Linear Technology LT3507A Quick setup guide

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DEMO MANUAL DC1781A

DESCRIPTION

LT3507A

Triple Monolithic Step-Down

Regulator with LDO

Democircuit1781AisaTripleMonolithicStep-DownRegu-

lator with LDO featuring the LT3507A. The demo circuit

is designed for 1.8V, 3.3V, 5.0V and 2.5V outputs from a

7V to 36V input. The current capability of each channel

is 2.7A, 1.5A, 1.8A and 0.3A respectively. Independent

input voltage, feedback, soft-start and power good pins

for each channel simplify complex power supply tracking/

sequencing requirements.

All three converters are either synchronized to a common

external clock input or single-resistor programmable from

250kHz to 2.5MHz using internal oscillator. At all frequen-

cies, a 180° phase shift between VOUT1 and the other two

outputs is maintained, reducing input voltage ripple and 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.

PERFORMANCE SUMMARY

component size. Programmable frequency allows for opti-

mization between efficiency and external component size.

Each output can be independently disabled using its own

soft-start pin, or by using the SD terminal the entire part

can be placed in a low quiescent current shutdown mode.

The LT3507A data sheet gives a complete description of

the part, operation and application information. The data

sheet must be read in conjunction with this quick start

guide for demo circuit 1781A.

Design files for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C)

PARAMETER CONDITIONS VALUE

Minimum Input Voltage 7V

Maximum Input Voltage 36V

Output Voltage VOUT1 V

IN = 7~36V 1.80V ±3%

Output Voltage VOUT2 VIN = 7~36V 3.33V ±3%

Output Voltage VOUT3 VIN = 7~36V 5.0V ±3%

Output Voltage VOUT4 VIN = 7~36V 2.52V ±3%

Switching Frequency 450kHz ±10%

Maximum Output Current IOUT1 VIN = 7~36V 2.7A

Maximum Output Current IOUT2 VIN = 7~36V 1.5A

Maximum Output Current IOUT3 VIN = 7~36V 1.8A

Maximum Output Current IOUT4 VIN = 7~36V 0.3A

Voltage Ripple VOUT1 VIN = 12V, IOUT1 = 2.7A <20mV

Voltage Ripple VOUT2 VIN = 12V, IOUT2 = 1.5A <20mV

Voltage Ripple VOUT3 VIN = 12V, IOUT3 = 1.8A <20mV

Voltage Ripple VOUT4 VIN = 12V, IOUT4 = 0.3A <10mV

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DEMO MANUAL DC1781A

QUICK START PROCEDURE

Demo circuit 1781A is easy to set up to evaluate the

performance of the LT3507A. Refer to Figure 2 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 input or output

voltage ripple by touching the probe tip directly across

the VIN or VOUT and GND terminals. See Figure 3 for

proper scope probe technique.

1. With power off, connect the input power supply to VIN

and GND.

2. Turn on the power at the input.

NOTE. Make sure that the input voltage does not ex-

ceed 36V.

3. Check for the proper output voltages.

NOTE. If there is no output, temporarily disconnect

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

4. Once the proper output voltages are established, adjust

the load within the operating range and observe the

output voltage regulation, ripple voltage, efficiency and

other parameters.

Figure 1. DC1781A Buck Channel Efficiency at VIN = 12V, f = 450kHz

LOAD CURRENT (A)

0.3

EFFICIENCY (%)

100

0.6 1.8 2.1 2.4 2.70.9 1.2

DC1781A F01

1.5

VOUT1 = 5.0V

VOUT1 = 3.3V

VOUT1 = 1.8V

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DEMO MANUAL DC1781A

QUICK START PROCEDURE

Figure 2. DC1781A Proper Equipment Setup

Figure 3. Measuring Input or Output Ripple

GND

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DEMO MANUAL DC1781A

QUICK START PROCEDURE

SYNC FUNCTION

Install a 10k R20 resistor if the board is synchronized from

an external signal generator.

Figure 4. Cut Line for the EMI Filter Installation

EMI FILTER

Install EMI filters on the backside of the DC1781A, how-

ever, a trace cut is required for the insertion of the option

circuit. See Figure 4 for the cut line.

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DEMO MANUAL DC1781A

PARTS LIST

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 3 CIN1, CIN2, CIN3 CAP., X7R, 2.2μF, 50V, 10%, 1210 TDK, C3225X7R1H225K

2 1 C1 CAP., X7R, 0.47μF, 25V, 10%, 0603 MURATA, GRM188R71E474KA12D

3 2 C2, C9 CAP., X7R, 0.22μF, 25V, 10%, 0603 TDK, C1608X7R1E224K

4 2 C3, C10 CAP., X5R, 47μF, 10V, 20%, 1206 TAIYO YUDEN, LMK316BJ476ML-T

5 1 C4 CAP., X5R, 22μF, 6.3V, 20%, 1206 TAIYO YUDEN, JMK316BJ226ML

6 3 C5, C6, C11 CAP., X7R, 680pF, 50V, 10%, 0402 AVX, 04025C681KAT

7 4 C7, C8, C13, C20 CAP., X5R, 0.1μF, 10V, 10%, 0402 AVX, 0402ZD104KAT

8 1 C12 CAP., X5R, 2.2μF, 6.3V, 20%, 0603 TAIYO YUDEN, JMK107BJ225MA

9 3 C15, C17, C19 CAP., NPO, 47pF, 50V, 5%, 0402 AVX, 04025A470JAT

10 1 D4 DIODE, SCHOTTKY, B340A, SMA-DIODE DIODES INC., B340A

11 2 D5, D6 DIODE, SCHOTTKY, B240A, SMA-DIODE DIODES INC., B240A

12 3 D7, D8, D9 DIODE, SCHOTTKY, CMDSH-4E, SOD323 CENTRAL SEMI., CMDSH-4E

13 1 L1 IND., 4.7μH NIC, NPIM74C4R7MTRF

14 1 L2 IND., 8.2μH NIC, NPIM74C8R2MTRF

15 1 L3 IND., 10μH NIC, NPIM74C100MTRF

16 1 Q1 XTOR, NPN, 50V LOW SATURATION, MLP322 ZETEX, ZXTCM322TA

17 5 R1, R2, R3, R15, R22 RES., CHIP, 100k, 1/16W, 1%, 0402 YAGEO, RC0402FR-07100KL

18 1 R4 RES., CHIP, 12.4k, 1/16W, 1%, 0402 VISHAY, CRCW040212K4FKEA

19 1 R5 RES., CHIP, 31.6k, 1/16W, 1% 0402 VISHAY, CRCW040231K6FKEA

20 3 R6, R7, R11 RES., CHIP, 20k, 1/16W, 1% 0402 VISHAY, CRCW040220K0FKEA

21 3 R8, R9, R23 RES., CHIP, 10k, 1/16W, 1% 0402 YAGEO, RC0402FR-0710KL

22 1 R10 RES., CHIP, 53.6k, 1/16W, 1% 0402 VISHAY, CRCW040253K6FKEA

23 1 R12 RES., CHIP, 10.2k, 1/16W, 1% 0402 NIC, NRC04F1022TRF

24 1 R13 RES., CHIP, 1.07k, 1/16W, 1% 0402 YAGEO, RC0402FR-071K07L

25 1 R14 RES., CHIP, 49.9k, 1/16W, 1% 0402 VISHAY, CRCW040249K9FKEA

26 1 R16 RES., CHIP, 499, 1/16W, 1% 0402 AAC, CR05-4990FM

27 1 R17 RES., CHIP, 18.2k, 1/16W, 1% 0402 VISHAY, CRCW040218K2FKEA

28 1 R18 RES., CHIP, 3.32k, 1/16W, 1% 0402 VISHAY, CRCW04023K32FKEA

29 1 R19 RES., CHIP, 107k, 1/16W, 1% 0402 AAC, CR05-1073FM

30 1 U1 I.C., LT3507EUHF, QFN38UHF LINEAR TECH., LT3507EUHF

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DEMO MANUAL DC1781A

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Additional Demo Board Circuit Components

1 1 CIN4 CAP., ELECTROLYTIC, 22μF, 50V SANYO, 50CE22LX

2 0 C14, C16, C18, C28 CAP., 0402 OPT

3 0 C21 CAP., X7R, 0.01μF, 50V, 10%, 0603 OPT

4 0 C22 CAP., X7R, 2.2μF, 50V, 10%, 1210 OPT

5 0 C23 CAP., ELECTROLYTIC, 22μF 50V OPT

6 4 C24-C27 CAP., X5R, 1μF, 10V, 10%, 0603 MURATA, GRM188R61A105K

7 0 C29 CAP., 1206 OPT

8 0 D1, D2, D3 DIODE, SCHOTTKY, CMDSH-4E, SOD323 OPT

9 0 FB1 BEAD, 1206 OPT TAIYO YUDEN, FB MJ3216HS800

10 0 L4 IND., 22μH, OPT VISHAY, IHLP4040DZER220-M01

11 0 R20 RES., CHIP, 0402 OPT

12 0 R21 RES., CHIP, 0603 OPT

Hardware-For Demo Board Only:

1 10 E1, E2, E6-E9, E12-E15 TP, TURRET, 0.094" MILL-MAX, 2501-2-00-80-00-00-07-0

2 9 E3, E4, E5, E10, E11, E16-E19 TP, TURRET, 0.064" MILL-MAX, 2308-2-00-44

PARTS LIST

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DEMO MANUAL DC1781A

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 representa-

tion that the interconnection of its circuits as described herein will not infringe on existing patent rights.

SCHEMATIC DIAGRAM

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DEMO MANUAL DC1781A

LinearTechnology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ●FAX: (408) 434-0507 ●www.linear.com

LT 0711 • PRINTED IN USA

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 applica-

tion engineer.

Mailing Address:

Linear Technology

1630 McCarthy Blvd.

Milpitas, CA 95035

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