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LTM4604A Low Voltage, 4A DC/DC Module with Tracking FEATURES

DESCRIPTION
The LTM(R)4604A is a complete 4A switch mode DC/DC power supply with 1.75% total output voltage error. Included in the package are the switching controller, power FETs, inductor and all support components. Operating over an input voltage range of 2.375V to 5.5V, the LTM4604A supports an output voltage range of 0.8V to 5V, set by a single resistor. This high efficiency design delivers up to 4A continuous current (5A peak). Only bulk output capacitors are needed to complete the design. The 0.630mm LGA pads with 1.27mm pitch simplify PCB layout by providing standard trace routing and via placement. (The LTM4604A has smaller pads than the LTM4604.) The low profile package (2.3mm) enables utilization of unused space on the bottom of PC boards for high density point of load regulation. High switching frequency and a current mode architecture enable a very fast transient response to line and load changes without sacrificing stability. Fault protection features include foldback current protection, thermal shutdown and a programmable soft-start function. The LTM4604A is offered in a small thermally enhanced 15mm x 9mm x 2.3mm LGA package and is Pb free and RoHS compliant.
Complete Standalone Power Supply 1.75% Total DC Output Error (-40C to 125C) Wide Input Voltage Range: 2.375V to 5.5V 4A DC, 5A Peak Output Current 0.8V to 5V Output Output Voltage Tracking UltraFastTM Transient Response Power Good Indicator Current Mode Control Current Foldback Protection, Parallel/Current Sharing Up to 95% Efficiency Programmable Soft-Start Micropower Shutdown: IQ 7A Overtemperature Protection Small and Very Low Profile Package: 15mm x 9mm x 2.3mm LGA (0.630mm Pads)
APPLICATIONS

Telecom and Networking Equipment Servers Storage Cards ATCA Cards Industrial Equipment
, LT LTC and LTM are registered trademarks of Linear Technology Corporation. , Module and UltraFast are trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
3.3V to 2.5V/4A ModuleTM Regulator
VIN 3.3V 10F 6.3V VIN PGOOD COMP GND VOUT FB VIN 2.37k LTM4604A RUN/SS TRACK VOUT 2.5V 4A 22F 6.3V x2 EFFICIENCY (%) 100 95 90 85 80 75 70 65 0
Efficiency vs Output Current
VIN = 3.3V VOUT = 2.5V
4604A TA01a
1
2 3 OUTPUT CURRENT (A)
4
4604A TA01b
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LTM4604A ABSOLUTE MAXIMUM RATINGS
(Note 1)
PIN CONFIGURATION
TOP VIEW TRACK A 1 2 3 4 5 6 7 8 9 10 11 GND VOUT LGA PACKAGE 66-PIN (15mm x 9mm x 2.3mm) 0.630mm PAD SW RUN/ SS GND B VIN COMP FB C D E PGOOD F G
VIN, PGOOD ................................................. -0.3V to 6V COMP RUN/SS, FB, TRACK..........................-0.3V to VIN , SW, VOUT ........................................-0.3V to (VIN + 0.3V) Internal Operating Temperature Range (Note 2) ............................................. -40C to 125C Storage Temperature Range................... -55C to 125C
TJMAX = 125C, JA = 25C/W, JP = 7C/W, JC = 50C/W, WEIGHT = 1.0g
ORDER INFORMATION
LEAD FREE FINISH LTM4604AEV#PBF LTM4604AIV#PBF TRAY LTM4604AEV#PBF LTM4604AIV#PBF PART MARKING* LTM4604AV LTM4604AV PACKAGE DESCRIPTION 66-Lead (15mm x 9mm x 2.3mm) LGA 66-Lead (15mm x 9mm x 2.3mm) LGA TEMPERATURE RANGE (NOTE 2) -40C to 125C -40C to 125C
Consult LTC Marketing for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.Consult LTC Marketing for information on non-standard lead based finish parts. 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/
ELECTRICAL CHARACTERISTICS
SYMBOL VIN(DC) VOUT(DC) PARAMETER Input DC Voltage Output Voltage, Total Variation with Line and Load
The denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25C. VIN = 5V unless otherwise noted. See Figure 15.
CONDITIONS
RFB = 5.69k VIN = 2.375V to 5.5V, IOUT = 0A to 4A (Note 3) IOUT = 0A IOUT = 0A, CIN = 10F, COUT = 22F x3, RUN/SS = 0.01F, VOUT = 1.5V VIN = 3.3V VIN = 5V VIN = 3.3V, No Switching VIN = 3.3V, VOUT = 1.5V, Switching Continuous VIN = 5V, No Switching VIN = 5V, VOUT = 1.5V, Switching Continuous Shutdown, RUN = 0, VIN = 5V
MIN 2.375 1.482 1.474 1.75
TYP 1.5 1.5 2
MAX 5.5 1.518 1.522 2.3
UNITS V V V V
Input Specifications Undervoltage Lockout VIN(UVLO) Threshold Peak Input Inrush Current at IINRUSH(VIN) Start-Up
IQ(VIN NOLOAD)
Input Supply Bias Current
0.7 0.7 60 28 100 35 7
A A A mA A mA A
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LTM4604A ELECTRICAL CHARACTERISTICS
SYMBOL IS(VIN) PARAMETER Input Supply Current
The denotes the specifications which apply over the full internal operating temperature range, otherwise specifications are at TA = 25C. VIN = 5V unless otherwise noted. See Figure 15.
CONDITIONS VIN = 2.5V, VOUT = 1.5V, IOUT = 4A VIN = 3.3V, VOUT = 1.5V, IOUT = 4A VIN = 5V, VOUT = 1.5V, IOUT = 4A VIN = 3.3V, VOUT = 1.5V VOUT = 1.5V, VIN from 2.375V to 5.5V, IOUT = 0A VOUT = 1.5V, 0A to 4A (Note 3) VIN = 3.3V VIN = 5V IOUT = 0A VIN = 3.3V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V IOUT = 4A, VIN = 5V, VOUT = 1.5V VOUT = 1.5V, RUN/SS = 10nF, IOUT = 0A VIN = 3.3V VIN = 5V VOUT = 1.5V, IOUT = 1A Resistive Load, TRACK = VIN and RUN/SS = Float VIN = 3.3V VIN = 5V Load: 0% to 50% to 0% of Full Load, COUT = 22F x3 Ceramic VIN = 5V, VOUT = 1.5V Load: 0% to 50% to 0% of Full Load VIN = 5V, VOUT = 1.5V VIN = 3.3V, VOUT = 1.5V VIN = 5V, VOUT = 1.5V IOUT = 0A, VOUT = 1.5V 0.793 0.788 0.5 TRACK = 0.4V 0 4.975
MIN
TYP 2.9 2.2 1.45
MAX
UNITS A A A A %
Output Specifications IOUT(DC) Output Continuous Current Range (Note 3) Line Regulation Accuracy VOUT(LINE) VOUT VOUT(LOAD) VOUT VOUT(AC) fS VOUT(START) Output Ripple Voltage Load Regulation Accuracy
4 0.1 0.2

0.3 0.3 10 12 1.25
0.6 0.6
% % mVP-P mVP-P MHz
Output Ripple Voltage Frequency Turn-On Overshoot
20 20
mV mV
tSTART
Turn-on Time
1.5 1.0
ms ms
VOUT(LS) tSETTLE IOUT(PK) Control Section VFB IFB VRUN ITRACK V TRACK(OFFSET) V TRACK(RANGE) RFBHI PGOOD VPGOOD RPGOOD
Peak Deviation for Dynamic Load Step Settling Time for Dynamic Load Step Output Current Limit
25 10 8 8 0.8 0.8 0.2 0.65 0.2 30 4.99 0.807 0.808 0.8
mV s A A V V A V A mV V k
Voltage at FB Pin
RUN Pin On/Off Threshold TRACK Pin Current Offset Voltage Tracking Input Range Resistor Between VOUT and FB Pins PGOOD Range PGOOD Resistance
0.8 5.025
Open-Drain Pull-Down
7.5 90
150
%
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 LTM4604AE is guaranteed to meet performance specifications over the 0C to 125C internal operating temperature range. Specifications over the full -40C to 125C internal operating temperature range are assured
by design, characterization and correlation with statistical process controls. The LTM4604AI 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: See output current derating curves for different VIN, VOUT and TA.
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LTM4604A TYPICAL PERFORMANCE CHARACTERISTICS
Efficiency vs Output Current VIN = 2.5V
100 95 90 EFFICIENCY (%) EFFICIENCY (%) 85 80 75 70 65 0 100 95 90 85 80 75 70 65 2 4
4604A G01
Efficiency vs Output Current VIN = 3.3V
95 90 85 80 75 70 65 2 4
4604A G02
Efficiency vs Output Current VIN = 5V
EFFICIENCY (%)
VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 1 3 OUTPUT CURRENT (A)
VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 0 1 3 OUTPUT CURRENT (A)
VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V 0 1 2 3 OUTPUT CURRENT (A) 4
4604A G03
Minimum Input Voltage at 4A Load
3.5 3.0 2.5 VOUT (V) 2.0 1.5 1.0 0.5 0 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 VIN (V)
4604A G04
Load Transient Response
Load Transient Response
VOUT = 3.3V VOUT = 2.5V VOUT = 1.8V VOUT = 1.5V VOUT = 1.2V VOUT = 0.8V
ILOAD 2A/DIV VOUT 20mV/DIV
ILOAD 2A/DIV VOUT 20mV/DIV
VIN = 5V 20s/DIV VOUT = 1.2V , COUT = 4 x 22F 6.3V CERAMICS
4604A G05
VIN = 5V 20s/DIV VOUT = 1.5V , COUT = 4 x 22F 6.3V CERAMICS
4604A G06
Load Transient Response
Load Transient Response
Load Transient Response
ILOAD 2A/DIV VOUT 20mV/DIV
ILOAD 2A/DIV
ILOAD 2A/DIV VOUT 20mV/DIV
VOUT 20mV/DIV
20s/DIV VIN = 5V VOUT = 1.8V COUT = 3 x 22F, 6.3V CERAMICS
4604A G07
VIN = 5V 20s/DIV VOUT = 2.5V COUT = 3 x 22F, 6.3V CERAMICS
4604A G08
VIN = 5V 20s/DIV VOUT = 3.3V COUT = 2 x 22F, 6.3V CERAMICS
4604A G09
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LTM4604A TYPICAL PERFORMANCE CHARACTERISTICS
Start-Up Start-Up
VOUT 1V/DIV
VOUT 1V/DIV
IIN 1A/DIV
IIN 1A/DIV
VIN = 5V 200s/DIV VOUT = 2.5V COUT = 4 x 22F NO LOAD (0.01F SOFT-START CAPACITOR)
4604A G10
VIN = 5V 200s/DIV VOUT = 2.5V COUT = 4 x 22F 4A LOAD (0.01F SOFT-START CAPACITOR)
4604A G11
VFB vs Temperature
806 804 802 VFB (mV) 800 798 796 794 -50 VOUT (V) 1.6 1.4 1.2 1.0 0.8 0.6 0.4
Current Limit Foldback
-25
0 25 50 75 TEMPERATURE (C)
100
125
VOUT = 1.5V VIN = 5V 0.2 VIN = 3.3V VIN = 2.5V 0 4 5 3
7 6 OUTPUT CURRENT (A)
8
4604A G12
4604A G15
Short-Circuit Protection 1.5V Short, No Load
Short-Circuit Protection 1.5V Short, 4A Load
VOUT 0.5V/DIV
VOUT 0.5V/DIV
IIN 4A/DIV
IIN 1A/DIV
20s/DIV
4604A G13
100s/DIV
4604A G14
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LTM4604A PIN FUNCTIONS
VIN (B1, C1, C3-C7, D7, E6 and E7): Power Input Pins. Apply input voltage between these pins and GND pins. Recommend placing input decoupling capacitance directly between VIN pins and GND pins. VOUT (D8-D11, E8-E11, F6-F11, G6-G11): Power Output Pins. Apply output load between these pins and GND pins. Recommend placing output decoupling capacitance directly between these pins and GND pins. Review Table 4. GND (G3-G5, F3-F5, E4-E5, A1-A11, B6-B11, C8-C11): Power Ground Pins for Both Input and Output Returns. TRACK (E1): Output Voltage Tracking Pin. When the module is configured as a master output, then a soft-start capacitor is placed on the RUN/SS pin to ground to control the master ramp rate. Slave operation is performed by putting a resistor divider from the master output to ground, and connecting the center point of the divider to this pin on the slave regulator. If tracking is not desired, then connect the TRACK pin to VIN. Load current must be present for tracking. See Applications Information section. FB (G2): The Negative Input of the Error Amplifier. Internally, this pin is connected to VOUT with a 4.99k precision resistor. Different output voltages can be programmed with an additional resistor between FB and GND pins. Two power modules can current share when this pin is connected in parallel with the adjacent module's FB pin. See Applications Information section. COMP (G1): Current Control Threshold and Error Amplifier Compensation Point. The current comparator threshold increases with this control voltage. Two power modules can current share when this pin is connected in parallel with the adjacent module's COMP pin. PGOOD (F1): Output Voltage Power Good Indicator. Opendrain logic output that is pulled to ground when the output voltage is not within 7.5% of the regulation point. RUN/SS (D1): Run Control and Soft-Start Pin. A voltage above 0.8V will turn on the module, and below 0.5V will turn off the module. This pin has a 1M resistor to VIN and a 1000pF capacitor to GND. See Application Information section for soft-start information. The shut down pin should be pull low with a falling edge of 1s to ensure the device does not transition slowly through the internal under voltage lockout threshold. SW (B3 and B4): Switching Node of the circuit is used for testing purposes. This can be connected to copper on the board to improve thermal performance. Make sure not to connect it to other output pins.
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LTM4604A BLOCK DIAGRAM
PGOOD RSS 1M CSS 1000pF M1 CONTROL, DRIVE M2 INTERNAL COMP L C2 470pF R1 4.99k 10F 6.3V GND VOUT 22F 6.3V x3 VOUT 1.5V 4A 10F 6.3V x2 VIN 10F 6.3V VIN 2.375V TO 5.5V
RUN/SS CSSEXT 4.99k TRACK 5.76k COMP
TRACK SUPPLY
4604A BD
FB RFB 5.76k
SW
Figure 1. Simplified LTM4604A Block Diagram
DECOUPLING REQUIREMENTS TA = 25C. Use Figure 1 Configuration.
SYMBOL CIN COUT PARAMETER External Input Capacitor Requirement (VIN = 2.375V to 5.5V, VOUT = 1.5V) CONDITIONS IOUT = 4A MIN 10 22 100 TYP MAX UNITS F F
External Output Capacitor Requirement IOUT = 4A (VIN = 2.375V to 5.5V, VOUT = 1.5V)
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LTM4604A OPERATION
Power Module Description The LTM4604A is a standalone non-isolated switch mode DC/DC power supply. It can deliver up to 4A of DC output current with few external input and output capacitors. This module provides a precise regulated output voltage programmable via one external resistor from 0.8V DC to 5.0V DC over a 2.375V to 5.5V input voltage. A typical application schematic is shown in Figure 15. The LTM4604A has an integrated constant frequency current mode regulator with built-in power MOSFETs with fast switching speed. The typical switching frequency is 1.25MHz. With current mode control and internal feedback loop compensation, the LTM4604A module has sufficient stability margins and good transient performance under a wide range of operating conditions and with a wide range of output capacitors, even all ceramic output capacitors. Current mode control provides cycle-by-cycle fast current limit. In addition, foldback current limiting is provided in an overcurrent condition while VOUT drops. Internal overvoltage and undervoltage comparators pull the opendrain PGOOD output low if the output feedback voltage exits a 7.5% window around the regulation point. Furthermore, in an overvoltage condition, internal top FET M1 is turned off and bottom FET M2 is turned on and held on until the overvoltage condition clears. Pulling the RUN pin below 0.5V forces the controller into its shutdown state, turning off both M1 and M2. At low load current, the module works in continuous current mode by default to achieve minimum output voltage ripple. The TRACK pin is used for power supply tracking. See the Applications Information section. The LTM4604A is internally compensated to be stable over a wide operating range. Table 4 provides a guideline for input and output capacitance for several operating conditions. An excel loop analysis tool is provided for transient and stability analysis. The FB pin is used to program the output voltage with a single resistor connected to ground.
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LTM4604A APPLICATIONS INFORMATION
A typical LTM4604A application circuit is shown in Figure 15. External component selection is primarily determined by the maximum load current and output voltage. Refer to Table 4 for specific external capacitor requirements for a particular application. 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. The LTM4604A is 100% duty cycle, but the VIN to VOUT minimum dropout is a function of the load current. A typical 0.5V minimum is sufficient (see Typical Performance Characteristics). Output Voltage Programming The PWM controller has an internal 0.8V reference voltage. As shown in the Block Diagram, a 4.99k 0.5% internal feedback resistor connects the VOUT and FB pins together. The output voltage will default to 0.8V with no feedback resistor. Adding a resistor RFB from the FB pin to GND programs the output voltage: VOUT = 0.8 V * 4.99k + RFB RFB Without considering the inductor current ripple, the RMS current of the input capacitor can be estimated as: ICIN(RMS) = IOUT(MAX) % * D * (1- D)
In the above equation, % is the estimated efficiency of the power module. The bulk capacitor can be a switcherrated electrolytic aluminum capacitor, OS-CON capacitor for bulk input capacitance due to high inductance traces or leads. If a low inductance plane is used to power the device, then no input capacitance is required. The two internal 10F ceramics are typically rated for 2A to 3A of RMS ripple current. The worst-case ripple current for the 4A maximum current is 2A or less. Output Capacitors The LTM4604A is designed for low output voltage ripple. The bulk output capacitors defined as COUT are chosen with low enough effective series resistance (ESR) to meet the output voltage ripple and transient requirements. COUT can be a low ESR tantalum capacitor, a low ESR polymer capacitor or an X5R/X7R ceramic capacitor. The typical output capacitance range is 22F to 100F. Additional output filtering may be required by the system designer if further reduction of output ripple or dynamic transient spike is required. Table 4 shows a matrix of different output voltages and output capacitors to minimize the voltage droop and overshoot during a 2A/s transient. The table optimizes the total equivalent ESR and total bulk capacitance to maximize transient performance. The Linear Technology Module Power Design Tool can be provided for further optimization. Fault Conditions: Current Limit and Overcurrent Foldback The LTM4604A has current mode control, which inherently limits the cycle-by-cycle inductor current not only in steady-state operation, but also in transient. To further limit current in the event of an overload condition, the LTM4604A provides foldback current limiting as the output voltage falls. The LTM4604A device has overtemperature shutdown protection that inhibits switching operation around 150C.
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Table 1. FB Resistor vs Output Voltage
VOUT RFB 0.8V Open 1.2V 10k 1.5V 5.76k 1.8V 4.02k 2.5V 2.37k 3.3V 1.62k
Input Capacitors The LTM4604A module should be connected to a low acimpedance DC source. Two 10F ceramic capacitors are included inside the module. Additional input capacitors are only needed if a large load step is required up to a full 4A level. An input 47F bulk capacitor is only needed if the input source impedance is compromised by long inductive leads or traces. For a buck converter, the switching duty cycle can be estimated as: D= VOUT VIN
9
LTM4604A APPLICATIONS INFORMATION
Run Enable and Soft-Start The RUN/SS pin provides dual functions of enable and soft-start control. The RUN/SS pin is used to control turn on of the LTM4604A. While this pin is below 0.5V, the LTM4604A will be in a 7A low quiescent current state. A 0.8V threshold will enable the LTM4604A. This pin can be used to sequence LTM4604A devices. The soft-start control is provided by a 1M pull-up resistor (RSS) and a 1000pF capacitor (CSS) as drawn in the Block Diagram. An external capacitor can be applied to the RUN/SS pin to increase the soft-start time. A typical value is 0.01F. The approximate equation for soft-start is: t SOFTSTART = ln VIN * RSS (CSS + CSSEXT ) VIN - 1.8V pin must go beyond 0.8V to ensure the slave output has reached its final value. Load current must be present for proper tracking.
VIN 5V CIN1 10F 6.3V X5R OR X7R VIN PGOOD COMP GND VOUT FB RAMP CONTROL OR VIN RFB3 1.62k COUT1 22F 6.3V x3 X5R OR X7R LTM4604A RUN/SS TRACK CSSEXT VMASTER 3.3V 4A
where RSS and CSS are shown in the Block Diagram of Figure 1, 1.8V is the soft-start upper range, and CSSEXT is the additional capacitance for further soft-start contol. The soft-start function can also be used to control the output ramp-up time, so that another regulator can be easily tracked. An independent ramp control signal can be applied to the master ramp, otherwise, connect the TRACK pin to VIN to disable tracking. Output Voltage Tracking Output voltage tracking can be programmed externally using the TRACK pin. The output can be tracked up and down with another regulator. The master regulator's output is divided down with an external resistor divider that is the same as the slave regulator's feedback divider to implement coincident tracking. The LTM4604A uses a very accurate 4.99k resistor for the top feedback resistor. Figure 2 shows an example of coincident tracking. VTRACK = RFB2 *V 4.99k + RFB2 MASTER
VIN 5V CIN2 10F 6.3V X5R OR X7R VIN PGOOD COMP GND VOUT FB RFB2 5.76k RFB 5.76k COUT2 22F 6.3V x3 X5R OR X7R LTM4604A RUN/SS TRACK VSLAVE 1.5V 4A
RFB1 4.99k
4604A F02
Figure 2. Dual Outputs (3.3V and 1.5V) with Tracking
MASTER OUTPUT OUTPUT VOLTAGE (V)
SLAVE OUTPUT
V TRACK is the track ramp applied to the slave's TRACK pin. V TRACK applies the track reference for the slave output up to the point of the programmed value at which V TRACK proceeds beyond the 0.8V reference value. The V TRACK
TIME
4604A F03
Figure 3. Output Voltage Coincident Tracking
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LTM4604A APPLICATIONS INFORMATION
Ratio metric modes of tracking can be achieved by selecting different resistor values to change the output tracking ratio. The master output must be greater than the slave output for the tracking to work. Linear Technology Tracker Cad26 can be used to implement different tracking scenarios. The Master and Slave data inputs can be used to implement the correct resistor values for coincident or ratio tracking. The master and slave regulators require load current for tracking down. Power Good 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. COMP Pin The pin is the external compensation pin. The module has already been internally compensated for all output voltages. Table 4 is provided for most application requirements. The Linear Technology Module Power Design Tool can be provided for other control loop optimizations. Parallel Operation The LTM4604A device is an inherently current mode controlled device. Parallel modules will have very good current sharing. This will balance the thermals on the design. Figure 16 shows a schematic of the parallel design. The voltage feedback changes with the variable N as more modules are paralleled. The equation: 4.99k + RFB = 0.8 V * N RFB
VOUT
N is the number of paralleled modules. Thermal Considerations and Output Current Derating The power loss curves in Figures 4 and 5 can be used in coordination with the load derating curves in Figures 6 through 13 for calculating an approximate JA for the module with and without heat sinking methods with various airflow conditions. Thermal models are derived from several temperature measurements at the bench, and are correlated with thermal analysis software. Tables 2 and 3 provide a summary of the equivalent JA for the noted conditions. These equivalent JA parameters are correlated to the measured values and improve with air flow. The maximum junction temperature is monitored while the derating curves are derived.
2.0 1.8 1.6 1.4 WATTS 1.2 1.0 0.8 0.6
2.0 1.8 1.6 1.4 WATTS 1.2 1.0 0.8 0.6 0.4 0.2 0 0 1 5V TO 1.2V POWER LOSS 3.3V TO 1.2V POWER LOSS 3 2 LOAD CURRENT (A) 4 5
4604A F04
0.4 0.2 0 0 1
5V TO 2.5V POWER LOSS 3.3V TO 2.5V POWER LOSS 2 3 LOAD CURRENT (A) 4
4604A F05
5
Figure 4. 1.2V Power Loss
Figure 5. 2.5V Power Loss
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LTM4604A APPLICATIONS INFORMATION
4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F06
4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F07
Figure 6. 5VIN to 1.2VOUT No Heat Sink
4.0 3.5 LOAD CURRENT (A) LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F08
Figure 7. 5VIN to 1.2VOUT with Heat Sink
4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F09
Figure 8. 3.3VIN to 1.2VOUT No Heat Sink
Figure 9. 3.3VIN to 1.2VOUT with Heat Sink
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LTM4604A APPLICATIONS INFORMATION
4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 AMBIENT TEMPERATURE (C)
4606A F10
4.0 3.5 LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F11
Figure 10. 5VIN to 2.5VOUT No Heat Sink
Figure 11. 5VIN to 2.5VOUT with Heat Sink
4.0 3.5 LOAD CURRENT (A) LOAD CURRENT (A) 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F12
4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 70 75 0LFM 200LFM 400LFM 80 85 90 95 100 105 110 115 AMBIENT TEMPERATURE (C)
4606A F13
Figure 12. 3.3VIN to 2.5VOUT No Heat Sink
Figure 13. 3.3VIN to 2.5VOUT with Heat Sink
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LTM4604A APPLICATIONS INFORMATION
Table 2. 1.2V Output
DERATING CURVE Figures 6, 8 Figures 6, 8 Figures 6, 8 Figures 7, 9 Figures 7, 9 Figures 7, 9 VIN (V) 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 POWER LOSS CURVE Figure 4 Figure 4 Figure 4 Figure 4 Figure 4 Figure 4 AIR FLOW (LFM) 0 200 400 0 200 400 HEAT SINK None None None BGA Heat Sink BGA Heat Sink BGA Heat Sink JA (C/W) 25 22.5 21 21 20 18
Table 3. 2.5V Output
DERATING CURVE Figures 10, 12 Figures 10, 12 Figures 10, 12 Figures 11, 13 Figures 11, 13 Figures 11, 13 VIN (V) 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 3.3, 5 POWER LOSS CURVE Figure 5 Figure 5 Figure 5 Figure 5 Figure 5 Figure 5 AIR FLOW (LFM) 0 200 400 0 200 400 HEAT SINK None None None BGA Heat Sink BGA Heat Sink BGA Heat Sink JA (C/W) 25 21 21 21 18 16
Table 4. Output Voltage Response Versus Component Matrix (Refer to Figure 17), 0A to 2A Load Step Typical Measured Values
CIN VOUT (V) (CERAMIC) 1.2 1.2 1.2 1.5 1.5 1.5 1.8 1.8 1.8 2.5 2.5 2.5 3.3 3.3 3.3 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F 10F CIN (BULK) 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum 56F Aluminum COUT (CERAMIC) 100F 6.3V 22F x4 22F x4 100F 6.3V 22F x4 22F x4 100F 6.3V 22F x3 22F x3 100F 6.3V 22F x3 22F x3 100F 6.3V 22F x3 22F x3 CCOMP None None None None None None None None None None None None None None None VIN (V) 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 2.5 3.3 5 DROOP (mV) 21 23 24 19 21 21 25 30 30 22 25 25 22 25 25 PEAK-TOPEAK(mV) 43 45 46 41 43 43 50 60 60 45 55 55 50 56 56 RECOVERY LOAD STEP (s) (A/s) 10 10 10 10 10 10 10 10 10 12 12 12 15 15 15 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 RFB (k) 10 10 10 5.76 5.76 5.76 4.02 4.02 4.02 2.37 2.37 2.37 1.62 1.62 1.62
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LTM4604A APPLICATIONS INFORMATION
Safety Considerations The LTM4604A modules do not provide 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. Layout Checklist/Example The high integration of LTM4604A 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. * Place high frequency ceramic input and output capacitors next to the VIN, GND and VOUT pins to minimize high frequency noise. * Place a dedicated power ground layer underneath the unit. * To minimize the via conduction loss and reduce module thermal stress, use multiple vias for interconnection between top layer and other power layers. * Do not put vias directly on the pads unless they are capped. * SW pads can be soldered to board to improve thermal performance. Figure 14 gives a good example of the recommended layout.
GND
VOUT COUT CIN 10F 6.3V X5R OR X7R OPEN-DRAIN PULL UP COUT CSSEXT 0.01F
VIN 2.375V TO 5.5V
COUT
VIN PGOOD COMP GND VOUT FB RFB 5.69k LTM4604A RUN/SS TRACK
VOUT 1.5V 4A COUT 22F x3 6.3V X5R OR X7R
4604A F15
VIN
Figure 15. Typical 2.375V to 5.5V Input, 1.5V at 4A Design
CIN
GND
4604A F14
Figure 14. Recommended PCB Layout
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15
LTM4604A TYPICAL APPLICATIONS
VIN 2.375V TO 5V CIN1 10F 6.3V X5R OR X7R OPEN-DRAIN PULL UP VIN PGOOD COMP CSSEXT 0.01F GND VOUT FB RFB 2.87k COUT1 22F x3 6.3V X5R OR X7R REFER TO TABLE 4 VOUT 1.5V 8A CIN2 10F 6.3V X5R OR X7R VIN PGOOD COMP GND
4604A F16
VOUT = 0.8V x ((4.99k/N) + RFB)/RFB WHERE N IS THE NUMBER OF PARALLEL MODULES
LTM4604A RUN/SS TRACK
VOUT FB COUT2 22F x3 6.3V X5R OR X7R REFER TO TABLE 4
LTM4604A RUN/SS TRACK
Figure 16. Two LTM4604As in Parallel, 1.5V at 8A Design
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16
LTM4604A TYPICAL APPLICATIONS
VIN 3.3V TO 5V CIN 10F 6.3V X5R OR X7R 50k OPEN-DRAIN PULL UP VIN PGOOD COMP CSSEXT 0.01F GND VOUT FB RFB 2.37k LTM4604A RUN/SS TRACK VOUT 2.5V 4A
COUT 22F x3 6.3V X5R OR X7R REFER TO TABLE 4
4604A F17
Figure 17. 3.3V to 5V Input, 2.5V at 4A Design
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17
LTM4604A PACKAGE DESCRIPTION
LGA Package 66-Lead (15mm x 9mm x 2.32mm)
(Reference LTC DWG # 05-08-1820 Rev O)
DETAIL A 2.19 - 2.45 aaa Z
G
F
E
D
C
B
A
PAD 1
1
PAD "A1" CORNER 4
2 3 4 5
15.00 BSC 12.70 BSC SUBSTRATE
MOLD CAP
6 7
0.290 - 0.350 1.90 - 2.10 DETAIL B // bbb Z Z
8 9 10 11
X 9.00 BSC aaa Z Y
0.630 0.025 SQ. 68x eee S X Y DETAIL B 7.620 BSC
1.27 BSC
PADS SEE NOTES 3
PACKAGE TOP VIEW
0.315 0.315
PACKAGE BOTTOM VIEW
3.810
2.540
1.270
0.000
1.270
2.540
3.810
DETAIL A
6.350 5.080 3.810 2.540
NOTES: 1. DIMENSIONING AND TOLERANCING PER ASME Y14.5M-1994 2. ALL DIMENSIONS ARE IN MILLIMETERS 3 4 LAND DESIGNATION PER JESD MO-222 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
COMPONENT PIN "A1"
1.270 0.000 1.270 2.540 3.810 5.080 6.350 0.315 0.315
5. PRIMARY DATUM -Z- IS SEATING PLANE 6. THE TOTAL NUMBER OF PADS: 66 SYMBOL TOLERANCE aaa 0.15 bbb 0.10 eee 0.05
LTMXXXXXX Module
TRAY PIN 1 BEVEL PACKAGE IN TRAY LOADING ORIENTATION
LGA 66 0108 REV O
SUGGESTED PCB LAYOUT TOP VIEW
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18
LTM4604A PACKAGE DESCRIPTION
Pin Assignment Table (Arranged by Pin Number)
PIN NAME A1 A2 A3 A4 A5 A6 A7 A8 A9 GND GND GND GND GND GND GND GND GND PIN NAME B1 B2 B3 B4 B5 B6 B7 B8 B9 VIN - SW SW - GND GND GND GND PIN NAME C1 C2 C3 C4 C5 C6 C7 C8 C9 VIN - VIN VIN VIN VIN VIN GND GND PIN NAME D1 D2 D3 D4 D5 D6 D7 D8 D9 - - - - - VIN VOUT VOUT PIN NAME TRACK - - GND GND VIN VIN VOUT VOUT E2 E3 E4 E5 E6 E7 E8 E9 PIN NAME F1 F2 F3 F4 F5 F6 F7 F8 F9 PGOOD - GND GND GND VOUT VOUT VOUT VOUT PIN NAME G1 G2 G3 G4 G5 G6 G7 G8 G9 COMP FB GND GND GND VOUT VOUT VOUT VOUT
RUN/SS E1
A10 GND A11 GND
B10 GND B11 GND
C10 GND C11 GND
D10 VOUT D11 VOUT
E10 VOUT E11 VOUT
F10 VOUT F11 VOUT
G10 VOUT G11 VOUT
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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 representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
19
LTM4604A PACKAGE PHOTOGRAPH
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20 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0808 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2008

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