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dc1668baf
DEMO MANUAL DC1668B-A
Description
LTM4627EV
High Efficiency PolyPhase
Step-Down Power Supply
Demonstration circuit 1668B-A is a PolyPhase
®
power sup-
ply featuring two
LTM
®
4627
high efficiency synchronous
buck µModule
®
regulators. The DC1668B-A 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 30A 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-A 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-A 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 V
OUT
Remove V
OUT
SEL Jumper for V
OUT
= 0.6V
DC
0.6V
DC
, 1V
DC
, 1.2V
DC
, 1.5V
DC
1.8V
DC
,
2.5V
DC
, 3.3V
DC
Maximum Continuous Output Current I
OUT(MAX)
Current Derating May Be Necessary for Certain V
IN
, V
OUT
,
Frequency and Thermal Conditions
30A
DC
Default Operating Frequency
500kHz
External Clock Synchronous Frequency Range
250kHz to 770kHz
Output Voltage Ripple (Typical)
V
IN
= 12V, V
OUT
= 1.8V, 500kHz (20MHz BW)
< 30mV
P-P
at I
OUT
= 30A,
See Figure 6
Efficiency
V
IN
= 12V, V
OUT
= 1.8V, 500kHz
86.6% at I
OUT
= 30A, See Figure 3
Load Transient
V
IN
= 12V, V
OUT
= 1.8V
See Figure 5
Specifications are at T
A
= 25°C
Figure 1. LTM4627/DC1668B-A Demo Board
DC1668ba F01
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