LTM4616_技术文档

LTM4616

Dual 8A per Channel Low

V DC/DC µModule

IN

FEATURES

DESCRIPTION

The LTM^®4616 is a complete dual 2-phase 8A per channel

switch mode DC/DC power regulator system in a 15mm ×

15mmsurfacemountLGApackage.Includedinthepackage

are the switching controller, power FETs, inductor and all

support components. Operating from an input voltage

range of 2.7V to 5.5V, the LTM4616 supports two outputs

within a voltage range of 0.6V to 5V, each set by a single

external resistor. This high efﬁciency design delivers up

to 8A continuous current (10A peak) for each output. Only

bulk input and output capacitors are needed, depending

on ripple requirement. The part can also be conﬁgured for

a 2-phase single output at up to 16A.

■

Complete Dual DC/DC Regulator System

■

Input Voltage Range: 2.7V to 5.5V

■

Dual 8A Outputs, or Single 16A Output with a 0.6V

to 5V Range

Output Voltage Tracking and Margining

■

1.75ꢀ Total DC Output Error (–40°C to 125°C)

■

Current Mode Control/Fast Transient Response

■

Power-Good Tracking and Margining

■

Overcurrent/Thermal Shutdown Protection

■

Onboard Frequency Synchronization

■

Spread Spectrum Frequency Modulation

■

Multiphase Operation

Selectable Burst Mode^®Operation

■

The low proﬁle package (2.82mm) enables utilization

of unused space on the back side of PC boards for high

density point-of-load regulation.

■

Output Overvoltage Protection

■

Gold-Pad Finish Allows Soldering with Pb and Pb-

Free Solder Paste

■

Fault protection features include overvoltage protection,

overcurrent protection and thermal shutdown. The power

moduleisofferedinaspacesavingandthermallyenhanced

15mm × 15mm × 2.82mm LGA package. The LTM4616 is

Pb-free and RoHS compliant.

Small Surface Mount Footprint, Low Proﬁle

(15mm × 15mm × 2.82mm) LGA Package

APPLICATIONS

■

Telecom, Networking and Industrial Equipment

Different Combinations of Input and Output

■

Storage and ATCA, PCI Express Cards

Number of Inputs

Number of Outputs

I

(MAX)

OUT

■

Battery Operated Equipment

2

1

2

1

2

1

8A, 8A

L, LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation.

μModule is a trademark of Linear Technology Corporation. All other trademarks are the property

of their respective owners. Protected by U.S. Patents, including 5481178, 6580258, 6304066,

6127815, 6498466, 6611131, 6724174.

16A

8A, 8A

16A

TYPICAL APPLICATION

Efﬁciency vs Load Current

95

90

85

80

75

Dual Output DC/DC μModule™ Regulator

5V 3.3V

IN

OUT

V

5V

IN1

V

OUT1

V

IN1

OUT1

FB1

3.3V/8A

5V 2.5V

IN

OUT

100μF

10μF

LTM4616

ITHM1

2.21k

3.09k

V

3.3V TO 5V

10μF

IN2

V

OUT2

V

IN2

OUT2

FB2

2.5V/8A

100μF

ITHM2

GND2

70

0

GND1

2

4

6

8

4616 TA01a

LOAD CURRENT (A)

4616 TA01b

4616fa

1

LTM4616

ABSOLUTE MAXIMUM RATINGS

PIN CONFIGURATION

(Note 1)

V

, SV , V , SV ................................–0.3V to 6V

TOP VIEW

IN1

IN1 IN2 IN2

V

SGND2 & CONTROL

V

IN2

OUT2

CLKOUT1, CLKOUT2....................................–0.3V to 2V

PGOOD1, PLLLPF1, CLKIN1, PHMODE1,

M

L

MODE1, PGOOD2, PLLLPF2, CLKIN2,

K

J

PHMODE2, MODE2................................. –0.3V to V

IN

I

, I

, RUN1, FB1, TRACK1, MGN1,

GND2

TH1 THM1

H

G

F

SW2,

I/O & CONTROL

BSEL1, I , I

, RUN2, FB2, TRACK2,

TH2 THM2

MGN2, BSEL2......................................... –0.3V to V

IN

SGND1 & CONTROL

V

, V

, SW1, SW2............................ –0.3V to V

OUT1 OUT2

V

E

OUT1

V

IN1

Internal Operating Temperature Range

D

C

B

A

(Note 2) .............................................–40°C to 125°C

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

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

GND1

1

2

3

4

5

6

7

8

9

10

11

12

SW1, I/O & CONTROL

LGA PACKAGE

144-LEAD (15mm × 15mm × 2.8mm)

T

= 125°C, θ = 2°C/W, θ = 16°C/W

JP JC

JMAX

ORDER INFORMATION

LEAD FREE FINISH

LTM4616EV#PBF

LTM4616IV#PBF

TRAY

PART MARKING*

PACKAGE DESCRIPTION

INTERNAL TEMPERATURE RANGE

–40°C to 125°C

LTM4616EV#PBF

LTM4616IV#PBF

LTM4616V

144-Lead (15mm × 15mm × 2.82mm) LGA

LTM4616V

–40°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/

The ● denotes the speciﬁcations which apply over the –40°C to 125°C

ELECTRICAL CHARACTERISTICS

internal operating temperature range. T_A= 25°C, V_IN= 5V unless otherwise noted. Per the typical application in Figure 18. Speciﬁed

as each channel (Note 3).

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

●

V

Input DC Voltage

2.7

5.5

V

IN1(DC), IN2(DC)

V

, V

Output Voltage, Total Variation

with Line and Load

C

V

= 10μF × 1, C

= 100μF Ceramic,

OUT

OUT1(DC) OUT2(DC)

IN

100μF POSCAP, R = 6.65k

1.472

1.464

1.49

1.508

1.516

V

FB

= 2.7V to 5.5V,

IN

I

= I

to I

(Note 4)

OUT(DC)MAX

OUT

OUT(DC)MIN

Input Speciﬁcations

V

,

Undervoltage Lockout Threshold SV Rising

2.05

1.85

2.2

2.0

2.35

2.15

V

IN1(UVLO)

IN2(UVLO)

IN

SV Falling

IN

4616fa

2

LTM4616

ELECTRICAL CHARACTERISTICS ^The● denotes the speciﬁcations which apply over the –40°C to 125°C

internal operating temperature range. T_A= 25°C, V_IN= 5V unless otherwise noted. Per the typical application in Figure 18. Speciﬁed

as each channel (Note 3).

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

I

Input Supply Bias Current

V

IN

V

IN

V

IN

= 3.3V, V

= 1.5V, No Switching, Mode = V

IN

= 1.5V, No Switching, Mode = 0V

= 1.5V, Switching Continuous

400

1.15

55

μA

mA

Q(VIN1, VIN2)

OUT

V

= 5V, V

= 1.5V, No Switching, Mode = V

IN

= 1.5V, No Switching, Mode = 0V

= 1.5V, Switching Continuous

450

1.3

75

μA

mA

IN

OUT

Shutdown, RUN = 0, V = 5V

1

μA

IN

I

Input Supply Current

V

IN

V

IN

= 3.3V, V

= 1.5V, I = 8A

OUT

4.5

2.93

A

S(VIN1, VIN2)

OUT

= 5V, V

= 1.5V, I

= 8A

OUT

Output Speciﬁcations

I

Output Continuous Current Range V

(Note 4)

= 1.5V

OUT1(DC), OUT2(DC)

OUT

V

= 3.3V, 5.5V

0

8

5

A

IN

V

= 2.7V

●

ΔV

/V

Line Regulation Accuracy

Load Regulation Accuracy

V

= 1.5V, V from 2.7V to 5.5V, I

= 0A

0.1

0.25

%/V

OUT1(LINE) OUT1

OUT

IN

OUT

/V

OUT2(LINE) OUT2

ΔV

/V

V

OUT

= 1.5V (Note 4)

OUT1(LOAD) OUT1

OUT2(LOAD) OUT2

●

V

= 3.3V, 5.5V, I = 0A to 8A

LOAD

0.3

0.5

%

IN

= 2.7V, I

= 0A to 5A

LOAD

V

, V

Output Ripple Voltage

I

= 0A, C

OUT

= 100μF X5R Ceramic, V = 5V,

OUT IN

OUT1(AC) OUT2(AC)

OUT

V

= 1.5V

10

mV

P-P

f

Switching Frequency

SYNC Capture Range

Turn-On Overshoot

I

= 8A, V = 5V, V = 1.5V

OUT

1.25

0.75

1.5

1.75

2.25

MHz

S1, S2

OUT

IN

f

SYNC1, SYNC2

ΔV

C

= 100μF, V

= 1.5V, I

= 0A

OUT

OUT1(START),

OUT2(START)

OUT

V

OUT

= 3.3V

= 5V

10

mV

IN

V

t

Turn-On Time

C

= 100μF, V

= 1.5V, V = 5V,

IN

START1, START2

OUT

I

= 1A Resistive Load, Track = V

100

20

μs

IN

ΔV

Peak Deviation for Dynamic Load Load: 0% to 50% to 0% of Full Load,

mV

OUT1(LS),

OUT2(LS)

C

V

= 100μF Ceramic x2, 470μF POSCAP,

OUT

IN

= 5V, V

= 1.5V

OUT

t

I

t

Settling Time for Dynamic Load

Step

Load: 0% to 50% to 0% of Full Load, V = 5V,

OUT

10

μs

SETTLE1, SETTLE2

IN

V

= 1.5V, C

= 100μF

OUT

I

Output Current Limit

C

= 100μF

OUT1(PK), OUT2(PK)

OUT

V

= 2.7V, V

= 3.3V, V

= 1.5V

8

11

13

A

IN

OUT

V

= 5V, V

= 1.5V

OUT

Control Section

FB1, FB2

Voltage at FB Pin

I

= 0A, V

= 1.5V, V = 2.7V to 5.5V

0.590

0.587

0.596

0.602

0.606

V

OUT

IN

●

SS Delay

Internal Soft-Start Delay

90

μs

I

FB

0.2

μA

V

RUN Pin On/Off Threshold

RUN Rising

RUN Falling

1.4

1.3

1.55

1.4

1.7

1.5

V

RUN1, RUN2

TRACK1, TRACK2

Tracking Threshold (Rising)

Tracking Threshold (Falling)

Tracking Disable Threshold

RUN = V

0.57

0.18

IN

V

IN

RUN = 0V

V

– 0.5

4616fa

3

LTM4616

ELECTRICAL CHARACTERISTICS ^The● denotes the speciﬁcations which apply over the –40°C to 125°C

internal operating temperature range. T_A= 25°C, V_IN= 5V unless otherwise noted. Per the typical application in Figure 18. Speciﬁed

as each channel (Note 3).

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

R

Resistor Between V

and FB

OUT

9.95

10

10.05

kΩ

FBHI1, FBHI2

Pins

ΔV

PGOOD2

PGOOD Range

10

%

PGOOD1,

%Margining

Output Voltage Margining

Percentage

MGN = V , BSEL = 0V

4

9

14

–4

–9

–14

5

6

%

IN

MGN = V , BSEL = V

10

11

IN

MGN = V , BSEL = Float

15

–5

–10

–15

16

–6

–11

–16

IN

MGN = 0V, BSEL = 0V

MGN = 0V, BSEL = V

IN

MGN = 0V, BSEL = Float

Note 1: Stresses beyond those listed under Absolute Maximum Ratings

may cause permanent damage to the device. Exposure to any Absolute

Maximum Rating condition for extended periods may affect device

reliability and lifetime.

Note 2: The LTM4616E is guaranteed to meet performance speciﬁcations

over the 0°C to 125°C internal operating temperature range. Speciﬁcations

over the full –40°C to 125°C internal operating temperature range are

assured by design, characterization and correlation with statistical process

controls. The LTM4616I is guaranteed to meet speciﬁcations over the full

internal operating temperature range. Note that the maximum ambient

temperature is determined by speciﬁc operating conditions in conjunction

with board layout, the rated package thermal resistance and other

environmental factors.

Note 3: Two channels are tested separately and the same testing

conditions are applied to each channel.

Note 4: See Output Current Derating curves for different V , V

and T .

A

IN OUT

Speciﬁed as Each Channel

TYPICAL PERFORMANCE CHARACTERISTICS

Efﬁciency vs Load Current

100

95

90

85

80

75

70

100

95

100

95

CONTINUOUS MODE

90

85

90

85

80

75

70

80

75

70

5V 1.2V

IN

OUT

3.3V 1.2V

IN

OUT

5V 1.5V

IN

2.7V 1.0V

3.3V 1.5V

IN

OUT

5V 1.8V

IN

2.7V 1.5V

IN

3.3V 1.8V

IN

3.3V 2.5V

IN

5V 2.5V

IN

2.7V 1.8V

IN

5V 3.3V

IN

0

2

3

4

5

6

7

0

2

4

6

8

1

0

2

4

6

8

LOAD CURRENT (A)

LOAD CURRENT

4616 G03

4616 G02

4616 G01

4616fa

4

LTM4616

TYPICAL PERFORMANCE CHARACTERISTICS ^{Speciﬁed as Each Channel}

Burst Mode Efﬁciency with

5V Input

V_INto V_OUTStep-Down Ratio

100

90

80

70

60

50

40

4.0

3.5

3.0

2.5

4.0

3.5

3.0

2.5

I

= 5A

I

= 8A

OUT

V

= 1.2V

= 1.5V

= 1.8V

= 2.5V

= 3.3V

V

= 1.2V

= 1.5V

= 1.8V

= 2.5V

= 3.3V

OUT

2.0

1.5

2.0

1.5

1.0

0.5

0

1.0

0.5

0

V

= 1.5V

= 2.5V

= 3.3V

OUT

1

2

4

0

0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1

LOAD CURRENT (A)

1

2

4

0

5

6

0

5

6

3

V

(V)

V

(V)

IN

4616 G04

4616 G06

4616 G05

Supply Current vs V_IN

Load Transient Response

1.6

1.4

1.2

1

V

= 1.2V PULSE-SKIPPING MODE

I

O

V

LOAD

1A/DIV

V

OUT

0.8

0.6

0.4

0.2

0

50mV/DIV

= 1.2V BURST MODE

O

4616 G08

4616 G09

V

= 5V

20μs/DIV

V

= 5V

20μs/DIV

IN

OUT

IN

OUT

= 3.3V

= 2.5V

2A/μs STEP

= 2 × 100μF X5R, 470μF 4V POSCAP

2A/μs STEP

= 2 × 100μF X5R, 470μF 4V POSCAP

C

OUT

2.5

3

3.5

4

4.5

5

5.5

INPUT VOLTAGE (V)

4616 G07

Load Transient Response

I

LOAD

I

LOAD

1A/DIV

V

OUT

50mV/DIV

4616 G10

4616 G11

4616 G12

V

= 5V

20μs/DIV

V

= 5V

20μs/DIV

V

= 5V

20μs/DIV

IN

OUT

IN

OUT

IN

OUT

= 1.8V

= 1.5V

= 1.2V

2.5A/μs STEP

= 2 × 100μF X5R, 470μF 4V POSCAP

2.5A/μs STEP

= 2 × 100μF X5R, 470μF 4V POSCAP

2.5A/μs STEP

= 2 × 100μF X5R, 470μF POSCAP

C

OUT

4616fa

5

LTM4616

TYPICAL PERFORMANCE CHARACTERISTICS ^{Speciﬁed as Each Channel}

Start-Up

V_FBvs Temperature

Load Regulation vs Current

0

–0.1

–0.2

–0.3

–0.4

–0.5

–0.6

602

600

598

596

594

592

590

V

OUT

0.5V/DIV

V

= 5.5V

= 3.3V

IN

V

IN

2V/DIV

V

= 2.7V

IN

4616 G13

V

C

= 5V

50μs/DIV

IN

FC MODE

= 1.5V

OUT

V

= 3.3V

IN

OUT

= 100μF NO LOAD AND 8A LOAD

= 1.5V

(DEFAULT 100μs SOFT-START)

–25

0

50

–50

75 100 125

25

0

2

4

6

8

LOAD CURRENT (A)

TEMPERATURE (°C)

4616 G14

4616 G15

Short-Circuit Protection

(2.5V Short, No Load)

Short-Circuit Protection

(2.5V Short, 4A Load)

2.5V Output Current

3.0

2.5

V

IN

5V/DIV

2V/DIV

V

IN

OUT

V

OUT

2.0

1.5

I

LOAD

OUT

5A/DIV

I

SHORT

OUT

1.0

0.5

0

4616 G17

4616 G18

V

= 5V

50μs/DIV

V

= 5V

50μs/DIV

IN

OUT

IN

OUT

= 2.5V

0

5

10

15

20

OUTPUT CURRENT (A)

4616 G16

PIN FUNCTIONS

IN1 IN2

GND1 and GND2 (BANK2 and BANK5); (A1-A5, A12, B1-

B5, B7-B12, C3-C12, D3-D7) and (G1-G5, G12, H1-H5,

H7-H12, J3-J12, K3-K7): Power Ground Pins for Both

Input and Output Returns.

V

, V , (BANK1 and BANK2); (F1-F4, E1-E4, C1-C2,

D1-D2) and (J1-J2, K1-K2, L1-L4, M1-M4): Power Input

Pins. Apply input voltage between these pins and GND

pins. Recommend placing input decoupling capacitance

directly between V pins and GND pins.

IN

SV andSV (E5andL5):SignalInputVoltageforEach

IN1

IN2

Channel. This pin is internally connected to V through

V , V

OUT1 OUT2

(BANK3 and BANK6); (D9-D12, E9-E12,

IN

a lowpass ﬁlter.

F9-F12) and (K9-K12, L9-L12, M9-M12): Power Output

Pins. Apply output load between these pins and GND

pins. Recommend placing output decoupling capacitance

directly between these pins and GND pins. See Table 1.

SGND1 and SGND2 (F5 and M5): Signal Ground Pin for

Each Channel. Return ground path for all analog and low

power circuitry. Tie a single connection to the output

capacitor GND in the application. See layout guidelines

in Figure 17.

4616fa

6

LTM4616

PIN FUNCTIONS

MODE1 and MODE2 (A8 and G8): Mode Select Input for

Each Channel. Tying this pin high enables Burst Mode

operation. Tying this pin low enables forced continuous

operation. Floating this pin or tying it to V /2 enables

pulse-skipping operation.

Pin for Each Channel. Voltage tracking is enabled when

the TRACK voltage is below 0.57V. If tracking is not

desired, then connect the TRACK pin to SV . If TRACK

IN

is not tied to SV , then the TRACK pin’s voltage needs to

IN

be below 0.18V before the chip shuts down even though

RUN is already low. Do not ﬂoat this pin. A resistor and

capacitor can be applied to the TRACK pin to increase the

soft-start time of the regulator. TRACK1 and TRACK2 can

be tied together for parallel operation and tracking. See

the Applications section.

CLKIN1andCLKIN2(A7andG7):ExternalSynchronization

Input to Phase Detector for Each Channel. This pin is

internally terminated to SGND with a 50k resistor. The

phase-locked loop will force the internal top power PMOS

turn on to be synchronized with the rising edge of the

CLKIN signal. Connect this pin to SV to enable spread

FB1 and FB2 (D8 and K8): The Negative Input of the Error

IN

spectrum modulation. During external synchronization,

AmpliﬁerforEachChannel.Internally,thispinisconnected

make sure the PLLLPF pin is not tied to V or GND.

to V

with a 10k precision resistor. Different output

IN

OUT

voltages can be programmed with an additional resistor

between FB and GND pins. In PolyPhase^®operation, tying

the FB pins together allows for parallel operation. See

Applications section for details.

PLLLPF1 and PLLLPF2 (E6 and L6): Phase-Locked Loop

Lowpass Filter for Each Channel. An internal lowpass ﬁlter

is tied to this pin. In spread spectrum mode, placing a

capacitor here to SGND controls the slew rate from one

frequencytothenext. Alternatively, ﬂoatingthispinallows

I

and I (F8 and M8): Current Control Threshold and

TH2

TH1

normalrunningfrequencyat1.5MHz,tyingthispintoSV

ErrorAmpliﬁerCompensationPointforEachChannel. The

current comparator threshold increases with this control

voltage. Tie together in parallel operation.

IN

forces the part to run at 1.33 times its normal frequency

(2MHz), tying it to ground forces the frequency to run at

0.67 times its normal frequency (1MHz).

I

andI

(E7andL7):NegativeInputtotheInternal

THM1

THM2

PHMODE1 and PHMODE2 (A9 and G9): Phase Selector

Input for Each Channel. This pin determines the phase

relationshipbetweentheinternaloscillatorandCLKOUT.Tie

ithighfor2-phaseoperation,tieitlowfor3-phaseoperation,

I

Differential Ampliﬁer for Each Channel. Tie this pin to

TH

SGND for single phase operation on each channel. For

PolyPhase operation, tie the master’s I

connecting all of the I

to SGND while

THM

pins together at the master.

THM

and ﬂoat or tie it to V /2 for 4-phase operation.

IN

PGOOD1 and PGOOD2 (A11 and G11): Output Voltage

Power Good Indicator for Each Channel. Open-drain logic

output that is pulled to ground when the output voltage

is not within 10% of the regulation point. Power good

is disabled during margining.

MGN1 and MGN2 (A10 and G10): Voltage Margining Pin

forEachChannel.TiethispintoV

todisablemargining.

OUT

For margining, connect a voltage divider from V to GND

IN

with the center point connected to the MGN pin for the

speciﬁc channel. Each resistor should be close to 50k.

RUN1 and RUN2 (F6 and M6): Run Control Pin. A voltage

above 1.5V will turn on the module.

Margin High is within 0.3V of V , and Margin Low is

IN

within 0.3V of GND. See the Applications section and

Figure 18 for margining control. The speciﬁed tri-state

drivers are capable of the high and low requirements for

margining.

SW1 and SW2 (B6 and H6): Switching Node of Each

Channel That is Used for Testing Purposes. This can be

connected to copper on the board for improved thermal

performance.

BSEL1 and BSEL2 (A6 and G6): Margining Bit Select Pin

for Each Channel. Tying BSEL low selects 5% margin

value, tying it high selects 10% margin value. Floating it

CLKOUT1 and CLKOUT2 (F7 and M7): Output Clock

Signal for PolyPhase Operation. The phase of CLKOUT is

determined by the state of the PHMODE pin.

or tying it to V /2 selects 15% margin value.

IN

TRACK1andTRACK2(E8andL8):OutputVoltageTracking

PolyPhase is a registered trademark of Linear Technology Corporation.

4616fa

7

LTM4616

SIMPLIFIED BLOCK DIAGRAM

V

SGND2 & CONTROL

V

IN2

OUT2

M

L

K

J

GND2

H

G

F

SW2,

I/O & CONTROL

SGND1 & CONTROL

V

E

OUT1

V

IN1

D

C

B

A

GND1

1

2

3

4

5

6

7

8

9

10

11

12

SW1, I/O & CONTROL

4616 F01

TOP VIEW OF LGA PINOUT

LOOKING THROUGH COMPONENT

SV

IN1

V

INTERNAL

FILTER

IN1

3V TO 5.5V

+

TRACK1

10μF

C

IN1

PGND1

MGN1

BSEL1

V

OUT1

M1

M2

SW1

PGOOD1

MODE1

L

V

1.5V

8A

OUT1

POWER

CONTROL

RUN1

CLKIN1

CLKOUT1

PHMODE1

10μF

C

OUT1

PGND1

I

TH1

INTERNAL

COMP

50k

10k

PLLLPF1

FB1

INTERNAL

FILTER

R

SET1

6.65k

I

THM1

PGND1

SGND1

SV

IN2

V

INTERNAL

FILTER

IN2

3V TO 5.5V

+

TRACK2

10μF

C

IN2

PGND2

MGN2

BSEL2

V

OUT2

M3

M4

SW2

PGOOD2

MODE2

L

V

1.2V

8A

OUT2

POWER

CONTROL

RUN2

CLKIN2

CLKOUT2

PHMODE2

10μF

C

OUT2

PGND2

I

TH2

INTERNAL

COMP

50k

10k

PLLLPF2

FB2

INTERNAL

FILTER

R

SET2

10k

I

THM2

PGND2

SGND2

4616 BD

Figure 1. Simpliﬁed LTM4616 Block Diagram

4616fa

8

LTM4616

SIMPLIFIED BLOCK DIAGRAM

Table 1. Decoupling Requirements. T_A= 25°C, Block Diagram Conﬁguration.

SYMBOL

PARAMETER

CONDITIONS

MIN

TYP

MAX

UNITS

C

External Input Capacitor Requirement

IN1

IN2

(V = 2.7V to 5.5V, V

= 1.5V)

= 2.5V)

I

= 8A

22

μF

IN1

OUT1

OUT2

OUT1

OUT2

(V = 2.7V to 5.5V, V

IN2

C

OUT1

C

OUT2

External Output Capacitor Requirement

(V = 2.7V to 5.5V, V

= 1.5V)

= 2.5V)

I

= 8A

100

μF

IN1

OUT1

OUT2

OUT1

OUT2

(V = 2.7V to 5.5V, V

IN2

OPERATION

Pulling the RUN pins below 1.3V forces the regulators

into a shutdown state, by turning off both MOSFETs. The

TRACK pin is used for programming the output voltage

ramp and voltage tracking during start-up. See Applica-

tions Information section.

The LTM4616 is a dual-output standalone nonisolated

switching mode DC/DC power supply. It can provide two

8A outputs with few external input and output capacitors.

This module provides precisely regulated output voltages

programmable via external resistors from 0.6V to 5V

DC

over 2.7V to 5.5V input voltages. The typical application

The LTM4616 is internally compensated to be stable over

all operating conditions. Table 3 provides a guideline for

inputandoutputcapacitancesforseveraloperatingcondi-

tions. The Linear Technology μModule Power Design Tool

will be provided for transient and stability analysis. The

FB pin is used to program the output voltage with a single

external resistor to ground.

schematic is shown in Figure 18.

The LTM4616 has integrated constant frequency current

mode regulators and built-in power MOSFET devices with

fast switching speed. The typical switching frequency is

1.5MHz. For switching noise sensitive applications, it can

be externally synchronized from 0.75MHz to 2.25MHz.

Even spread spectrum switching can be implemented in

the design to reduce noise.

Multiphase operation can be easily employed with the

synchronizationandphasemodecontrols.Upto12phases

canbecascadedtorunsimultaneouslywithrespecttoeach

otherbyprogrammingthePHMODEpintodifferentlevels.

The LTM4616 has clock in and clock out for poly phasing

multiple devices or frequency synchronization.

With current mode control and internal feedback loop

compensation, the LTM4616 module has sufﬁcient stabil-

ity margins and good transient performance with a wide

range of output capacitors, even with all ceramic output

capacitors.

High efﬁciency at light loads can be accomplished with

selectableBurstModeoperationusingtheMODEpin.These

light load features will accommodate battery operation.

Efﬁciency graphs are provided for light load operation in

the Typical Performance Characteristics section.

Currentmodecontrolprovidescycle-by-cyclefastcurrent

limit and thermal shutdown in an overcurrent condition.

Internal overvoltage and undervoltage comparators pull

the open-drain PGOOD output low if the output feedback

voltage exits a 10% window around the regulation point.

The power good pins are disabled during margining.

Output voltage margining is supported, and can be pro-

gramed from 5% to 15% using the MGN and BSEL

pins.

4616fa

9

LTM4616

APPLICATIONS INFORMATION

The typical LTM4616 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.

step is required up to the 4A level. A 47μF to 100μF

surface mount aluminum electrolytic bulk capacitor can

be used for more input bulk capacitance. This bulk input

capacitor is only needed if the input source impedance is

compromisedbylonginductiveleads,tracesornotenough

source capacitance. If low impedance power planes are

used, then this 47μF capacitor is not needed.

V to V

Step-Down Ratios

IN

OUT

There are restrictions in the maximum V to V

step-

For a buck converter, the switching duty-cycle can be

estimated as:

IN

OUT

down ratio that can be achieved for a given input voltage.

Each output of the LTM4616 is 100% duty cycle, but the

V_OUT

V to V

IN

minimum drop out is still shown as a function

OUT

D =

V

of its load current. For 5V input, all outputs can deliver 8A.

For 3.3V input, all outputs can deliver 8A, except 2.5V

IN

OUT

Without considering the inductor current ripple, the RMS

current of the input capacitor can be estimated as:

which is limited to 6A. All outputs derived from 2.7V input

are limited to 5A.

I_OUT(MAX)

I_CIN(RMS)

=

• D • 1– D

Output Voltage Programming

(

)

η%

The PWM controller has an internal 0.596V reference

voltage. As shown in the Block Diagram, a 10k 0.5%

Intheaboveequation,η%istheestimatedefﬁciencyofthe

power module so the RMS input current at the worst case

for 8A maximum current is about 4A. The bulk capacitor

can be a switcher-rated electrolytic aluminum capacitor,

polymercapacitorforbulkinputcapacitance.Eachinternal

10μF ceramic input capacitor is typically rated for 2 amps

of RMS ripple current.

internal feedback resistor connects V

and FB pins

OUT

together. The output voltage will default to 0.596V with

no feedback resistor. Adding a resistor R from FB pin

FB

to GND programs the output voltage:

10k + R_FB

V_OUT= 0.596V •

R_FB

Output Capacitors

Table 2. FB Resistor vs Various Output Voltages

The LTM4616 is designed for low output voltage ripple

V

0.596V

Open

1.2V

10k

1.5V

1.8V

2.5V

3.3V

OUT

noise. The bulk output capacitors deﬁned as C

are

OUT

R

6.65k

4.87k

3.09k

2.21k

FB

chosenwithlowenougheffectiveseriesresistance(ESR)to

meettheoutputvoltagerippleandtransientrequirements.

For parallel operation of N the below equation can be

C

can be a low ESR tantalum capacitor, low ESR

used to solve for R . Tying the FB pins together for each

OUT

FB

polymercapacitororceramiccapacitor.Thetypicaloutput

capacitancerangeisfrom47μFto220μF.Additionaloutput

ﬁltering may be required by the system designer, if further

reduction of output ripples or dynamic transient spikes is

required.Table3showsamatrixofdifferentoutputvoltages

and output capacitors to minimize the voltage droop and

overshoot during a 3A/μs transient. The table optimizes

totalequivalentESRandtotalbulkcapacitancetooptimize

thetransientperformance.Stabilitycriteriaareconsidered

in the Table 3 matrix, and the Linear Technology μModule

Power Design Tool will be provided for stability analysis.

parallel output:

10k /N

R_FB=

V_OUT

0.596

−1

Input Capacitors

The LTM4616 module should be connected to a low AC

impedance DC source. For each regulator, three 10μF

ceramic capacitors are included inside the module.

Additional input capacitors are only needed if a large load

4616fa

10

LTM4616

APPLICATIONS INFORMATION

Table 3. Output Voltage Response Versus Component Matrix (Refer to Figure 18) 0A to 3A Load Step

TYPICAL MEASURED VALUES

C

OUT1

VENDORS

VALUE

PART NUMBER

C

OUT2

VENDORS

VALUE

PART NUMBER

TDK

22μF, 6.3V

22μF, 16V

100μF, 6.3V

C3216X7S0J226M

GRM31CR61C226KE15L

C4532X5R0J107MZ

GRM32ER60J107M

Sanyo POSCAP

470μF, 4V

4TPE470M

Murata

TDK

C

IN

(BULK) VENDORS VALUE

PART NUMBER

10CE100FH

Sanyo

100μF, 10V

Murata

V

C

V

(V)

DROOP PEAK-TO- PEAK

RECOVERY

TIME (μs)

LOAD STEP

R

FB

OUT

IN

OUT1

OUT2

IN

(V)

1.0

1.2

1.5

1.8

2.5

3.3

(CERAMIC) (BULK)* (CERAMIC)

(BULK)

I

C1

C3

(mV)

20

30

25

20

30

32

25

22

25

30

25

42

25

35

25

35

32

50

32

65

40

DEVIATION (mV)

(A/μs)

2.5

(kΩ)

14.7

10

TH

10μF

100μF

100μF × 2

22μF × 1

100μF × 2

22μF × 1

100μF × 2

22μF × 1

100μF × 2

22μF × 1

100μF × 1

22μF × 1

100μF × 2

22μF × 1

100μF × 1

22μF × 1

100μF × 2

22μF × 1

100μF × 2

22μF × 1

100μF × 1

22μF × 1

100μF × 1

22μF × 1

100μF × 1

22μF × 1

470μF

None

5

40

60

50

40

41

60

64

50

42

50

60

50

80

50

70

50

70

20

40

65

100

65

135

87

40

25

20

25

20

25

30

40

30

40

30

40

5

2.7

5

470μF

5

10

2.7

5

10

6.65

4.87

3.09

2.21

5

3.3

2.7

5

3.3

2.7

5

3.3

5

*Bulk capacitance is optional if V has very low input impedance.

IN

Multiphase operation will reduce effective output ripple as

a function of the number of phases. Application Note 77

discusses this noise reduction versus output ripple cur-

rent cancellation, but the output capacitance will be more

a function of stability and transient response. The Linear

Technology μModule Power Design Tool will calculate the

output ripple reduction as the phase number increases

by N times.

Burst Mode Operation

The LTM4616 is capable of Burst Mode operation on

each regulator in which the power MOSFETs operate

intermittentlybasedonloaddemand,thussavingquiescent

current. For applications where maximizing the efﬁciency

at very light loads is a high priority, Burst Mode operation

shouldbeapplied.ToenableBurstModeoperation,simply

tie the MODE pin to V . During this operation, the peak

IN

current of the inductor is set to approximately 20% of

4616fa

11

LTM4616

APPLICATIONS INFORMATION

the maximum peak current value in normal operation

mode is disabled and inductor current is prevented

from reversing until the LTM4616’s output voltage is in

regulation. Each regulator can be conﬁgured for Forced

Continuous mode.

even though the voltage at the I pin indicates a lower

TH

value. The voltage at the I pin drops when the inductor’s

TH

average current is greater than the load requirement. As

the I voltage drops below 0.2V, the BURST comparator

TH

Multiphase Operation

trips, causing the internal sleep line to go high and turn

off both power MOSFETs.

For output loads that demand more than 8A of current,

two outputs in LTM4616 or even multiple LTM4616s can

be cascaded to run out-of-phase to provide more output

currentwithoutincreasinginputandoutputvoltageripple.

The CLKIN pin allows the LTC4616 to synchronize to an

external clock (between 0.75MHz and 2.25MHz) and the

internal phase-locked loop allows the LTM4616 to lock

onto CLKIN’s phase as well. The CLKOUT signal can be

connectedtotheCLKINpinofthefollowingLTM4616stage

to line up both the frequency and the phase of the entire

In Burst Mode operation, the internal circuitry is partially

turned off, reducing the quiescent current to about 450μA

for each output. The load current is now being supplied

fromtheoutputcapacitors.Whentheoutputvoltagedrops,

causingI toriseabove0.25V,theinternalsleeplinegoes

TH

low,andtheLTM4616resumesnormaloperation.Thenext

oscillator cycle will turn on the top power MOSFET and the

switching cycle repeats. Each regulator can be conﬁgured

for BurstModeoperation.

system. Tying the PHMODE pin to SV , SGND or SV /2

IN

Pulse-Skipping Mode Operation

(ﬂoating) generates a phase difference (between CLKIN

and CLKOUT) of 180°, 120° or 90° respectively, which

correspondstoa2-phase,3-phaseor4-phaseoperation.A

total of 12 phases can be cascaded to run simultaneously

with respect to each other by programming the PHMODE

pin of each LTM4616 to different levels. For a 6-phase

example in Figure 2, the 2nd stage that is 120° out-of-

phase from the 1st stage can generate a 240° (PHMODE

= 0) CLKOUT signal for the 3rd stage, which then can

generate a CLKOUT signal that’s 420°, or 60° (PHMODE

Inapplicationswherelowoutputrippleandhighefﬁciency

atintermediatecurrentsaredesired, pulse-skippingmode

should be used. Pulse-skipping operation allows the

LTM4616toskipcyclesatlowoutputloads,thusincreasing

efﬁciencybyreducingswitchingloss.FloatingtheMODEpin

or tying it to V /2 enables pulse-skipping operation. This

IN

allows discontinuous conduction mode (DCM) operation

down to near the limit deﬁned by the chip’s minimum

on-time (about 100ns). Below this output current level,

the converter will begin to skip cycles in order to maintain

output regulation. Increasing the output load current

slightly, above the minimum required for discontinuous

conduction mode, allows constant frequency PWM. Each

regulator can be conﬁgured for Pulse-Skipping mode.

= SV ) for the 4th stage. With the 60° CLKIN input, the

IN

next two stages can shift 120° (PHMODE = 0) for each

to generate a 300° signal for the 6th stage. Finally, the

signal with a 60° phase shift on the 6th stage (PHMODE

is ﬂoating) goes back to the 1st stage. Figure 3 shows the

conﬁguration for 12-phase operation.

Forced Continuous Operation

A multiphase power supply signiﬁcantly reduces the

amount of ripple current in both the input and output

capacitors. The RMS input ripple current is reduced by,

and the effective ripple frequency is multiplied by, the

number of phases used (assuming that the input voltage

isgreaterthanthenumberofphasesusedtimestheoutput

voltage). The output ripple amplitude is also reduced by

the number of phases used.

In applications where ﬁxed frequency operation is more

critical than low current efﬁciency, and where the lowest

outputrippleisdesired,forcedcontinuousoperationshould

be used. Forced continuous operation can be enabled by

tying the MODE pin to GND. In this mode, inductor current

is allowed to reverse during low output loads, the I

TH

voltage is in control of the current comparator threshold

throughout, and the top MOSFET always turns on with

each oscillator pulse. During start-up, forced continuous

The LTM4616 device is an inherently current mode con-

trolled device, so parallel modules will have very good

4616fa

12

LTM4616

APPLICATIONS INFORMATION

(420)

60

0

120

240

180

300

+120

+180

+120

CLKIN CLKOUT

PHMODE

PHASE 1

PHMODE

PHASE 3

S

PHMODE

PHASE 5

PHMODE

PHASE 2

PHMODE

PHASE 4

PHMODE

VIN

4616 F02

PHASE 6

Figure 2. 6-Phase Operation

(390)

30

0

90

180

270

+90

+120

+90

CLKIN CLKOUT

PHMODE

PHASE 1

PHMODE

PHASE 4

PHMODE

PHASE 7

PHMODE

PHASE 10

PHMODE

PHASE 2

(420)

60

120

210

300

150

+90

+120

+90

CLKIN CLKOUT

PHMODE

PHASE 5

PHMODE

PHASE 8

PHMODE

PHASE 11

PHMODE

PHASE 3

PHMODE

PHASE 6

4616 F03

240

330

+90

CLKIN CLKOUT

PHMODE

PHASE 9

PHMODE

PHASE 12

Figure 3. 12-Phase Operation

current sharing. This will balance the thermals on the

Spread Spectrum Operation

design. Tie the I pins of each LTM4616 together to share

TH

Switchingregulatorscanbeparticularlytroublesomewhere

electromagnetic interference (EMI) is concerned.

the current evenly. To reduce ground potential noise, tie

the I

pins of all LTM4616s together and then connect

THM

Switching regulators operate on a cycle-by-cycle basis to

transfer power to an output. In most cases, the frequency

ofoperationisﬁxedbasedontheoutputload.Thismethod

of conversion creates large components of noise at the

frequency of operation (fundamental) and multiples of the

operating frequency (harmonics).

to the SGND of the master at the point it connects to the

output capacitor GND. See layout guideline in Figure 17.

Figure 19 shows a schematic of the parallel design. The

FB pins of the parallel module are tied together.

Input RMS Ripple Current Cancellation

Application Note 77 provides a detailed explanation of

multiphase operation. The input RMS ripple current can-

cellation mathematical derivations are presented, and a

graph is displayed representing the RMS ripple current

reductionasafunctionofthenumberofinterleavedphases.

Figure 4 shows this graph.

To reduce this noise, the LTM4616 can run in spread

spectrum operation by tying the CLKIN pin to SV .

IN

In spread spectrum operation, the LTM4616’s internal

oscillator is designed to produce a clock pulse whose

period is random on a cycle-by-cycle basis but ﬁxed

4616fa

13

LTM4616

APPLICATIONS INFORMATION

0.60

1-PHASE

2-PHASE

3-PHASE

4-PHASE

6-PHASE

0.55

0.50

0.45

0.40

0.35

0.30

0.25

0.20

0.15

0.10

0.05

0

0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5 0.55 0.6 0.65 0.7 0.75 0.8 0.85 0.9

DUTY FACTOR (V /V

)

O

IN

4616 F04

Figure 4. Normalized Input RMS Ripple Current vs Duty Factor for One to Six Channels (Phases)

between 70% and 130% of the nominal frequency. This

has the beneﬁt of spreading the switching noise over

a range of frequencies, thus signiﬁcantly reducing the

peak noise. Spread spectrum operation is disabled if

CLKIN is tied to ground or if it’s driven by an external

frequency synchronization signal. A capacitor value

of 0.01μF to 0.1μF be placed from the PLLLPF pin to

ground to control the slew rate of the spread spectrum

frequency change.

V

TRACK

is the track ramp applied to the slave’s track pin.

has a control range of 0V to 0.596V, or the internal

TRACK

V

reference voltage. When the master’s output is divided

down with the same resistor values used to set the slave’s

output, then the slave will coincident track with the master

until it reaches its ﬁnal value. The master will continue to

its ﬁnal value from the slave’s regulation point. Voltage

trackingisdisabledwhenV

Figure 5 will be equal to R for coincident tracking.

ismorethan0.596V.R in

TRACK

TA

FB

Thetrackpinofthemastercanbecontrolledbyanexternal

Output Voltage Tracking

ramp or by R and C in Figure 5 referenced to V . The

SR

IN

Output voltage tracking can be programmed externally

using the TRACK pin. The output can be tracked up and

downwithanotherregulator.Themasterregulator’soutput

is divided down with an external resistor divider that is the

sameastheslaveregulator’sfeedbackdividertoimplement

coincident tracking. The LTM4616 uses an accurate 10k

resistor internally for the top feedback resistor. Figure 5

shows an example of coincident tracking:

RC ramp time can be programmed using equation:

ꢀ

ꢃ

ꢀ

ꢃ

0.596V

t = – ln 1–

•R_SR• C_SR

ꢂ

ꢅ

ꢂ

ꢅ

V

ꢁ

ꢄ

ꢁ

ꢄ

IN

Ratiometric tracking can be achieved by a few simple

calculationsandtheslewratevalueappliedtothemaster’s

trackpin.Asmentionedabove,theTRACKpinhasacontrol

range from 0V to 0.596V. The master’s TRACK pin slew

ꢀ

ꢂ

ꢁ

ꢃ

10k

R

Slave = 1+

• V_TRACK

ꢅ

_TAꢄ

4616fa

14

LTM4616

APPLICATIONS INFORMATION

rate is directly equal to the master’s output slew rate in

Volts/Time:

Inratiometrictracking, adifferentslewratemaybedesired

for the slave regulator. R can be solved for when SR is

TB

slower than MR. Make sure that the slave supply slew rate

ischosentobefastenoughsothattheslaveoutputvoltage

will reach it ﬁnal value before the master output.

MR

• 10k = R_TB

SR

where MR is the master’s output slew rate and SR is the

slave’s output slew rate in Volts/Time. When coincident

tracking is desired, then MR and SR are equal, thus R

is equal to 10k. R is derived from equation:

For example: MR = 3.3V/ms and SR = 1.5V/ms. Then

R

TB

= 22.1k. Solve for R to equal to 4.87k.

TA

TB

TA

0.596V

MASTER OUTPUT

SLAVE OUTPUT

R_TA

=

V_TRACK

V

FB

+

–

10k R_FB

R_TB

whereV isthefeedbackvoltagereferenceoftheregulator

FB

TRACK

and V

is 0.596V. Since R is equal to the 10k top

TB

feedback resistor of the slave regulator in equal slew rate

or coincident tracking, then R is equal to R with V

TA

TB

FB

= V

. Therefore R = 10k and R = 6.65k in Figure

TRACK

TB TA

TIME

4616 F06

5. Figure 6 shows the output voltage for coincident

tracking.

Figure 6. Output Voltage Coincident Tracking

CLKIN1

V

4V TO 5.5V

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

IN

MASTER

3.3V/7A

V

OUT1

IN1

SV

FB1

IN1

R

RUN

10μF

FB1

RUN1

ITH1

2.21k

100μF

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

RSR

PHMODE1

TRACK1

MGN1

LTM4616

SLAVE

1.5V/8A

V

IN2

OUT2

FB2

CSR

SV

IN2

R

RUN

10μF

FB2

RUN2

ITH2

6.65k

100μF

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

MASTER

3.3V

PGOOD

BSEL

R

TB

10k

MGN2

R

TA

SW2

SGND1

GND1

SGND2

GND2

6.65k

4616 F05

FOR TRACK1:

1. TIE TO VIN TO DISABLE TRACK WITH DEFAULT 100μs SOFT START

2. APPLY A CONTROL RAMP WITH RSR AND CSR TIED TO V WITH t = –(ln(1–0.596/V ) • RSR • CSR))

IN

3. APPLY AN EXTERNAL TRACKING RAMP DIRECTLY

Figure 5. Dual Outputs (3.3V and 1.5V) with Tracking

4616fa

15

LTM4616

APPLICATIONS INFORMATION

Forapplicationsthatdonotrequiretrackingorsequencing,

MGN pin is low, it forces negative margining, in which the

output voltage is below the regulation point. When MGN is

high, the output voltage is forced to above the regulation

point. The MGN pin with a voltage divider is driven with a

small tri-state gate as shown in Figure 18 for three margin

states, (High, Low, and No Margin). The amount of output

voltage margining is determined by the BSEL pin. When

BSEL is low, it’s 5%. When BSEL is high, it’s 10%. When

BSEL is ﬂoating, it’s 15%. When margining is active, the

internaloutputovervoltageandundervoltagecomparators

are disabled and PGOOD remains high.

simply tie the TRACK pin to SV to let RUN control the

IN

turn on/off. Connecting TRACK to SV also enables the

IN

~100μs of internal soft-start during start-up.

Power Good

The PGOOD pin is an open-drain pin that can be used to

monitor valid output voltage regulation. This pin monitors

a 10% window around the regulation point. As shown

in Figure 20, the sequencing function can be realized in a

dualoutputapplicationbycontrollingtheRUNpinsandthe

PGOOD signals from each other. The 1.5V output begins

its soft starting after the PGOOD signal of 3.3V output

becomes high, and 3.3V output starts its shutdown after

the PGOOD signal of 1.5V output becomes low. This can

be applied to systems that require voltage sequencing

between the core and sub-power supplies.

Thermal Considerations and Output Current Derating

The power loss curves in Figures 7 and 8 can be used

in coordination with the load current derating curves in

Figures 9 to16 for calculating an approximate θ thermal

JA

resistance for the LTM4616 with various heatsinking and

airﬂow conditions. Both LTM4616 outputs are placed in

parallel for a total output current of 16A, and the power

loss curves are plotted for speciﬁc output voltages up to

16A.Thederatingcurvesareplottedwitheachoutputat8A

combined for a total of 16A. The output voltages are 1.2V,

2.5V and 3.3V. These are chosen to include the lower and

higher output voltage ranges for correlating the thermal

resistance. Thermal models are derived from several

temperature measurements in a controlled temperature

chamber along with thermal modeling analysis. The

junction temperatures are monitored while ambient

temperature increased with and without airﬂow. The

junctions are maintained at ~115°C while lowering output

Stability Compensation

The module has already been internally compensated

for all output voltages. Table 2 is provided for most ap-

plication requirements. The Linear Technology μModule

Power Design Tool will be provided for other control loop

optimization.

Output Margining

For a convenient system stress test on the LTM4616’s

output, the user can program each output to 5%, 10%

or 15% of its normal operational voltage. The MGN pin is

tied to the output voltage to disable margining. When the

8

7

6

5

4

3

2

8

7

6

5

4

3

2

1

5V 1.2V

3.3V 1.2V

IN

OUT

IN

OUT

5V 3.3V

IN

3.3V 2.5V

IN

0

8

0

4

12

16

8

0

4

12

16

LOAD CURRENT (A)

4616 F08

4616 F07

Figure 7. 1.2V, 2.5V Power Loss

Figure 8. 1.2V, 3.3V Power Loss

4616fa

16

LTM4616

APPLICATIONS INFORMATION

16

14

12

10

8

16

14

12

10

8

16

14

12

10

8

400 LFM

0 LFM

200 LFM

0 LFM

200 LFM

6

200 LFM

6

4

2

0

55

70

85

55

70

85

25

40

100

115

25

115

40

100

60

70

80

40

50

90 100 110

AMBIENT TEMPERATURE (°C)

4616 F09

4616 F11

4616 F10

Figure 9. 5V_INto 3.3V_OUT

with No Heatsink

Figure 10. 5V_INto 1.2V_OUT

with No Heatsink

Figure 11. 5V_INto 3.3V_OUT

with BGA Heatsink

16

14

12

10

8

16

14

12

10

8

16

14

12

10

8

400 LFM

0 LFM

400 LFM

0 LFM

200 LFM

6

200 LFM

4

2

0

60

80

40

100

120

50

70

90

30

110

60

70

80

40

50

90 100 110

AMBIENT TEMPERATURE (°C)

4616 F13

4616 F14

4616 F12

Figure 12. 5V_INto 1.2V_OUT

with BGA Heatsink

Figure 13. 3.3V_INto 1.2V_OUT

with No Heatsink

Figure 14. 3.3V_INto 2.5V_OUT

with No Heatsink

current or power while increasing ambient temperature.

The 115°C is chosen to allow for a 10°C margin window

relative to the maximum 125°C. The decreased output

current will decrease the internal module loss as ambient

temperatureisincreased.ThepowerlosscurvesinFigures7

and 8 show this amount of power loss as a function of

load current that is speciﬁed with both channels in paral-

lel. The monitored junction temperature of 115°C minus

the ambient operating temperature speciﬁes how much

moduletemperaturerisecanbeallowed.Asanexample,in

Figure 10 the load current is derated to 10A at ~ 80°C and

the power loss for the 5V to 1.2V at 10A output is ~3W.

If the 80°C ambient temperature is subtracted from the

115°C maximum junction temperature, then difference of

35°C divided by 3.2W equals a 10.9°C/W. Table 4 speciﬁes

a 10.5°C/W value which is very close. Table 4 and Table 5

provide equivalent thermal resistances for 1.2V and 3.3V

outputs, with and without airﬂow and heatsinking. The

printed circuit board is a 1.6mm thick four layer board

with two ounce copper for the two outer layers and one

ouncecopperforthetwoinnerlayers.ThePCBdimensions

are 95mm × 76mm. The BGA heatsinks are listed below

Table 5. At load currents on each channel from 3A to 8A

(6A to16A in parallel on the derate curves); the thermal

resistance values in Tables 4 and 5 are closely accurate.

As the load currents go below the 3A level on each channel

thethermalresistancestartstoincreaseduetothereduced

power loss on the board. The approximate thermal

resistance values for these lower currents is 15°C/W.

4616fa

17

LTM4616

APPLICATIONS INFORMATION

16

14

12

10

8

14

12

400 LFM

10

8

0 LFM

200 LFM

6

200 LFM

4

2

0

4

2

0

50 60 70 80 90 100 110

AMBIENT TEMPERATURE (°C)

40

120

50

70

90

30

110

AMBIENT TEMPERATURE (°C)

4616 F15

4616 F16

Figure 15. 3.3V_IN1.2V_OUTwith BGA Heatsink

Table 4. 1.2V Output

Figure 16. 3.3V_IN2.5V_OUTwith BGA Heatsink

DERATING CURVE

Figures 10, 13

Figures 12, 15

V

(V)

POWER LOSS CURVE

Figures 7, 8

AIR FLOW (LFM)

HEAT SINK

None

θ

JA

(°C/W)

IN

3.3, 5

0

10.5

8.0

7.0

9.5

6.3

5.2

Figures 7, 8

200

400

0

None

Figures 7, 8

None

Figures 7, 8

BGA Heat Sink

Figures 7, 8

200

400

Figures 7, 8

Table 5. 3.3V Output

DERATING CURVE

Figure 9

V

IN

(V)

POWER LOSS CURVE

Figure 8

AIR FLOW (LFM)

HEAT SINK

None

θ

(°C/W)

JA

5

0

10.5

8.0

7.0

9.8

7.0

5.5

Figure 9

5

Figure 8

200

400

0

None

Figure 9

Figure 8

None

Figure 11

Figure 8

BGA Heat Sink

Figure 11

Figure 8

200

400

Figure 11

Figure 8

Heatsink Manufacturer

Wakeﬁeld Engineering

AAVID Thermalloy

Part No: LTN20069

Phone Number: 603-635-2800

Phone Number: 603-224-9988

Part No: 375424B000346

Layout Checklist/Example

Safety Considerations

The high integration of LTM4616 makes the PCB board

layout very simple and easy. However, to optimize

its electrical and thermal performance, some layout

considerations are still necessary.

The LTM4616 modules do not provide isolation from V

IN

to V . There is no internal fuse. If required, a slow blow

OUT

fuse with a rating twice the maximum input current needs

to be provided to protect each unit from catastrophic

failure. The device does support thermal shutdown and

overcurrent protection.

• Use large PCB copper areas for high current paths,

including V , V , PGND1 and PGND2, V

OUT2

and thermal stress.

and

IN1 IN2

OUT1

V

. It helps to minimize the PCB conduction loss

4616fa

18

LTM4616

APPLICATIONS INFORMATION

• Place high frequency ceramic input and output capaci-

• Use a separated SGND ground copper area for com-

ponents connected to signal pins. Connect the SGND

to GND underneath the unit.

tors next to the V , GND and V

pins to minimize

IN

OUT

high frequency noise.

• Place a dedicated power ground layer underneath the

unit.

• For parallel modules, tie the I , FB and I

pins to-

TH

THM

gether. Use an internal layer to closely connect these

pins together. All of the I pins connect to the SGND

THM

• Tominimizetheviaconductionlossandreducemodule

thermal stress, use multiple vias for interconnection

between top layer and other power layers.

ofthemasterregulator,thenthemasterSGNDconnects

to GND.

Figure 17 gives a good example of the recommended

layout.

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

capped or plated over.

V

OUT1

IN1

VIA TO GND 2X

CONTROL1

M

L

C

OUT2

V

OUT1

C

IN1

V

IN1

K

J

H

G

F

GND1

CONTROL1 & 2

C

OUT2

E

V

OUT2

V

IN2

C

IN2

D

C

B

A

GND2

1

2

3

4

5

6

7

8

9

10

11

12

4616 F17

GND2

CONTROL2

LTM4616 TOP VIEW

GND2

Figure 17. Recommended PCB Layout

CLKIN1

V

3V TO 5.5V

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

IN1

V

OUT1

1.8V/8A

V

IN1

OUT1

FB1

SV

IN1

RUN1

100μF

10μF

4.87k

ITH1

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

V

IN

A2

PGOOD

BSEL

+

R4

V

PHMODE1

TRACK1

–

+

50k

OUT

I

OE

IN

MGN1

LTM4616

V

IN2

3V TO 5.5V

V

OUT2

V

IN2

V

OUT2

1.5V/8A

GND

R3

50k

SV

FB2

IN2

10μF

5 PIN SC70 PACKAGE

6.65k

RUN2

ITH2

100μF

s2

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

V

IN

BSEL: HIGH = 10%

FLOAT = 15%

LOW = 5%

A1

PGOOD

BSEL

+

V

A1, A2 PERICOM P174ST1G126CEX

TOSHIBA TC75Z126AFE

R2

50k

–

+

OUT

I

OE

MGN2

OE

IN

OUT

MGN MARGIN VALUE

IN

SW2

SGND1

GND1

SGND2

GND2

R1

50k

H

L

H

L

X

H

L

Z

H

L

+ Value of BSEL Selection

– Value of BSEL Selection

4616 F18

GND

5 PIN SC70 PACKAGE

V_IN/2 No Margin

Figure 18. Typical 3.2V to 5V_IN, to 1.8V, 1.5V Outputs

4616fa

19

LTM4616

APPLICATIONS INFORMATION

V

3V TO 5.5V

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

IN

V

OUT

1.5V/16A

V

IN1

OUT1

10μF

SV

IN1

RUN1

FB1

100μF

RUN

ENABLE

ITH1

3.32k

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

PHMODE1

TRACK1

MGN1

LTM4616

V

IN2

V

OUT2

10μF

SV

FB2

IN2

100μF

RUN2

ITH2

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

MGN2

SW2

SGND1

GND1

SGND2

GND2

4616 F19

Figure 19. LTM4616 Two Outputs Parallel, 1.5V at 16A Design

CLKIN

V

5V

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

IN

V

OUT1

3.3V/7A

V

IN1

V

OUT1

22μF

SHDNB

SV

IN1

RUN1

FB1

2.21k

ITH1

100μF

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

100k

PHMODE1

TRACK1

PGOOD2

SV

IN1

MGN1

LTM4616

V

OUT2

1.5V/8A

V

IN2

V

OUT2

SV

FB2

IN2

100μF

RUN2

ITH2

6.65k

100μF

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

100k

SHDNB

3.3V

1.5V

100k

PGOOD1

MGN2

SV

IN2

SW2

SGND1

GND1

SGND2

GND2

4616 F20

Figure 20. LTM4616 Output Sequencing Application

4616fa

20

LTM4616

APPLICATIONS INFORMATION

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

V

IN

V

OUT

1.2V AT 32A

IN1

OUT1

3V TO 6.5V

+

C1

470μF

6.3V

10μF

6.3V

SV

IN1

RUN1

FB1

2.47k

ITH1

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

SANYO POSCAP

10mꢀ

PHMODE1

TRACK1

TRACK INPUT

MGN1

OR 3V

IN

LTM4616

V

OUT2

IN2

+

C2

470μF

6.3V

10μF

6.3V

SV

FB2

IN2

RUN2

ITH2

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

MGN2

SW2

SGND1

GND1

SGND2

GND2

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

V

OUT1

IN1

+

C3

470μF

6.3V

10μF

6.3V

SV

IN1

RUN1

FB1

ITH1

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

PHMODE1

TRACK1

MGN1

LTM4616

V

OUT2

IN2

+

C5

22μF

6.3V

C4

22μF

6.3V

10μF

6.3V

SV

FB2

IN2

RUN2

ITH2

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

V

IN

3V TO 6.6V

MGN2

A1

+

R1

SW2

SGND1

GND1

SGND2

GND2

V

–

+

50k

4616 F21

I

OE

OUT

IN

R2

50k

GND

BSEL: HIGH = 10%

A1, A2 PERICOM P174ST1G126CEX

TOSHIBA TC75Z126AFE

6 PIN SC70 PACKAGE

FLOAT = 15%

LOW = 5%

OPTIONAL MARGINING CIRCUIT,

IF NOT USED TIE THE MGN PINS TO V

OUT

OE

IN

OUT

MGN MARGIN VALUE

H

L

H

L

X

H

L

Z

H

L

+ Value of BSEL Selection

– Value of BSEL Selection

V_IN/2 No Margin

Figure 21. Four Phase in Parallel, 1.2V at 32A

4616fa

21

LTM4616

APPLICATIONS INFORMATION

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

V

OUT1

IN

V

IN1

OUT1

3.3V/7A

4V TO 5.5V

10μF

RUN

ENABLE

SV

FB1

100μF

IN1

2.21k

RUN1

ITH1

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

PHMODE1

TRACK1

MGN1

LTM4616

V

OUT2

V

IN2

OUT2

FB2

2.5V/8A

SV

10μF

100μF

IN2

RUN2

ITH2

3.16k

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

3.3V

10k

MGN2

SW2

SGND1

GND1

SGND2

GND2

3.16k

SW1

CLKIN1 CLKOUT1 CLKIN2 CLKOUT2

V

OUT3

V

IN1

OUT1

1.8V/8A

100μF

SV

FB1

IN1

10μF

RUN1

ITH1

4.99k

100μF

PLLLPF1

MODE1

ITHM1

PGOOD1

BSEL1

3.3V

10k

PHMODE1

TRACK1

MGN1

LTM4616

V

OUT4

4.99k

V

IN2

OUT2

FB2

1.5V/8A

100μF

SV

IN2

10μF

6.65k

RUN2

ITH2

100μF

PLLLPF2

MODE2

PHMODE2

TRACK2

ITHM2

PGOOD2

BSEL2

3.3V

10k

MGN2

SW2

SGND1

GND1

SGND2

GND2

6.65k

4616 F22

Figure 22. 4-Phase, Four Outputs (3.3V, 2.5V, 1.8V and 1.5V) with Tracking

4616fa

22

LTM4616

PACKAGE DESCRIPTION

LGA Package

144-Lead (15mm × 15mm × 2.82mm)

(Reference LTC DWG # 05-08-1816 Rev A)

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

4616fa

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

LTM4616

PACKAGE DESCRIPTION

Pin Assignment Table

(Arranged by Pin Number)

PIN NAME

A1 GND1

A2 GND1

A3 GND1

A4 GND1

A5 GND1

A6 BSEL1

A7 CLKIN1

A8 MODE1

PIN NAME

B1 GND1

B2 GND1

B3 GND1

B4 GND1

B5 GND1

B6 SW1

B7 GND1

B8 GND1

C1

C2

V

D1

D2

V

IN1

V

IN1

E1

E2

E3

E4

V

IN1

V

IN1

V

IN1

V

IN1

F1

F2

F3

F4

V

IN1

V

IN1

V

IN1

V

IN1

C3 GND1

C4 GND1

C5 GND1

C6 GND1

C7 GND1

C8 GND1

C9 GND1

C10 GND1

C11 GND1

C12 GND1

D3 GND1

D4 GND1

D5 GND1

D6 GND1

D7 GND1

D8 FB1

E5 SV

F5 SGND1

E6 PLLFLTR1 F6 RUN1

IN1

E7 ITHM1

E8 TRACK1

E9 V_OUT1

E10 V_OUT1

E11 V_OUT1

E12 V_OUT1

F7 CLKOUT1

F8 ITH1

A9 PHMODE1 B9 GND1

D9 V_OUT1

D10 V_OUT1

D11 V_OUT1

D12 V_OUT1

F9 V_OUT1

F10 V_OUT1

F11 V_OUT1

F12 V_OUT1

A10 MGN1

A11 PGOOD1

A12 GND1

B10 GND1

B11 GND1

B12 GND1

PIN NAME

G1 GND2

G2 GND2

G3 GND2

G4 GND2

G5 GND2

G6 BSEL2

G7 CLKIN2

G8 MODE2

PIN NAME

H1 GND2

H2 GND2

H3 GND2

H4 GND2

H5 GND2

H6 SW2

PIN NAME

J1

J2

V

K1

K2

V

L1

L2

L3

L4

V

M1

M2

M3

M4

V

IN2

V

IN2

V

IN2

V

IN2

V

J3 GND2

J4 GND2

J5 GND2

J6 GND2

J7 GND2

J8 GND2

J9 GND2

J10 GND2

J11 GND2

J12 GND2

K3 GND2

K4 GND2

K5 GND2

K6 GND2

K7 GND2

K8 FB2

L5 SV

M5 SGND2

L6 PLLFLTR2 M6 RUN2

IN2

H7 GND2

H8 GND2

L7 ITHM2

L8 TRACK2

L9 V_OUT2

L10 V_OUT2

L11 V_OUT2

L12 V_OUT2

M7 CLKOUT2

M8 ITH2

G9 PHMODE2 H9 GND2

K9 V_OUT2

K10 V_OUT2

K11 V_OUT2

K12 V_OUT2

M9 V_OUT2

M10 V_OUT2

M11 V_OUT2

M12 V_OUT2

G10 MGN2

G11 PGOOD2

G12 GND2

H10 GND2

H11 GND2

H12 GND2

RELATED PARTS

PART NUMBER

DESCRIPTION

COMMENTS

LTC2900

Quad Supply Monitor with Adjustable Reset Timer

10A DC/DC μModule

Monitors Four Supplies; Adjustable Reset Timer

Basic 10A DC/DC μModule, LGA Package

LTM4600

LTM4600HVMP

Military Plastic 10A DC/DC μModule

Guaranteed Operation from –55°C to 125°C Ambient, LGA Package

LTM4601/

LTM4601A

12A DC/DC μModule with PLL, Output Tracking/

Margining and Remote Sensing

Synchronizable, PolyPhase Operation, LTM4601-1/LTM4601A-1 Version has no

Remote Sensing, LGA Package

LTM4602

LTM4603

6A DC/DC μModule

Pin Compatible with the LTM4600, LGA Package

6A DC/DC μModule with PLL and Outpupt Tracking/ Synchronizable, PolyPhase Operation, LTM4603-1 Version has no Remote

Margining and Remote Sensing

Sensing, Pin Compatible with the LTM4601, LGA Package

LTM4604A

LTM4608A

Low V 4A DC/DC μModule

2.375V ≤ V ≤ 5.5V, 0.8V ≤ V

≤ 5V, 9mm × 15mm × 2.3mm LGA Package

IN

OUT

Low V 8A DC/DC μModule

2.7V ≤ V ≤ 5.5V; 0.6V ≤ V

≤ 5V; 9mm × 15mm × 2.8mm LGA Package

OUT

IN

LTM8022/LTM8023 36V , 1A and 2A DC/DC μModule

Pin Compatible; 4.5V ≤ V ≤ 36V; 9mm × 11.25mm × 2.8mm LGA Package

IN

4616fa

LT 1108 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：	LTM4616
厂家：	Linear
描述：	Dual 8A per Channel Low VIN DC/DC μModule 每通道低输入电压的DC / DC微型模块双通道8A
文件：	总24页 (文件大小：309K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

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