DC1749A

DEMO MANUAL DC1749A LT8610 42V, 2.5A Micropower Synchronous Step-Down Regulator DESCRIPTION Demonstration circuit 1749A is a 42V, 2.5A micropower synchronous step-down regulator featuring the LT®8610. The LT8610 is a compact, high efficiency, high speed synchronous monolithic step-down switching regulator that consumes only 2.5μA of quiescent current when output is regulated at 3.3V. Top and bottom power switches, compensation components and other necessary circuits are inside of the LT8610 to minimize external components and simplify design. The SYNC pin on the demo board is grounded by default for low ripple burst mode operation. To synchronize to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Once JP1 is on SYNC position, a DC voltage of higher than 2V or INTVCC can be applied to the SYNC turret for pulse skipping operation. Figure 1 shows the efficiency of the circuit at 12V input. The demo board has an EMI filter installed. The EMI performance of the board is shown on Figure 2. Figure 3 shows the EMI performance of the board with the switching frequency change to 1MHz. The limit in Figure 2 and Figure 3 is EN55022 Class B. Both figures show the circuit passes the test with a wide margin. To use the EMI filter, the input should be tied to VEMI, not VIN. The LT8610 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this quick start guide for demo circuit 1749A. Design files for this circuit board are available at http://www.linear.com/demo L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. 12VIN to 3.3VOUT Efficiency 100 EFFICIENCY (%) 95 90 85 80 0 0.5 1 1.5 LOAD CURRENT (A) 2 2.5 1749 F01 Figure 1. LT8610 Efficiency from 12V to 3.3V dc1749af 1 DEMO MANUAL DC1749A DESCRIPTION Figure 2. LT8610 Demo Circuit EMI Performance, Switching Frequency = 700kHz Figure 3. LT8610 Demo Circuit EMI Performance, Switching Frequency = 1MHz PERFORMANCE SUMMARY (TA = 25°C) SYMBOL PARAMETER CONDITIONS VIN Input Supply Range VOUT Output Voltage IOUT Maximum Output Current FSW Switching Frequency EFE Efficiency at DC MIN TYP 3.8 3.168 3.3 MAX 42 V 3.465 V 2.5 630 IOUT = 1A 700 93 UNITS A 770 kHz % dc1749af 2 DEMO MANUAL DC1749A QUICK START PROCEDURE Demonstration circuit 1749A is easy to set up to evaluate the performance of the LT8610. Refer to Figure 4 and Figure 5 for proper measurement equipment setup and follow the procedure below: 2. With power off, connect the load to VOUT and GND. 1. With power off, connect the input power supply to VIN and GND. 5. Carefully evaluate other design parameters as needed. 3. Check JP1 setting 4. Turn on the power at the input. Figure 4. Proper Measurement Equipment Setup Figure 5. Measure Output Ripple dc1749af 3 DEMO MANUAL DC1749A PARTS LIST ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 1 C2 CAP, CER 4.7μF 50V 1206 TAIYO YUDEN UMK316BJ475KL-T 2 1 C4 CAP, CER 0.22μF 16V 0603 TAIYO YUDEN EMK107BJ224KA-T 3 1 C5 CAP, CER 4.7pF 25V 0402 AVX, 04023A4R7CAT2A 4 1 C6 CAP, CER 47μF 10V 1210 MURATA GRM32ER71A476KE15L 5 1 C7 CAP, CER 1.0μF 25V 0603 MURATA GCM188R71E105KA64 6 1 C8 CAP, CER 0.1μF 16V 0402 AVX, 0402YC104KAT2A 7 1 L1 IND, 4.7μH COILTRONICS HCM0703-4R7-R 8 1 R2 RES, 60.4k 1% 0402 VISHAY, CRCW040260K4FKED 9 1 R3 RES, 49.9k 1% 0402 VISHAY, CRCW040249K9FKED 10 2 R1, R4 RES, 1M 1% 0402 VISHAY, CRCW04021M00FKED 11 1 R5 RES, 412k 1% 0402 VISHAY, CRCW0402412KFKED 12 1 U1 IC, LT8610EMSE MSE16 LINEAR TECH.CORP. LT8610EMSE Additional Demo Board Circuit Components 1 1 C1 CAP, ALUM 22μF 63V SUNCON 63CE22BS 2 1 C10 CAP, CER 4.7μF 50V 1206 TAIYO YUDEN UMK316BJ475KL-T 3 1 C3 CAP, CER 4.7μF 50V 1206 MURATA GRM31CR71H475KA12L 4 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S221A 5 1 L2 IND, 4.7μH VISHAY, IHLP2020BZ-ER4R7M01 6 0 R6 RES, OPT 0402 OPT Hardware/Components (For Demo Board Only) 1 9 E1-E7, E9, E10 TESTPOINT TURRET 0.094" MILL-MAX-2501-2 2 1 JP1 HEADER 1X3 0.079" SAMTEC, TMM-103-02-L-S 3 1 XJP1 SHUNT, 0.079" CENTER SAMTEC, 2SN-BK-G 4 4 MH1-MH4 STAND-OFF, NYLON 0.50" TALL KEYSTONE, 8833 (SNAP ON) dc1749af 4 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. A B C D ( ( ( ( ( ( )% & X) 9  9,1 *1' 6