Linear Technology DC1668B-C Quick setup guide

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dc1668bcf
DEMO MANUAL DC1668B-C
DESCRIPTION
LTM4627EV
High Efficiency PolyPhase
Step-Down Power Supply
Demonstrationcircuit1668B-Cisa PolyPhase
®
power sup-
ply featuring four LT M
®
4627 high efficiency synchronous
buck µModule
®
regulators. The DC1668B-C input voltage
range is between 4.5V to 20V with a jumper programmable
output voltage from 0.6V to 3.3V. The demo circuit can
deliver up to 50A of load with excellent current-sharing.
Current derating may be necessary under certain operat-
ing conditions.
The LTM4627 can be synchronized to an external clock be-
tween 250kHz to 770kHz. The default switching frequency
for the DC1668B-C is set to 500kHz through the onboard L, LT, LTC, LTM, Linear Technology, PolyPhase, µModule and the Linear logo are registered
trademarks of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
PERFORMANCE SUMMARY
BOARD PHOTO
LTC6902 clock generator. The external clock interleaves
the paralleled phases to minimize input and output ripple.
DC1668B-C demonstrates that paralleling LTM4627 mod-
ules is easy and reliable. These features and the availability
of the LTM4627 in a compact thermally enhanced 15mm
×15mm × 4.32mm LGA package make the circuit ideal for
use in high density point of load regulation applications.
Design files for this circuit board are available at
http://www.linear.com/demo
PARAMETER CONDITIONS/NOTES VALUE
Maximum Input Voltage 20V
Minimum Input Voltage 4.5V
Output Voltage VOUT Remove VOUT SEL Jumper for VOUT = 0.6VDC 0.6VDC, 1VDC, 1.2VDC, 1.5VDC,
1.8VDC, 2.5VDC, 3.3VDC
Maximum Continuous Output Current IOUT(MAX) Current Derating May Be Necessary for Certain VIN,
VOUT, Frequency and Thermal Conditions
50ADC
Default Operating Frequency 500kHz
External Clock Synchronous Frequency Range 250kHz to 770kHz
Output Voltage Ripple (Typical) VIN = 12V, VOUT = 1.8V, 500kHz (20MHz BW) < 10mVP-P at IOUT = 50A, See Figure 6
Efficiency VIN = 12V, VOUT = 1.8V, 500kHz 87.7% at IOUT = 50A, See Figure 3
Load Transient VIN = 12V, VOUT = 1.8V See Figure 5
Specifications are at TA= 25°C
Figure 1. LTM4627/DC1668B-C Demo Board
DC1668bc F01

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DEMO MANUAL DC1688B-C
QUICK START PROCEDURE
Demonstrationcircuit 1668B-C is easy to set up to evaluate
the performance of paralleled LTM4627 modules. Please
refer to Figure 2 for proper measurement equipment setup
and follow the procedure below:
1. With power off, connect the input power supply, load,
meters, and VOUT BNC cable as shown in Figure 2.
Preset the load to 0A and VIN supply to be 0V. Place
jumpers in the following positions for a typical 1.8VOUT
application:
JP2 JP7 JP6
VOUT Select RUN TRACK/SS
1.8V OFF SOFT-START
2. Turn on the power at the input. Increase VIN to 12V
(Do not hot-plug the input supply or apply more than
the rated maximum voltage of 20V to the board or the
modules may be damaged).
3. Set the run pin jumper (JP7) to the ON position. The
output voltage should be regulated. The output voltage
meter should read 1.8V ±2% (1.76V to 1.84V).
4. Vary the input voltage from5Vto 20V and adjust the load
current from 0A to 50A. VOUT should remain regulated
at1.8V±2%. Observethe load regulation, output voltage
ripple, efficiency and other parameters. Output voltage
ripple should be measured at J6 with a BNC cable and
oscilloscope. The probe channel for VOUT should be set
at 50Ω termination resistance to match the BNC cable.
5. For optional load transient testing apply an adjustable
positive pulse signal between IOSTEP CLK and GND
pins. The pulse amplitude sets the load step current
amplitude. The pulse width should be short (< 1ms)
and pulse duty cycle should be low (< 15%) to limit the
thermal stress on the load transient circuit. The load
step current can be monitored with a BNC connected
to J5 (5mV/A).

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DEMO MANUAL DC1668B-C
QUICK START PROCEDURE
Figure 2. Test Setup of DC1668B (All Versions)
DC1668bc F02

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DEMO MANUAL DC1688B-C
QUICK START PROCEDURE
Figure 3. Measured Efficiency at 12VIN, 500kHz Figure 4. Thermal Capture at 12VIN, 1.8VOUT, 50A,
500kHz No Forced Airflow (Convection). TA= 29°C.
Figure 5. Measured Load Step Response Figure 6. Measured Output Voltage Ripple (20MHz BW)
LOAD CURRENT (A)
0
EFFICIENCY (%)
95
80
90
85
75
70
DC1668bc F03
30 504010 20
3.3VOUT
2.5VOUT
1.8VOUT
1.5VOUT
1.2VOUT
1VOUT
VOUT = 1.8V
IOUT DC = 25A
IOUT STEP = 25A
fSW = 500kHz
DC1668bc F05
VOUT
(100mV/DIV)
IOUT STEP (20A/DIV)
VOUT = 1.8V
IOUT = 50A
fSW = 500kHz
DC1668bc F06
VOUT (20mV/DIV)
DC1668bc F04

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DEMO MANUAL DC1668B-C
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 CIN1 CAP, 150µF 20% 35V ALUM SANYO 35MV150WXV
2 2 CIN13, CIN18, CIN20,
CIN22
CAP, 1210 22µF 20% 25V X5R AVX 12103D226MAT2A
3 2 COUT1, COUT5, COUT9,
COUT13
CAP, 1812 100µF 20% 6.3V X5R TDK C4532X5R0J107MZ
4 2 COUT20, COUT21, COUT25 CAP, 470µF 20% 4V POSCAP SANYO POSCAP 4TPF470ML
5 2 R8 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA
6 2 R18, R19 RES, 0603 10Ω 5% 1/10W AAC CR16-100JM
7 4 R30, R31, R32, R33 RES, 0603 100Ω 5% 1/10W KOA RK73B1JTTD101J
8 1 R34 RES, 0603 100k 5% 1/10W VISHAY CRCW0603100KJNEA
9 1 R35 RES, 0805 0Ω JUMPER VISHAY CRCW08050000Z0EA
10 1 U5 IC, LTC6902CMS LINEAR TECHNOLOGY LTC6902CMS
11 1 C12 CAP, 0603 100pF 10% 50V NP0 AVX 06035A101KAT2A
12 4 C52, C53, C54, C61 CAP, 0603 180pF 5% 50V NP0 AVX 06035A181JAT
13 1 C61 CAP, 0603 180pF 5% 50V NP0 AVX 06035A181JAT
14 2 C65, C67 CAP, 0603 1000pF 10% 50V NP0 AVX 06035A102KAT2A
15 1 R1 RES, 0603 7.5k 1% 1/10W VISHAY CRCW06037K50FKEA
16 1 R2 RES, 0603 10k 1% 1/10W VISHAY CRCW060310K0FKEA
17 1 R3 RES, 0603 4.75k 1% 1/10W VISHAY CRCW06034K75FKED
18 1 R4 RES, 0603 3.32k 1% 1/10W VISHAY CRCW0603K32FKEA
19 1 R12 RES, 0603 22.6k 1% 1/10W VISHAY CRCW060322K6FKEA
20 1 R14 RES, 0603 15k 1% 1/10W VISHAY CRCW060315K0FKEA
21 1 R27 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA
22 1 R29 RES, 0603 100k 1% 1/10W VISHAY CRCW0603100KFKEA
23 4 U1, U2, U3, U4 IC, MICRO MODULE LINEAR TECHNOLOGY LTM4627EV
Additional Demo Board Circuit Components
1 2 C14, C38 CAP, 0603 0.1µF 20% 16V X7R TAIYO YUDEN EMK107BJ104MA-T
2 1 C16 CAP, 0603 1µF 20% 10V X5R TAIYO YUDEN LMK107BJ105MA-T
3 1 C60 CAP, 0603 1000pF 10% 50V NP0 AVX 06035A102KAT2A
4 1 D1 DIODE, ZENER 350mW DIODES INC. MMBZ5227B
5 1 R7 RES, 0805 2k 5% 1/10W AAC CR10-202JM
6 1 Q14 XSTR,SUD50N03-10CP MOSFET SILICONIX SUD50N03-10CP
7 1 R10 RES, 0603 10k 5% 1/10W AAC CR16-103JM
8 2 R20 RES, 0603 0Ω JUMPER VISHAY CRCW06030000Z0EA
9 3 R11, R16, R17 RES, 2512 0.015Ω 1% 1W PANASONIC ERJM1WSF15MU
10 0 CIN2, CIN3 CAP, 1206 10µF 20% 35V X5R OPTION TAIYO YUDEN GMK316BJ106ML-T OPTION
11 0 CIN14, CIN19, CIN21,
CIN23
CAP, 1210 22µF 20% 25V X5R OPTION AVX 12103D226MAT2A OPTION
12 0 COUT2, COUT3, COUT6 CAP, 1812 100µF 20% 6.3V X5R OPTION TDK C4532X5R0J107MZ OPTION
13 0 COUT4, COUT7, COUT11,
COUT15
CAP, 1812 OPTION TAIYO YUDEN JMK432BJ107MU-T OPTION

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DEMO MANUAL DC1688B-C
PARTS LIST
ITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
14 0 COUT10, COUT14 CAP, 1812 100µF 20% 6.3V X5R OPTION TDK C4532X5R0J107MZ OPTION
15 0 COUT19 CAP, 1206 OPTION TAIYO YUDEN EMK316BJ475ML-T OPTION
16 0 COUT23, COUT26, COUT27 CAP, 470µF 20% 4V POSCAP OPTION SANYO POSCAP 4TPF470ML OPTION
17 0 COUT24 CAP, 1812 OPTION TAIYO YUDEN JMK316BJ226ML-T
18 0 C15 CAP, 0603 1µF 20% 10V X5R OPTION TAIYO YUDEN LMK107BJ105MA-T OPTION
19 0 C18, C55, C56, C57, C58,
C62, C74 TO C77
CAP, 0603 OPTION OPTION
20 0 C59, C63, C66, C68 CAP, 0805 OPTION OPTION
21 0 C64 CAP, 0603 1000pF 10% 50V NP0 OPTION AVX 06035A102KAT2A OPTION
22 0 C69, C71, C72, C73 CAP, 150µF 20% 35V ALUM OPTION SANYO 35MV150WXV OPTION
23 1 C70 CAP, 0603 0.22µF 20% 10V X5R OPTION TAIYO YUDEN LMK107BJ224MA-T OPTION
24 0 R9, R13, R15, R23, R24 RES, 0603 51k 5% 1/10W OPTION AAC CR16-513JM OPTION
25 0 R21, R22, R36 RES, 0603 OPTION OPTION
26 0 COUT22 CAP, 470µF 20% 4V POSCAP OPTION SANYO POSCAP 4TPF470ML OPTION
27 1 COUT25 CAP, 470µF 20% 4V POSCAP SANYO POSCAP 4TPF470ML
28 1 R26 RES, 0603 OPTION OPTION
Hardware
1 6 JP1, JP2, JP3, JP4, JP5,
JP8
HEADER, 2PIN, 2mm SAMTEC TMM 102-02-L-S
2 2 JP6, JP7 HEADER, 3PIN, 2mm SAMTEC TMM-103-02-L-S
3 4 J1, J2, J3, J4 STUD, PRESS-FIT PEM KFH-032-10
4 2 J5, J6 CONN, BNC, 5 PINS CONNEX 112404
510 TP1 TO TP8, TP13, TP14 TURRET MILL MAX 2501-2-00-80-00-00-07-0
6 3 JP1, JP6, JP7 SHUNT, 2mm SAMTEC 2SN-BK-G
7 4 STANDOFF, SNAP ON KEYSTONE_8834
8 8 J1, J2, J3, J4 NUT, BRASS #10-32 ANY
9 4 J1, J2, J3, J4 WASHER, BRASS #10 ANY
10 4 J1, J2, J3, J4 LUG, RING KEYSTONE 310 PbF

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DEMO MANUAL DC1668B-C
SCHEMATIC DIAGRAM

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DEMO MANUAL DC1688B-C
SCHEMATIC DIAGRAM

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DEMO MANUAL DC1668B-C
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