Linear Technology DC2251A Demo Manual

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Page 1

Description

DEMO MANUAL DC2251A

LTM8065

40V, 2.5A Silent Switcher

µModule Regulator

Demonstration circuit 2251A is a 40V, 3.5A peak, 2.5A continuous step-down μModule® regulator featuring the

LTM®8065. The demo board is designed for 5V output

from a 6V to 40V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The user adjustable features of the LTM8065 such as output voltage, switching frequency, soft-start and power good can be changed on DC2251A simply by modifying the appropriate resistors and/or capacitors.

The LTM8065 can be programmed to different operation modes. The SYNC pin on the demo board is grounded (JP1 at BURST position) by default for low ripple Burst Mode® operation. Pulse-skipping mode, spread spectrum mode or synchronization mode can be selected respectively by moving JP1 shunt to SYNC position and adding different signals to SYNC terminal. See Quick Start Procedure section for more details.

Figure 1 shows the efficiency of the circuit under different input voltages in Burst Mode operation. The rated maximum continuous load current is 2.5A, while derating is necessary for certain input voltage and thermal conditions. Figure 2 shows the LTM8065 derating curve on DC2251A demo board. The demo board has an optional EMI filter. To achieve high EMI/EMC performance, the input EMI filter is required and the input voltage should be applied at VIN_EMI terminal.

The LTM8065 data sheet gives a complete description of the part, operation and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 2251A.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2251A

L, LT, LTC, LTM, Linear Technology, Burst Mode, µModule and the Linear logo are registered trademarks of Analog Devices, Inc. All other trademarks are the property of their respective owners.

BoarD photo

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DEMO MANUAL DC2251A

LOAD CURRENT (A)

0.001

0.01

0.1110

EFFICIENCY (%)

DC2251A F01

12VIN24V

0 LFM

12VIN24VIN36V

AMBIENT TEMPERATURE (°C)

0255075100

125

DC2251A F02

performance summary

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

* Input Supply Range 6 40 V

OUT

** Maximum Continuous Output Current 2.5 A

OUT

EFE Efficiency at DC V

* When V ** Derating is necessary for certain V

Output Voltage 4.85 5 5.15 V

Switching Frequency VIN = 12V , I

voltage is low, the LTM8065 may skip switching cycles.

and thermal conditions.

Specifications are at TA = 25°C

= 2.5A 1 MHz

OUT

= 12V , I

= 2.5A 91.5 %

OUT

Figure 1. LTM8065 Demo Circuit DC2251A Efficiency vs. Load Current (fSW = 1MHz, V

= 5V, Burst Mode Operation)

OUT

Quick start proceDure

Demonstration circuit 2251A is easy to set up to evaluate the performance of the LTM8065. Refer to Figure 3 for proper measurement equipment setup and follow the procedure below:

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 output voltage ripple by touching the probe tip directly across the output capacitor. See Figure 4 for the proper scope technique.

1. Place JP1 on BURST position.

2. With power off, connect the input power supply to VIN and GND. If the input EMI filter is desired, install the filter and connect the input power supply to VIN_EMI and GND.

Figure 2. LTM8065 Demo Circuit DC2251A Maximum Load Current Derating

3. With power off, connect the load from VOUT to GND.

4. Turn on the power at the input.

NOTE. Make sure that the input voltage does not exceed

40V.

5. Check for the proper output voltage (V

OUT

= 5V).

NOTE. If there is no output, temporarily disconnect the

load to make sure that the load is not set too high or is shorted.

6. Once the proper output voltage is established, adjust the load within the operating ranges and observe the output voltage regulation, ripple voltage, efficiency and other parameters.

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Quick start proceDure

–

DC2251A F04

DEMO MANUAL DC2251A

7. JP1 is placed on BURST position by default, for the low ripple Burst Mode operation. When JP1 is placed on SYNC position, LTM8065 can operate in pulse-skipping mode, spread spectrum mode or synchronization mode respectively, based on the different SYNC terminal inputs. If SYNC terminal is floating, LTM8065 is in pulse-skipping mode. If an external clock is driving the SYNC terminal, LTM8065 is in synchronization mode.

POWER SUPPLY

Please make sure that RT should be choseN to set the LTM8065 switching frequency equal to or below the lowest SYNC frequency. If a 2.9V to 4.2V DC voltage is tied to the SYNC terminal, LTM8065 is in spread spectrum mode. This DC voltage can also be added through a voltage divider (R7 and R8) from the output. The recommended divider bottom resistor (R8) is 200k.

OUT

LOAD

–

DC2251A F03

Figure 4. Proper Measurement Equipment Setup

OUT

GND

Figure 3. Measuring Output Ripple

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DEMO MANUAL DC2251A

FREQUENCY (MHz)

0.511.522.533.544.5

–120

–100

–80

–60

–40

–20

DC2251A F05

Quick start proceDure

Figure 5. DC2251A Output Noise Spectrum, VIN = 12V, V

OUT

= 5V, I

= 2.5A, fSW = 1MHz

OUT

parts List

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 C1 CAP., X5R, 47µF, 10V, 20%, 0805 MURATA, GRM21BR61A476ME15L

2 1 C2 CAP., X5R, 4.7µF, 50V, 10%, 0805 MURATA, GRM21BR61H475KE51L

3 1 C3 CAP., X7R, 0.1µF, 16V, 10%, 0603 MURATA, GRM188R71C104KA01D

4 1 C5 CAP., X5R, 10µF, 25V, 20%, 0603 MURATA, GRM188R61E106MA73D

5 1 C10 CAP., X7R, 0.1µF, 50V, 10%, 0402 TDK, CGA2B3X7R1H104K050BB

6 2 R1, R5 RES., CHIP, 100k, 1/10W, 1%, 0603 VISHAY, CRCW0603100KFKEA

7 1 R2 RES., CHIP, 60.4k, 1/10W, 1%, 0603 VISHAY, CRCW060360K4FKEA

8 1 R3 RES., CHIP, 41.2k, 1/10W, 1%, 0603 VISHAY, CRCW060341K2FKEA

9 1 U1 IC., BGA, 36L, 6.25mm × 6.25mm × 2.32mm LINEAR TECH., LTM8065EY#PBF

Additional Demo Board Circuit Components

1 0 C4, C11 (OPT) CAP., 0603

2 0 C6 (OPT) CAP., X7R, 4.7µF, 50V, 10%, 1206

3 0 C8 (OPT) CAP., X7R, 0.1µF, 50V, 10%, 0402

4 1 C9 CAP., ALUM, 22µF, 63V, 20% SUN ELECTRONIC INDUSTRIES CORP., 63CE22BS

5 0 L1 (OPT) IND, 2.2µH, 4.45mm × 4.06mm WURTH ELEKTRONIK, 74437324022

6 1 R4 RES., CHIP, 0, 1/10W, 0603 VISHAY, CRCW06030000Z0EA

7 0 R6, R7, R8 (OPT) RES., 0603

Hardware: For Demo Board Only

1 10 E1-E6, E8-E11 TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0

2 0 E7 (OPT) TESTPOINT, TURRET, 0.094" PBF MILL-MAX, 2501-2-00-80-00-00-07-0

3 1 JP1 HEADER 3 PIN 0.079 SINGLE ROW WURTH ELEKTRONIK, 62000311121

4 1 XJP1 SHUNT, 0.079" CENTER WURTH ELEKTRONIK, 60800213421

5 4 MH1-MH4 STAND-OFF, NYLON, 0.375" SNAP ON KEYSTONE, 8832

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schematic Diagram

BIAS

VOUT

5V / 2.5A

GND

DEMO MANUAL DC2251A

SYNC

GND

LTM8065EY

VIN

BIAS

C11

OPT

AUX

VOUT

10uF

25V

47uF

10V

0805

OPT

VOUTF1VOUTF2VOUTF3VOUTF4VOUTF5VOUT

E10

OPT

BURST

GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND GND

E6 E5 E4 E3 E2 E1

D6 D5 D4 D3 D2 D1 C2

C1 B3 A6 A4 A1

E11

OPT

JP1

SYNC

VOUT

60.4K

SEE DEMO MANUAL

RUN

4.7uF

50V

0805

VIN

6V - 40V

C10

22uF

0.1uF

100K

63V

63CE22BS

50V

0402

GND

RUN

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.

OPT

VOUT

100K

41.2K

TR/SS

VIN

0.1uF

16V

2.2uH

74437324022

Wurth Elektronik

50V

1206

4.7uF

50V

0402

0.1uF

INPUT EMI FILTER

OPTIONAL

OPT

VIN_EMI

ALL CAPACITORS ARE 0603.

1. ALL RESISTORS ARE 0603.

NOTES: UNLESS OTHERWISE SPECIFIED

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DEMO MANUAL DC2251A

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

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LT 1017 • PRINTED IN USA

 LINEAR TECHNOLOGY CORPORATION 2017