Linear Technology DC1839A Quick setup guide

dc1839af

DEMO MANUAL DC1839A

DESCRIPTION

LTC3634

15V Dual 3A Monolithic

Step-Down Regulator Board

for DDR Power

Demonstration circuit 1839A is a dual output regulator

focused specifically for DDR memory power applications.

It’s builtbasedonthe LTC3634,a highvoltage dualchannel,

controlled on-time monolithic synchronousbuck regulator.

TheDC1839A hasan inputvoltage rangeof 3.6Vto 15V.The

output voltage of the first channel, VDDQ, of the DC1839A

has three fixed voltage settings; 1.5V, 1.8V, and 2.5V, and

is capable of delivering up to 3A of output current. The

second channel, VTT, is set to regulate to half the voltage

on the VDDQIN pin, which can be either the channel1

output or an external reference voltage. It can source or

sink a maximum of 3A. The LTC3634 also provides a 10mA

buffered output of half VDDQIN – VTTR, which is used to

providethe reference voltage needed for DDR applications.

With the use of a timing resistor, the DC1839A can have its

operating frequency programmed from 500kHz to 4MHz,

or the DC1839A can be easily synchronized to an external

clock, due to an internal phase-locked loop. The DC1839A

VDDQ outputcan operatein eitherBurst Mode

operation or

L, LT, LTC, LTM, μModule, 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.

PERFORMANCE SUMMARY

forced continuous mode. In Burst Mode operation, which

is the preferred mode of low load current operation, the DC

supply current is typically only 1.3mA (both channels) at

no load (sleep mode), and less than 15μA in shutdown. In

Burst Mode operation or continuous mode operation, the

DC1839A is a very efficient circuit at high load currents:

over 80% for either channel. The LTC3634 is also capable

of in-phase or 180° out-of-phase operation, and to allow

its output to track an external voltage, either coincidentally

or ratiometrically. The LTC3634 comes in a 28-pin QFN or

leaded package, which each having an exposed pad on

the bottom side of the IC for better thermal performance.

All of these features make the DC1839A an ideal circuit

for powering DDR memory applications.

Design files for this circuit board are available at

http://www.linear.com/demo

(TA= 25°C)

PARAMETER CONDITIONS VALUE

Minimum Input Voltage 3.6V

Maximum Input Voltage 15V

Output Voltage VOUT1 – VDDQ VIN = 3.6V to 15V, IOUT1 = 0A to 3A 1.5V ±2% (1.47V to 1.53V)

1.8V ±2% (1.764V to 1.836V)

2.5V ±2% (2.45V to 2.55V)

Typical Output Ripple VDDQ VIN = 12V, IOUT1 = 3A (20MHz BW) < 20mVP-P

Output Voltage VOUT2 – VTT VIN = 3.6V to 15V, IOUT2 = 0A to ±3A VOUT1 = 1.5V 0.75V ±3% (0.7275V to 0.7725V)

VOUT1 = 1.8V 0.9V ±3% (0.873V to 0.927V)

VOUT1 = 2.5V 1.25V ±3% (1.2125V to 1.2875V)

Typical Output Ripple VTT VIN = 12V, IOUT2 = ±3A (20MHz BW) < 20mVP-P

Nominal Switching Frequencies RT = 324k 1MHz

Burst Mode-to-CCM transition Channel 1: VIN = 12V, VOUT1 = 1.8V, fSW = 1 MHz IOUT1 = 1.6A

INTVCC 3.3V

VTTR VDDQIN = 2.5V 1.25V

dc1839af

DEMO MANUAL DC1839A

QUICK START PROCEDURE

The DC1839A is easy to set up to evaluate the performance

of the LTC3634. For a proper measurement equipment

configuration, set up the circuit according to the diagram

in Figure 1.

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 the proper scope probe

technique in Figure 2.

Please follow the procedure outlined below for proper

operation.

1. Connect the input power supply to the VIN and GND

terminals. Connect the loads between the VOUT and GND

terminals. Refer to Figure 1 for the proper measurement

equipment setup.

Before proceeding to operation, insert jumper shunts

XJP1 and XJP2 into the OFF positions of headers JP1

and JP2, shunt XJP3 into the forced continuous mode

(FCM) position of MODE header JP3, shunt XJP4 into

the 180° (out-of-phase) position of PHASE header JP4,

shunt XJP5 into the soft-start positions of TRACK/SS

header JP5, and shunt XJP6 into the VOUT1 voltage

options of choice of header JP6: 1.2V, 1.5V, or 1.8V.

2. Apply 5V at VIN. Measure both VOUTs; they should read

0V. If desired, one can measure the shutdown supply

current at this point. The supply current should be less

than 30μA in shutdown.

3. Turn on VOUT1, VDDQ, and VOUT2, VTT, by shifting shunts

XJP1 and XJP2 from the OFF positions to the ON posi-

tions. Both output voltages should be within a tolerance

of ±1%.

4. Vary the input voltage from 3.6V to 15V, the channel 1

load current from 0 to 3A, and the channel 2 load cur-

rent from 0 to ±3A (The VTT channel sinks as well as

sources current. An easy way to test this capability is

shown in the test set-up diagram; connect a variable

resistor from VIN to VOUT, along with an ampmeter. The

current will be VIN minus VOUT divided by the variable

resistor value). VDDQ output voltage tolerance should

be within ±2%, whereas the output voltage tolerance

of VTT should be within ±3%.

5. Set the load current of both outputs to 3A and the input

voltage to 12V, then measure each output ripple voltage

(refer to Figure 2 for proper measurement technique);

they should each measure less than 20mVAC. Also,

observe the voltage waveform at either switch node

(pins 16 and 17 for channel 1, and 23 and 24 for chan-

nel 2) of each regulator. (Both switch node waveforms

should be rectangular in shape and 180°out-of-phase

with each other). The switching frequencies should be

between 800kHz and 1.2MHz (T = 1.25μs and 0.833μs).

6. Withthe board under proper operation, observethe load

regulation, efficiency, in-phase operation (by changing

jumper XJP4 to the 90° position), or BurstMode op-

eration (by changing jumper XJP3 to the Burst Mode

position).

7. (Optional) Moving the zero ohm resistor at RVDDQ,

inserting it into RDDQIN, and applying a voltage to turret

VDDQIN allows channel2 output voltage (VTTR) to be

adjusted to any desired voltage (to one-half the voltage

at VDDQIN).

When finished, insert shunts XJP1 and XJP2 to the OFF

position(s) and disconnect the power.

Warning: If the power for the demo board is carried in

long leads, the input voltage at the part could ring, which

could affect the operation of the circuit or even exceed

the maximum voltage rating of the IC. To eliminate the

ringing, a small Poscap capacitor (for instance, AVX part

number TPSY226M035R0200) is inserted on the pads

between the input power and return terminals on the bot-

tom of the demo board. The (greater) ESR of the Poscap

will dampen the (possible) ringing voltage due to the use

of long input leads. On a normal, typical PCB, with short

traces, this capacitor is not needed.

dc1839af

DEMO MANUAL DC1839A

VARIABLE

RESISTOR

QUICK START PROCEDURE

Figure 1. Proper Measurement Equipment Setup

dc1839af

DEMO MANUAL DC1839A

QUICK START PROCEDURE

Figure 3. LTC3634 DC1839A Efficiency

Figure 2. Measuring Input or Output Ripple

GND

VIN

LOAD CURRENT (A)

EFFICIENCY (%)

100

dc1839a F03

3.01.5 2.51.0 2.00.5

VIN = 12V

VDDQ = 2.5V

VTT = 1.25V

fSW = 1MHz

Burst Mode OPERATION

L1 = 1μH

L2 = 0.47μH

VISHAY 2020BZ

dc1839af

DEMO MANUAL DC1839A

QUICK START PROCEDURE

Figure 4. VDDQ Load Step Response Figure 5. VTT Load Step Response

Figure 6. LTC3634 DC1839A Start-Up with Soft-Start

VIN = 12V

VDDQ = 1.8V

3A LOAD STEP (0A TO 3A)

FORCED CONTINUOUS MODE

fSW = 1MHz

EXTERNAL COMPENSATION: RITH1 = 18.2k, CITH1 = 680pF

TRACE 3: OUTPUT VOLTAGE (50mV/DIV AC)

TRACE 4: OUTPUT CURRENT (1A/DIV)

dc1839a F04

VIN = 12V

VTT = 0.9V

±3A LOAD STEP (–3A TO 3A)

FORCED CONTINUOUS MODE

fSW = 1MHz

EXTERNAL COMPENSATION: RITH2 = 15k, CITH2 = 1000pF

TRACE 3: OUTPUT VOLTAGE (50mV/DIV AC)

TRACE 4: OUTPUT CURRENT (2A/DIV)

dc1839a F05

VIN = 12V

VDDQ = 1.8V

VTT = 0.9V

3A LOAD (EACH)

FORCED CONTINUOUS MODE

fSW = 1MHz

CSS = 4700pF

TRACE 1: VDDQ OUTPUT (500mV/DIV)

TRACE 2: VTT OUTPUT (500mV/DIV)

TRACE 3: VTTR OUTPUT (1V/DIV)

TRACE 4: VRUN VOLTAGE (2V/DIV)

dc1839a F06

dc1839af

DEMO MANUAL DC1839A

ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER

Required Circuit Components

1 2 CBST1, CBST2 CAP, 0603, 0.1μF, 10%, 50V, X7R NIC NMC0603X7R104K50TRPF

2 1 CFFW1 CAP, 0402, 10pF, 5%, 25V, NPO NIC NMC0402NPO100J25TRPF

3 2 CIN1, CIN2 CAP, 1210, 47μF, 20%, 16V, X5R TAIYO YUDEN EMK325BJ476MM-T

4 1 CITH1 CAP, 0402, 680pF, 10%, 25V, X7R AVX 04023C681KAT2A

5 1 CITH2 CAP, 0402, 1000pF, 10%, 25V, X7R AVX 04023C102KAT2A

6 5 COUT1-COUT4, COUT6 CAP, 1812, 100μF, 20%, 6.3V, X5R TDK C4532X5R0J107M

7 1 CTTR CAP, 0603, 10nF, 10%, 16V, X7R AVX 0603YC103KAT2A

8 1 CVCC CAP, 0603, 1μF, 10%, 16V, X5R NIC NMC0603X5R105K16TRPF

9 1 L1 IND, 1.0μH VISHAY IHLP2020BZER1R0M01

10 1 L2 IND, 0.47μH VISHAY IHLP2020BZERR47M01

11 1 RFB1 RES, 0402, 34.8kΩ, 1%, 1/16W NIC NRC04F3482TRF

12 1 RITH1 RES, 0402, 18.2kΩ, 1%, 1/16W VISHAY CRCW040218K2FKED

13 1 RITH2 RES, 0402, 15kΩ, 1%, 1/16W VISHAY CRCW040215K0FKED

14 1 RT RES, 0402, 324kΩ, 1%, 1/16W NIC NRC04F3243TRF

15 1 RVDDQ RES, 0402, 0Ω, JUMPER NIC NRC04Z0TRF

16 1 R3 RES, 0402, 11kΩ, 1%, 1/16W NIC NRC04F1102TRF

17 1 U1 IC, MONOLITHIC SYNCHRONOUS STEP-DOWN REGULATOR LINEAR TECH LTC3634EFE

Additional Demo Board Circuit Components

1 0 CC1, CC2 OPTION CAP, 0402, 10pF, 5%, 25V, NPO NIC NMC0402NPO100J25TRPF

2 0 CDDQIN OPTION CAP, 0805, 10μF, 10%, 6.3V, X5R OPTION NIC NMC0805X5R106K6.3TRPLP3KF

3 0 CIN3, CIN4 OPTION CAP, 1210, 47μF, 20%, 16V, X5R TAIYO YUDEN EMK325BJ476MM-T

4 2 CIN5, CIN6 CAP, TANT. 7343, 22μF, 20%, 35V AVX TPSY226M035R0200

5 0 COUT5, COUT8 OPTION CAP, 1812, 100μF, 20%, 6.3V, X5R TDK C4532X5R0J107M OPTION

6 2 COUT7, COUT9 CAP, 0805, 10μF, 10%, 6.3V, X5R NIC NMC0805X5R106K6.3TRPLP3KF

7 1 CTR1 CAP, 0402, 4700pF, 10%, 50V, X7R TDK C1005X7R1H472K

8 0 CTTR1 CAP, 0603, 10nF, 10%, 16V, X7R AVX 0603YC103KAT2A OPTION

9 1 CVCC1 CAP, 0603, 1μF, 10%, 16V, X5R NIC NMC0603X5R105K16TRPF

10 0 RD1, RTR2, RD2, R6, RFREQ,

RDDQIN OPTION

RES, 0402 OPTION

11 2 RPG1, RPG2 RES, 0402, 100kΩ, 5%, 1/16W NIC NRC04J104TRF

12 1 RTR1 RES, 0402, 0Ω, JUMPER NIC NRC04Z0TRF

13 2 R1, R2 RES, 0402, 1MΩ, 5%, 1/16W NIC NRC04J105TRF

14 1 R4 RES, 0402, 17.4kΩ, 1%, 1/16W NIC NRC04F1742TRF

15 1 R5 RES, 0402, 23.2kΩ, 1%, 1/16W NIC NRC04F2322TRF

16 1 R7 RES, 0402, 1kΩ, 1%, 1/16W NIC NRC04F1001TRF

Hardware/Components (For Demo Board Only)

1 17 E1-E17 TURRET MILL-MAX 2501-2-00-80-00-00-07-0

2 4 JP1, JP2, JP4, JP5 HEADER, 3-PIN, 2mm SAMTEC TMM-103-02-L-S

3 1 JP3 HEADER, 3-PIN, DBL ROW 2mm SAMTEC TMM 103-02-L-D

4 1 JP6 HEADER, 4-PIN, DBL ROW 2mm SAMTEC TMM 104-02-L-D

5 6 JP1-JP6 SHUNT, 2mm SAMTEC 2SN-BK-G

PARTS LIST

dc1839af

DEMO MANUAL DC1839A

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

C C

B B

A A

[1]

3.6V - 15V

10mA

NOTES: UNLESS OTHERWISE SPECIFIED

[1] CIN5 AND CIN6 ARE INSERTED ON THEDC1839A TO DAMPEN THE (POSSIBLE)

RINGING VOLTAGE DUE TO THE USE OF LONG INPUT LEADS. ON A NORMAL, TYPICAL

PCB, WITH SHORT TRACES, CIN5 AND CIN6 ARE NOT NEEDED.

2. ALL RESISTOR AND CAPACITOR CASE SIZE ARE0402.

IHLP-2020BZERR47M01

VISHAY

IHLP-2020BZER1R0M01

VISHAY

(FORCED

CONTINUOUS

MODE)

30603060

OPT

2.5V 1.8V 1.5V USER SELECT

VDDQSEL

0603 0603

[1] OPT

OPT

DUAL DDR MONOLITHIC

TOM G.

N/A

LTC3634EFE

DEMO CIRCUIT 1839A

SYNCHRONOUS STEP-DOWN REGULATOR

Thursday,June30,2011

SIZE

DATE:

.VER.ONCI

SHEET OF

TITLE:

APPROVALS

PCBDES.

APPENG.

TECHNOLOGY

Fax: (408)434-0507

Milpitas, CA 95035

Phone: (408)432-1900

1630 McCarthy Blvd.

LTC Confidential-For Customer Use Only

CUSTOMER NOTICE

LINEAR TECHNOLOGYHAS MADE ABEST EFFORTTO DESIGNA

CIRCUIT THAT MEETSCUSTOMER-SUPPLIED SPECIFICATIONS;

HOWEVER,IT REMAINSTHECUSTOMER'S RESPONSIBILITYTO

VERIFY PROPER AND RELIABLE OPERATION IN THE ACTUAL

APPLICATION. COMPONENT SUBSTITUTIONAND PRINTED

CIRCUIT BOARD LAYOUT MAY SIGNIFICANTLYAFFECTCIRCUIT

PERFORMANCE OR RELIABILITY. CONTACT LINEAR

TECHNOLOGYAPPLICATIONS ENGINEERINGFOR ASSISTANCE.

THIS CIRCUIT IS PROPRIETARY TO LINEARTECHNOLOGY AND

SCHEMATIC

SUPPLIEDFOR USE WITHLINEAR TECHNOLOGYPARTS.

SCALE = NONE

www.linear.com

TOM G.

PRODUCTION 11-80-601

REVISION HISTORY

ETADNOITPIRCSED APPROVEDECO REV

INTVCC

VIN VIN

VIN

INTVCC INTVCC

INTVCC

VIN

INTVCC

RD2

OPT

E16 GND

CIN6

22uF

35V

7343

JP2

OFF

RUN21

CIN1

47uF

16V

1210

E10

INTVCC

E17

VIN2

JP5

TRACKSS

TRACK 1

CBST2

0.1uF

OPT

CVCC1

1uF

324k

CFFW1

10pF

23.2k

RTR2

OPT

RVDDQ

E4 VDDQ

100uF

COUT8

6.3V

1812

RPG2

100K

CIN4

47uF

16V

1210

10uF

CDDQIN

OPT

0805

TRACK1 100uF

COUT2

6.3V

1812

11k

100uF

COUT3

6.3V

1812

CITH1

680pF

100uF

COUT4

6.3V

1812

E13 VTTR

E12

SYNC

PGOOD1

L1 1.0uH

VIN1

CIN2

47uF

16V

1210

CVCC

1uF

E11 VDDQIN

E8 PGOOD2

RDDQIN

OPT

RITH1

18.2k

10uF

COUT9

6.3V

0805

100uF

COUT1

6.3V

1812

RFREQ

OPT

CITH2

1000pF

L2 0.47uH

CIN5

22uF

35V

7343

RITH2

15k

E5 VTT

100uF

COUT5

6.3V

1812

JP4

180°

90°

PHASE1

CBST1

0.1uF

CTTR1

10nF

OPT

E14 GND

JP6

1 2

3 4

5 6

7 8

100uF

COUT6

6.3V

1812

10uF

COUT7

6.3V

0805

E7 GND

LTC3634EFE

PGOOD1

PHMODE

RUN1

MODE/SYNC

RUN2

SGND

VDDQIN

PGOOD2

VFB2

ITH2

VON2

SW2

VIN2

BOOST2

VTTR

INTVCC

BOOST1

VIN1

SW1

VON1

ITH1

TRACKSS1

VFB1

PGND

CC1

10pF

OPT

CTTR

10nF

RPG1

100K

E15

GND

JP1

OFF

RUN11

E3 GND

CC2

10pF

OPT

JP3

MODE

FCM

BURSTMODE

SYNC 1 2

3 4

5 6

17.4k

RFB1

34.8k

RTR1

GND

CIN3

47uF

16V

1210

CTR1

4700pF

RD1

OPT

dc1839af

DEMO MANUAL DC1839A

Linear Technology 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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