DEMO MANUAL DC1668B-C
LTM4627EV
High Efficiency PolyPhase
Step-Down Power Supply
Description
Demonstration circuit 1668B-C is a PolyPhase
®
power sup-
ply featuring four
LTM
®
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
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
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
PARAMETER
Maximum Input Voltage
Minimum Input Voltage
Output Voltage V
OUT
Maximum Continuous Output Current I
OUT(MAX)
Default Operating Frequency
External Clock Synchronous Frequency Range
Output Voltage Ripple (Typical)
Efficiency
Load Transient
Specifications are at T
A
= 25°C
VALUE
20V
4.5V
CONDITIONS/NOTES
Remove V
OUT
SEL Jumper for V
OUT
= 0.6V
DC
Current Derating May Be Necessary for Certain V
IN
,
V
OUT
, Frequency and Thermal Conditions
0.6V
DC
, 1V
DC
, 1.2V
DC
, 1.5V
DC
,
1.8V
DC
, 2.5V
DC
, 3.3V
DC
50A
DC
500kHz
250kHz to 770kHz
V
IN
= 12V, V
OUT
= 1.8V, 500kHz (20MHz BW)
V
IN
= 12V, V
OUT
= 1.8V, 500kHz
V
IN
= 12V, V
OUT
= 1.8V
< 10mV
P-P
at I
OUT
= 50A, See Figure 6
87.7% at I
OUT
= 50A, See Figure 3
See Figure 5
BoarD photo
DC1668bc F01
Figure 1. LTM4627/DC1668B-C Demo Board
dc1668bcf
1
DEMO MANUAL DC1688B-C
Quick start proceDure
Demonstration circuit 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 V
OUT
BNC cable as shown in Figure 2.
Preset the load to 0A and V
IN
supply to be 0V. Place
jumpers in the following positions for a typical 1.8V
OUT
application:
JP2
V
OUT
Select
1.8V
JP7
RUN
OFF
JP6
TRACK/SS
SOFT-START
4. Vary the input voltage from 5V to 20V and adjust the load
current from 0A to 50A. V
OUT
should remain regulated
at 1.8V±2%. Observe the 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 V
OUT
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).
2. Turn on the power at the input. Increase V
IN
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).
dc1668bcf
2
DEMO MANUAL DC1668B-C
Quick start proceDure
DC1668bc F02
Figure 2. Test Setup of DC1668B (All Versions)
dc1668bcf
3
DEMO MANUAL DC1688B-C
Quick start proceDure
95
90
EFFICIENCY (%)
85
80
75
70
3.3V
OUT
2.5V
OUT
1.8V
OUT
1.5V
OUT
1.2V
OUT
1V
OUT
0
10
20
30
LOAD CURRENT (A)
40
50
DC1668bc F04
DC1668bc F03
Figure 3. Measured Efficiency at 12V
IN
, 500kHz
Figure 4. Thermal Capture at 12V
IN
, 1.8V
OUT
, 50A,
500kHz No Forced Airflow (Convection). T
A
= 29°C.
V
OUT
(100mV/DIV)
V
OUT
(20mV/DIV)
I
OUT
STEP (20A/DIV)
DC1668bc F05
DC1668bc F06
V
OUT
= 1.8V
I
OUT
DC = 25A
I
OUT
STEP = 25A
f
SW
= 500kHz
V
OUT
= 1.8V
I
OUT
= 50A
f
SW
= 500kHz
Figure 5. Measured Load Step Response
Figure 6. Measured Output Voltage Ripple (20MHz BW)
dc1668bcf
4
DEMO MANUAL DC1668B-C
parts List
ITEM
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
1
2
3
4
5
6
7
8
9
10
11
12
13
QTY
1
2
2
2
2
2
4
1
1
1
1
4
1
2
1
1
1
1
1
1
1
1
4
2
1
1
1
1
1
1
2
3
0
0
0
0
REFERENCE
CIN1
CIN13, CIN18, CIN20,
CIN22
COUT1, COUT5, COUT9,
COUT13
R8
R18, R19
R30, R31, R32, R33
R34
R35
U5
C12
C52, C53, C54, C61
C61
C65, C67
R1
R2
R3
R4
R12
R14
R27
R29
U1, U2, U3, U4
C14, C38
C16
C60
D1
R7
Q14
R10
R20
R11, R16, R17
CIN2, CIN3
CIN14, CIN19, CIN21,
CIN23
COUT2, COUT3, COUT6
COUT4, COUT7, COUT11,
COUT15
PART DESCRIPTION
CAP, 150µF 20% 35V ALUM
CAP, 1210 22µF 20% 25V X5R
CAP, 1812 100µF 20% 6.3V X5R
MANUFACTURER/PART NUMBER
SANYO 35MV150WXV
AVX 12103D226MAT2A
TDK C4532X5R0J107MZ
SANYO POSCAP 4TPF470ML
VISHAY CRCW06030000Z0EA
AAC CR16-100JM
KOA RK73B1JTTD101J
VISHAY CRCW0603100KJNEA
VISHAY CRCW08050000Z0EA
LINEAR TECHNOLOGY LTC6902CMS
AVX 06035A101KAT2A
AVX 06035A181JAT
AVX 06035A181JAT
AVX 06035A102KAT2A
VISHAY CRCW06037K50FKEA
VISHAY CRCW060310K0FKEA
VISHAY CRCW06034K75FKED
VISHAY CRCW0603K32FKEA
VISHAY CRCW060322K6FKEA
VISHAY CRCW060315K0FKEA
VISHAY CRCW06030000Z0EA
VISHAY CRCW0603100KFKEA
LINEAR TECHNOLOGY LTM4627EV
TAIYO YUDEN EMK107BJ104MA-T
TAIYO YUDEN LMK107BJ105MA-T
AVX 06035A102KAT2A
DIODES INC. MMBZ5227B
AAC CR10-202JM
SILICONIX SUD50N03-10CP
AAC CR16-103JM
VISHAY CRCW06030000Z0EA
PANASONIC ERJM1WSF15MU
TAIYO YUDEN GMK316BJ106ML-T OPTION
AVX 12103D226MAT2A OPTION
TDK C4532X5R0J107MZ OPTION
TAIYO YUDEN JMK432BJ107MU-T OPTION
Required Circuit Components
COUT20, COUT21, COUT25 CAP, 470µF 20% 4V POSCAP
RES, 0603 0Ω JUMPER
RES, 0603 10Ω 5% 1/10W
RES, 0603 100Ω 5% 1/10W
RES, 0603 100k 5% 1/10W
RES, 0805 0Ω JUMPER
IC, LTC6902CMS
CAP, 0603 100pF 10% 50V NP0
CAP, 0603 180pF 5% 50V NP0
CAP, 0603 180pF 5% 50V NP0
CAP, 0603 1000pF 10% 50V NP0
RES, 0603 7.5k 1% 1/10W
RES, 0603 10k 1% 1/10W
RES, 0603 4.75k 1% 1/10W
RES, 0603 3.32k 1% 1/10W
RES, 0603 22.6k 1% 1/10W
RES, 0603 15k 1% 1/10W
RES, 0603 0Ω JUMPER
RES, 0603 100k 1% 1/10W
IC, MICRO MODULE
CAP, 0603 0.1µF 20% 16V X7R
CAP, 0603 1µF 20% 10V X5R
CAP, 0603 1000pF 10% 50V NP0
DIODE, ZENER 350mW
RES, 0805 2k 5% 1/10W
XSTR,SUD50N03-10CP MOSFET
RES, 0603 10k 5% 1/10W
RES, 0603 0Ω JUMPER
RES, 2512 0.015Ω 1% 1W
CAP, 1206 10µF 20% 35V X5R OPTION
CAP, 1210 22µF 20% 25V X5R OPTION
CAP, 1812 100µF 20% 6.3V X5R OPTION
CAP, 1812 OPTION
Additional Demo Board Circuit Components
dc1668bcf
5
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