Linear Technology DC2565A Demo Manual

Description

DEMO MANUAL DC2565A

LT8607

42V, 0.75A Micropower Synchronous

Step-Down Regulator

Demonstration Circuit 2565A is a 42V, 0.75A micropower
synchronous step-down regulator featuring the LT®8607.
The demo board is designed for 5V output from a 5.5V
to 42V input. The wide input range allows a variety of
input sources, such as automotive batteries and indus­trial supplies. The LT8607

is a compact, high efficiency,
high speed synchronous monolithic step-down switch­ing regulator that consumes less than 3μA of quiescent
current when output is regulated at 5V. Top and bottom
power switches, compensation components and other
necessary circuits are inside of the LT8607 to minimize
external components and simplify design.

The SYNC pin on the demo board is grounded by default
for low ripple Burst Mode® operation. Move JP1 to PULSE
SKIPPING position can change the operation mode to
pulse-skipping operation. Once JP1 is on SPREAD SPEC­TRUM position, VCC is applied to the SYNC pin for low
EMI spread spectrum operation. To synchronous to an
external clock, move JP1 to SYNC and apply the external
clock to the SYNC turret. Figure 1 shows the efficiency
of the circuit.

The demo board has an EMI filter installed. The radiated
EMI performances of the board (with EMI filter) are shown
in Figure 2 and Figure 3. The red lines in Figure 2 and
Figure 3 are CISPR25 Class 5 peak limit. To use the EMI
filter, the input should be tied to V

, not VIN. An induc-

EMI

tor L2, which is a 0Ω jumper on the board by default
now, can be added in the EMI filter to further reduce the
conducted emission.

The LT8607 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 DC2565A.

Design files for this circuit board are available at

http://www.linear.com/demo/DC2565A

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

performance summary

SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS

V

IN

V

OUT

I

OUT

f

SW

EFE Efficiency at DC V

Input Voltage Range 5.5 42 V

Output Voltage 4.8 5 5.2 V

Maximum Output Current 0.75 A

Switching Frequency 1.85 2 2.15 MHz

Specifications are at TA = 25°C

= 12V, I

IN

= 0.75A 92.4 %

OUT

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1

DEMO MANUAL DC2565A

DC2565A F01

Quick start proceDure

DC2565A is easy to set up to evaluate the performance
of the LT8607. Refer to Figure 4 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. See Figure 5 for the proper scope
technique.

1. Set an input power supply that is capable of 42V/0.75A.

Then turn off the supply.

2. With power off, connect the supply to the input termi-

nals V

and GND.

IN

3. Turn on the power at the input.

NOTE: Make sure that the input voltage never exceeds

42V.

4. Check for the proper output voltage of 5V. Turn off the

power at the input.

5. Once the proper output voltage is established, connect
a variable load capable of sinking 0.75A at 5V to the
output terminals V

and GND. Set the current for 0A.

OUT

a. If efficiency measurements are desired, an ammeter

can be put in series with the output load in order to
measure the DC2565A’s output current.

b. A voltmeter can be placed across the output ter-

minals in order to get an accurate output voltage
measurement.

6. Turn on the power at the input.

NOTE: If there is no output, temporarily disconnect the

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

7. Once the proper output voltage is established again,
adjust the load and/or input within the operating range
and observe the output voltage regulation, ripple volt­age, efficiency and other desired parameters.

8. An external clock can be added to the SYNC termi­nal when SYNC function is used (JP1 on the SYNC
position). Please ensure that the chosen RT sets the
LT8607 switching frequency to equal or below the low­est SYNC frequency. See the Synchronization section
in the data sheet.

Figure 1. Efficiency vs Load Current at 2MHz Switching Frequency

2

100

95

90

85

80

75

70

EFFICIENCY

65

60

55

50

0

0.3 0.45 0.6 0.75

0.15
I

OUT

(A)

VIN = 12V

= 24V

V

IN

dc2565af

Quick start proceDure

DEMO MANUAL DC2565A

50

VERTICAL POLARIZATION

45

PEAK DETECTOR

40

35

30

25

20

15

10

AMPLITUDE (dBuV/m)

–10

5

0

–5

100 200 300 400 500 600 700 800 900 1000

0

FREQUENCY (MHz)

CLASS 5 PEAK LIMIT
FIXED FREQUENCY
SPREAD SPECTRUM MODE

DC2565A F02

Figure 2. LT8607 Demo Circuit EMI Performance in CISPR25
Radiated Emission Test, Antenna Polarization: Vertical
(VIN = 14V, V

OUT

= 5V, I

= 0.75A, 2MHz Switching Frequency)

OUT

50

HORIZONTAL POLARIZATION

45

PEAK DETECTOR

40

35

30

25

20

15

10

AMPLITUDE (dBuV/m)

–10

5

0

–5

100 200 300 400 500 600 700 800 900 1000

0

FREQUENCY (MHz)

CLASS 5 PEAK LIMIT
FIXED FREQUENCY
SPREAD SPECTRUM MODE

DC2565A F03

Figure 3. LT8607 Demo Circuit EMI Performance in CISPR25
Radiated Emission Test, Antenna Polarization: Horizontal
(VIN = 14V, V

OUT

= 5V, I

= 0.75A, 2MHz Switching Frequency)

OUT

Figure 4. Proper Measurement Equipment Setup

V

OUT

GND

Figure 5. Measuring Output Ripple

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DEMO MANUAL DC2565A

parts List

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 C2 CAP., X7R, 4.7µF, 50V, 10% 1206 MURATA, GRM31CR71H475K

2 1 C4 CAP., X7R, 0.22µF, 16V, 10%, 0603 MURATA, GRM188R71C224KA01D

3 1 C5 CAP., C0G, 10pF, 25V, 5%, 0603 AVX, 06033A100JAT2A

4 1 C6 CAP., X7R, 22µF, 10V, 10%, 1206 MURATA, GRM31CR71A226KE15L

5 1 C7 CAP., X7R, 1.0µF, 25V, 10%, 0603 MURATA, GRM188R71E105KA12D

6 1 C8 CAP., X7R, 0.01µF, 16V, 10%, 0603 MURATA, GRM188R71C103KA01D

7 1 L1 IND., 3.3µH WURTH ELECTRONICS, 74438336033

8 1 R2 RES., CHIP, 18.2k, 1/10W, 1%, 0603 VISHAY, CRCW060318K2FKEA

9 1 R3 RES., CHIP, 49.9k, 1/10W, 1%, 0603 VISHAY, CRCW060349K9FKEA

10 2 R1, R4 RES., CHIP, 1M, 1/10W, 1%, 0603 VISHAY, CRCW06031M00FKEA

11 1 R5 RES., CHIP, 187k, 1/10W, 1%, 0603 VISHAY, CRCW0603187KFKEA

12 1 U1 IC, REGULATOR, MSE10 LINEAR TECH., LT8607EMSE#PBF

Additional Demo Board Circuit Components

1 1 C1 CAP., ALUM 22µF 63V SUN ELECT, 63CE22BS

2 2 C3, C10 CAP., X7R, 4.7µF, 50V, 10% 1206 MURATA, GRM31CR71H475K

3 1 C9 CAP., X7R, 4.7µF, 16V, 10%, 0805 MURATA, GRM21BR71C475K73L

4 1 C11 CAP., X7R, 1µF, 50V, 10%, 0805 MURATA, GRM21BR71H105KA12L

5 2 C12, C13 CAP., X7R, 0.1µF, 50V, 10%, 0603 MURATA, GRM188R71H104KA93D

6 1 FB1 FERRITE BEAD 0805 TDK, MPZ2012S331AT000

7 1 L2 RES., CHIP, 0Ω, 3/4W, 2010 VISHAY, CRCW20100000Z0EF

8 0 R6 (OPT.) RES., 0603

Hardware: For Demo Board Only

1 9 E1-E9 TESTPOINT, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0

2 1 E10 (OPT.) TESTPOINT, TURRET, 0.094"

3 1 JP1 DOUBLE ROW HEADER 2 × 4 0.079" WURTH ELECTRONICS, 62000821121

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

5 4 MH1-MH4 STAND-OFF, NYLON 0.50" TALL WURTH ELECTRONICS, 702935000

4

dc2565af

schematic Diagram

D

VOUT

5V /0.75A

GND

DEMO MANUAL DC2565A

PG

E3

C4

L1

0.22µF

VOUT

3.3µH

2

10

C9

C6

74438336033

SW

EN/UV

1

2

1

BST

U1

LT8607EMSE

3

VIN

9

4.7µF

22µF

SYNC

5

16V

10V

R3

0805

1206

8

3

PG

VCC

E4

R4

49.9k

6

7

FB

TR/SS

1.00M

4

E8

1

C5

10pF

R5

187k

GND

11

RT

2

3

R2

18.2k

R6

(Opt)

R1

1.00M

C13

0.1µF

50V

C2

4.7µF

50V

1206

SUNCON

63CE22BS

C1

22µF

4

5

E10

VIN

5.5V - 42V

D

63V

+

0 2010

L2

C10

4.7µF

FB1

C3

4.7µF

MPZ2012S331AT000

C12

0.1µF

C11

1µF

E1

VEMI

5.5V - 42V

50V

50V

50V

50V

GND

1206

1206

0805

E2

E6

EN/UV

C C

VCC

E5

SYNC

JP1

C7

1 2

VCC

1µF

SYNC

(2MHz)

SPREAD SPECTRUM

PULSE SKIPPING

BURST

4

6

8

357

E7

TR/SS

C8

0.01µF

4

E9

GND

B B

ALL CAPACITORS ARE 0603.

NOTES: UNLESS OTHERWISE SPECIFIED

1. ALL RESISTORS ARE 0603.

5

A A

dc2565af

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.

5

DEMO MANUAL DC2565A

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:

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1630 McCarthy Blvd.

Milpitas, CA 95035

Copyright © 2004, Linear Technology Corporation

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dc2565af

LT 0517 • PRINTED IN USA

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