LTM4650-1 Demonstration Manual DC2378A-B
Description
Demonstration circuit DC2378A-B features the LTM®4650EY-1, a high-efficiency, high-density, dual 25A, single 50A, switch mode step-down power module regulator. The input voltage is from 4.5V to 15V. The output voltage is programmable from 0.6V to 1.8V. DC2378A-B can deliver 25A maximum current from each channel. Output current derating is necessary for certain VIN, VOUT, and thermal conditions. The board operates in continuous conduction mode in heavy load conditions. For high efficiency at low load currents, the MODE jumper (JP1) selects pulse-skipping mode for noise-sensitive applications or Burst Mode® operation in less noise-sensitive applications. Two outputs can be connected in parallel for a single 50A output solution with optional jumper resistors. The board allows the user to program how its output ramps up and down through the TRACK/SS pin. The output can be set up to either coincidentally or ratiometrically track with another supply's output. Remote output voltage sensing is available for improved output voltage regulation at the load point. These features and the availability of the LTM4650EY-1 in a compact 15mm × 15mm × 5.01mm BGA package make it ideal for use in many high-density point-of-load regulation applications. The LTM4650-1 data sheet must be read in conjunction with this demo manual for working on or modifying the demo circuit DC2378A-B.
Design files for this circuit board are available at http://www.linear.com/demo/DC2378A-B.
Trademarks: LV, LT, LTC, LTM, Linear Technology, the Linear logo, and Burst Mode are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners.
Figure 1. LTM4650-1/DC2378A-B Demo Board
A photograph of the DC2378A-B demonstration board. Key components visible include the LTM4650-1 module (U1), input/output connectors (VIN+, VIN-, VOUT1, VOUT2), jumpers (JP1, JP2, JP3, JP4, JP5), test points (TRACK1, TRACK2, RUN1, RUN2, PGOOD1, PGOOD2, IOSTEP CLK, CLKIN, TEMP, EXTVCC), and output capacitors (COUT1, COUT7, COUT11, COUT17). Labels indicate voltage/current ratings for channels (1V/25A, 1.5V/25A).
Performance Summary
Specifications are at TA = 25°C
| PARAMETER | CONDITIONS | MIN | TYP | MAX | UNITS |
|---|---|---|---|---|---|
| Input Voltage Range | 4.5 | 15 | V | ||
| Output Voltage VOUT1 | VIN = 4.5V ~ 15V, IOUT1 = 0A ~ 25A, JP1: CCM | 1.5 ±1.5% | V | ||
| Output Voltage VOUT2 | VIN = 4.5V ~ 15V, IOUT2 = 0A ~ 25A, JP1: CCM | 1 ±1.5% | V | ||
| Per-Channel Maximum Continuous Output Current | Derating Is Necessary for Certain VIN, VOUT and Thermal Conditions, See Data Sheet for Detail. | 25 (Per-Channel) | A | ||
| Default Operating Frequency | 500 | kHz | |||
| Resistor Programmable Frequency Range | 250 | 780 | kHz | ||
| External Clock Sync. Frequency Range | 400 | 780 | kHz | ||
| Efficiency of Channel 1 | VIN = 12V, VOUT1 = 1.5V, IOUT1 = 25A, fSW = 500kHz | 88.8 | % | ||
| See Figure 4 | |||||
| Efficiency of Channel 2 | VIN = 12V, VOUT2 = 1V, IOUT2 = 25A, fSW = 500kHz | 86.5 | % | ||
| See Figure 5 | |||||
| Load Transient of Channel 1 | VIN = 12V, VOUT1 = 1.5V, ISTEP = 12.5A ~ 18.75A | See Figure 6 | |||
| Load Transient of Channel 2 | VIN = 12V, VOUT2 = 1V, ISTEP = 12.5A ~ 18.75A | See Figure 7 |
Quick Start Procedure
Demonstration circuit DC2378A-B is easy to set up to evaluate the performance of the LTM4650EY-1. Please refer to Figure 2 for proper measurement setup and follow the procedure below:
- Place jumpers in the following positions for a typical application:
JP1 MODE JP2 RUN1 JP3 RUN2 JP4 TRACK1 SEL. JP5 TRACK2 SEL. CCM ON ON SOFT-START SOFT-START - With power off, connect the input power supply, load and meters as shown in Figure 2. Preset the load to 0A and VIN supply to 12V.
- Turn on the power supply at the input. The output voltage in channel 1 should be 1.5V ±1.5% (1.4775V ~ 1.5225V) and the output voltage in channel 2 should be 1V ±1.5% (0.985V ~ 1.015V).
- Once the proper output voltage is established, adjust the load within the operating range and observe the output voltage regulation, output voltage ripple, efficiency and other parameters. Output ripple should be measured at J1 and J2 with BNC cables. 50Ω termination should be set on the oscilloscope or BNC cables.
- (Optional) For optional load transient test, apply an adjustable pulse signal between IOSTEP CLK and GND test point. Pulse amplitude (3V ~ 3.5V) sets the load step current amplitude. The output transient current can be monitored at the BNC connector J3 (10mV/A). The pulse signal should have very small duty cycle (< 1%) to limit the thermal stress on the transient load circuit. Switch the jumper resistors R34 or R35 (on the backside of boards) to apply load transient on channel 1 or channel 2 correspondingly.
- (Optional) LTM4650-1 can be synchronized to an external clock signal. Place the JP1 jumper on EXT_CLK and apply a clock signal (0V ~ 5V, square wave) on the CLKIN test point.
- (Optional) The outputs of LTM4650-1 can track another supply. The jumpers JP4 and JP5 allow choosing soft-start or output tracking. If tracking external voltage is selected, the corresponding test points, TRACK1 and TRACK2, need to be connected to a valid voltage signal.
- (Optional) LTM4650-1 can be configured for a 2-phase single output at up to 50A on DC2378A-B. Install 0Ω resistors on R14, R17, R28, R39, R43, R44, R45 and remove R7, R19. Output voltage is set by R25 based on equation Vout = 0.6V(1 + 60.4k/R25).
Figure 2. Test Setup of DC2378A-B
A diagram illustrating the test setup for the DC2378A-B. It shows connections for input voltage (VIN+, VIN-) from a power supply with an ammeter in series, and to the load (Load1, Load2) with voltmeters and ammeters connected to measure output voltage (VOUT1, VOUT2) and current. Test points like RUN1, RUN2, SOFT-START, TRACK1, TRACK2 are indicated. BNC connectors (J1, J2) are shown for oscilloscope connections.
Figure 3. Measuring Output Voltage Ripple
A diagram showing how to measure output voltage ripple. A voltage probe is connected across the output terminals (VOUT, GND) of the demo board, with the probe tip placed close to the output capacitors.
Figure 4. Measured Efficiency on Channel 1
Graph showing measured efficiency (%) versus output load current (A) for Channel 1. Plots are shown for 5VIN, 1.5VOUT and 12VIN, 1.5VOUT conditions, with the switching frequency at 500kHz and Channel 2 disabled.
Figure 5. Measured Efficiency on Channel 2
Graph showing measured efficiency (%) versus output load current (A) for Channel 2. Plots are shown for 5VIN, 1VOUT and 12VIN, 1VOUT conditions, with the switching frequency at 500kHz and Channel 1 disabled.
Figure 6. Measured Channel 1 12.5A to 18.75A Load Transient
Oscilloscope trace showing the output voltage response to a load transient from 12.5A to 18.75A for Channel 1 (VIN = 12V, VOUT1 = 1.5V). The trace displays the output voltage deviation during the current step.
Figure 7. Measured Channel 2 12.5A to 18.75A Load Transient
Oscilloscope trace showing the output voltage response to a load transient from 12.5A to 18.75A for Channel 2 (VIN = 12V, VOUT2 = 1V). The trace displays the output voltage deviation during the current step.
Figure 8. Measured Output Voltage Ripple at 12V Input, 1.5V/25A with Standard Demo Circuit Default Setup
Oscilloscope trace showing the output voltage ripple for Channel 1 under specific input and output conditions (12V input, 1.5V output). The trace displays the small AC variations on the DC output voltage.
Figure 9. Measured Output Voltage Ripple at 12V Input, 1V/25A with Standard Demo Circuit Default Setup
Oscilloscope trace showing the output voltage ripple for Channel 2 under specific input and output conditions (12V input, 1V output). The trace displays the small AC variations on the DC output voltage.
Figure 10. Thermal Capture at 12VIN, 1.5VOUT at 25A and 1VOUT at 25A
A thermal image of the DC2378A-B demo board operating under load. The image displays temperature distribution across the board, with the LTM4650-1 module showing the highest temperature (around 77°C) under the specified test conditions (12VIN, 1.5VOUT at 25A and 1VOUT at 25A, ambient temperature 23°C, 200 LFM airflow, no heat sink).
Parts List
Required Circuit Components:
| ITEM | QTY | REFERENCE | PART DESCRIPTION | MANUFACTURER/PART NUMBER |
|---|---|---|---|---|
| 1 | 1 | CIN1 | CAP., ALUM. ELECT.,330µF, 25V, 20% | PANASONIC, 25SVPF330M |
| 2 | 4 | CIN2, CIN3, CIN4, CIN5 | CAP., 22µF,X5R, 25V, 10%,1210 | MURATA, GRM32ER61E226KE15L |
| 3 | 4 | COUT9, COUT10, COUT12, COUT18 | CAP., POSCAP, 470µF, 2.5V, 0.005Ω, 7343 | PANASONIC, ETPF470M5H |
| 4 | 10 | COUT2, COUT3, COUT4, COUT5, COUT6 COUT8, COUT13, COUT14, COUT15, COUT16 | CAP., 100µF, X5R, 6.3V, 20%, 1210 | AVX, 12106D107MAT2A |
| 5 | 1 | C1 | CAP., 4.7µF, X5R, 16V,20%, 0805 | KEMET, C0805C475M4PACTU |
| 6 | 1 | C2 | CAP., 1µF,X7R, 25V,10%, 0805 | AVX, 08053C105KAT2A |
| 7 | 2 | C5, C7 | CAP., 0.1µF, X5R, 25V, 10%, 0603 | AVX, 06033D104KAT2A |
| 8 | 1 | C10 | CAP., 220pF, X7R, 100V,10%, 0603 | AVX, 06031C221KAT2A |
| 9 | 1 | C12 | CAP., 47pF, X7R, 50V,10%, 0603 | AVX, 06035A470J4T2A |
| 10 | 4 | C13, C14, C15, C16 | CAP., 1µF, X7R, 10V,10%, 0603 | AVX, 0603ZC105KAT2A |
| 11 | 1 | C17 | CAP., 3.3nF, X7R, 50V,10%, 0603 | AVX, 06035C332KAT2A |
| 12 | 1 | C18 | CAP., 4.7nF, X7R, 50V,10%, 0603 | AVX, 06035C472KAT2A |
| 13 | 1 | Q1 | XSTR., N-CH, 40V, DPAK-2, TO-252 | VISHAY, SUD50N04-8M8P-4GE3 |
| 14 | 4 | R1, R3, R22, R26 | RES., 10 OHMS, 1/10W, 1%, 0603 | NIC, NRC06F10R0TRF |
| 15 | 1 | R5 | RES., 100k, 1/10W, 1%, 0603 | VISHAY, CRCW0603100KFKEA |
| 16 | 4 | R9, R12, R15, R18 | RES.., 60.4k, 1/10W,1%, 0603 | VISHAY, CRCW060360K4FKEA |
| 17 | 2 | R10, R13 | RES.., 6.04k, 1/10W,1%, 0603 | VISHAY, CRCW06036K04FKEA |
| 18 | 1 | R19 | RES., 90.9k, 1/10W,1%, 0603 | VISHAY, CRCW060390K9FKEA |
| 19 | 3 | R24, R27, R36 | RES., 10k, 1/10W,1%, 0603 | YAGEO, RC0603FR-0710KL |
| 20 | 1 | R25 | RES., 40.2k, 1/10W,1%, 0603 | VISHAY, CRCW060340K2FKEDA |
| 21 | 1 | R30 | RES., 121k, 1/10W,1%, 0603 | VISHAY, CRCW0603121KFKEA |
| 22 | 1 | R37 | RES., HIGH POWER, 0.01Ω, 2W,1%, 2512 | VISHAY, WSL2512R0100FEA18 |
| 23 | 1 | R46 | RES., 21k, 1/10W,1%, 0603 | YAGEO, RC0603FR-0721KL |
| 24 | 1 | R47 | RES., 20k, 1/10W,1%, 0603 | YAGEO, RC0603FR-0720KL |
| 25 | 1 | U1 | I.C., 16X16X5.01-BGA | LINEAR TECH., LTM4650EY-1#PBF |
| Additional Demo Board Circuit Components | ||||
| 1 | 0 | COUT1, COUT7, COUT11, COUT17 | CAP., OPT, 7343 | OPT |
| 2 | 0 | C3, C4, C6, C8, C9, C11 | CAP., OPTION, 0603 | OPT |
| 3 | 0 | R2, R4, R6, R8, R11, R14, R16, R17, R20, R23, R28, R31, R33, R39, R40, R41, R42, R48 | RES., OPTION, 0603 | OPT |
| 4 | 4 | R7, R21, R29, R32 | RES., 0Ω, 1/10W, 0603 | VISHAY, CRCW06030000Z0EA |
| 5 | 1 | R34 | RES., 0Ω, 1/2W, 2010 | VISHAY, CRCW20100000Z0EF |
| 6 | 0 | R35 | RES., OPTION, 2010 | OPT |
| 7 | 0 | R38, R43, R44, R45 | RES., OPTION, 2512 | OPT |
| Hardware: For Demo Board Only | ||||
| 1 | 16 | E1, E3, E4, E5, E6, E7, E8, E9, E10, E12, E13, E14, E15, E16, E17, E18 | TEST POINT, TURRET, .094" MTG. HOLE | MILL-MAX, 2501-2-00-80-00-00-07-0 |
| 2 | 1 | JP1 | CONN., HEADER, 2×4, 2mm | WURTH ELEKTRONIK, 62000821121 |
| 3 | 3 | JP2, JP3, JP4 | CONN., HEADER, 1×3, 2mm | WURTH ELEKTRONIK, 62000311121 |
Additional components listed for connectors and jumpers:
| ITEM | QTY | REFERENCE | PART DESCRIPTION | MANUFACTURER/PART NUMBER |
|---|---|---|---|---|
| 4 | 1 | JP5 | CONN., HEADER, 2×3, 2mm | WURTH ELEKTRONIK, 62000621121 |
| 5 | 5 | XJP1, XJP2, XJP3, XJP4, XJP5 | SHUNT, 2mm | WURTH ELEKTRONIK, 60800213421 |
| 6 | 3 | J1, J2, J3 | CONN., BNC STR PCB JK, THRU- HOLE, 5 PINS | CONNEX 112404 |
| 7 | 2 | J4, J5 | CONN., JACK, BANANA, NON-INSULATED, 0.218" | KEYSTONE, 575-4 |
| 8 | 4 | J6, J7, J8, J9 | STUD, TESTPIN | PEM KFH-032-10 |
| 9 | 8 | J6, J7, J8, J9 (x2) | NUT, BRASS 10-32 | ANY #10-32 |
| 10 | 4 | J6, J7, J8, J9 | RING, LUG #10 | KEYSTONE, 8205, #10 |
| 11 | 4 | J6, J7, J8, J9 | WASHER, TIN PLATED BRASS | ANY #10, #10EXT BZ TN |
| 12 | 4 | (STAND-OFF) | STANDOFF, NYLON, SNAP-ON, 0.500" | KEYSTONE, 8833 |
Schematic Diagrams
Detailed schematic diagrams of the DC2378A-B demonstration circuit are provided. These diagrams illustrate the interconnection of the LTM4650EY-1 power module with input filtering (capacitors CIN1-CIN5), output filtering (capacitors COUT1-COUT18), control jumpers (JP1-JP5), test points, and various resistors and optional components. The diagrams show configurations for dual-channel operation, single-channel operation, and load transient testing.
Key notes from the schematic include: "UNLESS OTHERWISE SPECIFIED: 1. ALL RESISTORS AND CAPACITORS ARE 0603."
The diagrams also include revision history, customer notices regarding design responsibility, and contact information for Linear Technology Applications Engineering.
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 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 may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety measures typically found in finished commercial goods. As a prototype, this product may not meet the technical requirements of EU directives like electromagnetic compatibility. If the evaluation kit does not meet specifications, it may be returned within 30 days for a full refund. The warranty is exclusive and in lieu of all other warranties. The user assumes all responsibility and liability for proper and safe handling of the goods and releases LTC from all claims arising from handling or use. Precautions regarding electrostatic discharge are necessary. Products may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). No license is granted under any patent right or other intellectual property. LTC assumes no liability for applications assistance, customer product design, software performance, or infringement of patents. LTC services customers worldwide, and this transaction is not exclusive. Users must read the DEMO BOARD manual prior to handling the product and should 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, contact an LTC application engineer.
Mailing Address: Linear Technology, 1630 McCarthy Blvd., Milpitas, CA 95035.
Copyright © 2004, Linear Technology Corporation.
