LTM4609IVPBF_技术文档

LTM4609

36V , 34V High Efﬁciency

IN

OUT

Buck-Boost DC/DC µModule

FEATURES

DESCRIPTION

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.

n

Single Inductor Architecture Allows V Above,

IN

Below or Equal to V

OUT

n

Wide V Range: 4.5V to 36V

IN

OUT

n

Wide V

OUT

Range: 0.8V to 34V

n

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

Small, Low Proﬁle Surface Mount LGA Package

(15mm × 15mm × 2.8mm)

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.

APPLICATIONS

n

Faultprotectionfeaturesincludeovervoltageandfoldback

current protection. The DC/DC μModule^®is offered in a

small thermally enhanced 15mm × 15mm × 2.8mm LGA

package. The LTM4609 is Pb-free and RoHS compliant.

Telecom, Servers and Networking Equipment

n

Industrial and Automotive Equipment

n

High Power Battery-Operated Devices

L, LT, LTC, LTM, Linear Technology, the Linear logo and μModule are registered trademarks of

Linear Technology Corporation. All other trademarks are the property of their respective owners.

TYPICAL APPLICATION

Efﬁciency and Power Loss

vs Input Voltage

30V/2A Buck-Boost DC/DC μModule with 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

IN

PLLIN

V

OUT

+

10μF

50V

330μF

50V

FCB

ON/OFF

RUN

LTM4609

5.6μH

SW1

SW2

R

SENSE

+

SENSE

R2

0.1μF

15mΩ

s2

–

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

4609fa

1

LTM4609

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

(See Table 6 Pin Assignment)

V ............................................................. –0.3V to 36V

OUT

IN

V

TOP VIEW

BANK 2

............................................................. 0.8V to 36V

INTV , EXTV , RUN, SS, PGOOD.............. –0.3V to 7V

CC

M

L

SW1, SW2 .................................................... –5V to 36V

V , COMP................................................ –0.3V to 2.4V

FB

BANK 4

K

BANK 1

BANK 3

FCB, STBYMD....................................... –0.3V to INTV

CC

J

PLLIN........................................................ –0.3V to 5.5V

PLLFLTR.................................................... –0.3V to 2.7V

Operating Temperature Range

H

G

BANK 5

F

(Note 2)....................................................–40°C to 85°C

Junction Temperature ........................................... 125°C

Storage Temperature Range...................–55°C to 125°C

Solder Temperature (Note 3)................................. 245°C

E

D

C

BANK 6

B

A

1

2

3

4

5

6

7

8

9

10

11

12

LGA PACKAGE

141-LEAD (15mm s 15mm s 2.8mm)

T

JMAX

= 125°C, θ = 4°C/W, WEIGHT = 1.5g

JP

ORDER INFORMATION

LEAD FREE FINISH

LTM4609EV#PBF

LTM4609IV#PBF

PART MARKING*

PACKAGE DESCRIPTION

TEMPERATURE RANGE

LTM4609V

141-Lead (15mm × 15mm × 2.8mm) LGA

–40°C to 85°C

LTM4609V

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/

The l denotes the speciﬁcations which apply over the –40°C to 85°C

ELECTRICAL CHARACTERISTICS

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_IN= 12V. Per typical application (front page) conﬁguration.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Input Speciﬁcations

l

V

Input DC Voltage

4.5

36

4

V

IN(DC)

IN(UVLO)

Q(VIN)

Undervoltage Lockout Threshold

V

Falling

3.4

IN

I

Input Supply Bias Current

Normal

2.8

1.6

35

mA

μA

Standby

Shutdown Supply Current

V

RUN

V

RUN

= 0V, V

> 2V

= Open

STBYMD

60

4609fa

2

LTM4609

ELECTRICAL CHARACTERISTICS ^Thel denotes the speciﬁcations which apply over the –40°C to 85°C

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_IN= 12V. Per typical application (front page) conﬁguration.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Output Speciﬁcations

I

Output Continuous Current Range

(See Output Current Derating Curves

V

= 32V, V = 12V

OUT

10

4

A

OUTDC

IN

= 6V, V

= 12V

OUT

for Different V , V

and T )

A

IN OUT

Reference Voltage Line Regulation

Accuracy

V

IN

= 4.5V to 36V, V

= 1.2V (Note 4)

0.002

0.02

%/V

ΔV /V

FB FB(NOM)

COMP

l

Load Regulation Accuracy

V

COMP

V

COMP

= 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)

Switch Section

M1 t

M3 t

Turn-On Time (Note 5)

Turn-Off Time

Drain to Source Voltage V = 12V,

50

40

25

20

50

220

10

14

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

DS

Bias Current I = 10mA

SW

Turn-Off Time

Drain to Source Voltage V = 12V,

ns

f

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

Bias Current I = 3A

mΩ

DS(ON)

SW

Static Drain-to-Source

On-Resistance

Bias Current I = 3A

20

SW

Static Drain-to-Source

On-Resistance

Bias Current I = 3A

SW

Static Drain-to-Source

On-Resistance

Bias Current I = 3A

SW

Oscillator and Phase-Locked Loop

f

Nominal Frequency

V

= 1.2V

= 0V

260

170

340

300

200

400

50

330

220

440

kHz

kΩ

NOM

LOW

HIGH

PLLFLTR

Lowest Frequency

Highest Frequency

= 2.4V

R

PLLIN Input Resistance

Phase Detector Output Current

PLLIN

I

f

< f

> f

–15

15

μA

PLLFLTR

PLLIN

OSC

4609fa

3

LTM4609

ELECTRICAL CHARACTERISTICS ^Thel denotes the speciﬁcations which apply over the –40°C to 85°C

temperature range, otherwise speciﬁcations are at T_A= 25°C, V_IN= 12V. Per typical application (front page) conﬁguration.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

Control Section

l

V

Feedback Reference Voltage

RUN Pin ON/OFF Threshold

Soft-Start Charging Current

Start-Up Threshold

V

= 1.2V

0.792

1

0.8

1.6

0.808

2.2

V

FB

COMP

RUN

I

SS

V

= 2.2V

1

1.7

μA

V

RUN

V

Rising

0.4

0.7

STBYMD(START)

STBYMD(KA)

FCB

STBYMD

Keep-Active Power On Threshold

Forced Continuous Threshold

Forced Continuous Pin Current

Rising, V

= 0V

1.25

0.8

V

RUN

0.76

–0.3

0.84

–0.1

5.5

V

I

V

= 0.85V

FCB

–0.2

5.3

μA

V

FCB

V

Burst Inhibit (Constant Frequency)

Threshold

Measured at FCB Pin

BURST

DF

Maximum Duty Factor

% Switch M4 On

% Switch M1 On

99

%

ns

(BOOST, MAX)

(BUCK, MAX)

t

Minimum On-Time for Synchronous Switch M1 (Note 6)

Switch in Buck Operation

200

250

ON(MIN, BUCK)

RFBHI

Resistor Between V

and V Pins

99.5

5.7

100

100.5

kΩ

OUT

FB

Internal V Regulator

CC

l

INTV

Internal V Voltage

V

I

> 7V, V = 5V

EXTVCC

6

6.3

2

V

%

CC

IN

Internal V Load Regulation

= 0mA to 20mA, V

= 5V

0.3

5.6

300

60

ΔV /V

LDO LDO

CC

EXTVCC

V

EXTV Switchover Voltage

I

= 20mA, V

Rising

5.4

V

EXTVCC

CC

EXTVCC

EXTV Switchover Hysteresis

mV

ΔV

CC

EXTVCC(HYS)

EXTV Switch Drop Voltage

I

CC

= 20mA, V

= 6V

150

CC

EXTVCC

Current Sensing Section

l

V

Maximum Current Sense Threshold Boost Mode

Buck Mode

160

–130

190

–150

mV

SENSE(MAX)

–95

V

Minimum Current Sense Threshold Discontinuous Mode

–6

mV

μA

SENSE(MIN, BUCK)

SENSE

–

+

I

Sense Pins Total Source Current

V

SENSE

= V

= 0V

SENSE

–380

PGOOD

PGOOD Upper Threshold

PGOOD Lower Threshold

PGOOD Hysteresis

V

Rising

Falling

5.5

7.5

–7.5

2.5

10

%

V

ΔV

FB

FBH

–5.5

–10

ΔV

FB

FBL

Returning

ΔV

FB

FB(HYS)

V

PGL

PGOOD Low Voltage

I

= 2mA

= 5V

0.2

0.3

1

PGOOD

I

PGOOD Leakage Current

V

μA

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.

Note 3: See Application Note 100.

Note 4: The LTM4609 is tested in a feedback loop that servos V

to a

COMP

speciﬁed voltage and measures the resultant V

.

FB

Note 5: Turn-on and turn-off time are measured using 10% and 90%

Note 2: The LTM4609E is guaranteed to meet performance speciﬁcations

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 full

–40°C to 85°C temperature range.

levels. Transition delay time is measured using 50% levels.

Note 6: 100% test at wafer level only.

4609fa

4

LTM4609

TYPICAL PERFORMANCE CHARACTERISTICS ^{(Refer to Figure 18)}

Efﬁciency vs Load Current

6V_INto 12V_OUT

Efﬁciency vs Load Current

12V_INto 12V_OUT

Efﬁciency vs Load Current

32V_INto 12V_OUT

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

SKIP CYCLE

DCM

CCM

BURST

DCM

BURST

DCM

CCM

0.01

0.1

1

10

100

0.01

0.1

1

10

0.01

0.1

1

10

LOAD CURRENT (A)

4609 G03

4609 G01

4609 G02

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

IN

OUT

IN

OUT

32V to 20V

32V to 30V

24V TO 5V

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)

4609 G05

4609 G06

4609 G04

Transient Response from

12V_INto 12V_OUT

Transient Response from

6V_INto 12V_OUT

Efﬁciency vs Load Current

100

95

90

85

80

75

70

I

OUT

2A/DIV

V

OUT

200mV/DIV

4609 G09

4609 G08

200μs/DIV

LOAD STEP: 0A TO 3A AT CCM

5V to 16V

IN

OUTPUT CAPS: 4x 22μF CERAMIC CAPS AND

2x 180μF ELECTROLYTIC CAPS

OUT

OUTPUT CAPS: 4x 22μF CERAMIC CAPS AND

2x 180μF ELECTROLYTIC CAPS

5V to 24V

IN

5V to 30V

IN

2x 15mΩ SENSING RESISTORS

0

0.5

1

1.5

2

2.5

3

LOAD CURRENT (A)

4609 G07

4609fa

5

LTM4609

TYPICAL PERFORMANCE CHARACTERISTICS

Transient Response from

32V_INto 12V_OUT

Start-Up with 6V_INto 12V_OUTat

_OUT= 4A

Start-Up with 32V_INto 12V_OUTat

_OUT= 5A

I

L

5A/DIV

I

OUT

2A/DIV

I

IN

2A/DIV

5A/DIV

V

OUT

V

100mV/DIV

V

OUT

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

Short Circuit with 32V_INto 12V_OUT

at I_OUT= 5A

Short Circuit with 12V_INto 34V_OUT

at I_OUT= 2A

Short Circuit with 6V_INto 12V_OUT

at I_OUT= 4A

V

OUT

10V/DIV

V

OUT

5V/DIV

I

IN

2A/DIV

V

OUT

5V/DIV

I

IN

I

IN

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

4609fa

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

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 is

CC

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.

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

frequencyoftheinternaloscillatorwithanACorDCvoltage.

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.

4609fa

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 _{T = 25°C. Use Figure 1 conﬁguration.}

A

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

C

External Input Capacitor Requirement

I

= 4A

10

μF

IN

OUT

(V = 4.5V to 36V, V

= 12V)

IN

OUT

C

OUT

External Output Capacitor Requirement

(V = 4.5V to 36V, V = 12V)

I

= 4A

200

300

μF

OUT

IN

OUT

4609fa

8

LTM4609

OPERATION

Power Module Description

frequency can be synchronized by the input clock signal

from the PLLIN pin. The typical switching frequency is

400kHz.

The LTM4609 is a non-isolated buck-boost DC/DC power

supply. It can deliver a wide range output voltage from

0.8V to 34V over a wide input range from 4.5V to 36V,

by only adding the sensing resistor, inductor and some

external input and output capacitors. It provides precisely

regulated 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 enabled at light loads in the LTM4609 to improve its

efﬁciency, while the forced continuous mode and discon-

tinuous mode operations are used for constant frequency

applications. Foldback current limiting is activated in an

overcurrent condition as V drops. Internal overvoltage

FB

andundervoltagecomparatorspulltheopen-drainPGOOD

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

control, ultralow R

FETs with fast switching speed

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 frequency

of LTM4609 can be operated from 200kHz to 400kHz by

setting the voltage on the PLLFLTR pin. Alternatively, its

IfanexternalbiassupplyisappliedontheEXTV pin,then

CC

an efﬁciency improvement will occur due to the reduced

powerlossintheinternallinearregulator.Thisisespecially

true at the higher input voltage range.

Burst Mode is a registered trademark of Linear Technology Corporation.

APPLICATIONS INFORMATION

The typical LTM4609 application circuit is shown in

Figure 18. External component selection is primarily

determined by the maximum load current and output

voltage. Refer to Table 3 for speciﬁc external capacitor

requirements 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 PLLIN is left open, the PLLFLTR pin goes low, forc-

ing the oscillator to its minimum frequency.

Output Voltage Programming

The PWM controller has an internal 0.8V 1% reference

voltage. As shown in the Block Diagram, a 100k 0.5%

internal feedback resistor connects V

and V pins

FB

OUT

FB

together. Adding a resistor R from the V pin to the

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 low. The maximum switching frequency is

approximately 400kHz.

SGND pin programs the output voltage:

100k +R_FB

V_OUT= 0.8V •

R_FB

Table 1. R_FBResistor (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

FREQUENCY SYNCHRONIZATION

R

FB

The LTM4609 can also be synchronized to an external

sourceviathePLLINpininsteadofadjustingthevoltageon

the PLLFLTR pin directly. The power module has a phase-

V

OUT

R

FB

4609fa

9

LTM4609

APPLICATIONS INFORMATION

locked loop comprised of an internal voltage controlled

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 ranges

from 200kHz to 400kHz, corresponding to a DC voltage

input from 0V to 2.4V at PLLFLTR. During the start-up of

the regulator, the phase-lock loop function is disabled.

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 discon-

tinuous 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

0.5

1.0

1.5

2.0

2.5

PLLFLTR PIN VOLTAGE (V)

Input Capacitors

4609 F02

In boost mode, since the input current is continuous, only

minimuminputcapacitorsarerequired.However,theinput

current is discontinuous in buck mode. So the selection

Figure 2. Frequency vs PLLFLTR Pin Voltage

Low Current Operation

of input capacitor C is driven by the need of ﬁltering the

Toimprovetheefﬁciencyatlowcurrentoperation,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

V_OUT

D=

FCB PIN

0V to 0.75V

0.85V to 5V

>5.3V

BUCK

BOOST

V

IN

Force Continuous Mode

Skip-Cycle Mode

Force Continuous Mode

Burst Mode Operation

DCM with Constant Freq

Without considering the inductor current ripple, the RMS

current of the input capacitor can be estimated as:

DCM with Constant Freq

I_OUT(MAX)

When the FCB pin voltage is lower than 0.8V, the controller

behavesasacontinuous,PWMcurrentmodesynchronous

switching regulator. When the FCB pin voltage is below

I_CIN(RMS)

=

• D•(1−D)

η

In the above equation, η is the estimated efﬁciency of the

V

– 1V, but greater than 0.8V, the controller enters

INTVCC

power module. C can be a switcher-rated electrolytic

IN

Burst Mode operation in boost operation or enters skip-

cycle mode in buck operation. During boost operation,

Burst Mode operation is activated if the load current is

aluminum capacitor, OS-CON capacitor or high volume

ceramic capacitors. Note the capacitor ripple current rat-

4609fa

10

LTM4609

APPLICATIONS INFORMATION

ings are often based on temperature and 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.

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)

L_BOOST

≥

V²_OUT(MAX)• ƒ •I_OUT(MAX)•Ripple%

Output Capacitors

In boost mode, the discontinuous current shifts from the

V_OUT• V_IN(MAX)− V

(

)

OUT

L_BUCK

where:

≥

input to the output, so the output capacitor C

must be

OUT

V

_IN(MAX)• ƒ •I_OUT(MAX)•Ripple%

capable of reducing the output voltage 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

I_OUT(MAX)• V

− V

IN(MIN)

(

)

OUT

Ripple% is allowable inductor current ripple, %

V_RIPPLE,BOOST

=

C_OUT• V_OUT• ƒ

V

is maximum output voltage, V

OUT(MAX)

is maximum input voltage, V

IN(MAX)

V_OUT• V_IN(MAX)− V

(

)

OUT

V_RIPPLE,BUCK

=

is output voltage, V

8 •L •C_OUT• V_IN(MAX)• ƒ²

OUT

I

is maximum output load current, A

OUT(MAX)

The steady ripple due to the voltage drop across the ESR

(effective series resistance) is given by:

The inductor should have low DC resistance to reduce the

2

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.

V_ESR,BUCK= ΔI_L(MAX)•ESR

V_ESR,BOOST=I_L(MAX)•ESR

The LTM4609 is designed for low output voltage ripple.

R

SENSE

Selection and Maximum Output Current

The bulk output capacitors deﬁned as C

are chosen

OUT

withlowenoughESRtomeettheoutputvoltagerippleand

transient requirements. C can be the low ESR tantalum

R

is chosen based on the required inductor current.

SENSE

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.

OUT

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.

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:

⎛

⎞

⎟

ΔI_L

V

IN

160mV

I_{OUT(MAX,BOOST)}

=

−

•

⎜

R

2

V_OUT

⎝

⎠

SENSE

Inductor Selection

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

4609fa

11

LTM4609

APPLICATIONS INFORMATION

In buck mode, the allowed maximum average load cur-

rent is:

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:

ΔI_L

2

130mV

R_SENSE

I_{OUT(MAX,BUCK)}

=

+

R1+R2

V _UVLO=

•1.6V

R2

The maximum current sensing R

mode is:

value for the boost

SENSE

Power Good

R_{SENSE(MAX,BOOST)}

=

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, and tracks

with margining.

2•160mV • V

2•I_{OUT(MAX,BOOST)}• V_OUT+ ΔI_L• V

IN

The maximum current sensing R

mode is:

value for the buck

SENSE

COMP Pin

This pin is the external compensation pin. The module

has already been internally compensated for most output

voltages. A spice model will be provided for other control

loop optimization.

2•130mV

R_{SENSE(MAX,BUCK)}

=

2•I_{OUT(MAX,BUCK)}– ΔI_L

A20%to30%marginonthecalculatedsensingresistoris

usually recommended. Please refer to Table 3 for the rec-

ommended sensing resistors for different applications.

Fault Conditions: Current Limit and Overcurrent

Foldback

LTM4609 has a current mode controller, which inherently

limitsthecycle-by-cycleinductorcurrentnotonlyinsteady

state operation, but also in transient. Refer to Table 3.

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:

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 •C_SS

1.7µA

t_SOFTSTART

=

Standby Mode (STBYMD)

When the RUN pin falls below 1.6V, then soft-start pin is

resettoallowforpropersoft-startcontrolwhentheregula-

torisenabledagain.Currentfoldbackandforcecontinuous

mode are disabled during the soft-start process. 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.

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

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

Run Enable

voltage greater than 1.25V, the internal regulator (INTV )

CC

The RUN pin is used to enable the power module. The pin

can be driven with a logic input, and not exceed 6V.

will be on even when the controller is shut down (RUN

4609fa

12

LTM4609

APPLICATIONS INFORMATION

pin voltage <1.6V). In this mode, the onboard 6V linear

regulator can provide power to keep-alive functions such

as a keyboard controller.

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.

INTV and EXTV

CC

The power loss curves in Figures 5 and 6 can be used

in coordination with the load current derating curves in

An internal P-channel low dropout regulator produces 6V

at the INTV pin from the V supply pin. INTV powers

Figures 7 to 14 for calculating an approximate θ for

CC

IN

CC

JA

the control chip and internal circuitry within the module.

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

TheLTM4609alsoprovidestheexternalsupplyvoltagepin

EXTV . When the voltage applied to EXTV rises above

CC

5.7V, the internal regulator is turned off and an internal

switch connects the EXTV pin to the INTV pin thereby

CC

supplyinginternalpower.Theswitchremainscloseaslong

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

OUT

θ ofthecondition.Acompleteexplanationofthethermal

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

Ensure that EXTV ≤ V .

DESIGN EXAMPLES

CC

IN

The following list summarizes the three possible connec-

tions for EXTV :

Buck Mode Operation

CC

As a design example, use input voltage V = 12V to 36V,

IN

1. EXTV left open (or grounded). This will cause INTV

CC

V

= 12V and ƒ = 400kHz.

OUT

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

This is the normal connection for a 6V regulator and

provides the highest efﬁciency.

3. EXTV connected to an external supply. If an external

CC

To set the output voltage at 12V, the resistor R from V

pin to ground should be chosen as:

FB

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

V_OUT− 0.8V

the MOSFET gate drive requirements.

R_FB=

≈7.15k

Thermal Considerations and Output Current Derating

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 practical

operating region. If the maximum output power P is 120W

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.

4609fa

13

LTM4609

APPLICATIONS INFORMATION

at buck mode, we can get the current ripple ratio of the

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:

current ripple ΔI to the maximum inductor current I as

L

follows:

2

(V – V_OUT)• V_OUT

ΔI_L

I_L

IN

=

ΔV_OUT(P-P)=ESR • ΔI_L

V •L • ƒ •P

IN

If a total low ESR of about 5mΩ is chosen for output ca-

pacitors, the maximum output ripple of 21.5mV occurs at

the input voltage of 36V with the current ripple at 4.3A.

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.

Boost Mode Operation

At buck mode, sensing resistor selection is based on

the maximum output current and the allowed maximum

sensing threshold 130mV.

For boost mode operation, use input voltage V = 5V to

IN

12V, V

= 12V and ƒ = 400kHz.

OUT

Set the PLLFLTR pin and R as in buck mode.

FB

2•130mV

2•(P / V_OUT)− ΔI_L

R_SENSE

=

If the maximum output power P is 50W at boost mode

and the module efﬁciency η is about 90%, we can get

the current ripple ratio of the current ripple ΔI to the

Consider the safety margin about 30%, we can choose

the sensing resistor as 9mΩ.

L

maximum inductor current I as follows:

L

2

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.

(V_OUT− V )• V η

ΔI_L

I_L

IN

=

V_OUT•L • ƒ •P

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.

At boost mode, sensing resistor selection is based on

the maximum input current and the allowed maximum

sensing threshold 160mV.

0.8

2.5μH

2•160mV

0.6

R_SENSE

=

3.3μH

P

2•

+ ΔI_L

η• V

IN(MIN)

4.7μH

0.4

0.2

0

6μH

Consider the safety margin about 30%, we can choose

the sensing resistor as 8mΩ.

12

18

24

30

36

INPUT VOLTAGE V (V)

IN

4609 F03

Figure 3. Current Ripple Ratio at Different Inputs for Buck Mode

4609fa

14

LTM4609

APPLICATIONS INFORMATION

0.8

Wide Input Mode Operation

1.5μH

Ifawideinputrangeisrequiredfrom5Vto36V,themodule

will work in different operation modes. If input voltage

0.6

V = 5V to 36V, V

= 12V and ƒ = 400kHz, the design

IN

OUT

2.5μH

0.4

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.

3.3μH

4.7μH

0.2

0

5

6

7

8

9

10

11

12

INPUT VOLTAGE V (V)

IN

4609 F04

Figure 4. Current Ripple Ratio at Different Inputs for Boost Mode

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.

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.

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. If

assuming that the ESR dominates the output ripple, the

output ripple is as follows:

Safety Considerations

TheLTM4609modulesdonotprovideisolationfromV to

IN

V

OUT

.Thereisnointernalfuse.Ifrequired,aslowblowfuse

with a rating twice the maximum input current needs to be

ΔV_OUT(P-P)=ESR •I_L(MAX)

provided to protect each unit from catastrophic failure.

If a total low ESR about 5mΩ is chosen for output capaci-

tors,themaximumoutputrippleof70mVoccursattheinput

voltage of 5V with the peak inductor current at 14A.

An RC snubber is recommended on SW1 to obtain low

switching noise, as shown in Figure 17.

4609fa

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

SENSE

VENDORS

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

I

*

OUT(MAX)

IN

OUT

SENSE

IN

OUT1

OUT2

(0.5W RATING)

(CERAMIC)

(BULK)

(CERAMIC)

(BULK)

(A)

5

10

12

16

20

24

2 × 16mW 0.5W

2 × 18mW 0.5W

2 × 20mW 0.5W

2 × 18mΩ 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 × 18mW 0.5W

2 × 16mW 0.5W

2 × 14mW 0.5W

2 × 20mW 0.5W

2 × 20mΩ 0.5W

2 × 22mΩ 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

3.3

4.7

2.2

3.3

4.7

3.3

2.2

3.3

4.7

6

None

150μF 35V

150μF 50V

150μF 35V

150μF 50V

150μF 35V

150μF 50V

4 × 22μF 25V

2 × 22μF 25V

4 × 22μF 25V

2 × 22μF 25V

4 × 22μF 25V

2 × 22μF 25V

4 × 22μF 25V

2 × 22μF 25V

4 × 22μF 25V

2 × 22μF 25V

2 × 180μF 16V

2 × 150μF 20V

2 × 150μF 50V

4

11

10

9

15

20

24

32

36

6

2 × 10μF 25V

2 × 10μF 50V

None

9

4

16

20

24

32

36

5

2 × 10μF 25V

2 × 10μF 50V

None

11

10

9

2.5

4

8

None

12

20

24

32

36

5

None

8

2 × 10μF 25V

2 × 10μF 50V

NONE

10

9

3.3

6

2

10

32

36

5

NONE

5

2 × 10μF 50V

NONE

9

8

3.3

4.7

7

1.5

5

12

32

36

NONE

2 × 10μF 50V

8

4609fa

16

LTM4609

APPLICATIONS INFORMATION

Table 3. Typical Components (ƒ = 400kHz) Continued

V

(V)

V

(V)

R

Inductor

(μH)

C

I

*

IN

OUT

SENSE

IN

OUT1

OUT2

OUT(MAX)

(0.5W RATING)

(CERAMIC)

(BULK)

(CERAMIC)

(BULK)

(A)

5

30

34

2 × 16mꢀ 0.5W

2 × 14mꢀ 0.5W

1 × 12mꢀ 0.5W

1 × 13mꢀ 0.5W

2 × 18mꢀ 0.5W

2 × 16mꢀ 0.5W

1 × 12mꢀ 0.5W

3.3

4.7

2.5

4.7

3.3

4.7

5.6

2.5

NONE

150μF 50V

4 × 22μF 50V

2 × 22μF 50V

4 × 22μF 50V

2 × 22μF 50V

2 × 150μF 50V

1.3

3

12

32

36

5

2 × 10μF 50V

NONE

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

36V TO 20V

IN

3

2

1

0

5V TO 16V

IN

OUT

5V TO 30V

IN

0

1

2

3

0

1

2

3

4

5

6

7

8

9

LOAD CURRENT (A)

4609 F05

4609 F06

Figure 5. Boost Mode Operation

Figure 6. Buck Mode Operation

4609fa

17

LTM4609

TYPICAL APPLICATIONS

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

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

5V TO 16V

IN

5V TO 16V

IN

Figure 7. 5V_INto 16V_OUTwithout Heat Sink

Figure 8. 5V_INto 16V_OUTwith 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

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. 5V_INto 30V_OUTwithout Heat Sink

Figure 10. 5V_INto 30V_OUTwith 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)

32V TO 12V

WITH 0LFM

32V TO 12V

WITH 0LFM

IN

OUT

IN

OUT

32V TO 12V

WITH 200LFM

32V TO 12V

WITH 200LFM

IN

32V TO 12V

WITH 400LFM 4609 F11

32V TO 12V

WITH 400LFM 4609 F12

IN

Figure 11. 32V_INto 12V_OUTwithout Heat Sink

Figure 12. 32V_INto 12V_OUTwith Heat Sink

4609fa

18

LTM4609

TYPICAL APPLICATIONS

8

7

6

5

4

3

2

1

8

7

6

5

4

3

2

1

0

25 35 45 55 65 75 85 95 105

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

IN

OUT

36V TO 20V

IN

36V TO 20V

IN

Figure 13. 36V_INto 20V_OUTwithout Heat Sink

Figure 14. 36V_INto 20V_OUTwith 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

(°C/W)*

11.4

8.5

OUT

JA

16, 30

0

Figure 7, 9

Figure 5

200

400

0

None

Figure 7, 9

Figure 5

None

7.5

Figure 8, 10

Figure 5

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

(°C/W)*

8.2

OUT

JA

12, 20

0

Figure 11, 13

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

7.5

Figure 12, 14

Figure 6

200

400

5.3

Figure 12, 14

Figure 6

4.8

HEAT SINK MANUFACTURER

Wakeﬁeld Engineering

Aaivd Thermalloy

PART NUMBER

LTN20069

PHONE NUMBER

603-635-2800

603-224-9988

375424B00034G

*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 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

4609fa

19

LTM4609

APPLICATIONS INFORMATION

Layout Checklist/Example

• Use a separated SGND ground copper area for com-

ponents connected to signal pins. Connect the SGND

to PGND underneath the unit.

The high integration of LTM4609 makes the PCB board

layoutverysimpleandeasy.However,tooptimizeitselectri-

cal and thermal performance, some layout considerations

are still necessary.

Figure 15. gives a good example of the recommended

layout.

• UselargePCBcopperareasforhighcurrentpath,includ-

SW1

SW2

V

IN

ing V , R

, SW1, SW2, PGND and V . It helps to

IN SENSE

OUT

minimize the PCB conduction loss and thermal stress.

L1

• Place high frequency input and output ceramic capaci-

tors next to the V , PGND and V

pins to minimize

IN

OUT

high frequency noise

–

+

• RouteSENSE andSENSE leadstogetherwithminimum

PC trace spacing. Avoid sense lines passing through

noisy areas, such as switch nodes.

C

IN

R

V

SENSE

OUT

• Place a dedicated power ground layer underneath the

unit.

C

OUT

• Tominimizetheviaconductionlossandreducemodule

thermal stress, use multiple vias for interconnection

between the top layer and other power layers

+

–

SGND

PGND

R

4609 F15

SENSE

• Do not put vias directly on pads, unless the vias are

capped.

KELVIN CONNECTIONS TO R

SENSE

Figure 15. Recommended PCB Layout

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

4609fa

20

LTM4609

TYPICAL APPLICATIONS

V

IN

CLOCK SYNC

5V TO 12V

4.7μF

35V

V

12V

4A

OUT

V

PLLIN

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)

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

L1: TOKO FDA1254

Figure 18. Wide Input Mode with 5V to 36V Input, 12V at 4A Output

4609fa

21

LTM4609

TYPICAL APPLICATIONS

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

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

INTV

CC

LTC6908-1

PLLFLTR

R

5.1V

SENSE

+

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

ꢁR_FB

N

–

SS

V_OUTꢀ 0.8V

SENSE

R_FB

WHERE N IS THE NUMBER

OF PARALLELED MODULES.

SGND

V

FB

PGND

4609 TA06

Figure 20. Two-Phase Parallel, 12V at 8A Design

4609fa

22

LTM4609

PACKAGE DESCRIPTION

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

4609fa

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.

23

LTM4609

PACKAGE DESCRIPTION

Pin Assignment Table 6

(Arranged by Pin Number)

PIN NAME

A1 PGND

A2 PGND

A3 PGND

A4 SENSE

A5 SENSE

A6 SS

PIN NAME

J1 SW1

J2 SW1

J3 SW1

J4 SW1

PIN NAME

L1 SW1

L2 SW1

L3 SW1

L4 SW1

C1 PGND

C2 PGND

C3 PGND

C4 PGND

C5 PGND

C6 PGND

C7 PGND

C8 PGND

C9 PGND

E1

E2

V

G1

V

OUT

V

OUT

V

OUT

V

OUT

G2

E3 PGND

E4 PGND

E5 PGND

E6 PGND

E7 PGND

E8 PGND

E9 PGND

E10 PGND

E11 PGND

E12 PGND

G3

+

–

G4

G5

R

J5

J6

J7

R

SENSE

R

SENSE

R

SENSE

L5

L6

R

SENSE

R

SENSE

OUT

G6

A7 SGND

A8 RUN

A9 FCB

G7

L7 SW2

L8 SW2

L9 SW2

G8

J8 SW2

J9 SW2

G9

A10 STBYMD C10 PGND

G10

G11

G12

H1

J10

J11

J12

V

IN

V

IN

V

IN

L10

L11

L12

V

IN

V

IN

V

IN

A11 PGND

A12 PGND

B1 PGND

B2 PGND

B3 PGND

B4 PGND

C11 PGND

C12 PGND

D1 PGND

D2 PGND

D3 PGND

D4 PGND

F1

F2

F3

F4

V

OUT

V

OUT

V

OUT

V

OUT

V

K1 SW1

K2 SW1

K3 SW1

K4 SW1

M1 SW1

M2 SW1

M3 SW1

M4 SW1

H2

OUT

H3

OUT

H4

OUT

B5 PGOOD D5 PGND

F5 INTV

H5

R

SENSE

R

SENSE

R

SENSE

R

SENSE

R

SENSE

R

SENSE

R

SENSE

R

SENSE

K5

K6

R

M5

M6

R

CC

SENSE

B6

V

D6 PGND

D7 PGND

F6 EXTV

H6

FB

CC

B7 COMP

F7

–

H7

K7 SW2

K8 SW2

K9 SW2

M7 SW2

M8 SW2

M9 SW2

B8 PLLFLTR D8 PGND

F8

–

H8

B9 PLLIN

B10 PGND

B11 PGND

B12 PGND

D9 PGND

D10 PGND

D11 PGND

D12 PGND

F9

–

H9

F10

F11

F12

R

H10

H11

H12

K10

K11

K12

V

IN

V

IN

V

IN

M10 V

M11 V

M12 V

SENSE

IN

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

Synchronous Operation; Single Inductor; 4V ≤ V ≤ 36V; 0.8V ≤ V

LTC3780

36V Buck-Boost Controller

10V Buck-Boost Controller

10A DC/DC μModule

≤ 30V

OUT

IN

LTC3785

Synchronous; No R

™; 2.7V ≤ V ≤ 10V; 2.7V ≤ V

≤ 10V

OUT

SENSE

IN

LTM4600

Basic 10A DC/DC μModule

LTM4601/LTM4601A 12A DC/DC μModule with PLL, Output

Synchronizable, PolyPhase^®Operation to 48A, LTM4601-1 Has No Remote

Tracking/ Margining and Remote Sensing

Military Plastic 10A DC/DC μModule

6A DC/DC μModule

Sensing

LTM4600HVMP

LTM4602

–55°C ≤ T ≤ 125°C Operation; 15mm × 15mm × 2.8mm LGA

A

Pin Compatible with the LTM4600

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

2.375V ≤ V ≤ 5.5V; 0.8V ≤ V

≤ 5V; 9mm × 15mm × 2.3mm

IN

OUT

LTM4605/LTM4607

LTM4606/LTM4612

LTM4608A

5A High Efﬁciency Buck-Boost DC/DC μModules Pin Compatible with LTM4609, Lower Voltage Versions of the LTM4609

Ultralow Noise DC/DC μModules

Low EMI; LTM4606 Veriﬁed by Xilinx to Power Rocket IO™; CISPR22 Compliant

8A, Low V , DC/DC μModule

2.7V ≤ V ≤ 5.5V; 0.6V ≤ V ≤ 5V; 9mm × 15mm × 2.8mm

IN

OUT

No R

is a trademark of Linear Technology Corporation. PolyPhase is a registered trademark of Linear Technology Corporation.

SENSE

4609fa

LT 0809 REV A • PRINTED IN USA

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

24

●

(408) 432-1900 FAX: (408) 434-0507 www.linear.com


型号：	LTM4609IVPBF
厂家：	Linear
描述：	36VIN, 34VOUT High Effi ciency Buck-Boost DC/DC μModule 36VIN ， 34VOUT高艾菲效率降压 - 升压型DC / DC微型模块
文件：	总24页 (文件大小：293K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LTM4609IVPBF [Linear]

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