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LTM4628

4628fe

For more information www.linear.com/LTM4628

TYPICAL APPLICATION

DESCRIPTION

Dual 8A or Single 16A

DC/DC µModule Regulator

The LT M

4628 is a complete dual 8A output switching

mode DC/DC power supply and can be easily configured

to provide a single 2-phase 16A output. Included in the

package are the switching controller, power FETs, inductor,

and all supporting components. Operating from an input

voltage range of 4.5V to 26.5V, the LTM4628 supports

two outputs each with an output voltage range of 0.6V to

5.5V, set by a single external resistor. Its high efficiency

design delivers 8A continuous current for each output.

Only a few input and output capacitors are needed.

The device supports frequency synchronization, multi

phase operation,

Burst Mode operation and output voltage

tracking for supply rail sequencing. It has an onboard

temperature diode for device temperature monitoring.

High switching frequency and a current mode architec

ture enable a very fast transient response to line and load

changes without sacrificing stability.

Fault

protection features include overvoltage and over-

current protection

The power module is offered in space

saving and thermally enhanced 15mm × 15mm × 4.32mm

LGA and 15mm × 15mm × 4.92mm BGA packages. The

LTM4628 is available with SnPb (BGA) or RoHS compli

ant terminal finish.

L, LT , LT C , LT M , Linear Technology, the Linear logo, µModule, Burst Mode and PolyPhase

are registered and LTpowerCAD is a trademarks of Linear Technology Corporation. All other

trademarks are the property of their respective owners.

Dual 8A, 1.5V and 1.2V Output DC/DC µModule

Regulator

FEATURES

APPLICATIONS

Complete Standalone Dual Power Supply

Single 16A or Dual 8A Output

Wide Input Voltage Range: 4.5V to 26.5V

Output Voltage Range: 0.6V to 5.5V

±1.5% Total DC Output Error

Differential Remote Sense Amplifier

Current Mode Control/Fast Transient Response

Adjustable Switching Frequency

Overcurrent Foldback Protection

Multiphase Parallel Current Sharing with

Multiple LTM4628s

Frequency Synchronization

Internal Temperature Sensing Diode Output

Selectable Burst Mode

Operation

Soft-Start/Voltage Tracking

Output Overvoltage Protection

Small Surface Mount Footprint, Low Profile

15mm × 15mm × 4.32mm LGA and

15mm × 15mm × 4.92mm BGA Packages

Telecom and Networking Equipment

Storage and ATCA Cards

Industrial Equipment

Efficiency and Power Loss

at 12V Input

4628 TA01a

LTM4628

TEMP

RUN1

RUN2

TRACK1

TRACK2

SET

470µF

6.3V

40.2k

100µF

6.3V

PHASMD

OUT1

OUTS1

SW1

FB1

FB2

COMP1

COMP2

OUTS2

OUT2

1.2V AT 8A

OUT1

1.5V AT 8A

SW2

PGOOD2

MODE_PLLIN CLKOUT INTV

EXTV

PGOOD1

SGND GND DIFFP DIFFN

DIFFOUT

60.4k

470µF

6.3V

100µF

6.3V

100k

10k

5.1V ZENER

* PULL-UP RESISTOR AND

ZENER ARE OPTIONAL.

4.5V TO

26.5V

120k

0.1µF

10µF

35V

×4

4.7µF

LOAD CURRENT (A)

EFFICIENCY (%)

POWER LOSS (W)

2.0

1.8

1.4

1.2

1.6

1.0

0.2

0.4

0.6

0.8

4628 TA01b

831 5 6 7

POWER LOSS

EFFICIENCY

1.2V

1.5V

Downloaded from Arrow.com.

Summary of content (36 pages)

PAGE 1
LTM4628 Dual 8A or Single 16A DC/DC µModule Regulator FEATURES n n n n n n n n n n n n n n n n DESCRIPTION Complete Standalone Dual Power Supply Single 16A or Dual 8A Output Wide Input Voltage Range: 4.5V to 26.5V Output Voltage Range: 0.6V to 5.5V ±1.
PAGE 2
LTM4628 ABSOLUTE MAXIMUM RATINGS (Note 1) DIFFP, DIFFN.......................................... –0.3V to INTVCC VFB1, VFB2, COMP1, COMP2 (Note 6)......... –0.3V to 2.7V INTVCC Peak Output Current.................................100mA Internal Operating Temperature Range (Note 2)................................................... –40°C to 125°C Storage Temperature Range................... –55°C to 125°C Peak Package Body Temperature........................... 245°C VIN....................................
PAGE 3
LTM4628 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range (Note 2). Specified as each individual output channel. TA = 25°C, VIN = 12V and VRUN1, VRUN2 at 5V unless otherwise noted, per the typical application in Figure 28.
PAGE 4
LTM4628 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full internal operating temperature range (Note 2). Specified as each individual output channel. TA = 25°C, VIN = 12V and VRUN1, VRUN2 at 5V unless otherwise noted, per the typical application in Figure 28.
PAGE 5
LTM4628 ELECTRICAL CHARACTERISTICS 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 LTM4628 is tested under pulsed load conditions such that TJ ≈ TA. The LTM4628E is guaranteed to meet specifications from 0°C to 125°C internal temperature.
PAGE 6
LTM4628 TYPICAL PERFORMANCE CHARACTERISTICS 1.5V Load Transient 1.8V Load Transient VOUT 50mV/DIV VOUT 50mV/DIV IOUT 2A/DIV IOUT 2A/DIV 100µs/DIV 2.5V Load Transient VOUT 100mV/DIV IOUT 2A/DIV 100µs/DIV 4628 G07 4628 G08 100µs/DIV 4628 G09 12VIN , 1.5VOUT , 0A TO 4A LOAD STEP AT 4A/µs COUT1 4× 100µF 6.3V X5R CERAMIC 1210 CASE SIZE SWITCHING FREQUENCY 500kHz CFF CAPACITOR = 47pF 12VIN , 1.8VOUT , 0A TO 4A LOAD STEP AT 4A/µs COUT1 4× 100µF 6.
PAGE 7
LTM4628 TYPICAL PERFORMANCE CHARACTERISTICS COMP1 and COMP2 vs Output Current IOUT1 and IOUT2 vs Total Current for Parallel Operation 9 8 7 1.2 6 1.1 5 4 1.0 0.9 3 0.8 2 0.7 1 0.6 0 0 2 VITH1 VITH2 1.3 COMP (V) IOUT1 AND IOUT2 (A) 1.4 IOUT1 IOUT2 8 10 12 14 4 6 TOTAL OUTPUT CURRENT (A) 16 0.5 0 1 2 3 4 5 6 7 OUTPUT CURRENT (A) 4628 G16 PIN FUNCTIONS 8 9 4628 G17 (Recommended to Use Test Points to Monitor Signal Pin Connections.
PAGE 8
LTM4628 PIN FUNCTIONS (Recommended to Use Test Points to Monitor Signal Pin Connections.) TRACK1, TRACK2 (E5, D8): Output Voltage Tracking Pin and Soft-Start Inputs. Each channel has a 1.3µA pull-up current source. When one channel is configured to be master of the two channels, then a capacitor from this pin to ground will set a soft-start ramp rate. The remaining channel can be set up as the slave, and have the master’s output applied through a voltage divider to the slave output’s track pin.
PAGE 9
LTM4628 SIMPLIFIED BLOCK DIAGRAM PGOOD1 TRACK1 VIN SS CAP 100µA = VIN RT VIN CIN1 10µF 35V 1µF GND RT TEMP MTOP1 SW1 CLKOUT 0.68µH RUN1 MODE_PLLIN VOUT1 2.2µF MBOT1 PHASEMD CIN2 10µF 35V + 1.5V/8A COUT1 GND VOUTS1 COMP1 60.4k VFB1 INTERNAL COMP SGND RFB1 40.2k POWER CONTROL PGOOD2 TRACK2 SS CAP VIN INTVCC CIN3 10µF 35V 1µF 4.7µF GND EXTVCC MTOP2 SW2 0.68µH RUN2 CIN4 10µF 35V VOUT2 2.2µF MBOT2 + 1.2V/8A COUT2 GND VOUTS2 COMP2 fSET 60.4k XI + – VFB2 RFB2 60.
PAGE 10
LTM4628 OPERATION Power Module Description The LTM4628 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 and setup components. This module provides precisely regulated output voltages programmable via external resistors from 0.6VDC to 5VDC over 4.5V to 26.5V input voltages. The typical application schematic is shown in Figure 28.
PAGE 11
LTM4628 APPLICATIONS INFORMATION The typical LTM4628 application circuit is shown in Figure 28. External component selection is primarily determined by the maximum load current and output voltage. Refer to Table 4 for specific external capacitor requirements for particular applications. VIN to VOUT Step-Down Ratios There are restrictions in the maximum VIN and VOUT stepdown ratio that can be achieved for a given input voltage.
PAGE 12
LTM4628 APPLICATIONS INFORMATION Input Capacitors The LTM4628 module should be connected to a low acimpedance DC source. For the regulator input three 22µF, or four 10µF input ceramic capacitors are used for RMS ripple current. 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 compromised by long inductive leads, traces or not enough source capacitance.
PAGE 13
LTM4628 APPLICATIONS INFORMATION Pulse-Skipping Mode Operation should be used. Forced continuous operation can be enabled by tying the MODE_PLLIN pin to SGND. In this mode, inductor current is allowed to reverse during low output loads, the COMP voltage is in control of the current comparator threshold throughout, and the top MOSFET always turns on with each oscillator pulse.
PAGE 14
LTM4628 APPLICATIONS INFORMATION onto incoming clock phase as well. The CLKOUT signal can be connected to the MODE_PLLIN pin of the following stage to line up both the frequency and the phase of the entire system. Tying the PHASMD pin to INTVCC, SGND, or left floating generates a phase difference (between MODE_PLLIN and CLKOUT) of 120 degrees, 60 degrees, or 90 degrees respectively.
PAGE 15
LTM4628 APPLICATIONS INFORMATION Frequency Selection and Phase-Locked Loop (MODE_PLLIN and fSET Pins) The LTM4628 device is operated over a range of frequencies to improve power conversion efficiency. It is recommended to operate the lower output voltages or lower duty cycle conversions at lower frequencies to improve efficiency by lowering power MOSFET switching losses. Higher output voltages or higher duty cycle conversions can be operated at higher frequencies to limit inductor ripple current.
PAGE 16
LTM4628 APPLICATIONS INFORMATION INTVCC C10 4.7µF R2 10k PGOOD 5V TO 16V INTERMEDIATE BUS C3 22µF 25V R1 10k D1 5.1V ZENER C2 22µF 25V C1 22µF 25V R6 120k TEMP VOUTS1 RUN1 SW1 RUN2 VFB1 RTA 60.4k 1.5V fSET COMP2 PHASMD VOUTS2 VOUT2 SW2 PGOOD2 SGND GND DIFFP RFB 60.4k COMP1 R4 100k RAMP TIME tSOFTSTART = (CSS /1.3µA) • 0.6V 1.5V AT 8A C6 100µF 6.3V VFB2 LTM4628 TRACK2 RTB 60.4k PGOOD1 VOUT1 VIN TRACK1 MASTER CSS 0.
PAGE 17
LTM4628 APPLICATIONS INFORMATION when the RUN pin is below 1.2V. The total soft-start time can be calculated as: For example, MR = 1.5V/1ms, and SR = 1.2V/1ms. Then RTB = 76.8k. Solve for RTA to equal to 49.9k.  C  tSOFT-START =  SS  • 0.6V  1.3µA  Regardless of the mode selected by the MODE_PLLIN pin, the regulator channels will always start in pulse-skipping mode up to TRACK = 0.5V. Between TRACK = 0.5V and 0.
PAGE 18
LTM4628 APPLICATIONS INFORMATION INTVCC and EXTVCC The LTM4628 module has an internal 5V low dropout regulator that is derived from the input voltage. This regulator is used to power the control circuitry and the power MOSFET drivers. This regulator can source up to 70mA, and typically uses ~30mA for powering the device at the maximum frequency. EXTVCC allows an external 5V supply to power the LTM4628 and reduce power dissipation from the internal low dropout 5V regulator.
PAGE 19
LTM4628 APPLICATIONS INFORMATION temperature relationship that makes diodes suitable temperature sensors. The IS term in the equation above is the extrapolated current through a diode junction when the diode has zero volts across the terminals. The IS term varies from process to process, varies with temperature, and by definition must always be less than ID.
PAGE 20
LTM4628 APPLICATIONS INFORMATION Thermal Considerations and Output Current Derating The thermal resistances reported in the Pin Configuration section of the data sheet are consistent with those parameters defined by JESD 51-12 and are intended for use with finite element analysis (FEA) software modeling tools that leverage the outcome of thermal modeling, simulation, and correlation to hardware evaluation performed on a µModule package mounted to a hardware test board defined by JESD 51-9 (“Test Boards for
PAGE 21
LTM4628 APPLICATIONS INFORMATION JUNCTION-TO-AMBIENT RESISTANCE (JESD 51-9 DEFINED BOARD) CASE (TOP)-TO-AMBIENT RESISTANCE JUNCTION-TO-CASE (TOP) RESISTANCE JUNCTION JUNCTION-TO-BOARD RESISTANCE AMBIENT JUNCTION-TO-CASE CASE (BOTTOM)-TO-BOARD (BOTTOM) RESISTANCE RESISTANCE BOARD-TO-AMBIENT RESISTANCE 4628 F10 µMODULE DEVICE Figure 10.
PAGE 22
LTM4628 APPLICATIONS INFORMATION The 1.0V and 3.3V power loss curves in Figures 11 and 12 can be used in coordination with the load current derating curves in Figures 13 to 24 for calculating an approximate θJA thermal resistance for the LTM4628 with various heat sinking and airflow conditions. The power loss curves are taken at room temperature, and are increased with multiplicative factors according to the ambient temperature. The approximate factors are: 1.35 for 115°C and 1.4 for 120°C.
PAGE 23
LTM4628 APPLICATIONS INFORMATION 8 24V TO 1V 12V TO 1V 5V TO 1V 5 24V TO 3.3V POWER LOSS 12V TO 3.3V POWER LOSS 5V TO 3.3V POWER LOSS 7 CH1 AND CH2 COMBINED LOAD CURRENT 6 POWER LOSS (W) POWER LOSS (W) 6 4 3 2 5 4 3 2 1 2 4 6 8 10 12 14 0 16 0 2 4 4628 F11 Figure 11. 1V Power Loss 12 10 8 6 4 2 0 0 20 40 60 80 100 16 14 10 8 6 4 2 20 40 60 80 10 8 6 4 2 0 16 100 120 6 4 2 20 40 60 80 100 Figure 15.
PAGE 24
LTM4628 0 LFM 200 LFM 400 LFM 14 12 10 8 6 4 2 0 0 20 40 60 80 100 16 0 LFM 200 LFM 400 LFM 14 12 10 8 6 4 2 0 120 20 0 AMBIENT TEMPERATURE (°C) 4628 F20 CH1 AND CH2 COMBINED LOAD CURRENT CH1 AND CH2 COMBINED LOAD CURRENT 10 8 6 4 2 0 20 40 80 100 0 LFM 200 LFM 400 LFM 14 12 10 8 6 4 2 0 120 0 20 60 80 100 120 40 60 80 100 120 AMBIENT TEMPERATURE (°C) 4628 F21 12 0 60 Figure 22. 5V to 3.3V Derating Curves with Heat Sink Figure 21. 24V to 3.
PAGE 25
LTM4628 APPLICATIONS INFORMATION Table 2. 1.0V Output DERATING CURVE VIN (V) POWER LOSS CURVE AIR FLOW (LFM) HEAT SINK θJA (°C/W) Figures 13, 14, 15 5, 12, 24 Figure 11 0 None 9.5 to 11 Figures 13, 14, 15 5, 12, 24 Figure 11 200 None 6.4 Figures 13, 14, 15 5, 12, 24 Figure 11 400 None 5.6 Figures 16, 17, 18 5, 12, 24 Figure 11 0 BGA Heat Sink 9.0 to 10.5 Figures 16, 17, 18 5, 12, 24 Figure 11 200 BGA Heat Sink 6.
PAGE 26
LTM4628 APPLICATIONS INFORMATION Table 4 Output Voltage Response vs Component Matrix (Refer to Figure 28) 0A to 4A Load Step Typical Measured Values COUT1 AND COUT2 CERAMIC VENDORS VALUE PART NUMBER COUT1 AND COUT2 BULK VENDORS VALUE AVX 10µF 35V 1812DD106KAT Sanyo POSCAP 470µF 2R5 Murata 22µF 16V GRM43ER61C226KE01 Sanyo POSCAP 470µF 6.3V TDK 100µF 6.3V C4532X5R0J107MZ Murata 100µF 6.3V GRM32ER60J107M AVX 100µF 6.
PAGE 27
LTM4628 APPLICATIONS INFORMATION Figures 25 and 26 show thermal images of the LTM4628 in LGA package with or without BGA heat sink and no air flow or 200LFM air flow. These images equate to a paralleled 3.3V output at 16A design operating at 92% efficiency from 12V input. Figure 25a.12VIN to 3.3VOUT, 16A, No Heat Sink, No Air Flow Figure 25b.12VIN to 3.3VOUT, 16A, No Heat Sink, 200LFM Figure 25 Figure 26a. 12VIN to 3.3VOUT,16A, with Heat Sink, No Air Flow Figure 26b. 12VIN to 3.
PAGE 28
LTM4628 APPLICATIONS INFORMATION Safety Considerations • Place a dedicated power ground layer underneath the unit. The LTM4628 modules do not provide galvanic isolation from VIN to VOUT. There is no internal fuse. If required, a slow blow 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 over current protection. A temperature diode is provided for monitoring internal temperature.
PAGE 29
LTM4628 TYPICAL APPLICATIONS INTVCC C10 4.7µF R2 10k PGOOD1 MODE_PLLIN 7V TO 16V INTERMEDIATE BUS R1 10k CIN1 22µF 25V D1 5.1V ZENER CIN2 22µF 25V CIN3 22µF 25V R6 120k EXTVCC PGOOD1 VOUT1 TEMP VOUTS1 RUN1 SW1 RUN2 VFB1 TRACK1 TRACK1 C5 0.1µF CLKOUT INTVCC VIN C9 0.1µF VFB2 LTM4628 TRACK2 TRACK2 COUT1 100µF 6.3V fSET COMP2 PHASMD VOUTS2 VOUT2 R4 100k SW2 R8 60.4k CFF 100pF 1.2V COMP1 GND DIFFP INTVCC PGOOD2 DIFFOUT DIFFN 1.5V AT 8A R6 40.2k 1.2V AT 8A C4 100µF 6.
PAGE 30
LTM4628 TYPICAL APPLICATIONS INTVCC C10 4.7µF R2 10k PGOOD1 5V TO 16V INTERMEDIATE BUS D1 5.1V ZENER MODE_PLLIN R1 10k C3 22µF 25V C2 22µF 25V C1 22µF 25V R6 120k CLKOUT INTVCC EXTVCC PGOOD1 VOUT1 VIN TEMP VOUTS1 RUN1 SW1 RUN2 VFB1 TRACK1 C5 0.1µF R9 60.4k 1.2V R7 90.9k VFB2 LTM4628 TRACK2 C6 100µF 6.3V R8 90.9k COMP1 fSET COMP2 PHASMD VOUTS2 VOUT2 R4 100k SW2 PGOOD2 GND DIFFP DIFFN 1.2V AT 8A C8 470µF 6.3V R5 60.4k 1V AT 8A INTVCC 10k SGND + C4 100µF 6.
PAGE 31
LTM4628 TYPICAL APPLICATIONS INTVCC CLK1 7V TO 16V INTERMEDIATE BUS R1 10k RUN C3 22µF 25V MODE_PLLIN C2 22µF 25V C1 22µF 25V R6 10k R2 5k PGOOD1 EXTVCC PGOOD1 VIN TRACK1 D1 5.1V ZENER CLKOUT INTVCC C10 4.7µF VOUT1 TEMP VOUTS1 RUN1 RUN2 SW1 VFB1 TRACK1 VFB2 LTM4628 TRACK2 COMP2 PHASMD VOUTS2 PGOOD2 GND DIFFP DIFFN C4 100µF 6.3V + C7 470µF 6.3V COMP SW2 SGND C8 470µF 6.3V R5 60.4k VOUT2 R4 100k + VFB COMP1 fSET C6 100µF 6.3V PGOOD1 DIFFOUT 1.2V AT 32A C16 4.
PAGE 32
LTM4628 PACKAGE DESCRIPTION Table 5.
PAGE 33
For more information www.linear.com/LTM4628 PACKAGE TOP VIEW 3.1750 SUGGESTED PCB LAYOUT TOP VIEW 3.1750 4.4450 5.7150 6.9850 X 15 BSC Y 6.9850 5.7150 DETAIL B LAND DESIGNATION PER JESD MO-222, SPP-010 DETAILS OF PAD #1 IDENTIFIER ARE OPTIONAL, BUT MUST BE LOCATED WITHIN THE ZONE INDICATED. THE PAD #1 IDENTIFIER MAY BE EITHER A MOLD OR MARKED FEATURE 3 4 2. ALL DIMENSIONS ARE IN MILLIMETERS 7 PACKAGE ROW AND COLUMN LABELING MAY VARY AMONG µModule PRODUCTS.
PAGE 34
aaa Z 0.630 ±0.025 Ø 144x 0.0 E PACKAGE TOP VIEW 3.1750 3.1750 SUGGESTED PCB LAYOUT TOP VIEW 1.9050 4 0.6350 0.0000 0.6350 PIN “A1” CORNER 1.9050 Downloaded from Arrow.com. Y For more information www.linear.com/LTM4628 6.9850 5.7150 4.4450 3.1750 1.9050 0.6350 0.0000 0.6350 1.9050 3.1750 4.4450 5.7150 6.9850 X D aaa Z SYMBOL A A1 A2 b b1 D E e F G H1 H2 aaa bbb ccc ddd eee H1 SUBSTRATE NOM 4.92 0.60 4.32 0.75 0.63 15.00 15.00 1.27 13.97 13.97 0.32 4.00 MAX 5.12 0.70 4.42 0.
PAGE 35
LTM4628 REVISION HISTORY REV DATE DESCRIPTION PAGE NUMBER A 06/11 Updated Typical Application Efficiency graph Updated Pin Configuration 3, 4 Updated Pin Functions section 7, 8 Updated Decoupling Requirements table 9 Updated Figure 3 13 Updated Figures 29 and 31 C 7/11 8/12 2 Updated Electrical Characteristics Various text updated in Applications Information section B 1 11 to 22 30, 32 Changed Typical value of RFBHI1, RFBHI2 to 60.
PAGE 36
LTM4628 TYPICAL APPLICATION 5V C10 4.7µF R2 10k PGOOD1 24V C8 10µF 35V R1 10k MODE_PLLIN CLKOUT INTVCC C3 10µF 35V D1 5.1V ZENER C2 10µF 35V C1 10µF 35V R6 240k VOUTS1 RUN1 SW1 RUN2 VFB1 INTVCC C9 0.1µF R8 13.3k COMP1 fSET COMP2 PHASMD VOUTS2 VOUT2 SW2 SGND GND DIFFP DIFFN R6 8.25k 3.3V AT 8A 3.3V 10k PGOOD2 DIFFOUT COUT2 470µF 6.3V COUT1 100µF 6.3V VFB2 LTM4628 TRACK2 TRACK2 5V AT 8A VOUT1 TEMP TRACK1 TRACK1 C5 0.1µF EXTVCC PGOOD1 VIN C4 100µF 6.3V C7 470µF 6.