be chosen by considering the worst case in the practi-
cal operating region. If the maximum output power P is
120W at buck mode, we can get the current ripple ratio
For the input capacitor, use a low ESR sized capacitor to
handle the maximum RMS current. Input capacitors are
required to be placed adjacent to the module. In Figure 16,
the 10µF ceramic input capacitors are selected for their
ability to handle the large RMS current into the converter.
The100µFbulkcapacitorisonlyneedediftheinputsource
impedance is compromised by long inductive leads or
traces.
of the current ripple ΔI to the maximum inductor current
L
I as follows:
L
2
(V – VOUT )• VOUT
ΔIL
IL
IN
=
For the output capacitor, the output voltage ripple and
transient requirements require low ESR capacitors. If
assuming that the ESR dominates the output ripple, the
output ripple is as follows:
V •L • ƒ •P
IN
Figure 3 shows the current ripple ratio at different input
voltagesbasedontheinductorvalues:2.5µH,3.3µH,4.7µH
and 6µH. If we need about 40% ripple current ratio at all
inputs, the 4.7µH inductor can be selected.
ΔVOUT(P-P) = ESR • ΔIL
If a total low ESR of about 5mΩ is chosen for output
capacitors, the maximum output ripple of 21.5mV occurs
at the input voltage of 36V with the current ripple at 4.3A.
At buck mode, sensing resistor selection is based on
the maximum output current and the allowed maximum
sensing threshold 130mV.
2•130mV
2•(P / VOUT )− ΔIL
Boost Mode Operation
RSENSE
=
For boost mode operation, use input voltage V = 5V to
IN
12V, V
= 12V and ƒ = 400kHz.
OUT
Consider the safety margin about 30%, we can choose
the sensing resistor as 9mΩ.
Set the PLLFLTR pin and R as in buck mode.
FB
If the maximum output power P is 50W at boost mode
0.8
and the module efficiency η is about 90%, we can get
V
= 12V
OUT
2.5µH
ƒ = 400kHz
the current ripple ratio of the current ripple ΔI to the
L
maximum inductor current I as follows:
0.6
0.4
0.2
0
L
3.3µH
4.7µH
2
(VOUT − V )• V η
ΔIL
IL
IN
IN
=
VOUT •L • ƒ •P
6µH
12
18
24
30
36
INPUT VOLTAGE V (V)
IN
4609 F03
Figure 3. Current Ripple Ratio at Different Inputs for Buck Mode
4609fc
14
LTM4609
applications inForMation
0.8
If assuming that the ESR dominates the output ripple,
the output ripple is as follows:
V
= 12V
OUT
ƒ = 400kHz
1.5µH
0.6
0.4
0.2
0
ΔVOUT(P-P) = ESR •IL(MAX)
2.5µH
If a total low ESR about 5mΩ is chosen for output capaci-
tors, the maximum output ripple of 70mV occurs at the
input voltage of 5V with the peak inductor current at 14A.
3.3µH
4.7µH
An RC snubber is recommended on SW1 to obtain low
switching noise, as shown in Figure 17.
5
6
7
8
9
10
11
12
INPUT VOLTAGE V (V)
IN
Wide Input Mode Operation
4609 F04
Figure 4. Current Ripple Ratio at Different Inputs for Boost Mode
Ifawideinputrangeisrequiredfrom5Vto36V,themodule
will work in different operation modes. If input voltage
Figure 4 shows the current ripple ratio at different input
voltages based on the inductor values: 1.5µH, 2.5µH,
3.3µH and 4.7µH. If we need 30% ripple current ratio at
all inputs, the 3.3µH inductor can be selected.
V = 5V to 36V, V
= 12V and ƒ = 400kHz, the design
IN
OUT
needs to consider the worst case in buck or boost mode
design. Therefore, the maximum output power is limited
to 60W. The sensing resistor is chosen at 8mΩ, the input
capacitor is the same as the buck mode design and the
output capacitor uses the boost mode design. Since the
maximum output ripple normally occurs at boost mode
in the wide input mode design, more inductor ripple cur-
rent, up to 150% of the inductor current, is allowed at
buck mode to meet the ripple design requirement. Thus,
a 3.3µH inductor is chosen at the wide input mode. The
maximum output ripple voltage is still 70mV if the total
ESR is about 5mΩ.
At boost mode, sensing resistor selection is based on
the maximum input current and the allowed maximum
sensing threshold 160mV.
2•160mV
RSENSE
=
P
2•
+ ΔIL
η • V
IN(MIN)
Consider the safety margin about 30%, we can choose
the sensing resistor as 8mΩ.
Additionally, the current limit may become very high when
the module runs at buck mode due to the low sensing
resistor used in the wide input mode operation.
For the input capacitor, only minimum capacitors are
needed to handle the maximum RMS current, since it
is a continuous input current at boost mode. A 100µF
capacitor is only needed if the input source impedance is
compromised by long inductive leads or traces.
Safety Considerations
The LTM4609 modules do not provide isolation from V
IN
Since the output capacitors at boost mode need to filter
the square wave current, more capacitors are expected
to achieve the same output ripples as the buck mode.
to V . There is no internal fuse. If required, a slow blow
OUT
fuse with a rating twice the maximum input current needs
tobeprovidedtoprotecteachunitfromcatastrophicfailure.
4609fc
15
LTM4609
applications inForMation
Table 3. Typical Components (ƒ = 400kHz)
C
VENDORS
PART NUMBER
C
OUT2
VENDORS
PART NUMBER
OUT1
TDK
C4532X7R1E226M (22µF, 25V)
PART NUMBER
Sanyo
16SVP180MX (180µF, 16V), 20SVP150MX (150µF, 20V)
PART NUMBER
INDUCTOR VENDORS
R
VENDORS
SENSE
Toko
FDA1254
Vishay
Panasonic
Power Metal Strip Resistors WSL1206-18
Thick Film Chip Resistors ERJ12
Sumida
CDEP134, CDEP145, CDEP147
V
(V)
V
(V)
R
Inductor
(µH)
C
C
C
C
I
*
IN
OUT
SENSE
IN
IN
OUT1
OUT2
OUT(MAX)
(0.5W RATING)
(CERAMIC)
(BULK)
(CERAMIC)
(BULK)
(A)
5
10
10
10
10
10
10
12
12
12
12
12
12
16
16
16
16
16
16
16
20
20
20
20
24
24
24
24
2 × 16mW 0.5W
2 × 18mW 0.5W
2 × 20mW 0.5W
2 × 18mΩ 0.5W
2 × 22mΩ 0.5W
2 × 22mΩ 0.5W
2 × 14mΩ 0.5W
2 × 16mW 0.5W
2 × 18mW 0.5W
2 × 18mΩ 0.5W
2 × 22mΩ 0.5W
2 × 22mΩ 0.5W
2 × 18mW 0.5W
2 × 16mW 0.5W
2 × 14mW 0.5W
2 × 20mW 0.5W
2 × 20mΩ 0.5W
2 × 22mΩ 0.5W
2 × 22mΩ 0.5W
2 × 18mΩ 0.5W
2 × 18mΩ 0.5W
1 × 12mΩ 0.5W
1 × 13mΩ 0.5W
2 × 16mΩ 0.5W
2 × 18mΩ 0.5W
1 × 14mΩ 0.5W
1 × 13mΩ 0.5W
2.2
2.2
3.3
3.3
4.7
4.7
2.2
2.2
3.3
3.3
4.7
4.7
3.3
3.3
2.2
2.2
3.3
4.7
6
None
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 50V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 50V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 35V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
4 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
4 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
4 × 22µF 25V
4 × 22µF 25V
4 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
4 × 22µF 25V
4 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
4 × 22µF 25V
4 × 22µF 25V
2 × 22µF 25V
2 × 22µF 25V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 180µF 16V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 20V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
4
11
10
10
9
15
20
24
32
36
6
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 50V
2 × 10µF 50V
None
9
4
16
20
24
32
36
5
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 50V
2 × 10µF 50V
None
11
10
9
9
9
2.5
4
8
None
12
20
24
32
36
5
None
8
2 × 10µF 25V
2 × 10µF 25V
2 × 10µF 50V
2 × 10µF 50V
NONE
10
10
9
9
3.3
3.3
6
2
10
32
36
5
NONE
5
2 × 10µF 50V
2 × 10µF 50V
NONE
9
8
8
3.3
4.7
4.7
7
1.5
5
12
32
36
NONE
2 × 10µF 50V
2 × 10µF 50V
8
8
4609fc
16
LTM4609
applications inForMation
Table 3. Typical Components (ƒ = 400kHz) Continued
V
(V)
V
(V)
R
Inductor
(µH)
C
C
C
C
I
*
IN
OUT
SENSE
IN
IN
OUT1
OUT2
OUT(MAX)
(0.5W RATING)
(CERAMIC)
(BULK)
(CERAMIC)
(BULK)
(A)
5
30
30
30
30
34
34
34
34
2 × 16mΩ 0.5W
2 × 14mΩ 0.5W
1 × 12mΩ 0.5W
1 × 13mΩ 0.5W
2 × 18mΩ 0.5W
2 × 16mΩ 0.5W
1 × 12mΩ 0.5W
1 × 12mΩ 0.5W
3.3
4.7
2.5
4.7
3.3
4.7
5.6
2.5
NONE
NONE
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
150µF 50V
4 × 22µF 50V
4 × 22µF 50V
2 × 22µF 50V
2 × 22µF 50V
4 × 22µF 50V
4 × 22µF 50V
4 × 22µF 50V
2 × 22µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
2 × 150µF 50V
1.3
3
12
32
36
5
2 × 10µF 50V
2 × 10µF 50V
NONE
8
8
1
12
24
36
NONE
3
NONE
5
2 × 10µF 50V
8
INDUCTOR MANUFACTURER
WEBSITE
PHONE NUMBER
408-321-9660
847-297-0070
Sumida
Toko
www.sumida.com
www.toko.com
SENSING RESISTOR MANUFACTURER
WEBSITE
PHONE NUMBER
949-462-1816
814-362-5536
800-433-5700
Panasonic
KOA
www.panasonic.com/industrial/components
www.koaspeer.com
Vishay
www.vishay.com
*Maximum load current is based on the Linear Technology DC1198A at room temperature with natural convection. Poor board layout design may
decrease the maximum load current.
(Power Loss includes all external components)
typical applications
7
6
5
4
7
6
5
4
3
2
1
0
32V TO 12V
IN
OUT
OUT
36V TO 20V
IN
3
2
1
0
5V TO 16V
IN
OUT
OUT
5V TO 30V
IN
0
1
2
3
0
1
2
3
4
5
6
7
8
9
LOAD CURRENT (A)
LOAD CURRENT (A)
4609 F05
4609 F06
Figure 5. Boost Mode Operation
Figure 6. Buck Mode Operation
4609fc
17
LTM4609
typical applications
3.0
3.0
2.5
2.0
1.5
1.0
0.5
0
2.5
2.0
1.5
1.0
0.5
5V TO 16V
WITH 0LFM
WITH 200LFM
WITH 400LFM
IN
OUT
OUT
OUT
5V TO 16V
IN
5V TO 16V
IN
0
25 35 45 55 65 75 85 95 105 115
AMBIENT TEMPERATURE (°C)
25
45
65
85
105
125
AMBIENT TEMPERATURE (°C)
4609 F07
4609 F08
5V TO 16V
WITH 0LFM
WITH 200LFM
WITH 400LFM
IN
OUT
OUT
OUT
5V TO 16V
IN
5V TO 16V
IN
Figure 7. 5VIN to 16VOUT without Heat Sink
Figure 8. 5VIN to 16VOUT with Heat Sink
1.50
1.25
1.00
0.75
0.50
1.50
1.25
1.00
0.75
0.50
5V TO 30V
IN
WITH 0LFM
WITH 200LFM
WITH 400LFM
5V TO 30V
IN
WITH 0LFM
WITH 200LFM
WITH 400LFM
0.25
0
OUT
OUT
OUT
OUT
OUT
OUT
0.25
0
5V TO 30V
IN
5V TO 30V
IN
5V TO 30V
IN
5V TO 30V
IN
25 35 45 55 65 75 85 95 105
AMBIENT TEMPERATURE (°C)
25 35 45 55 65 75 85 95 105
AMBIENT TEMPERATURE (°C)
4609 F10
4609 F09
Figure 9. 5VIN to 30VOUT without Heat Sink
Figure 10. 5VIN to 30VOUT with Heat Sink
10
9
8
7
6
5
4
3
2
1
0
10
9
8
7
6
5
4
3
2
1
0
25
35
45
55
65
75
85
95
25
35
45
55
65
75
85
95
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
32V TO 12V
WITH 0LFM
32V TO 12V
WITH 0LFM
IN
OUT
OUT
OUT
IN
OUT
OUT
OUT
32V TO 12V
WITH 200LFM
32V TO 12V
WITH 200LFM
IN
IN
32V TO 12V
WITH 400LFM 4609 F11
32V TO 12V
WITH 400LFM 4609 F12
IN
IN
Figure 11. 32VIN to 12VOUT without Heat Sink
Figure 12. 32VIN to 12VOUT with Heat Sink
4609fc
18
LTM4609
typical applications
8
7
6
5
4
3
2
1
8
7
6
5
4
3
2
1
0
0
25 35 45 55 65 75 85 95 105
25 35 45 55 65 75 85 95 105
AMBIENT TEMPERATURE (°C)
AMBIENT TEMPERATURE (°C)
4609 F13
4609 F14
36V TO 20V
WITH 0LFM
WITH 200LFM
WITH 400LFM
36V TO 20V
WITH 0LFM
WITH 200LFM
WITH 400LFM
IN
OUT
OUT
OUT
IN
OUT
OUT
OUT
36V TO 20V
36V TO 20V
IN
IN
36V TO 20V
36V TO 20V
IN
IN
Figure 13. 36VIN to 20VOUT without Heat Sink
Figure 14. 36VIN to 20VOUT with Heat Sink
applications inForMation
Table 4. Boost Mode
DERATING CURVE
Figure 7, 9
V
(V)
POWER LOSS CURVE
Figure 5
AIR FLOW (LFM)
HEAT SINK
None
θ
JA
(°C/W)*
11.4
8.5
OUT
16, 30
16, 30
16, 30
16, 30
16, 30
16, 30
0
Figure 7, 9
Figure 5
200
400
0
None
Figure 7, 9
Figure 5
None
7.5
Figure 8, 10
Figure 8, 10
Figure 8, 10
Figure 5
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
11.0
7.9
Figure 5
200
400
Figure 5
7.1
Table 5. Buck Mode
DERATING CURVE
Figure 11, 13
V
(V)
POWER LOSS CURVE
Figure 6
AIR FLOW (LFM)
HEAT SINK
None
θ
JA
(°C/W)*
8.2
OUT
12, 20
0
Figure 11, 13
12, 20
12, 20
12, 20
12, 20
12, 20
Figure 6
200
400
0
None
5.9
Figure 11, 13
Figure 6
None
5.4
Figure 12, 14
Figure 6
BGA Heat Sink
BGA Heat Sink
BGA Heat Sink
7.5
Figure 12, 14
Figure 6
200
400
5.3
Figure 12, 14
Figure 6
4.8
HEAT SINK MANUFACTURER
Aavid Thermalloy
PART NUMBER
WEBSITE
375424B00034G
www.aavidthermalloy.com
www.coolinnovations.com
Cool Innovations
4-050503P to 4-050508P
*The results of thermal resistance from junction to ambient θ are based on the demo board DC 1198A. Thus, the maximum temperature on board is treated
JA
as the junction temperature (which is in the µModule regulator for most cases) and the power losses from all components are counted for calculations. It
has to be mentioned that poor board design may increase the θ
.
JA
4609fc
19
LTM4609
applications inForMation
Layout Checklist/Example
•ꢀ Placeꢀaꢀdedicatedꢀpowerꢀgroundꢀlayerꢀunderneathꢀtheꢀ
unit.
The high integration of LTM4609 makes the PCB board
layoutverysimpleandeasy.However,tooptimizeitselectri-
cal and thermal performance, some layout considerations
are still necessary.
•ꢀ Toꢀminimizeꢀtheꢀviaꢀconductionꢀlossꢀandꢀreduceꢀmoduleꢀ
thermal stress, use multiple vias for interconnection
between the top layer and other power layers
•ꢀ Doꢀnotꢀputꢀviasꢀdirectlyꢀonꢀpads,ꢀunlessꢀtheꢀviasꢀareꢀ
•ꢀ UseꢀlargeꢀPCBꢀcopperꢀareasꢀforꢀhighꢀcurrentꢀpath,ꢀinclud-
capped.
ing V , R
, SW1, SW2, PGND and V . It helps to
IN SENSE
OUT
minimize the PCB conduction loss and thermal stress.
•ꢀ UseꢀaꢀseparatedꢀSGNDꢀgroundꢀcopperꢀareaꢀforꢀcom-
ponents connected to signal pins. Connect the SGND
to PGND underneath the unit.
•ꢀ Placeꢀhighꢀfrequencyꢀinputꢀandꢀoutputꢀceramicꢀcapaci-
tors next to the V , PGND and V
pins to minimize
IN
OUT
high frequency noise
Figure 15. gives a good example of the recommended
layout.
–
+
•ꢀ RouteꢀSENSE andSENSE leadstogetherwithminimum
PC trace spacing. Avoid sense lines passing through
noisy areas, such as switch nodes.
SW1
SW2
V
IN
L1
C
IN
R
SENSE
V
OUT
C
OUT
+
–
SGND
PGND
PGND
R
SENSE
4609 F15
KELVIN CONNECTIONS TO R
SENSE
Figure 15. Recommended PCB Layout
(LGA Shown, for BGA Use Circle Pads)
4609fc
20
LTM4609
typical applications
V
IN
CLOCK SYNC
12V TO 36V
10µF
50V
×2
V
12V
10A
OUT
V
PLLIN
IN
PGOOD
RUN
V
OUT
+
100µF
25V
ON/OFF
FCB
L1
4.7µH
LTM4609
COMP
INTV
SW1
SW2
CC
R1
PLLFLTR
EXTV
1.5k
R
CC
SENSE
+
R3
1k
STBYMD
SENSE
C3
0.1µF
R2
9mΩ
–
SS
SENSE
SGND
V
FB
PGND
R
FB
7.15k
4609 TA02
Figure 16. Buck Mode Operation with 12V to 36V Input
V
IN
CLOCK SYNC
5V TO 12V
4.7µF
V
12V
4A
OUT
V
PLLIN
35V
IN
PGOOD
RUN
V
OUT
+
330µF
25V
22µF
25V
×2
ON/OFF
FCB
LTM4609
COMP
2200pF
2Ω
INTV
SW1
SW2
CC
R1
1.5k
PLLFLTR
L1
3.3µH
OPTIONAL
FOR LOW
SWITCHING NOISE
R3
1k
EXTV
CC
R
SENSE
+
STBYMD
SENSE
C3
0.1µF
R2
8mΩ
–
SS
SENSE
SGND
V
FB
PGND
R
FB
7.15k
4609 TA03
Figure 17. Boost Mode Operation with 5V to 12V Input with Low Switching Noise (Optional)
4609fc
21
LTM4609
typical applications
V
IN
CLOCK SYNC
5V TO 36V
10µF
50V
×2
V
12V
4A
OUT
V
PLLIN
IN
PGOOD
RUN
V
OUT
+
330µF
25V
22µF
25V
×4
ON/OFF
FCB
2200pF
LTM4609
COMP
INTV
SW1
CC
R1
1.5k
2Ω
L1
3.3µH
PLLFLTR
SW2
R3
1k
EXTV
CC
R
SENSE
+
STBYMD
SENSE
C3
0.1µF
R2
8mΩ
–
SS
SENSE
SGND
V
FB
PGND
R
FB
7.15k
4609 TA04
Figure 18. Wide Input Mode with 5V to 36V Input, 12V at 4A Output
V
IN
CLOCK SYNC
8V TO 36V
10µF
50V
×2
V
32V
2A
OUT
V
PLLIN
IN
PGOOD
RUN
V
OUT
+
220µF
50V
ON/OFF
FCB
L1
4.7µH
LTM4609
COMP
INTV
SW1
SW2
CC
R1
PLLFLTR
EXTV
1.5k
R
CC
SENSE
+
R3
1k
STBYMD
SENSE
C3
0.1µF
R2
9mΩ
–
SS
SENSE
SGND
V
FB
PGND
R
FB
2.55k
4609 TA05
Figure 19. 32V at 2A Design
4609fc
22
LTM4609
typical applications
V
IN
5V TO 36V
CLOCK SYNC 0° PHASE
PLLIN
10µF
50V
V
12V
8A
OUT
R5
100k
V
IN
PGOOD
RUN
V
OUT
+
C2
330µF
25V
FCB
L1
3.3µH
22µF
25V
×2
LTM4609
COMP
SW1
SW2
200Ω
INTV
CC
LTC6908-1
PLLFLTR
R
5.1V
SENSE
+
5.1V
ZENER
C1
EXTV
CC
SENSE
0.1µF
+
V
OUT1
OUT2
MOD
R2
8mΩ
STBYMD
R4
324k
–
GND
SET
SS
SENSE
C3
0.1µF
SGND
V
FB
PGND
R
*
FB
2-PHASE OSCILLATOR
3.57k
CLOCK SYNC 180° PHASE
PLLIN
10µF
50V
V
IN
PGOOD
V
OUT
+
C4
330µF
25V
FCB
L2
3.3µH
22µF
25V
×2
LTM4609
RUN
COMP
SW1
SW2
INTV
CC
PLLFLTR
EXTV
R
SENSE
+
*R IS SELECTED USING
FB
SENSE
CC
R3
8mΩ
STBYMD
100k
+RFB
–
SS
N
SENSE
VOUT = 0.8V
RFB
WHERE N IS THE NUMBER
OF PARALLELED MODULES.
SGND
V
FB
PGND
4609 TA06
Figure 20. Two-Phase Parallel, 12V at 8A Design
4609fc
23
LTM4609
package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
Z
b b b
Z
6 . 9 8 5 0
5 . 7 1 5 0
4 . 4 4 5 0
3 . 1 7 5 0
1 . 9 0 5 0
0 . 6 3 5 0
0 . 0 0 0 0
0 . 6 3 5 0
1 . 9 0 5 0
3 . 1 7 5 0
4 . 4 4 5 0
5 . 7 1 5 0
6 . 9 8 5 0
a a a
Z
4609fc
24
LTM4609
package Description
Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings.
/ / b b b
Z
6 . 9 8 5 0
5 . 7 1 5 0
4 . 4 4 5 0
3 . 1 7 5 0
1 . 9 0 5 0
0 . 6 3 5 0
0 . 0 0 0 0
0 . 6 3 5 0
1 . 9 0 5 0
3 . 1 7 5 0
4 . 4 4 5 0
5 . 7 1 5 0
6 . 9 8 5 0
a a a
Z
4609fc
25
LTM4609
package Description
Pin Assignment Table 6 (Arranged by Pin Number)
PIN NAME FUNCTION PIN NAME FUNCTION PIN NAME FUNCTION PIN NAME FUNCTION PIN NAME FUNCTION PIN NAME FUNCTION
A1
A2
PGND
PGND
PGND
C1
C2
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
E1
E2
V
V
G1
G2
V
V
V
V
J1
J2
SW1
SW1
SW1
SW1
L1
L2
SW1
SW1
SW1
SW1
OUT
OUT
OUT
OUT
OUT
OUT
A3
C3
E3
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
PGND
G3
J3
L3
+
A4
SENSE
SENSE
SS
C4
E4
G4
J4
L4
–
A5
C5
E5
G5
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
J5
R
L5
R
SENSE
SENSE
SENSE
SENSE
SENSE
A6
C6
E6
G6
J6
R
R
L6
R
A7
SGND
RUN
C7
E7
G7
J7
L7
SW2
SW2
SW2
A8
C8
E8
G8
J8
SW2
SW2
L8
A9
FCB
C9
E9
G9
J9
L9
A10
A11
A12
B1
STBYMD
PGND
PGND
PGND
PGND
PGND
PGND
PGOOD
C10
C11
C12
D1
D2
D3
D4
D5
D6
D7
D8
D9
D10
D11
D12
E10
E11
E12
F1
G10
G11
G12
H1
J10
J11
J12
K1
K2
K3
K4
K5
K6
K7
K8
K9
K10
K11
K12
V
V
V
L10
L11
L12
M1
M2
M3
M4
M5
M6
M7
M8
M9
M10
M11
M12
V
V
V
IN
IN
IN
IN
IN
IN
V
OUT
V
OUT
V
OUT
V
OUT
V
SW1
SW1
SW1
SW1
SW1
SW1
SW1
SW1
OUT
OUT
OUT
OUT
B2
F2
H2
V
B3
F3
H3
V
V
B4
F4
H4
B5
F5
INTV
H5
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
SENSE
R
R
CC
SENSE
SENSE
SENSE
SENSE
B6
V
F6
EXTV
H6
R
R
FB
CC
B7
COMP
PLLFLTR
PLLIN
PGND
F7
–
–
–
H7
SW2
SW2
SW2
SW2
SW2
SW2
B8
F8
H8
B9
F9
H9
B10
B11
B12
F10
F11
F12
R
SENSE
R
SENSE
R
SENSE
H10
H11
H12
V
V
V
V
V
V
IN
IN
IN
IN
IN
IN
PGND
PGND
4609fc
26
LTM4609
revision history (Revision history begins at Rev B)
REV
DATE
DESCRIPTION
PAGE NUMBER
B
10/10 MP-grade part added. Reflected throughout the data sheet.
1-26
C
03/12 Added the BGA Package option and updated the Typical Application.
Updated the Pin Configuration and Order Information sections.
Updated Note 2.
1
2
4
Added INTV maximum load current.
7
CC
Updated the recommended heat sinks table.
Added BGA Package drawing.
19
25
28
Updated the Related Parts table.
4609fc
Information furnished by Linear Technology Corporation is believed to be accurate and reliable.
However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa-
tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.
27
LTM4609
package photos
relateD parts
PART NUMBER
DESCRIPTION
COMMENTS
Synchronous Operation; Single Inductor, 4V ≤ V ≤ 36V, 0.8V ≤ V
LTC3780
36V Buck-Boost Controller
≤ 30V
OUT
IN
LTC3785
10V Buck-Boost Controller
Synchronous, No R
™, 2.7V ≤ V ≤ 10V, 2.7V ≤ V
≤ 10V
OUT
SENSE
IN
LTM4601/LTM4601A 12A DC/DC µModule Regulator with PLL, Output Synchronizable, PolyPhase® Operation to 48A, LTM4601-1 Has No Remote
Tracking/ Margining and Remote Sensing
Sensing
LTM4603
6A DC/DC µModule with PLL and Output
Tracking/Margining and Remote Sensing
Synchronizable, PolyPhase Operation, LTM4603-1 Version Has No Remote
Sensing, Pin Compatible with the LTM4601
LTM4604A
4A, Low V , DC/DC µModule Regulator
2.375V ≤ V ≤ 5.5V, 0.8V ≤ V
≤ 5V, 9mm × 15mm × 2.32mm
IN
IN
OUT
LTM4605/LTM4607 5A High Efficiency Buck-Boost DC/DC µModule
Regulators
Pin Compatible with LTM4609, Lower Voltage Versions of the LTM4609
LTM4606/LTM4612 Ultralow Noise DC/DC µModule Regulators
Low EMI, LTM4606 Verified by Xilinx to Power Rocket IO™, CISPR22 Compliant
LTM4608A
LTM4627
8A, Low V , DC/DC µModule Regulator
2.7V ≤ V ≤ 5.5V, 0.6V ≤ V
≤ 5V, 9mm × 15mm × 2.82mm
IN
IN
OUT
20V, 15A DC/DC Step-Down µModule Regulator
4.5V ≤ V ≤ 20V, 0.6V ≤ V
≤ 5V, PLL Input, V
Tracking, Remote Sense
IN
OUT
OUT
Amplifier, 15mm × 15mm × 4.32mm LGA or 15mm × 15mm × 4.92mm BGA
4609fc
LT 0312 REV C • PRINTED IN USA
LinearTechnology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7417
28
l
l
LINEAR TECHNOLOGY CORPORATION 2009
(408) 432-1900 FAX: (408) 434-0507 www.linear.com
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