QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 432 HIGH EFFICIENCY SYNCHRONOUS STEP-DOWN REGULATOR LTC1875 or LTC1879 DESCRIPTION Demonstration circuit 432 is a step-down converter, featuring either the LTC1875 or LTC1879 high frequency monolithic switching regulators. With an input voltage range from 2.65V to 6V, the LTC1875 is ideal for Li-Ion applications, such as PDAs, cellular phones, and digital cameras. For applications with higher input voltages, the LTC1879 is the choice with its maximum input voltage limit of 10V. Both devices have switch current limits over 1A (LTC1875-1.6A, LTC1879-1.8A), which allows these ICs to deliver high(er) power to small, low-profile applications. While the standard operating frequency of both parts is 550 kHz, the switching can be externally set as high as 750 kHz. All these features make the LTC1879 (DC432A) or LTC1875 (DC432B) perfectly suited for battery-powered, surface mount applications. Design files for this circuit board are available. Call the LTC factory. Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 2.65V Maximum Input Voltage (LTC1875) Maximum Input Voltage (LTC1879) 6V 10V VOUT (LTC1875) VOUT (LTC1879) IOUT = 0A to 1.5A IOUT = 0A to 1.2A 0.8V 2% to VIN 2% 0.8V 2% to VIN 2% IOUT (LTC1875) IOUT (LTC1879) 1.5A 1.2A Nominal Switching Frequency 550kHz QUICK START PROCEDURE Demonstration circuit 432 is easy to set up to evaluate the performance of the LTC1875 or LTC1879. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. Refer to Figure 2 for proper placement of the scope probe. 1. Place jumper JP2 in the SHDN position. 2. Select the desired output voltage, using jumper JP3. The fixed output options are 1.8V, 2.5V, and 3.3V. Too set the output voltage to a custom value, insert a resistor into RFB5. 3. Connect the load between the Vout and GND termi- nals on the bottom right-side of the board. 4. With power off, connect the input power supply to Vin and GND (which are at the bottom left-side of the board). Turn on the power at the input. NOTE: If evaluating the LTC1875, do not exceed 6V in- put; if evaluating the LTC1879, do not exceed 10V in. 5. Place jumper JP2 in the RUN position. 6. Check for the proper output voltages. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 7. Once the proper output voltages are established, ad- just the loads within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 432 HIGH EFFICIENCY SYNCHRONOUS STEP-DOWN REGULATOR + - + + + + - - - - + LOAD - Figure 1. Proper Measurement Equipment Setup for both versions of the board: LTC1879 (DC432A) and LTC1875 (DC432B) GND VIN Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2 PG RUN DC432B DC432A Assembly Type Rpg 100K COUT L1 2. 65-6V 10uF , 10V PCB SILKSCREEN CIN2 U1 2.65-10V LTC1879EGN LTC1875EGN 10uF , 16V 150K Rc 10K Rpl Vin 2200p F Cpl U1 Cc1 47pF 1 JP2 RUN SHDN 3 1 Cin1, Cin2 * VERSION TABLE Css 0. 1uF Rss 1M 3 JP1 Burst Mod e Pulse - skip 2 Cc2 1.5 1.2 Iout(A) 220pF ** Space Provided for an Optional Resistor to Program a Custom Output Voltage CIN1 RFB1 CFFW CSS RSS E3 E2 CC1 RC CC2 CPL RPL E1 RIN RPG 4 14 16 2 15 * ITH PGOOD PLL_LPF RUN/SS E6 SYNC/MODE U1 E8 E7 Vfb SWN2 SWN1 SWP2 SWP1 PVin2 PVin1 SGND 1 SYNC CBYP D1 PGND 7 2 13 SVin PGND 10 3 11 6 12 5 9 8 JP3 2.5V 1.8V Cout 47uF 6.3V Rfb3 412K 10 Rfb2 698K D1 MBR052 0 (Opt. ) 4.7u H L1 0.1uF Cbyp Rin Cffw 3.3V Rfb4 280K 22pF OPEN ** Rfb5 optional Rfb1 887K 10uF * Cin1 10uF * Cin2 E5 E4 Vout 1.8V / 2.5V / 3.3V Iout * Vin * QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 432 HIGH EFFICIENCY SYNCHRONOUS STEP-DOWN REGULATOR 3 5 4 3 2 1 Rin E4 D Cbyp JP1 Burst Mode Pulse -skip 1 2 SYNC 3 RUN D 13 PVin1 8 PVin2 9 SWP1 5 SWP2 12 L1 Rpl PLL_LPF 10K 4 Cc2 Cc1 47pF 220pF SWN2 11 Vfb ITH Vout 1.8V / 2.5V / 3.3V Iout * Cout 47uF 6.3V D1 MBR0520 (Opt.) Cffw 22pF Rfb1 887K Rfb4 280K Rfb5 optional C 3 10 Rc 150K SWN1 PGOOD PGND 14 PG 7 2200pF 6 E5 4.7uH PGND 16 E3 RUN/SS SGND C SYNC/MODE 1 Rpg 100K 2 Cpl Css 0.1uF 10uF Vin * * Cin2 10uF 1 2 E2 15 JP2 RUN SHDN Rss 1M * Cin1 0.1uF U1 * SVin 3 E1 10 Rfb2 698K Rfb3 412K ** U1 Vin Iout(A) 10uF, 16V LTC1879EGN 2.65-10V 1.2 DC432B 10uF, 10V LTC1875EGN 2.65-6V 1.5 CFFW RFB1 U1 OPEN E6 L1 CONTRACT NO. D1 CIN2 3.3V B E7 CIN1 2.5V RIN RPG CBYP CSS RSS Cin1, Cin2 DC432A CC1 RC CC2 CPL RPL Assembly Type B 1.8V JP3 VERSION TABLE * APPROVALS E8 COUT DRAWN A June Wu DATE 5/22/01 TECHNOLOGY 1630 McCarthy Blvd. Milpitas, CA 95035 Phone: (408)432-1900 Fax: (408)434-0507 TITLE A CHECKED LTC1879EGN/LTC1875EGN, High Efficiency Synchronous Step-Down Regulator APPROVED PCB SILKSCREEN ENGINEER TOM GROSS 5/22/01 DESIGNER ** Space Provided for an Optional Resistor to Program a Custom Output Voltage. 5 4 Wednesday, June 05, 2002 3 SIZE CAGE CODE SCALE: FILENAME: 2 DWG NO REV A Demo Circuit 432A / 432B SHEET 1 1 OF 1 Bill Of Material Demo Bd. #432A Linear Technology Corporation LTC1879EGN 6/17/2005 10:05 AM Item Qty Reference 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 2 1 1 1 2 1 1 0 8 2 1 3 1 1 1 1 1 1 0 1 1 1 1 1 1 Cbyp,Css Cc1 Cc2 Cffw Cin1,Cin2 Cout Cpl D1 (OPT.) E1-E7 JP1,JP2 JP3 JP1,JP2,JP3 L1 Rc Rfb1 Rfb2 Rfb3 Rfb4 Rfb5 (optional) Rin Rpg Rpl Rss U1 Part Description CAP., X7R, 0.1uF, 16V, 20% 0603 CAP., NPO, 47pF, 50V, 10% 0402 CAP., X7R, 220pF, 50V, 20% 0402 CAP., NPO, 22pF, 50V, 10% 0402 CAP., X5R, 10uF, 16V, 20% 1210 CAP., X5R, 47uF, 6.3V, 20% 1812 CAP., X7R, 2200pF, 50V, 20% 0402 DIODE, MBR0520 TURRET, JUMPER, 0.079, 3 PIN JUMPER, DOUBLE ROW 0.079X4 SHUNT, INDUCTOR,4.7uH, D63LCB RES.,CHIP, 150K, 1/16W, 5% 0402 RES.,CHIP, 887K, 1/16W, 1% 0402 RES.,CHIP, 698K, 1/16W, 1% 0402 RES.,CHIP, 412K, 1/16W, 1% 0402 RES.,CHIP, 280K, 1/16W, 1% 0402 RES.,CHIP, 0402 RES.,CHIP, 10, 1/16W, 1% 0402 RES.,CHIP, 100K, 1/16W, 5% 0402 RES.,CHIP, 10K, 1/16W, 5% 0402 RES.,CHIP, 1M, 1/16W, 5% 0402 I.C., LTC1879EGN, SSOP-16GN PRINTED CIRCUIT BOARD Page 1 - of - 1 Manufacture / Part # AVX, 0603YC104MAT AVX, 04025A470KAT AVX, 04025C221MAT AVX, 04025A220KAT TAIYO YUDEN, EMK325BJ106MN TDK, C4532X5R0J476M AVX, 04025C222MAT MILL-MAX2501-2 COMM CON2802S-03G1 COMM CON2202S-08G1 COMM CON. CCIJ2MM-138G TOKO, A921CY-4R7M AAC, CR05-154JM AAC, CR05-8873FM AAC, CR05-6983FM AAC, CR05-4123FM AAC, CR05-2803FM AAC, CR05-10R0FM AAC, CR05-104JM AAC, CR05-103JM AAC, CR05-105JM LINEAR, LTC1879EGN DEMO BOARD DC432A