Linear Technology DC1480A Quick setup guide

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DEMO MANUAL DC1480A

DESCRIPTION

LTC3865EUH-1

Dual 5A Synchronous Buck

Converter with Pin Selectable Outputs

Demonstration circuit 1480A is a dual output synchronous

buck DC/DC converter featuring the LTC

3865EUH-1. The

input voltage range is from 4.5V to 14V. The outputs are

3.3V/5A and 1.8V/5A. Each output voltage can be precisely

programmed to a preset value within 1% error with the

VID pins. The demo board uses a high density, two sided

drop-in layout. The package of LTC3865EUH-1 is a small,

low thermal impedance 5mm × 5mm 32-Lead QFN.

The light load operation mode of the converter is de-

termined with the MODE/PLLIN pin. Use JP1 jumper to

select Burst Mode

operation, pulse-skipping mode or

L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks

of Linear Technology Corporation. All other trademarks are the property of their respective

owners.

PARAMETER CONDITION VALUE

Input Voltage Range 4.5V to 14V

Output Voltage, VOUT1 VIN = 4.5V to 14V, IOUT1 = 0A to 5A 3.3V ±1%

Output Voltage, VOUT2 VIN = 4.5V to 14V, IOUT2 = 0A to 5A 1.8V ±1%

Maximum Output Current, IOUT1 VIN = 4.5V to 14V, VOUT1 = 3.3V 5A

Maximum Output Current, IOUT2 VIN = 4.5V to 14V, VOUT2 = 1.8V 5A

Typical Full Load Efﬁciency, Channel 1 VIN = 12V, VOUT1 = 3.3V, IOUT1 = 5A 91.6%

Typical Full Load Efﬁciency, Channel 2 VIN = 12V, VOUT2 = 1.8V, IOUT2 = 5A 86.6%

Typical Switching Frequency 500kHz

PERFORMANCE SUMMARY

forced continuous mode operation. Switching frequency

is preset at about 500kHz. This frequency can be modi-

ﬁed by changing R5 value at the FREQ pin. The converter

can also be externally synchronized from 250kHz to

770kHz through MODE/PLLIN pin (SYNC terminal on the

board). To shut down a channel, force its RUN pin below

1.2V (Jumper: OFF). The power good output (PGOOD1

or PGOOG2 terminal) is low when that channel output

exceeds ±10% regulation window.

Design ﬁles for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C)

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DEMO MANUAL DC1480A

QUICK START PROCEDURE

Demonstration circuit 1480A is easy to set up to evaluate

the performance of the LTC3865EUH-1. Refer to Figure 1

for the proper measurement equipment setup and follow

the procedure below:

Jumper positions:

JP1 (MODE): PS

JP2, JP3 (RUN1/RUN2): ON

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

(4.5V to 14V) and GND (input return).

2. Connect the load #1 between VOUT1 and GND (Initial

load: no load); connect the load #2 between VOUT2 and

GND (Initial load: no load).

3. Connect the DVMs to the input and outputs.

4. Turn on the input power supply and check for the proper

output voltages. With current VID pin setting, VOUT1

should be 3.3V ±1%; VOUT2 should be 1.8V ±1%.

5. Once the proper output voltages are established,

adjust the loads within the operating range and observe

the output voltage regulation, ripple voltage and other

parameters.

6. If necessary, change the resistor options on VID pins

for other output voltages according to Table 1.

Note 1. When measuring the output or input voltage ripple, do not use the

long ground lead on the oscilloscope probe. See Figure 2 for the proper

scope probe technique. Short, stiff leads need to be soldered to the (+)

and (–) terminals of an output capacitor. The probe’s ground ring needs to

touch the (–) lead and the probe tip needs to touch the (+) lead.

Note 2. To accurately measure the output voltages and efﬁciency, measure

VOUT1 and VOUT2 on output capacitors COUT2 and COUT4 directly.

OUTPUT VOLTAGE PROGRAMMING

The output voltages of both channels can be programmed

to preset values. There are two VID pins for each channel:

VID11, VID12 for VOUT1, and VID21, VID22 for VOUT2. See

Table 1 for details.

Table 1. Output Voltage Programming

VID11/VID21 VID12/VID22 VOUT1/VOUT2 (V)

INTVCC INTVCC 5V (VIN ≥ 5V)

INTVCC FLOAT 3.3V

INTVCC GND 2.5V

FLOAT INTVCC 1.8V

FLOAT FLOAT 0.6 or External Divider

FLOAT GND 1.5V

GND INTVCC 1.2V

GND FLOAT 1V

GND GND 1.1V

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DEMO MANUAL DC1480A

Rail Tracking

Demonstration circuit 1480A is conﬁgured for independent

turn-on of VOUT1 and VOUT2. The ramp rate for VOUT1 is

determined by the TRK/SS1 cap at C6 and the ramp rate

for VOUT2 is determined by the TRK/SS2 capacitor at

C14. This board can be modiﬁed on the bench to allow

VOUT1 to track an external signal. It can also be modiﬁed

to allow VOUT2 to track VOUT1 or to allow VOUT2 to track

an external signal. Tables 2 and 3 cover the rail tracking

options for each rail.

Table 2. VOUT1 Tracking Options (3.3V)

TRACK1 DIVIDER TRK/SS1 CAPACITOR

CONFIGURATION R7 R9 C6

Soft-Start without Tracking (Original Board) 0Ω Not Stuffed 0.1µF

External Coincident Tracking 45.3kΩ 10kΩ Not Stuffed

Table 3. VOUT2 Tracking Options (1.8V)

TRACK2 DIVIDER TRK/SS2 CAPACITOR

CONFIGURATION R15 R14 R17 C14

Soft-Start without Tracking (Original Board) 0Ω Not Stuffed Not Stuffed 0.1µF

Coincident Tracking to VOUT1 (3.3V) 0Ω 20kΩ 10kΩ Not Stuffed

External Coincident Tracking 20kΩ Not Stuffed 10kΩ Not Stuffed

Figure 1. Proper Measurement Equipment Setup

QUICK START PROCEDURE

–

VIN

SUPPLY

IIN

IOUT1

IOUT2

VIN

VOUT1

LOAD

VOUT2

LOAD

VOUT2

VOUT1

–

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DEMO MANUAL DC1480A

Figure 2. Measuring Output Voltage Ripple

COUT

VOUT

+ –

GND 1480a F02

QUICK START PROCEDURE

Figure 3. Efﬁciency vs Load Current (VIN = 12V,

VOUT1 = 3.3V, 500kHz)

Figure 4. Efﬁciency vs Load Current (VIN = 12V,

VOUT2 = 1.8V, 500kHz)

LOAD CURRENT (A)

0.01

EFFICIENCY (%)

100

0.1 1 10

1480a F03

VIN = 12V

VOUT = 3.3V

ILOAD = 5A MAX

CCM

LOAD CURRENT (A)

0.01

EFFICIENCY (%)

100

0.1 1 10

1480a F04

VIN = 12V

VOUT = 1.8V

ILOAD = 5A MAX

CCM

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DEMO MANUAL DC1480A

PARTS LIST

ITEM QUANTITY REFERENCE-DESCRIPTION DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 1 CIN1 Cap, Alum 39µF 16V 20% OSCON-C6 OSCON 16SVP39M

2 2 CIN3, CIN2 Cap, X5R 10µF 16V 20% 1206 Taiyo Yuden EMK316BJ106ML

3 2 COUT1, COUT3 Cap, X5R 10µF 6.3V 10% 1206 Taiyo Yuden JMK316BJ106KL-T

4 2 COUT2, COUT4 Cap, POSCAP 220µF 4V 20% Sanyo 4TPE220MF

5 4 C1, C5, C10, C15 Cap, X7R 1000pF 50V 10% 0603 AVX 06035C102KAT1A

6 5 C3, C6, C7, C12, C14 Cap, X7R 0.1µF 25V 10% 0603 AVX 06033C104KAT2A

7 2 C4,C13 Cap, X5R 1µF 6.3V 10% 0603 Taiyo Yuden JMK107BJ105KA-T

8 1 C8 Cap, X5R 4.7µF 16V 20% 0805 Taiyo Yuden EMK212BJ475MG

9 1 C9 Cap, NPO 220pF 25V 10% 0603 AVX 06033A221KAT2A

10 1C11 Cap, X7R 470pF 50V 5% 0603 AVX 06035C471JAT1A

11 1C16 Cap, X5R 1µF 16V 20% 0805 Taiyo Yuden EMK212BJ105MG

12 2D1, D2 Schottky Diode, 30V CMDSH-3 Central Semi. CMDSH-3TR

13 2L1, L2 Inductor, 2.2µH IHLP-2525CZ-01 Vishay IHLP-2525CZERM01 2R2uH

14 2 Q2, Q1 Dual MOSFET N-Channel, 30V Siliconix Vishay Si4816BDY

15 2 RS1, RS2 Res, LRC 0.006 0.25W 5% 1206 IRC LRF1206-01-R006-J

16 3 R1, R33, R38 Res, Chip 10k 0.06W 5% 0603 Vishay CRCW060310K0JNEA

17 7 R2, R6, R7, R11, R15, R16, R21 Res, Chip 0Ω 1/16W 1A 0603 Vishay CRCW06030000Z0EA

18 4 R3, R4, R18, R20 Res, Chip 100 0.06W 5% 0603 Vishay CRCW0603100RJNEA

19 1R5 Res, Chip 162k 0.06W 1% 0603 Vishay CRCW0603162KFKEA

20 1R8 Res, Chip 2.2 0.06W 5% 0603 Vishay CRCW06032R20JNEA

21 1R10 Res, Chip 24.9k 0.06W 1% 0603 Vishay CRCW060324K9FKEA

22 1R13 Res, Chip 15k 0.06W 5% 0603 Vishay CRCW060315K0JNEA

23 2R19, R22 Res, Chip 100k 0.06W 5% 0603 Vishay CRCW0603100KJNEA

24 1U1 IC, Voltage Regulator QFN (32) (UH) 5mm × 5mm Linear Technology LTC3865EUH-1

Additional Circuit Components

1 2 CIN5,CIN4 Cap, 0805

2 1 C2 Cap, 0603

3 2 Q3, Q4 (SyncFet) N-Channel, Dual Fairchild FDS6982AS

4 20 R9, R12, R14, R17, R23, R24

R25, R26, R27, R28, R29, R30, R31

R32, R34, R35, R36, R37, R39, R40

Res, 0603

Hardware Demo Board Only

1 17 E1, E2, E3 ,E4, E5, E6, E7, E8, E9, E10 Turret, Testpoint 0.094” Mill Max 2501-2-00-80-00-00-07-0

2 E11, E12, E13, E14, E15, E16, E17

3 1 JP1 Headers, 4 Pins 2mm Ctrs. Samtec TMM-104-02-L-S

4 2 JP2, JP3 Headers, 3 Pins 2mm Ctrs. Samtec TMM-103-02-L-S

5 3 XJP1, XJP2, XJP3 Shunt, 2mm Ctrs. Samtec 2SN-BK-G

6 4 MH1 to MH4 Stand-Off, Nylon 0.25” Tall Keystone, 8831(Snap On)

7 1 FAB, 1480A_ Rev0 Demo Circuit 1480A

8 2 Stencil 1480A Stencil #1480A

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DEMO MANUAL DC1480A

SCHEMATIC DIAGRAM

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DEMO MANUAL DC1480A

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, noresponsibility 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.

SCHEMATIC DIAGRAM

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DEMO MANUAL DC1480A

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

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

 LINEAR TECHNOLOGY CORPORATION 2010

LT 1010 • 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 direc-

tive 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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