DEMO BOARD MANUAL DC324 LTC1876 High Efficiency, Low Cost, 3-Output Power Supply DESCRIPTION Demonstration Board DC324 is a high efficiency, low cost design using the LTC1876. This demo board provides three regulated outputs from a single IC: 3.3V/5A, 5V/5A and 12V/200mA, along with two LDO outputs at 3.3V and 5V. Using only a small number of surface mount components, this design is ideal for network equipment, notebook computers and other portable applications that require low profile, small board area and minimum system cost. High efficiency and low EMI are also achieved by operating the two main power stages 180 out of phase, which, in turn, results in long battery life and smaller input capacitors. All three main outputs can be adjusted externally and the 12V regulator is configured to receive its input from the 3.3V output, the 5V output or an external supply. DC324 highlights the capabilities of the LTC1876, which incorporates a dual out-ofphase, step-down switching controller and a step-up regulator with an internal 1A, 36V switch. It uses a constant frequency, current mode architecture to provide excellent line and load regulation for all three outputs. The operating frequency of the step-down controller is DC programmable from 150kHz to 300kHz and the frequency of the step-up regulator is fixed at 1.2MHz, allowing the use of tiny, low cost capacitors and inductors. Protection features of the controller include an overvoltage soft latch, an overcurrent latch-off (which can be externally defeated) and internal current foldback for overload situations. At low output currents, two modes of operation are available: Burst Mode operation to maintain high efficiency and burst disable mode to maintain constant frequency operation. The controller is also capable of very low dropout operation, with a 99% maximum duty cycle. To be compatible with battery operation, the input range of this demo board is 7.5V to 24V for the 3.3V and 5V outputs and from 3V to10V for the 12V output. Gerber files for this circuit board are available. Call the LTC factory. PERFORMANCE SUMMARY (Operating Temperature Range: 0C to 50C) PARAMETERS Input Voltages Output Voltages Load Currents CONDITIONS Step-Down Channels (VOUT = 5V and 3.3V); Limited by External MOSFET Drive and Breakdown Requirement Step-Up Channel (VOUT = 12V) Step-Down Channel 1; Externally Adjustable Step-Down Channel 2; Externally Adjustable Step-Up Channel; Externally Adjustable 5V Linear Regulator 3.3V Linear Regulator Step-Down Channels VIN2 = 3.3V Step-Up Channel VIN2 = 10V VALUE 5.2V to 30V 2.6V to 11V 5.00V 0.10V 3.30V 0.07V 12.00V 0.24V 5.00V 4% 3.30V 4% 0 to 5A, 6A Peak 200mA 600mA PARAMETERS Frequencies Output Ripple Voltages Line Regulation Load Regulation Supply Current Shutdown Current Standby Current Efficiency CONDITIONS Step-Down Channels; Externally Adjustable; FREQSET Pin Tied to INTVCC Step-Up Channel; Fixed Step-Down Channel 1; 20MHz BW; VIN = 15V; IO = 5A Step-Down Channel 2; 20MHz BW; VIN = 15V; IO = 5A Step-Up Channel; 20MHz BW; VIN2 = 5V; IO = 200mA Step-Down Channel 1; VIN = 7.5V to 24V Step-Down Channel 2; VIN = 7.5V to 24V Step-Up Channel; VIN = 3.3V to 10V Step-Down Channel 1; VIN = 15V; VOUT1 = 5.00V; IO = 0 to 5A Step-Down Channel 2; VIN = 15V; VOUT2 = 3.30V; IO = 0 to 5A Step-Up Channel; VIN = 5V; VOUT3 = 12.00V; IO = 0 to 200mA VIN = 15V; All Three Channels On; EXTVCC = VOUT1 VIN = 15V; STBYMD = 0 VIN = 15V; 1M Resistor from STBYBD to VIN; 5V INTVCC and 3.3V LDO On; RUN/SS1 = RUN/SS2 = AUXSD = 0 VIN = 15V; VIN2 = VOUT1; 4A Load at 5V Channel (Not Including the Supply Current to 12V Channel); 5A Load at 3.3V Channel; 200mA at 12V Channel VALUE 300kHz 1.2MHz 60mVP-P 60mVP-P 50mVP-P 5mV 5mV 5mV -60mV -60mV -10mV 80A* 20A 170A 90% *400A including the supply current from EXTVCC. Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See the LTC1876 data sheet for more information. TYPICAL PERFORMANCE CHARACTERISTICS 1; 5V Channel Vin(V) 15 15 15 15 15 15 15 15 15 15 (Both 3.3V and 12V Channels are Iin(A) Vout(V) Iout(A) 0.004 5.02 0 0.01 5.01 0.015 0.023 5 0.052 0.041 4.99 0.102 0.182 4.99 0.496 0.356 4.98 1.004 0.706 4.98 2.003 1.066 4.98 3.002 1.44 4.98 4.002 1.822 4.97 4.99 OFF) Eff.(%) 0 50.1 75.36232 82.76098 90.66081 93.63146 94.19207 93.49568 92.26833 90.74387 2; 3.3V Channel (Both 5V and 12V Channels are OFF) Vin(V) Iin(A) Vout(V) Iout(A) Eff.(%) 15 0.004 3.38 0 0 15 0.008 3.37 0.014 39.31667 15 0.017 3.356 0.051 67.12 15 0.03 3.346 0.102 75.84267 15 0.131 3.339 0.505 85.81145 15 0.251 3.337 1.004 88.98667 15 0.488 3.335 2.003 91.2569 15 0.735 3.334 3.002 90.78157 15 0.995 3.329 4.001 89.24174 15 1.264 3.32 4.99 87.37764 3; 12V Channel (Both 5V and 3.3V Channels are Vin(V) Iin(mA) Vout(V) Iout(mA) 5 6 11.96 0 5 46 11.97 14 5 145 11.95 51 5 280 11.94 101 5 336 11.94 122 5 392 11.94 142 5 452 11.94 163 5 502 11.94 181 5 563 11.94 201 OFF) Eff.(%) 0 72.86087 84.06207 86.13857 86.70714 86.50408 86.11593 86.1012 85.25542 100 Efficiency of 5V 95 90 Efficiency of 3.3V 85 80 75 70 65 60 Vin=15V 55 50 0.01 0.1 1 Load Current (A) 10 90 85 Efficiency of 12V 80 75 70 65 60 Vin2=5V 55 50 10 100 Load Current (mA) 1000 MEASUREMENT SETUP The circuit shown in Figure 1 provides three fixed voltages: 5V, 3.3V and 12V, at currents of up to 5A, 5A and 200mA, respectively. Figure 2 illustrates the correct measurement setup to be used to verify the typical numbers found in the Performance Summary table. Small spring clip leads are very convenient for small-signal bench testing but should not be used at the current and impedance levels associated with this switching regulator. Soldered wire connections are requited to properly ascertain the performance of this demonstration board. Do not tie the grounds together off the test board. The six jumpers on the left side of the board are settable as follows: the center pin is connected to ground when the jumper is in the rightmost position. The center pin is connected to a positive bias source when the jumper is in the leftmost position. The jumper below L2 at the lower right side of the board is used to select the input supply for the step-up channel. VOUT2 (3.3V) is selected if this jumper is in the leftmost position and VOUT1 (5V) is selected if it is in the rightmost position. This jumper should be left off when a separate power supply is used through the VIN2 terminal near the jumper. Refer to the Jumper Configuration table for jumper functions. QUICK START GUIDE This demonstration board is easily set up to evaluate the performance of the LTC1876. Please follow the procedure outlined below for proper operation. LOAD LTC1876CG DEMO CIRCUIT 324A HIGH EFFICIENCY LOW COST 3-OUTPUT POWER SUPPLY GND 5V/5A GND PGOOD INTVCC VIN RUN/SS FREQ + STDBY - FCB 3.3V RUN/SS2 LOAD 3.3V/5A VOUT1 VIN2 VOUT2 AUXSD 12V/O.2A GND VIN2 LOAD Figure 2. DC324A Test and Measurement Setup 1. Refer to Figure 2 for board orientation and proper measurement equipment setup. 2. Place the jumpers as shown in the diagram. Temporarily leave the STDBY jumper off. 3. Connect the desired loads between VOUT1, VOUT2 and VOUT3 and their closest GND terminals on the board. The loads can be up to 5A for VOUT1 and VOUT2 and 200mA for VOUT3. Soldered wires should be used when load current exceeds 1A in order to achieve optimum performance. 4. Connect the input power supply to the VIN and GND terminals on the right edge of the board. Do not increase VIN over 30V or the MOSFETs may be damaged. The recommended VIN to start is <7V. 5. Switch on the step-down channel(s) by removing the RUN/SS1 or RUN/SS2 jumpers. 6. Measure VOUT1 and VOUT2 to verify output voltages of 5.00V 0.10V and 3.30V 0.07V, respectively, at load currents of up to 5A each. 7. Connect the jumper below L2 to select the input supply for the step-up channel. Refer to the Measurement Setup section for proper connection. When VOUT1 or VOUT2 is selected, reduce the load level of the selected output below 4A or the total load current of the selected channel may exceed 5A. 8. Switch on the step-up channel by placing the AUXSD jumper in the leftmost position. Active loads can cause confusing results. Refer to the active load discussion in the Operation section. JUMPER CONFIGURATION RUN/SS FREQ STDBY FCB RUN/SS2 AUXSD VIN2 Left Over-Current Latch-Off of Channel 1 Defeated 300kHz for Channels 1 and 2 5V and 3.3V LDOs Turned On Discontinuous Operation Enabled at Channels 1 and 2 Over-Current Latch-Off of Channel 2 Defeated Channel 3 Enabled VIN2 = VOUT2 Selected Right Channel 1 Shut Off 150kHz for Channels 1 and 2 Channels 1 and 2 Shut Off Forced Continuous Operation at Channels 1 and 2 Channel 2 Shut Off Channel 3 Shut Off VIN2 = VOUT1 Selected Open Over-Current Latch-Off of Channel 1 Enabled 230kHz for Channels 1 and 2 Channels 1 and 2 Released Do Not Leave This Jumper Open Over-Current Latch-Off of Channel 2 Enabled Channel 3 Shut Off A Separate Supply Selected through VIN2 Terminal Bill Of Material Demo Bd. #324A Linear Technology Corporation LTC1876CG 6/16/2005 12:09 PM Item Qty Reference Part Description Manufacture / Part # 1 2 3 4 5 6 7 8 9 10 11 12 13 6 2 2 1 1 1 1 1 4 3 2 1 1 C1,C4,C7,C16,C21,C29 C2,C20 C3,C19 C5 C6 C8 C9 C10 C11,C24,C25,C26 C12,C13,C18 C14,C17 C15 C22 Capacitor, X7R 0.1uF 10V 20% Capacitor, NPO 27pF 25V 5% Capacitor, NPO 1000pF 25V 5% Capacitor, Alum 33uF 35V 10% Capacitor, Spcl. Poly. 47uF 6.3V 20% Capacitor, Tant. 4.7uF 10V 20% Capacitor, NPO 220pF 25V 5% Capacitor, Spcl. Poly. 56uF 4V 20% Capacitor, Y5V 1uF 10V 80% Capacitor, X7R .01uF 10V 10% Capacitor, NPO 33pF 50V 10% Capacitor, NPO 470pF 25V 5% Capacitor, Tant. 10uF 20V 20% AVX 0603ZC104MAT2A AVX 06033A270JAT1A AVX 06033A102JAT1A OSCON 35CV33BS PANASONIC EEFCD0J470R AVX TACR475M010R AVX 06033A221JAT1A PANASONIC EEFCD0G560R AVX 0603ZG105ZAT2A AVX 0603ZC103KAT1A AVX 06035A330KAT1A AVX 06033A471JAT1A AVX TPSB106M020 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 1 0 1 2 2 1 1 6 7 2 1 2 2 3 2 1 6 1 1 1 1 C23 C27 (Optional) C28 C30,C31 D1,D4 D3 D5 XJP1-XJP2,XJP4-XJP7 JP1-JP7 L2,L1 L3 Q1,Q2 R1,R13 R3,R9,R14 R4,R10 R5 R6,R17-R21 R7 R8 R11 R12 Capacitor, X7R 2.2uF 25V 20% Capacitor, X7R 10uF 35V 20% Capacitor, X5R 10uF 25V 20% Capacitor, Y5V 10uF 35V 20% Diode, Rectifier, 40V / 40Amp Schottky (Comm-Anode) Schottky Diode SHUNT, .079" CENTER Headers, 3 pins Inductor, 4.6uH Inductor, 10uH Mosfet N-Chan. Dual Resistor, LRC 0.010 0.25W 1% Resistor, Chip 1M 0.06W 5% Resistor, Chip 20K 0.06W 1% Resistor, Chip 105K 0.06W 1% Resistor, Chip 10 0.06W 5% Resistor, Chip 15K 0.06W 5% Resistor, Chip 6.8K 0.06W 5% Resistor, Chip 63.4K 0.06W 1% Resistor, Chip 10.2K 0.06W 1% AVX 12103C225MAT2A Taiyo Yuden GMK325BJ106M Taiyo Yuden TMK432BJ106MN-T Taiyo Yuden GMK325F106ZH Diodes Inc. B140B-13 Zetex BAT54ATA Central Semi. Corp CMDSH-3 COMM-CON CCIJ2MM-138G Comm-Conn. 2870MS-03G2 Sumida CEP123-4R6MC TOKO A920CY-100M Fairchild FDS6990A IRC LRF1206-01-R010-F AAC CR16-105JM AAC CR16-2002FM AAC CR16-1053FM AAC CR16-100JM AAC CR16-153JM AAC CR16-682JM AAC CR16-6342FM AAC CR16-1022FM Page 1 - of - 2 Bill Of Material Demo Bd. #324A Linear Technology Corporation LTC1876CG 6/16/2005 12:09 PM Item Qty Reference 35 36 37 38 39 40 41 42 1 1 11 1 4 4 1 1 R15 R16 TP1-TP11 U1 Part Description Resistor, Chip 86.6K 0.06W 1% Resistor, Chip 100K 0.06W 5% Turret, Testpoint I.C., LTC1876CG Stand-Off Nylon-Hex 4-40 1/4" Screw,#4-40 1/4" PRINTED CIRCUIT BOARDS STENCIL Note:please return empty reels. Thanks. Page 2 - of - 2 Manufacture / Part # AAC CR16-8662FM AAC CR16-104JM Mill Max 2501-2 Linear Tech. Corp. LTC1876CG Keystone 1902A Any DEMO BOARD DC324A STENCIL DC324A