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LTM4649

4649f

For more information www.linear.com/LTM4649

TYPICAL APPLICATION

FEATURES DESCRIPTION

10A Step-Down DC/DC

µModule Regulator

The LTM

4649 is a complete 10A high efficiency switching

mode step-down DC/DC µModule

regulator in a 9mm ×

15mm × 4.92 BGA package. Included in the package are

the switching controller, power FETs, inductor, and all sup-

port components. Operating over an input voltage range

of 4.5V to 16V, the LTM4649 supports an output voltage

range of 0.6V to 3.3V, set by a single external resistor. This

high efficiency design delivers 10A continuous current.

Only bulk input and output capacitors are needed.

High switching frequency and a current mode architecture

enables a very fast transient response to line and load

changes without sacrificing stability. The device supports

frequency synchronization, programmable multiphase

operation, spread spectrum, output voltage tracking for

supply rail sequencing.

Fault protection features include overvoltage protection,

overcurrent protection. The LTM4649 is offered in a small

thermally enhanced 9mm × 15mm × 4.92mm BGA pack-

age. The LTM4649 is RoHS compliant.

Efficiency and Power Loss

at 12V and 5V Input

Current Derating: 12V Input,

1.5V

OUT

, No Heat Sink

4.5V to 16V Input, 1.5V Output DC/DC

µModule Regulator

APPLICATIONS

10A DC Output Current

Input Voltage Range: 4.5V to 16V

Output Voltage Range: 0.6V Up to 3.3V

No Heat Sink or Current Derating Up to 85°C

Ambient Temperature

±1.5% Total DC Voltage Output Error

Multiphase Operation with Current Sharing

Remote Sense Amplifier

Built-In General Use Temperature Monitor

Selectable Pulse-Skipping Mode/Burst Mode

Operation for High Efficiency at Light Load

Soft-Start/Voltage Tracking

Protection: Output Overvoltage and Overcurrent

Foldback

9mm × 15mm × 4.92mm BGA Package

Telecom, Networking and Industrial Equipment

Point of Load Regulation

L, LT, LTC, LTM, Burst Mode, µModule, PolyPhase, Linear Technology and the Linear logo are

registered trademarks of Linear Technology Corporation. All other trademarks are the property

of their respective owners. Protected by U.S. Patents, including 5481178, 5705919, 5929620,

6100678, 6144194, 6177787, 6304066 and 6580258. Other patents pending.

INTV

RUN

MODE

PHMODE

TRACK/SS

TEMP

OUT

OUT_LCL

DIFFOUT

DIFFP

DIFFN

COMP

PGOOD

CLKIN FREQ

LTM4649

GND

0.1µF

100µF

6.3V

×2

6.65k

22µF

16V

×2

4.5V TO 16V

OUT

1.5V

10A

CLKOUT

4649 TA01a

LOAD CURRENT (A)

EFFICIENCY (%)

POWER LOSS (W)

0.5

1.0

1.5

2.0

2.5

3.0

2 4 6 8

4649 TA01b

= 12V

= 5V

AMBIENT TEMPERATURE (°C)

LOAD CURRENT (A)

40 60 80

4649 TA01c

100 120

400LFM

200LFM

0LFM

Summary of content (28 pages)

PAGE 1
LTM4649 10A Step-Down DC/DC µModule Regulator FEATURES n n n n n n n n n n n n DESCRIPTION 10A DC Output Current Input Voltage Range: 4.5V to 16V Output Voltage Range: 0.6V Up to 3.3V No Heat Sink or Current Derating Up to 85°C Ambient Temperature ±1.
PAGE 2
LTM4649 ABSOLUTE MAXIMUM RATINGS (Note 1) VIN.............................................................. –0.3V to 18V VOUT........................................................... –0.3V to 3.6V INTVCC, PGOOD, RUN (Note 5)..................... –0.3V to 6V MODE, CLKIN, TRACK/SS, DIFFP, DIFFN, DIFFOUT, PHASMD................................ –0.3V to INTVCC VFB............................................................. –0.3V to 2.7V COMP (Note 6)........................................... –0.3V to 2.
PAGE 3
LTM4649 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V per typical application. SYMBOL PARAMETER VIN Input DC Voltage CONDITIONS l 4.5 16 V VOUT(RANGE) Output Voltage Range l 0.6 3.3 V VOUT(DC) Output Voltage, Total Variation with Line and Load l 1.477 1.50 1.523 V 1.1 1.25 1.4 V CIN = 10µF × 1,COUT = 100µF Ceramic, 100µF POSCAP, RFB = 6.
PAGE 4
LTM4649 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25°C (Note 2). VIN = 12V per typical application.
PAGE 5
LTM4649 TYPICAL PERFORMANCE CHARACTERISTICS 100 95 95 90 90 85 80 VOUT = 1V, 450kHz VOUT = 1.2V, 450kHz VOUT = 1.5V, 450kHz VOUT = 2.5V, 750kHz VOUT = 3.3V, 750kHz 70 65 0 2 4 6 90 85 80 VOUT = 1V, 450kHz VOUT = 1.2V, 450kHz VOUT = 1.5V, 450kHz VOUT = 2.5V, 450kHz VOUT = 3.3V, 450kHz 70 65 VIN = 12V VOUT = 1.
PAGE 6
LTM4649 TYPICAL PERFORMANCE CHARACTERISTICS 5VIN, 3.3VOUT Load Transient 12VIN, 3.3VOUT Load Transient IOUT 5A/DIV AC IOUT 5A/DIV AC VOUT 100mV/DIV AC VOUT 100mV/DIV AC Soft-Start with No Load IIN 1A/DIV VOUT 0.5V/DIV VSW 10V/DIV 4649 G10 50µs/DIV 5VIN, 3.3VOUT, 5A TO 10A LOAD STEP COUT = 2 • 220µF 4V CERAMIC CAPACITOR NO CFF CAPACITOR 4649 G11 50µs/DIV 12VIN, 3.3VOUT, 5A TO 10A LOAD STEP, 750kHz COUT = 2 • 220µF 4V CERAMIC CAPACITOR NO CFF CAPACITOR 12VIN, 1.5VOUT IO = 0A START-UP CSS = 0.
PAGE 7
LTM4649 PIN FUNCTIONS PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG µModule PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY. GND (A1-A5, A7-A11, B1, B9-B11, E1, F3, F5, G1-G7): Ground Pins for Both Input and Output Returns. All ground pins need to connect with large copper areas underneath the unit. TEMP (A6): Onboard Temperature Diode for Monitoring the VBE Junction Voltage Change with Temperature. See the Applications Information section. CLKIN (B3): External Synchronization Input to Phase Detector Pin.
PAGE 8
LTM4649 PIN FUNCTIONS DIFFP (F8): Input to the Remote Sense Amplifier. This pin connects to the output remote sense point. Connect to ground when not used. COMP (F6): Current Control Threshold and Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Tie all COMP pins together in parallel operation. DIFFOUT (G8): Output of the Remote Sense Amplifier. This pin connects to the VOUT_LCL pin for remote sense applications. Otherwise float when not used.
PAGE 9
LTM4649 OPERATION Power Module Description The LTM4649 is a high performance single output standalone nonisolated switching mode DC/DC power supply. It can provide up to 10A output current with few external input and output capacitors. This module provides precisely regulated output voltage programmable via an external resistor from 0.6VDC to 3.3VDC over a 4.5V to 16V input range. The typical application schematic is shown in Figure 17.
PAGE 10
LTM4649 APPLICATIONS INFORMATION The typical LTM4649 application circuit is shown in Figure 17. External component selection is primarily determined by the maximum load current and output voltage. Refer to Table 3 for specific external capacitor requirements for particular applications. VIN to VOUT Step-Down Ratios There are restrictions in the VIN to VOUT step-down ratio that can be achieved for a given input voltage.
PAGE 11
LTM4649 APPLICATIONS INFORMATION required. Table 3 shows a matrix of different output voltages and output capacitors to minimize the voltage droop and overshoot during a 5A/µs transient. The table optimizes total equivalent ESR and total bulk capacitance to optimize the transient performance. Stability criteria are considered in the Table 3 matrix, and the Linear Technology µModule Power Design Tool will be provided for stability analysis.
PAGE 12
LTM4649 APPLICATIONS INFORMATION The CLKOUT signal together with CLKIN pin can be used to cascade additional power stages to achieve the multiphase power supply solution. Tying the PHMODE pin to INTVCC, GND, or (floating) generates a phase difference (between CLKIN and CLKOUT) of 180°, 120°, or 90° respectively as shown in Table 2. A total of 4 phases can be cascaded to run simultaneously with respect to each other by programming the PHMODE pin of each LTM4649 channel to different levels.
PAGE 13
LTM4649 APPLICATIONS INFORMATION Input RMS Ripple Current Cancellation Application Note 77 provides a detailed explanation of multiphase operation. The input RMS ripple current cancellation mathematical derivations are presented, and a graph is displayed representing the RMS ripple current reduction as a function of the number of interleaved phases (see Figure 4). Minimum On-Time Minimum on-time tON is the smallest time duration that the LTM4649 is capable of turning on the top MOSFET.
PAGE 14
LTM4649 APPLICATIONS INFORMATION Regardless of the mode selected by the MODE pin, the regulator channels will always start in pulse-skipping mode up to TRACK/SS = 0.5V. Between TRACK/SS = 0.5V and 0.54V, it will operate in forced continuous mode and revert to the selected mode once TRACK/SS > 0.54V. In order to track with another channel once in steady state operation, the LTM4649 is forced into continuous mode operation as soon as VFB is below 0.54V regardless of the setting on the MODE pin.
PAGE 15
LTM4649 APPLICATIONS INFORMATION OUTPUT VOLTAGE (V) MASTER OUTPUT SLAVE OUTPUT TIME 4649 F06 Figure 6. Output Coincident Tracking Waveform TRACK/SS pin. As mentioned above, the TRACK/SS pin has a control range from 0V to 0.6V. The master’s TRACK/ SS pin slew rate is directly equal to the master’s output slew rate in Volts/Time. The equation: MR • 10k = RTB SR where MR is the master’s output slew rate and SR is the slave’s output slew rate in Volts/Time.
PAGE 16
LTM4649 APPLICATIONS INFORMATION SW Pins The SW pin is generally for testing purposes by monitoring the pin. The SW pin can also be used to dampen out switch node ringing caused by LC parasitic in the switched current path. Usually a series R-C combination is used called a snubber circuit. The resistor will dampen the resonance and the capacitor is chosen to only affect the high frequency ringing across the resistor.
PAGE 17
LTM4649 APPLICATIONS INFORMATION DIODE VOLTAGE (V) 1.0 ID = 100µA 0.8 ∆VD 0.6 0.4 –173 –73 27 TEMPERATURE (°C) 127 4649 F07 Figure 7.
PAGE 18
LTM4649 APPLICATIONS INFORMATION A graphical representation of the aforementioned thermal resistances is given in Figure 8; blue resistances are contained within the μModule regulator, whereas green resistances are external to the µModule regulator. As a practical matter, it should be clear to the reader that no individual or sub-group of the four thermal resistance parameters defined by JESD 51-12 or provided in the Pin Configuration section replicates or conveys normal operating conditions of a μModule.
PAGE 19
LTM4649 APPLICATIONS INFORMATION airflow or heat sinking in a properly define chamber. This θJB + θBA value is shown in the Pin Configuration section and should accurately equal the θJA value because approximately 100% of power loss flows from the junction through the board into ambient with no airflow or top mounted heat sink. 3.0 12 2.5 2.5 10 2.0 2.0 1.5 1.0 0.5 0 2 4 6 LOAD CURRENT (A) 1.0 0 10 8 1.5 0.5 VOUT = 3.3V VOUT = 1.5V 0 LOAD CURRENT (A) 3.
PAGE 20
LTM4649 APPLICATIONS INFORMATION while ambient temperature is increased with and without airflow. The power loss increase with ambient temperature change is factored into the derating curves. The junctions are maintained at 120°C maximum while lowering output current or power with increasing ambient temperature. The decreased output current will decrease the internal module loss as ambient temperature is increased.
PAGE 21
LTM4649 APPLICATIONS INFORMATION Layout Checklist/Example The high integration of LTM4649 makes the PCB board layout very simple and easy. However, to optimize its electrical and thermal performance, some layout considerations are still necessary. • Use large PCB copper areas for high current path, including VIN, GND and VOUT. It helps to minimize the PCB conduction loss and thermal stress.
PAGE 22
LTM4649 APPLICATIONS INFORMATION Table 3. Output Voltage Response vs Component Matrix (Refer to Figure 18) 0A to 5A Load Step Typical Measured Values CIN (BULK)* VENDORS CIN PART NUMBER (CERAMIC) 150µF, 16V SANYO OSCON 25HVH150MT VENDORS 22µF, 16V MURATA PART NUMBER COUT (CERAMIC) VENDORS GRM32ER71C226KE18L 100µF, 6.
PAGE 23
LTM4649 TYPICAL APPLICATIONS FREQ VIN 4.5V TO 16V CIN 22µF 16V VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT RUN LTM4649 MODE PHMODE TEMP GND DIFFP COUT2 100µF 6.3V DIFFN VFB TRACK/SS C1 0.1µF COUT1 100µF 6.3V VOUT 1.5V 10A COMP PGOOD CLKOUT RFB 6.65k 4649 F17 Figure 17. 4.5V to 16VIN, 1.5V at 10A Design 1M VIN 4.5V TO 16V FREQ CIN 22µF 16V CIN 22µF 16V VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT RUN MODE LTM4649 PHMODE TRACK/SS C1 0.1µF TEMP GND 100µF 6.3V ×2 VOUT 3.
PAGE 24
LTM4649 TYPICAL APPLICATIONS VIN 4.5V TO 16V CIN1 22µF 16V RUN FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT RUN MODE LTM4649 PHMODE C1 0.1µF CIN2 22µF 16V PGOOD CLKOUT FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT LTM4649 FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT LTM4649 TRACK/SS TEMP GND COUT5 100µF 6.3V COUT6 100µF 6.3V COMP PGOOD CLKOUT PHMODE COUT4 100µF 6.3V DIFFP DIFFN TEMP GND MODE COUT3 100µF 6.3V VFB TRACK/SS RUN RFB 6.
PAGE 25
LTM4649 TYPICAL APPLICATIONS VIN 4.5V TO 16V CIN1 22µF 16V FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT RUN MODE LTM4649 PHMODE CIN2 22µF 16V VOUT1 R3 10k R4 3.09k DIFFP COMP PGOOD CLKOUT FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT MODE COUT2 100µF 6.3V LTM4649 PHMODE COUT4 100µF 6.3V DIFFP VOUT2 2.5V 10A TRACK/SS COMP TEMP GND PGOOD CLKOUT LTM4649 DIFFP PGOOD CLKOUT FREQ VIN CLKIN VOUT INTVCC VOUT_LCL SW DIFFOUT LTM4649 R5 4.99k COUT7 100µF 6.
PAGE 26
0.630 ±0.025 Ø 68x SUGGESTED PCB LAYOUT TOP VIEW 2.540 PACKAGE TOP VIEW 1.270 4 0.3175 0.000 0.3175 PIN “A1” CORNER E 1.270 aaa Z 2.540 Y For more information www.linear.com/LTM4649 6.350 5.080 3.810 2.540 1.270 0.000 3.810 5.080 6.350 D X aaa Z NOM 4.92 0.60 4.32 0.75 0.63 15.00 9.00 1.27 12.70 7.62 0.32 4.00 DIMENSIONS b1 A2 MAX 5.12 0.70 4.42 0.90 0.66 NOTES DETAIL B PACKAGE SIDE VIEW 0.37 4.05 0.15 0.10 0.20 0.30 0.15 TOTAL NUMBER OF BALLS: 68 0.27 3.95 MIN 4.72 0.
PAGE 27
LTM4649 PACKAGE DESCRIPTION PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG µModule PRODUCTS. REVIEW EACH PACKAGE LAYOUT CAREFULLY.
PAGE 28
LTM4649 TYPICAL APPLICATION VIN 4.5V TO 16V CIN1 22µF 16V CLKIN VIN VOUT_LCL SW DIFFOUT RUN MODE INTVCC FREQ VOUT INTVCC LTM4649 DIFFP COMP PGOOD CLKOUT CIN2 22µF 16V COUT2 100µF 6.3V R1 10k CLKIN VIN R3 10k FREQ VOUT INTVCC VOUT_LCL SW DIFFOUT RUN R2 10k INTVCC VFB TRACK/SS TEMP GND COUT1 100µF 6.3V DIFFN PHMODE MASTER SLOPE CLOCK VOUT 1.2V 10A MODE LTM4649 PHMODE TRACK/SS TEMP GND COUT3 100µF 6.3V DIFFP VOUT 1.8V COUT4 10A 100µF 6.3V DIFFN VFB COMP PGOOD CLKOUT R4 4.