DEMO MANUAL DC2148A LT8709 Negative Input Synchronous Multi-Topology DC/DC Controller Description Demonstration circuit 2148A features the LT®8709, a negative input synchronous multi-topology DC/DC controller designed for negative input power supplies where the highest input supply voltage is ground. Examples of these circuits include negative buck, negative boost, negative buck-boost and negative inverting. The DC2148A is a negative buck-boost with an operating input voltage range from –4.5V to –38V and an output voltage of –12V, however this demo circuit can be easily reconfigured for other negative input topologies. The maximum output current for DC2148A is 5A, the switching frequency is 400kHz and the maximum efficiency with a –12V input is 91%. The output voltage is programmed with a single resistor R7 and a –4.22V turn-on threshold is programmed with resistor divider R3 and R4. Current sense resistor R1 programs the switch current limit and current sense resistor R2 programs an output current limit. Filters can be added to the switch and output current sense resistors using component placeholders on the PCB. The IMON output voltage is proportional to output current and a 0.1µF capacitor C17 filters IMON. This demo circuit uses logic-level 60V NMOS and PMOS that operate down to a –4.5V input voltage. Diode D1 is in parallel with the PMOS to improve efficiency. Resistors can be added to the gate drives of both NMOS and PMOS. There are placeholders so the NMOS and PMOS can be paralleled. Ceramic capacitors are used at both the circuit input and output because of their small size and high ripple current capability. The input has an aluminum electrolytic capacitor in addition to the ceramic capacitors and there is a placeholder to add an electrolytic capacitor at the output. The MODE input is pulled up to INTVCC by 100k resistor R14 which allows discontinuous conduction mode (DCM) and pulse-skipping operation. There is a placeholder that can be used to connect MODE to –VIN instead of INTVCC for continuous conduction mode (CCM) switching. The switching frequency is adjustable using resistor R5. The SYNC input can be used to synchronize the switching frequency. Zero ohm jumper R16 from SYNC to –VIN must be removed prior to using the SYNC input. Feedback loop compensation can be optimized using components R6, C7 and C8. Capacitor C14 at the SS pin programs soft-start. PG is an open-collector status flag output and is pulled up to the INTVCC pin voltage by the 100k resistor R23. There are placeholders to add level shifting circuitry for EN/FBIN, SYNC and PG signals. In addition, the demo circuit is designed to be easily reconfigured to many other applications, including the example schematics in the data sheet. The PCB has extensive vias for thermal performance. Synchronous switching and negative input operation make the LT8709 attractive for negative input, high-power voltage regulator circuits. The LT8709EFE is available in a thermally enhanced 20-lead TSSOP package. The LT8709 data sheet must be read in conjunction with this demo manual to properly use or modify DC2148A. Design files for this circuit board are available at http://www.linear.com/demo/DC2148A 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. dc2148af 1 DEMO MANUAL DC2148A Performance Summary PARAMETER Specifications are at TA = 25°C CONDITIONS MIN TYP MAX –4.5 Minimum Input Voltage, V–VIN UNITS V –38 Maximum Input Voltage, V–VIN V Maximum Output Current (See Figure 2), IOUT –12V > V–VIN > –38V V–VIN = –4.5V Input EN/FBIN Turn-On Voltage, V–VIN R3 = 13.3k, R4 = 10k 1%, VGND,–VIN = Rising Output Voltage, VOUT R7 = 130k Efficiency V–VIN = –12V, IOUT = 2.5A 91 % Switching Frequency R5 = 88.7k 400 kHz Output Current Limit R2 = 0.006Ω, 1% 8.3 A 2 5 2.5 A A –4.22 –12.5 V –11.7 V dc2148af DEMO MANUAL DC2148A Quick Start Procedure To use DC2148A to evaluate the performance of the LT8709, refer to Figure 1 for the proper measurement equipment setup, Figure 2 for the maximum output current versus input voltage and then follow the procedure: NOTE: Make sure that the voltage applied to –VIN does exceed –38V. A GND to –VIN voltage that is greater than 38V may cause voltage spikes that occur during switching to exceed the voltage ratings at the drains of the NMOS and PMOS. NOTE: 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 to terminals across the –VIN or VOUT capacitors. See Figure 3 for proper scope probe technique. 1.Connect the EN/FBIN terminal to –VIN with a clip-on lead. Connect the power supply (with power off), load, and meters as shown in Figure 1. 2.After all connections are made, turn on the input power and verify that the input voltage is between –4.5V and –38V. 3.Remove the clip-on lead from EN/FBIN. Verify that the output voltage is –12V. NOTE: If the output voltage is low, temporarily disconnect the load to make sure that it is not set too high. Once the proper output voltage is established, adjust the input voltage and load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other parameters. Figure 1. Proper Measurement Equipment Setup for DC2148A dc2148af 3 DEMO MANUAL DC2148A Quick Start Procedure MAXIMUM OUTPUT CURRENT (A) 6 5 4 3 2 1 0 0 –5 –10 –15 –20 –25 –30 –35 –40 INPUT VOLTAGE (V) DC2148A F01 Figure 2. Maximum Output Current vs Input Voltage VOUT PGND Figure 3. Proper Scope Probe Technique 4 dc2148af DEMO MANUAL DC2148A Quick Start Procedure 100 95 EFFICIENCY (%) 90 85 80 75 70 65 60 V–VIN = –4.5V V–VIN = –12V V–VIN = –18V 55 50 0 1 2 3 4 LOAD CURRENT (A) 5 6 DC2148A F04 Figure 4. Efficiency VOUT 500mV/DIV 100mV/DIV IOUT 2A/DIV 1µs/DIV DC2148A F05 Figure 5. Output Voltage Ripple at 5A Output Current, V–VIN = –12V, VOUT = –12V 200µs/DIV DC2148A F06 Figure 6. Output Voltage Load Transient Response, V–VIN = –12V, VOUT = –12V, IOUT = 2.5A to 5A to 2.5A dc2148af 5 DEMO MANUAL DC2148A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER Required Circuit Components 1 5 C1, C2, C3, C4, C18 Cap., X5R 10µF 50V 10% 1210 MURATA GRM32ER61H106KA12L 2 5 C5, C6, C11, C12, C13 Cap., X5R 22µF 16V 20% 1210 TDK C3225X5R1C226M 3 1 C7 Cap., X7R 4.7nF 25V 10% 0603 AVX 06033C472KAT2A 4 1 C8 Cap., NPO 47pF 25V 10% 0603 AVX 06033A470KAT2A 5 2 C9, C16 Cap., X7R 2.2µF 100V 10% 1210 Murata GRM32ER72A225KA35L 6 2 C10, C15 Cap., X7R 2.2µF 16V 20% 0805 Taiyo Yuden EMK212BJ225MG 7 1 C14 Cap., X5R 0.22µF 50V 20% 0603 TDK C1608X5R1H224M 8 1 C17 Cap., X7R 0.1µF 25V 10% 0603 AVX 06033C104KAT2A 9 1 D1 Diode Schottky, 60V/3Amp SOD-128 Philips(NXP) PMEG6030EP 10 1 L1 Inductor, 3.5µH ± 20% Würth Electronik 74485540350 11 1 MN1 MOSFET, Single N-Channel 22A/60V Power 56 Fairchild Semi. FDMS86520L 12 1 MP1 MOSFET, Single P-Channel 60V DPAK Vishay SUD19P06-60-E3 13 1 R1 Res., 0.002 2W 1% 2512 Vishay WSL-2512-2L000-F-EA 14 1 R2 Res., 0.006 1W 1% 2512 Vishay WSL-2512-6L000-F-EA 15 1 R3 Res., Chip 13.3k 0.06W 1% 0603 Vishay CRCW060313K3FKEA 16 1 R4 Res., Chip 10.0k 0.06W 1% 0603 Vishay CRCW060310K0FKEA 17 1 R5 Res., Chip 88.7k 0.06W 1% 0603 Vishay CRCW060388K7FKEA 18 1 R6 Res., Chip 10k 0.06W 5% 0603 Vishay CRCW060310K0JNEA 19 1 R7 Res., Chip 130k 0.06W 1% 0603 Vishay CRCW0603130KFKEA 20 1 U1 I.C., Volt. Reg. TSSOP20-FE/CB Linear Tech. Corp. LT8709EFE Additional Demo Board Circuit Components 1 0 C20, C23, C24, C25, C30, C31, C32 (Opt) Cap., 0603 2 1 C21 Cap., Alum 220µF 50V 20% 10mm Dia. SMD 3 0 C19, C22, C27, C28, C29, C35, C36, C37 (Opt) Cap., 1210 4 0 C26 (Opt) Cap., 8mm Dia. SMD 5 0 C33, C34, C39 (Opt) Cap., 0805 Sun Elect. 50CE220AX 6 0 C38 (Opt) Cap., X7R 0.1µF 100V 10% 1206 AVX 12061C104KAT2A 7 0 D2, D3 (Opt) Schottky Barrier 100V SOD323 NXP Semi. BAT46WJ 8 0 D4 (Opt) Schottky Diode PowerDi5 9 0 D5 (Opt) Diode, SOD-323 10 0 MN2 (Opt) MOSFET, Single N-Channel 60V PowerPAK SO8 11 0 MP2 (Opt) MOSFET, Single P-Channel PowerPAK SO8 12 0 Q1 (Opt) Trans., PNP SOT23 Zetex FMMT593 13 0 Q2 (Opt) XSTR, NPN SOT-23 Diode Inc. MMBT2222A 14 0 R8, R9, R10, R11, R12, R13, R15, R17, R18, R21, R22, R25, R26, R31, R32, R33, R34, R37, R38, R39, R45 (Opt) Res., 0603 6 dc2148af DEMO MANUAL DC2148A Parts List ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER 15 2 R14, R23 Res., Chip 100k 0.06W 5% 0603 Vishay CRCW0603100KJNEA 16 2 R16, R20 Res/Jumper, Chip 0Ω 0.25W 5A 0603 Vishay CRCW06030000Z0EA 17 1 R19 Res/Jumper, Chip 0Ω 1.5W 16A 2512 Vishay CRCW25120000ZOEA 18 0 R24, R27, R28, R29, R36 (Opt) Res., 2512 19 0 R30, R35, R40 (Opt) Res., Chip 1k 0.06W 5% 0603 Vishay CRCW06031K00JNEA 20 0 R41 (Opt) Res., Chip 100k 0.06W 5% 0603 Vishay CRCW0603100KJNEA 21 0 R42, R43, R44 (Opt) Res., Chip 20k 0.06W 5% 0603 Vishay CRCW060320K0JNEA Hardware: For Demo Board Only 1 11 E1, E2, E3, E4, E5, E6, E7, E8, E9, E10, E11 Turret, Testpoint Mill Max 2501-2-00-80-00-00-07-0 2 4 J1, J2, J3, J4 Connector, Banana Jack Keystone 575-4 3 4 MH1-MH4 STAND-OFF, NYLON 0.50" Tall (SNAP ON) Keystone 8833 dc2148af 7 ‐4.5V TO ‐38V + C18 10µF 50V 1210 C1 10µF 50V 1210 C2 10µF 50V 1210 SYNC MODE EN/FBIN ‐VIN ‐4.5V TO ‐38V E6 E5 E4 E3 SYNC EN/FBIN NOTE: UNLESS OTHERWISE SPECIFIED 1) ALL RESISTRORS 5%, 0603 2) ALL CAPACITORS 0603 E2 C21 220µF 50V 10mm Dia. SMD J2 ‐VIN J1 C3 10µF 50V 1210 C4 10µF 50V 1210 (Opt) (Opt) C24 C23 R8 (Opt) ‐VIN (Opt) C25 4 GND R16 0 Ohm (Opt) R15 100k R14 10.0k 1% C10 2.2uF 16V 0805 INTVCC 2.2µF 100V R3 1210 13.3k 1% R4 C9 R10 (Opt) MN1 FDMS86520L L1A 3.5µH 74485540350 Wurth Electronik L1A‐1 1 INTVCC 0.002 1% 2W 2512 R9 (Opt) R1 GND 12 19 17 16 13 INTVCC SYNC MODE EN/FBIN GND CSP BG 22uF 16V 1210 22uF 16V 1210 C6 (Opt) 1210 C5 (Opt) 1210 C28 C22 D1 PMEG6030EP MP1‐D MP1‐S R2 0.006 1% 1W 2512 C14 0.22µF R5 88.7k 1% 400kHz U1 LT8709EFE 6 PGND 14 CSN SS 3 11 BG RT 18 ‐VIN 20 15 CSP 10 TG 7 ISP 21 R11 R13 (Opt) BIAS ISN ISP TG IMON VC FBY PG PG 4 5 2 C17 0.1µF IMON INTVEE 9 1 BIAS 8 (Opt) R18 (Opt) R17 MP1 SUD19P06‐60‐E3 (Opt) R12 (Opt) INTVEE ISN 8 ‐VIN E1 C7 4.7nF R6 10k C15 2.2uF 16V 0805 C8 47pF R20 0 Ohm R45 (Opt) C16 2.2µF 100V 1210 2512 R19 0 Ohm L1B‐3 (Opt) 130k 1% C20 R7 R23 100k INTVCC L1B 2 3.5µH 74485540350 Wurth Electronik 3 C13 22uF 16V 1210 C11 22uF 16V 1210 C12 22uF 16V 1210 * SEE FIGURE 2 FOR IOUT MAX. VS. -VIN C19 (Opt) 1210 TG INTVCC SYNC * E8 PG E11 ‐VIN E10 IMON E9 VOUT ‐12V ‐4.5V TO ‐38V EN/FBIN PG BIAS ‐VIN CSP MP1‐S BG INTVEE ISN ISP L1B‐3 PGND C26 8mm Dia . SMD (Opt) VOUT J4 MP1‐D L1A‐1 + J3 E7 DEMO MANUAL DC2148A Schematic Diagram dc2148af ‐VIN INTVCC ‐VIN SYNC EN/FBIN PG BIAS CSP MP1‐S BG INTVEE ISN ISP L1B‐3 TG MP1‐D L1A‐1 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. C39 VOUT (Opt) 2512 R38 (Opt) R37 (Opt) (Opt) 0805 BIAS ISP R28 INTVEE ISN (Opt) R21 R32 (Opt) R31 (Opt) (Opt) 2512 ISP (Opt) R22 ‐VIN C31 (Opt) ISP D4 2 1 (Opt) C30 ISN C32 (Opt) L1B‐3 MP2 (Opt) PowerPAK SO8 C34 (Opt) 0805 TG VOUT L1A‐1 (Opt) PowerDi5 3 R33 (Opt) BIAS R26 (Opt) R34 (Opt) ISN INTVCC D5 (Opt) SOD‐323 (Opt) 0805 C33 (Opt) 2512 R27 (Opt) 1210 (Opt) 2512 C36 (Opt) 1210 R24 INTVEE ISN R29 R25 (Opt) ISP MP1‐S MP1‐D (Opt) 1210 C27 C35 R42 20k (Opt) VOUT PG C37 (Opt) 1210 R30 1k (Opt) OPTIONAL LEVEL SHIFTING CIRCUITRY D3 BAT46WJ (Opt) SOD323 C29 (Opt) 1210 E12 V_EXT E13 PGND (Opt) 2512 R36 R43 20k (Opt) Q2 MMBT2222A (Opt) SOT‐23 R35 1k (Opt) ‐VIN CSP ‐VIN EN/FBIN R41 100k (Opt) SYNC R44 20k (Opt) Q1 FMMT593 (Opt) SOT23 R40 1k (Opt) ‐VIN D2 BAT46WJ (Opt) SOD323 L1A‐1 BG C38 0.1uF 100V (Opt) 1206 R39 (Opt) MN2 (Opt) PowerPAK SO8 DEMO MANUAL DC2148A Schematic Diagram dc2148af 9 DEMO MANUAL DC2148A 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 30 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 1630 McCarthy Blvd. Milpitas, CA 95035 Copyright © 2004, Linear Technology Corporation 10 Linear Technology Corporation dc2148af LT 0315 • PRINTED IN USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com LINEAR TECHNOLOGY CORPORATION 2015