Specifications are at T A = 25 C

Transcription

1 Description Demo circuit 574 is a high efficiency, high frequency step-down converter incorporating the LTC 6 monolithic synchronous regulator. The DC574A has an input voltage range of.5v to 5.5V and is capable of delivering up to A of output current. The output voltage of the DC574A can be set as low as 0.6V, the reference voltage of the LTC6. The operating frequency range of the DC574A is either set to a fixed.5 MHz by connecting the frequency pin to SV IN, set by an external resistor, or synchronized to an external clock, with a range up to 4MHz. At low load currents, the DC574A can operate in both noise sensitive applications (due to the capability of the LTC6 to operate in pulse-skipping mode) or in high efficiency applications, because the LTC6 also has Burst-Mode capability. The Burst Mode clamp can be set externally. Of course, in (forced) continuous mode, or large load current applications, the DC574A is a very DEMO MANUAL DC574A LTC6 Isolated RS485/RS4 µmodule Transceiver Power efficient circuit over 90%. The DC574A consumes less than 00µA of quiescent current during sleep operation and, during shut-down, it consumes less than µa. The DC574A can track another voltage, due to the LTC6 track function, for easy power supply sequencing. Extra features include frequency and current fold-back, and an adjustable 0.V-to-0.6V external reference. Because of the high switching frequency of the LTC6, which is programmable up to 4 MHz, the DC574A uses low profile surface mount components. All these features make the DC574A perfectly suited for portable computer and distributed power applications. Design files for this circuit board are available at L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. Performance Summary Specifications are at T A = 5 C SYMBOL CONDITIONS VALUE Minimum Input Voltage.5V Maximum Input Voltage 5.5V Run/Shutdown GND = Shutdown V IN = RUN Output Voltage Regulation V IN =.5V to 5.5V, I OUT = 0A to A.V ±4% (.5V.48V) V IN =.5V to 5.5V, I OUT = 0A to A.8V ±4% (.78V.87V) V IN =.V to 5.5V, I OUT = 0A to A.5V ±4% (.4V.6V) V IN =.9V to 5.5V, I OUT = 0A to A.V ±4% (.68V.4V) Typical Output Ripple Voltage V IN = 5V, V OUT =.8V, I OUT = A (0MHz BW) <0mV PP Burst Mode V IN = 5V, V OUT =.8V <600mA Pulse-Skip Mode V IN = 5V, V OUT =.8V <500mA Nominal Switching Frequency R T = 65k MHz ± 0%

2 Quick Start Procedure Table. Jumper Description JUMPER FUNCTION RANGE/SETTING (DEFAULT) JP Output Voltage Setting..V J Mode: Forced Continuous Mode (FCM), Burst Mode (BM or BMEC), or Pulse-Skip Mode(SYNC) (FCM) BMEC BM PSM J Run (ON) OFF J Tracking (TRACK), Internal Soft-Start (INT SS), or External Soft-Start (EXT SS) (EXT SS) (INT SS) TRACK J4 DDR Memory Termination (OFF) ON J5 External or Internal ITH Compensation (EXT) INT J6 Frequency Setting: Timing Resistor (R T ), Internally Synchronized (.5 MHz), or Externally Synchronized (R T ) INT SYNC EXT SYNC J9 External Burst Mode Clamp Voltage (SET) EXT Demonstration Circuit 574 is easy to set up to evaluate the performance of the LTC6. For proper measurement equipment configuration, set up the circuit according to the diagram in Figure. Before proceeding to test, insert shunts into the.v position of the output voltage header JP, into the FCM (forced continuous mode) position of MODE header J, into the OFF position of RUN header J, into the EXT SS (external soft-start) position of Track/SS header J, into the OFF position of DDR header J4, into the EXT (external) position of COMP header J5, into the R T position of R T /SYNC header J6 and into the SET position of VBMCV header J9. 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 V IN or V OUT and GND terminals. See Figure for proper scope probe measurement technique. With the DC574 set up according to the proper measurement configuration and equipment in Figure, apply 6.V at V IN (Do not hot-plug V IN or increase V IN over the rated maximum supply voltage of 5.5V, or the part may be damaged.). Measure V OUT ; it should read 0V. Turn on the circuit by inserting the shunt in header J into the ON position. The output voltage should be regulating. Measure V OUT it should measure.v ±% (.76V to.4v). Vary the input voltage from.5v to 5.5V and adjust the load current from 0A to A. V OUT should regulate around.v. Measure the output ripple voltage; it should measure less than 0mV AC. Observe the voltage waveform at the switch pins (the other side of the inductor from the output). Verify the switching frequency is between.6mhz and.4mhz (T = 65ns and 46ns), and that the switch node waveform is rectangular in shape. Change the J shunt from forced continuous mode to Burst Mode operation or pulse-skip mode. Set the input voltage to 5V and the output current to any current less than 600mA. Observe the discontinuous mode of operation at the switch node, and measure the output ripple voltage. It should measure less than 00 mv. Insert the J shunt into the OFF position and move the shunt in the.v output JP header into any of the two remaining output voltage option headers:.8v (JP),.5V (JP), or.v (JP4). Just as in the.v V OUT test, the output voltage should read V OUT ±% tolerance under static line and load conditions and ± tolerance under dynamic line and load conditions (±% total). Also, the circuit operation in discontinuous mode will be the same. When finished, turn off the circuit by inserting the shunt in header J into the OFF position.

3 Quick Start Procedure I IN V S LOAD V OUT I OUT DC574A F0 Figure. Proper Measurement Equipment Setup VIN GND Figure. Measuring Input or Output Ripple

4 Quick Start Procedure OUTPUT RIPPLE VOLTAGE 0V/DIV SWITCH VOLTAGE V/DIV V IN =.V V OUT =.8V I OUT = A f SW = MHz 00ns/DIV DC574 F0 Figure. Switch Node and Output Ripple Voltage Waveforms 4

5 Quick Start Procedure OUTPUT VOLTAGE 00mV/DIV AC OUTPUT CURRENT A/DIV V IN =.V V OUT =.8V.5A LOAD STEP (0.5A TO A) FORCED CONTINUOUS MODE f SW = MHz 0µs/DIV DC574 F04 Figure 4. Load Step Response 5

6 Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components CFF CAP., G0G, pf, 5V, 5% 060 AVX, 060A0JATA CIN, CIN CAP., X7R, µf, 6.V, 0% 06(0) AVX, 066C6MATA COUT, COUT CAP., X5R, µf, 6.V, 0% 0 MURATA, GRMDR60J6ME9 4 L INDUCTOR, 0.47µH IHLP-00BZ-0 VISHAY, IHLP00BZERR47M 5 R, R RES., CHIP, 65k, /0W, 060 VISHAY, CRCW06065KFKEA 6 U IC., LTC6EFE TSSOP-0L LINEAR TECH., LTC6EFE#PBF Additional Demo Board Circuit Components 0 CC (OPT) CAP., 0805 OPT CFILT CAP., X7R, µf, 6.V, 0% 060 AVX, 0606C05KATA CIN CAP., TANT., 00µF, 0V, 0% 74 AVX, TPSW07M00R COUT6 OPT CAP., TANT., 00µF, 0V, 0% 74 AVX, TPSW07M00R050 5 CITH CAP., X7R, 000pF, 50V, 0% 060 AVX, 0605C0KATA 6 0 COUT, COUT4, CIN4 OPT CAP., X5R, 00µF, 6.V, 0% 0 OPT* MURATA, GRMER60J07ME0 7 COUT5 CAP., X7R, 0µF, 6.V, 0% 0805 AVX, 08056C06MATA 8 CSS CAP., X7R, 0.0µF, 50V, 0% 060 AVX, 0605C0KATA 9 C CAP., C0G, 0pF, 5V, 0% 060 AVX, 060A00KATA 0 RFILT RES., CHIP, 4, /0W, 5% 060 VISHAY, CRCW0604R0JNEA RITH RES., CHIP, 5k, /0W, 060 VISHAY, CRCW0605K0FKEA 4 RSS, RSD, RM, RM RES., CHIP, 4.87M, /0W, 060 VISHAY, CRCW0604M87FKEA RM RES., CHIP, 0k, /0W, 060 VISHAY, CRCW0600KFKEA 4 RPG RES., CHIP, 00k, /0W, 5% 060 VISHAY, CRCW06000KJNEA 5 RTR, RM4 RES., CHIP, 00k, /0W, 060 VISHAY, CRCW06000KFKEA 6 0 RT, RM5, RTR, R6 (OPT) RES., CHIP, OPT RT RES., CHIP, 65k, /0W, 060 VISHAY, CRCW06065KFKEA 8 R RES., CHIP, 8.5k, /0W, 060 VISHAY, CRCW0608K5FKEA 9 R4 RES., CHIP, 5.k, /0W, 060 VISHAY, CRCW0605KFKEA 0 R5 RES., CHIP, 6.5k, /0W, 060 VISHAY, CRCW0606K5FKEA Hardware: For Demo Board Only 5 JP, JP, JP, JP4, JP5 PIN SINGLE ROW HEADER SAMTEC, TMM0-0-L-S J X4, DOUBLE ROW HEADER SAMTEC, TMM04-0-L-D J, J5, JP9 PIN SINGLE ROW HEADER SAMTEC, TMM0-0-L-S 4 J, J6 X, DOUBLE ROW HEADER SAMTEC, TMM0-0-L-D 5 J4 X, DOUBLE ROW HEADER SAMTEC, TMM0-0-L-D 6 8 XJ-XJ6, XJ9, XJP SHUNT, 0.079" CENTER SAMTEC, SN-BK-G 7 0 TP-TP0 TESTPOINT, TURRET,.094" pbf MILL-MAX,

7 Schematic Diagram A B C D E PGOOD 5% U LTC6EFE TP VIN 5 6 PVin L.5V - 5.5V CIN CIN4 CIN 0 PVin 0.47uH CIN 00uF 00uF uf PVin_d VISHAY uf SVin IHLP00BZERR47M V 6.V 6.V RFILT VOUT GND 4 CFILT SW 9 7 TP4 A uf SW TP SW 4 COUT5 SW COUT COUT COUT COUT4 RITH 0uF COUT6 6 uf uf 00uF 00uF 6.V RUN Ith 5k 00uF 6.V 6.V 6.V 6.V ON OFF J CC C Run GND 0pF 7 CITH TP5 Track/SS 000pF J TRACK/SS INT SS TRACK RTR TRACK 4 Vfb 5 TP7 00k EXT SS 5 6 JP R.V INT SYNC Rt EXT SYNC J4 DDR 4 RM GND 4.87M R6 JP5 TP6 SYNC USER SELECT J TP8 MODE (FORCED CONTINUOUS FCM RM4 GND MODE) PSM 4 J9 00k TP9 (PULSE-SKIP MODE) (BURST MODE EXTERNAL CLAMP) (BURST MODE) J6 Rt / SYNC BMEC BM RM 4.87M ON OFF RT 65k COMP INT EXT R5 6.5k JP JP J5.8V.5V.V SET EXT VBMCV Voutset CFF pf RSD 4.87M RTR RPG 00k PGood DDR NC NC NC Mode Rt/Sync PGND SGND RT TP RSS 4.87M CSS 0.0uF 6 8 RM5 65K R 8.5K R4 5.K JP4 R 65k RM 0k (Vout Burst Mode Clamp Voltage) CONTRACT NO. 60 McCarthy Blvd. Milpitas, CA 9505 BMECV APPROVALS DATE TECHNOLOGY Phone: (408)4-900 Fax: (408) TP0 DRAWN Antonina K. 7//09 TITLE CHECKED (Burst Mode External Clamp Voltage) A B CUSTOMER NOTICE LINEAR TECHNOLOGY HAS MADE A BEST EFFORT TO DESIGN A CIRCUIT THAT MEETS CUSTOMER-SUPPLIED SPECIFICATIONS; HOWEVER, IT REMAINS THE CUSTOMER'S RESPONSIBILITY TO VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL APPLICATION. COMPONENT SUBSTITUTION AND PRINTED CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLY AFFECT CIRCUIT PERFORMANCE OR RELIABILITY. CONTACT LINEAR TECHNOLOGY APPLICATIONS ENGINEERING FOR ASSISTANCE. THIS CIRCUIT IS PROPRIETARY TO LINEAR TECHNOLOGY AND SUPPLIED FOR USE WITH LINEAR TECHNOLOGY PARTS. C APPROVED ENGINEER DESIGNER T. Gross 7//09 SIZE LTC6EFE A MONOLITHIC SYNCHRONOUS STEP-DOWN REGULATOR CAGE CODE DWG NO REV D DC574A Wednesday, August 05, 009 SCALE: FILENAME: SHEET OF E A 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. 7

8 DEMONSTRATION BOARD IMPORTANT NOTICE Linear Technology Corporation (LTC) provides the enclosed product(s) under the following AS IS conditions: This demonstration board (DEMO BOARD) kit being sold or provided by Linear Technology is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not provided by LTC for commercial use. As such, the DEMO BOARD herein may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including but not limited to product safety measures typically found in finished commercial goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may or may not meet the technical requirements of the directive, or other regulations. If this evaluation kit does not meet the specifications recited in the DEMO BOARD manual the kit may be returned within 0 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY THE SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. EXCEPT TO THE EXTENT OF THIS INDEMNITY, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user releases LTC from all claims arising from the handling or use of the goods. Due to the open construction of the product, it is the user s responsibility to take any and all appropriate precautions with regard to electrostatic discharge. Also be aware that the products herein may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No License is granted under any patent right or other intellectual property whatsoever. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or any other intellectual property rights of any kind. LTC currently services a variety of customers for products around the world, and therefore this transaction is not exclusive. Please read the DEMO BOARD manual prior to handling the product. Persons handling this product must have electronics training and observe good laboratory practice standards. Common sense is encouraged. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact a LTC application engineer. Mailing Address: Linear Technology 60 McCarthy Blvd. Milpitas, CA 9505 Copyright 004, Linear Technology Corporation 8 LT 07 PRINTED IN USA Linear Technology Corporation 60 McCarthy Blvd., Milpitas, CA (408) FAX: (408) LINEAR TECHNOLOGY CORPORATION 07

9 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Analog Devices Inc.: DC574A