LINEAR 10A High Performance Point-of-Load DC/DC Module Regulator 4.5V to 28V Input 0.6V to 5V Output in a 15mm × 15mm × 2.8mm Package Design Note 385
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1. ECHNOLOGY NO 4h P S 10A High Performance Point of Load DC DC UModule Regulator 4 5V to 28V Input 0 6V to 5V Output in a 15mm x 15mm x 2 8mm Package Design Note 385 Eddie Beville Introduction Advancements in board assembly PCB layout and digital IC integration have produced a new generation of densely populated high performance systems The board mounted point of load POL DC DC power sup plies in these systems are subject to the same demand ing size high power and performance requirements as other subsystems The rigorous new POL demands are difficult to meet with traditional controller or regulator ICs or power modules For such demanding applications an ideal POL power supply must meet high performance specifications while simplifying board assembly mounting similar to other surface mount ICs on the board without requiring special tooling Such POL DC DC regulators must also demon Strate exceptional thermal performance with innovative packaging technology Power density increases without the danger of overheating and shortened device life The LTM 4600 uModule regulator does all of these things 10A DC DC Module Regulator in IC Form Factor The LTM4600 uModule regulator is a complete power supply point of load DC DC regulator with a low profile IC form factor The controller onboard inductor MOSFETs and compensation circuitry are all housed ina 15mm x 15mm x 2 8m2. The LTM4600 Offers Unprecedented Power Density in a Small Package 03 1 1 385 VIN EXTVec Vout 2 5V lout 10A B V LTM4600EV RUN SS SVIN COMP SGND PGOOD PGND DN385 F02 C1 TDK C3216X5R1E106MT C2 TDK C1005CO0G1H101K C3 TAIYO YUDEN JMK316BJ226ML T501 C4 SANYO POS CAP 4TPE470MCL Figure 2 Few Components Are Required in this 2 5V 10A Application EFFICIENCY 2 2 4 6 8 10 12 LOAD CURRENT A DN385 F03 Figure 3 Efficiency of the Application in Figure 2 Thermally Enhanced Packaging The Module regulator package has extremely low thermal resistance of 6 C W and 15 C W junction to case and junction to ambient respectively It allows heat sinking from both the top and bottom of the device Figure 4 shows the top view thermal imaging of the LTM4600 at full throttle with no airflow and heat sink Refer to Application Note 103 for detailed thermal analysis and measurements Fast Transient Response A unique feature of the LTM4600 is its no clock latency valley current mode architecture This feature allows very fast loop response to rapid load transients with minimum output capacitance Typically the output voltage turns around in 4 to 6 microseconds and fully recovers in 20 to Data Sheet Download www linear com DN385 F04 CONDITIONS 25 C NO AIR FLOW NO HEATSINK NO EXT Vec Figure 4 The LTM4600 Exhibits Impressive Thermal Performance Even Withou
3. m LGA surface mount package which weighs only 1 73g Figure 1 These size parameters allow the LTM4600 to be mounted on the back side of a system board taking advantage of the otherwise unused space The pModule regulator switches at a nominal 800kHz in a synchronous topology to offer very high efficiency in a small form factor and low profile The uModule regulator is offered in two versions The LTM4600EV operates from an input supply range of 4 5V to 20V the LIM4600HVEV operates from 4 5V to 28V Both offer adjustable output voltages from 0 6V to 5V and output currents of 14A peak and 10A continuous Fault protection features include overvoltage protection and overcurrent protection Quick and Easy Design Figure 2 shows a typical LTM4600EV design for a 2 5V output and Figure 3 shows the efficiency of the circuit Although bulk capacitors on the input and output suffice in most applications this design uses two low ESR 10uF 25V ceramic capacitors to reduce input RMS ripple The output voltage is set with an external resistor from the Voset pin to ground The output capacitors are selected for low ESR to maintain an initial voltage droop of the output voltage to approximately AVouT ILoapstep Resp in a transient step 4J LI LTC LTM Linear Technology Module and the Linear logo are registered trademarks of Linear Technology Corporation All other trademarks are the property of their respective owners vill Figure 1
4. t Air Flow and Heat Sink 24V to 3 3V at 10A Top View For a Color Representation Download the File at www linear com 25 microseconds Figure 5 shows the transient deviation of only 55mV on a 2 5V output with a 5A load step The 6us of turnaround is achieved with only a 470uF POS cap and the three 22uF ceramics AIAN a ee M25 0us Chis 35mV_ 25 s DIV DN385 F05 2 5V AT 5A Ds LOAD STEP Cour 3 220F 6 3V CERAMICS 4700F 4V SANYO POS CAP C3 100pF Figure 5 Load Transient Response for the Application in Figure 2 Paralleling the pModule Regulator for 20A Output Two LTM4600 pModule regulators can be used in parallel to double the output current The current mode architec ture and precision current limiting allow two modules to equally share the output current thus maximizing efficiency and equally distributing the heat For applications help call 408 432 1900 Ext 2593 T begged Corporation 1630 McCarthy Blvd Milpitas CA 95035 7417 408 432 1900 FAX 408 434 0507 www linear com dn385fa LT TP 0311 REV A 305K PRINTED IN THE USA LI MYE LINEAR TECHNOLOGY CORPORATION 2006
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