LTM4627EV
1
DESCRIPTION
Demonstrationcircuit1669featurestheLTM
®
4627EV
µModuleregulator,ahigh‐performancehighefficiency
step‐downregulator.TheLTM4627EVhasanoperating
inputvoltagerangeof4.5Vto20Vandisabletoprovide
anoutputcurrentofupto15A.Theoutputvoltageis
programmablefrom0.6Vto5Vandcanberemotely
sensedwiththeinternaloptionaldifferentialremote
sensingamplifier.TheLTM4627EVisacompleteDC‐DC
pointofloadregulatorinathermallyenhanced15mmx
15mmx4.32mmLGApackagerequiringonlyafewin‐
putandoutputcapacitors.Thisregulatorisinternally
compensatedandemploysconstantfrequencycurrent
modearchitecture,enablingafasttransientresponse
andstablecontrolloopoverawiderangeofoutputca‐
pacitance.Itsupportsfrequencysynchronizationand
BurstMode
®
operationforincreasedlightloadefficien‐
cy.Outputvoltagetrackingisalsoavailablethroughthe
TRACK/SSpinforsupplyrailsequencing.TheLTM4627
datasheetmustbereadinconjunctionwiththisdemo
manualforworkingonormodifyingdemocircuit1669.
Designfilesforthiscircuitboardareavailableat
http://www.linear.com/demo
Table 1.
PerformanceSummary
PARAMETERCONDITIONS/NOTES VALUE
InputVoltageRange 4.5V‐20V
OutputVoltageV
OUT
j
umperselectable 1.0V
DC
,1.2V
DC
,1.5V
DC
,2.5V
DC
,
1.8V
DC
,3.3V
DC
MaximumContinuousOutputCurrentDe‐ratingisnecessaryforcertainoperating
conditions.Seedatasheetfordetails
15A
DC
DefaultOperatingFrequency 500kHz
ExternalClockSync.frequencyrange 250kHz–770kHz
EfficiencyV
IN
=12V,V
OUT
=1.8V,I
OUT
=15A 86.6%SeeFigure2
DEMO BOARD PHOTO
DEMOCIRCUIT166
9
DEMOMANUA
L
LTM4627E
V
15AStep‐DownµModuleRegulato
r
LTM4627EV
2
QUICK START PROCEDURE
Demonstration circuit 1669 is easy to set up to
evaluate the performance o f the LTM4627EV.
Please refer to Figure 1 for test setup connections
and follow the proced ure below.
1. With power off, place the jumpers in the follow-
ing positions for a typical 1.8V
out
application:
JP1
JP2 JP3
JP4
TRACK/SS RUN MODE V
OUT
Select
SOFTSTART ON CCM 1.8V
2. Before connecting input supply, load and me -
ters, pre-set the inp ut voltage supply to be l ess
than 20V. Pre- se t the load current to 0A.
3. With power off, connect the load, input voltage
supply and meters as shown in Figure 1.
4. Turn on input power supply. The output voltage
meter should display th e selected ou tp u t volt-
age ± 2%.
5. Once the proper outp ut vo ltage is established,
adjust the load current within the 0-15A range
and observe the load regulation, efficiency,
and other parameters. Output voltage ripple
should be measured at J4 with a BNC cable
and oscilloscope.
6. To observe increased light load efficiency
place the Mode pin jumper (JP3) in the Burst
Mode position. To observe increased light load
efficiency with a reduced outpu t ripple a s co m-
pared to Burst Mode
®
place the Mode pin
jumper in the Pulse skip position.
7. For optional load transient testing apply an ad-
justable positive pulse signal between IOSTEP
CLK and GND pins. The pulse amplitude sets
the load step current amplitude. The pulse
width should be short (< 1us) and pulse duty
cycle s hould be low (< 15%) to limit the ther-
mal stress on the load transient circuit. The
load step current can be monitored with a BNC
connected to J3 (15mV/A).
Note:
To set the output voltage to 5V turn off the in-
put supply power, apply the following changes
listed below.
R7 R6 R12 JP4
Remove 0 ohm 8.25k (1%) 1V
LTM4627EV
3
Figure1.TestSetupofDC1669
V
IN
Load
0‐15A
+
‐
+
‐
+
‐
+
‐
+
‐
+
‐
AA
V
V
LTM4627EV
4
V
in
(V)V
out
(V)C
out
BulkC
out
CeramicOther
121.8330uF/6.3V
POSCAP
2x100uF6.3VC10=47pF
C19=330pF
V
in
(V) V
out
(V) I
out
(A) AirflowAmbient(ºC)
12 1.8 15 NaturalConvection 27
Figure2.MeasuredSupplyEfficiencyat12Vin&18Vin
Figure3.Measuredloadtransientresponse(7.5A‐15Aloadstep)Figure4.Measuredthermalcapture
V
OUT
:100mV/div
I
OUTSTEP
:3.33Adiv
LTM4627EV
5
